Red color – 30 min talks
Blue color – 15 minute talks
Green color - posters
STELLAR PHYSICS AND EVOLUTION
GALEX AND STAR FORMATION
Bianchi Luciana
Johns Hopkins University,USA
The Galaxy Evoution Explorer (GALEX) has provided far-UV and near-UV imaging
over a wide sky coverage. Catalogs of >100 million UV sources enable advances in a variety of
fields, from hot stellar objects in the Milky Way to QSOs and star-forming galaxies out to
redshift ~2, and provide a roadmap for future UV missions. A deep, comprehensive view of the
young stellar populations in hundreds of nearby galaxies, afforded by GALEX's wide-field UV
imaging, allows us to characterize their spatially-resolved and time-resolved recent star
formation. In addition, star formation was revealed in extreme low-density environments, where
it is elusive at other wavelengths. The results shed new light on the process of star formation in
different conditions, and its interplay with interstellar dust. UV measurements of more distant
galaxies probe their evolution and the Universe's star-formation history since redshift ~2.
THE CRITICAL ROLE OF UV AND EUV SPECTROSCOPY IN THE STUDY OF
WHITE DWARF EVOLUTION
Barstow Martin
University of Leicester, UK
This talk will review the important contributions that UV/EUV spectroscopic studies of
white dwarfs have made to the study of their composition and evolution. The results from past
missions such as IUE, ROSAT and EUVE will be discussed together with the more recent
contributions from HST and rocket-borne spectrographs. Finally, the capabilities of the
refurbished HST will be outlined before a discussion of the future needs for the study of white
dwarf spectra.
YOUNG STARS
Gomez de Castro Ana Ines1 and Lamzin Sergey2
1 - UCM, Spain
2 - SAI MSU, Russia
We consider problems of young stars physics that could be solved with WSO-UV. At
first we discuss in which way the character and parameters of accretion process can be found
from the analysis of C IV 1550, Si IV 1400 and N V 1240 line profiles in the case of classical T
Tauri stars. We also discuss where CIII 1908, Si III 1892 and molecular hydrogen lines are
originated in these objects. Then we consider in which way one can extract information about the
structure of inner regions of FUORs accretion disks from UV observation. A number of
observational tests are proposed to investigate the nature of activity of Ae/Be Herbig stars.
Finally we discuss the problem of interstellar extinction in star formation regions.
GASEOUS FLOW STRUCTURE IN CLOSE BINARY STARS
Bisikalo Dmitry
Institute of Astronomy RAS, Russia)
We discuss main features of the flow structure in close binaries (CBs). Three-dimensional
HD and MHD numerical simulations are used to study the flow pattern in a close binary system
after it has reached the steady-state accretion regime. It is shown that the main flow features in
non-magnetic CBs are the stationary accretion disk, circum-disk halo and a number of shock
waves: bow shock caused by the motion of the accretor and the disk in the gas of the circumbinary envelope; "hot line" formed due to the interaction between the circum-disk halo and
stream from the inner Lagrange point L1, and two arms of the tidal shock. When the magnetic
field of the accretor is taken into account, new structural elements appear: the magnetosphere
region becomes distinguishable, and the matter is accreted via funnel flows. Using HD and MHD
simulation results along with the Doppler tomography technique allowed us to identify the main
flow features in CBs and to confirm the validity of the flow structure model.
Special attention is paid to the observational manifestations of flow structure features in
the UV band.
NASA SWIFT UVOT OBSERVATIONS OF SUPERNOVAE: IDEAS FOR WSO
Peter Milne
University of Arizona, USA
We report on NUV observations of supernovae of all types as obtained by the UVOT
instrument on the NASA Swift mission. Over 80 SNe have been observed since March 2005,
with many campaigns being initiated very soon after the SN explosion. In particular, we find
relatively modest variations within the near-peak emission from normal SNe Ia. This finding is
important for large optical/NIR high-z SN surveys, as adding rest-frame NUV emission permits
either more color information or larger redshift coverage. Throughout the talk, we will
emphasize ideas as to how WSO might take this aspect of NUV astronomy to the next step.
UV SPECTROSCOPY OF THE EXCITING STAR OF THE PLANETARY NEBULA
NGC 246
Rauch T.,1 Werner K.,1 Kruk J. W.2
1 - University of Tuebingen, Germany
2 - Johns Hopkins University, U.S.A.
The central star of the planetary nebula NGC 246 is the brightest (V = 11.78 mag) and
one of the heavy-weights (about 0.9 solar masses) of the PG 1159 spectral class. These stars
(about 40 known) are strongly hydrogen-deficient, with a typical abundance pattern He:C:O =
33:50:17 by mass. About every other has a surrounding planetary nebula.
We present a spectral analysis of the central star of NGC 246 by means of state-of-the-art
NLTE model atmospheres based on UV spectra obtained with FUSE, HST/STIS, and IUE.
We summarize our present evolutionary picture of PG 1159 stars.
HST COS OBSERVATIONS OF THE HOT BARE STELLAR CORE H1504+65
Werner K., Rauch, T.
University of Tuebingen, Germany
We present UV spectroscopy of the unique white dwarf H1504+65 obtained with the
HST Cosmic Origins Spectrograph. The stellar atmosphere has a unique composition. Being H-
and He-deficient it is composed of C, O, Ne, and Mg. The evolutionary history is unclear.
H1504+65 could be a naked O/Ne/Mg white dwarf, i.e. the descendant of a super-AGB star. If
true, then this would be the first proof of the existence of such (single) white dwarfs.
PERIODIC VARIABILITY IN THE EMISSION SPECTRUM OF YOUNG STARS
N.Z.Ismailov1,2, F.N.Alimardanova1, O.V.Khalilov1, G.R.Baheddinova1
1 - Shamakha Astrophysical Observatory, Azerbaijan
2 - Baku State University, Azerbaijan
Results of long time spectral observations of classic T Tauri and Ae/Be Herbig type stars
were presented. For investigations we have used spectral material in the visual range which was
obtained in the 2 m telescope of ShAO NAS of Azerbaijan and in the ultraviolet range from
archive IUE spectrums. For the star T Tau we have discovered 33 day periodic variability in both
visual and UV range emission lines, which simultaneously shows synchronal periodicity in the
light polarization in the visual range.
For BP Tau we have obtained a periodicity 8.275±0.005 day for intensity of the UV
emission lines. But this period is unstable for different seasons of observations.
During some years on the CCD spectrograms we have studying of the Hα and Hβ
emission line profiles for AB Aur. It was showed that the absorption component in the short
wing of emissions Hα and Hβ are varied with characteristic time ~20 days for AB Aur. It was
showed that the UV spectrum of AB Aur have some short-time variability with characteristic
time a few hours. Moreover a variability of the structure of line profiles also we have derived.
The basic variability in the atmosphere of АВ Aur occurs in the bottom layers of an
environment, in nearby areas to the surface of the star where matter accretion velocity reaches up
to 300 km/s.
For the star HD 216629 we have obtained variations in intensities, line structures of Hα
and Hβ line emissions from night to night for characteristic time a few hours.
We concluded that the activity of the emission spectrum in young stars possible was
occurred active dynamical processes in the circumstellar discs, which may be promote for planet
formation processes.
ATMOSPHERIC PARAMETERS OF THE B-SUPERGIANT HD 198478 FROM THE UV
SPECTRA
Jurkic, Tomislav; Sarta Dekovic, Mariza; Dominis Prester, Dijana; Kotnik-Karuza, Dubravka
Department of Physics, University of Rijeka, Croatia
We determined atmospheric parameters of the Galactic early B-supergiant HD198478 (55
Cyg) from the UV silicon lines taken from the high-resolution 1150-1980 Å IUE spectra.
TLUSTY numerical code was used to model the stellar atmosphere and to determine the
temperature and surface gravity assuming a non-LTE plane parallel hydrostatic stellar
atmosphere with microturbulence. The synthesized spectra were broadened by the IUE
instrumental profile, rotational and macroturbulent velocity with ROTIN numerical code. The
silicon 1265 Å, 1309 Å, 1313 Å, 1417 Å, 1526 Å, 1782 Å and 1294-1303 Å multiplet lines of
different ionization levels (Si II and Si III) were modeled, leading to the temperature, surface
gravity, rotational and macroturbulent velocity values. Our results have shown that the line
broadening cannot be explained by rotational velocity only, but additional macroturbulent
velocity component should be taken into account. HD 198478 shows a significant degeneracy in
velocity, which means that the individual contributions of the macroturbulence and rotation in
the total velocity broadening cannot be distinguished. Adequate fit of TLUSTY models to the
observed non-resonant silicon lines suggests that the non-LTE plane-parallel hydrostatic stellar
model without wind contribution can be used to explain such lines. We have obtained similar
results using the HST STIS spectra in the same procedure, thus showing that the IUE spectra,
despite their lacking quality compared to the STIS spectra, are reliable enough in determination
of the B supergiants' photospheric parameters.
SINGLE-BINARY STAR SEPARATION BY ULTRAVIOLET COLOR-INDICES
DIAGRAMS
O.Yu.Malkov1, A.V.Mironov2, S.G.Sichevskij1
1 - Institute of Astronomy RAS, Russia
2 - SAI MSU, Russia
Color-indices diagrams are powerful tools for parameterization of stars. Also, detection
of a composite flux in photometry can serve as an indication of a photometrically unresolved
binarity and can contribute to the parameterization of the components of binary systems. A main
goal of the present study is to develop a method of automatic photometric detection of binaries,
based on multi-color photometry, theoretical stellar spectral energy distributions and general
understanding of binary evolution. In particular, we consider an ultraviolet photometry where, in
combination with optical and infrared photometry, interstellar reddening can be easier
distinguished from temperature reddening.
The following procedure is applied to achieve the declared goal. One can compose
possible pairs of components, based on evolution concept. This can be done for various stages of
binary evolution. Theoretical spectrophotometric spectral energy distributions and response
functions of ultraviolet photometric bands in appropriate sky surveys allows us to compute colorindices of such pairs, when they are unresolved, as well as of single stars. Usage of an interstellar
extinction law gives us theoretical color-indices of reddened objects, both single stars and
unresolved binaries. When plotted on a multidimensional color space, they allow us to indicate
areas, where unresolved binaries can be easily separated from single stars, and identify binaries
among objects, cross-matched in photometric surveys.
MINING THE GALEX SPECTROSCOPIC DATABASE
Emanuele Bertone
INAOE, Mexico
The GALEX General Data Release 4/5 includes 174 spectroscopic tiles, obtained from
slitless grism observations. We report the preliminary results of our analysis of the ultraviolet
spectral morphology of point-like GALEX sources, focusing our attention on the thousands of
stellar objects present in the data base. We have defined a suitable system of spectroscopic
indices, which measure the main mid-UV features at the GALEX low spectral resolution, and
employed it to determine the atmospheric parameters of the stars.
ULTRAVIOLET OBSERVATIONS OF SUPERNOVAE
Filomena Bufano
INAF-OAPd, Italy
The emission in the ultraviolet (UV) domain contains valuable information about
supernova (SN) explosions: it is highly sensitive to the metallicity of the SN ejecta; it gives
indications on the SN progenitors structure and on how they exploded; it reveals the environment
structure and thus the precursors pre-explosion activity, by mean of the ejecta-circumstellar
material interaction.
Moreover, considering that the forthcoming high-redshift SN surveys will be conducted
in the optical and IR ranges, which sample the UV rest-frame emission of the SN, the knowledge
of the UV spectral evolution of the local SNe is essential to properly exploit the surveys
outputs.Despite the wide interest, to date the sample of SN spectroscopically observed in the UV
is still small.
After a general overview on our current understanding of SN UV emission, we present
the entire Swift/UVOT archive of SN spectroscopic observations, obtained during its first two
years of observations (2005--2006). Important steps toward the characterization of SNe in the
Ultraviolet have been achieved, about both thermonuclear and core-collapse explosions.
We show also the very interesting case of SN 2005ay, the first target observed in the
framework of a wide observational program for the multiwavelength study of Core Collapse
SNe. We present SN 2005ay UV spectroscopy taken with GALEX, as well as the exceptional
amount of spectroscopic and photometric data obtained in the Optical-NIR range (107 Optical +
19 NIR photometric epochs and 20 optical spectra) with 11 different ground-based telescopes,
which makes SN 2005ay a SN with one of the best coverages ever. Finally, we show the
remarkable similarity we found among the UV properties of Type IIP SNe, which, if confirmed
by a future larger sample, would indicate the cosmological use of these objects as a promising
prospect.
THE MOST LUMINOUS B SUPERGIANTS
Negueruela Ignacio(Universidad de Alicante, Spain), Najarro Francisco (CAB-CSIC), Clark J.
Simon (Open University), Urbaneja Miguel (Institute for Astronomy, Hawaii)
We present high-quality spectra of the most luminous B-type hypergiants, Cyg OB2 and
HD~80077, and derive their stellar parameters by fitting them with tailored models developed
with the codes FASTWIND and CMFGEN. Both stars show little chemical evolution, in spite of
huge luminosities and very high initial masses ~100Mʘfor Cyg OB2). We also present data on
three very luminous ($MV~-9) B-type hypergiants in the starburst open cluster Westerlund~1,
which seem to follow the redwards branch of the cluster isochrone, again suggesting that they
are relatively unevolved stars. We summarise the evidence suggesting that very massive stars
may appear as relatively normal, but extremely luminous B supergiants close to the end of the
hydrogen core burning phase and discuss the prospects of UV spectroscopy for some of these
objects.
UV LINE PROFILES AS A PROBE FOR ATOMIC DIFFUSION THEORY IN
STELLAR ATMOSPHERES
Ryabchikova Tatiana1,, LeBlanc Francis2
1 - Institute of Astronomy RAS Moscow Russia
2 - Universite de Moncton, Moncton, Canada
In quiet stellar atmospheres that are stabilized, for example, by the presence of strong
magnetic fields, a non-uniform distribution of chemical elements (abundance stratification) is
predicted by the diffusion theory. Spectroscopic observations of magnetic Ap stars provide a
strong support for the diffusion theory. Stratification predictions in the upper atmosphere, in
particular, strongly depend on the magnetic field geometry. Optical lines used in stratification
analysis of Ap stars do not probe the upper atmospheric layers and, hence, cannot provide
reliable information on abundance gradients there. We show the expected effect of stratification
on the profiles of strong lines in the UV region and how these lines may be used for constraining
diffusion theory.
DETAILED CHEMICAL COMPOSITION OF STARS WITH LARGE PROPER
MOTIONS ON THE SPECTRA IN GROUND-BASED UV.
V.Klochkova, T.Mishenina, V.Panchuk, S.Korotin, V.Marsakov, N.Tavolganskaya, I.Usenko.
SAO RAS, Russia
Based on spectral data (R=60000) taken with the spectrograph NES of the 6-meter
telescope within the wavelength 3550-5100A, we determined parameters (effective temperature,
surface gravity, microturbulent velocity metallicity, and radial velocity) of the sample of 14
metal-deficient G-K stars with large proper motions. The use of echelle spectra allowed the
model atmosphere method to be applied both for the determination of abundances of 20 chemical
elements including heavy metals from Sr to Dy. Abundances of Mg, Al, Sr and Ba are calculated
within non-LTE approach. Taking into account chemical composition and kinematical
parameters of stars studied we determined their belonging to galactic populations. Chemical
composition of the star BD+80 245 distant from the galactic plane agrees with belonging to the
accreting halo: besides overdeficiency of $\alpha$-process elements the star has overdeficiency
of s-process element barium: [Ba/Fe]=-1.46. The ratio content of radioactive element Th to that
of the r-process element Eu as well as cosmochronological age are determined for selected stars.
ORIGIN AND EVOLUTION OF THE GOULD BELT, AND A FUTURE
ULTRAVIOLET VIEW
Paola Sestito, Ana Ines Gomez de Castro
UCM, Spain
The Gould Belt is a predominant feature of the local system, appearing as a partial ring of
stars tilted toward the galactic plane by about 16-20 degrees. This structure contains several Oand B-type stars, and may represent the local spiral arm to which the Sun belongs.
In this review we first present a historical overview of the Gould Belt, focusing on the
structural properties and origin, and revising the works carried out during the years. Then, we
present an on-going investigation of the regions of major interest in the Gould Belt using data
from the UV space mission GALEX: as a staring point we focus on the Taurus region, and in
particular on the characterization of T Tauri stars showing variability (flares).
The statistical investigation methods adopted are discussed.
WSO AND THE WINDS OF MASSIVE STARS
Miriam Garcia Garcia
Instituto de Astrofisica de Canarias, Spain
The spectrographs at the WSO will provide again access to wavelengths shorter than
1200A. Previous observatories operating in the 1150-2000A range(such as IUE and HST-STIS)
have proved extremely useful to study the outflows of OB type stars, which display wind profiles
in the UV. However, the lambda<1200 range is critical as it contains important diagnostic lines
for clumping and shocks in the wind, as found by FUSE-based analyses. We explore how the
WSO can contribute to study the winds of massive stars.
ISSIS AND THE PURSUIT OF LOCAL GROUP BLUE MASSIVE STARS:
Miriam Garcia Garcia
Instituto de Astrofisica de Canarias, Spain
The Local Group galaxies enable us to study the impact of metallicity on the structure
and evolution of massive stars through spectroscopic analyses. However, the initial color-based
target selection for spectroscopy, though relatively successful, usually produces lists dominated
by B-type modest-mass stars. We have developed a friends of friends code to find OB
associations in Local Group galaxies (Garcia et al. 2009). The interpretation of the association's
color-magnitude diagrams (CMDs) and the automatic determination of evolutionary masses for
the members, allow a more insightful choice of candidates for spectroscopy and to spot out
potential advanced evolutionary stages (Garcia et al. 2010).
Because of its large field of view and high spatial resolution at ultraviolet (UV)
wavelengths, ISSIS at the WSO is a potential discovery machine of resolved blue massive stars
in nearby galaxies. Our code can be easily modified to choose candidate OB stars based on ISSIS
magnitudes on the UV, where hot young massive stars are intrinsically brighter and their color
degeneracy is broken. The combination of our algorithm and ISSIS's panchromatic photometry
can readily produce a list of the most massive stars of the Local Group.
CRITERIA FOR THE SPECTRAL CLASSIFICATION OF NORMAL AND YOUNG B
STARS IN UV
Kurchakov A.V., Knyazeva L.N., Pavlova L.A
Observatory, Fesenkov Astrophysical Institute, Almaty, Kazakhstan
We have demonstrated how high-resolution UV ( data INES) spectra can provide to
estimates classification criteria normal B stars and Be Herbig stars with envelopes. Previous
UV classification schemes for normal B stars have tended to rely heavily on the strongest lines in
spectrum –Si IV(1400A), C IV (1550) and N V(1240) –which are known to be formed in stellar
wind. The Si II lines at 1264,1310, and 1533A were assumed to be photosphere, while the
lower excitation Si II lines at 1260 and 1526A were assumed to interstellar for types early than
B3.
We choose for classification normal stars lines- Si IV (1393.8, 1402.8), Si III (1309A),
C II (1336A), N IV (1488A) and S II (1261A), for stars with envelop in the 1200-1900 spectral
region we choose - Si IV (1393.8, 1402.8), Si III(1309A), C II (1336A), N IV (1488A), C IV
(1550), N IV (1720), N III (1750) and Al III (1860).
UV OBSERVATIONS OF sdB STARS
Savanov I.
Institute of Astronomy RAS, Russia
We review the basic properties of the hot subdwarf stars (which are core helium-burning stars at
the blue end of the horizontal branch) with special attention to the important contributions that
UV photometric and spectroscopic studies of these objects should make to the understanding of
their composition and evolution. Abundance determinations, parameters of atmosphers,
pulsations and the problem of the origin of the UV-upturn phenomenon should be discussed .
ENERGETIC HYDROGEN AND HYDROGEN CLOUD FORMATION AROUND HD
209458b
H. Lammer (1), M. Holmstrom (2) A. Ekenbaeck (2), P. Wurz (3), J.-M. Grießmeier (4),
F. Selsis (5, 6), M. L. Khodachenko (1)
(1) Space Research Institute, Austrian Academy of Sciences, Schmiedlstr. 6, A-8042 Graz,
Austria
(2) Swedish Institute of Space Physics, P.O. Box 812, SE-98128 Kiruna, Sweden, (3)
Physikalisches Institut, University of Bern, Sidlerstr. 5, CH-3012 Bern, Switzerland
(4) Netherlands Institute for Radio Astronomy, Oude Hoogeveensedijk 4, NL-7991 PD
Dwingeloo, The Netherlands
(5) Université de Bordeaux, Observatoire Aquitain des Sciences de l'Univers, 2 rue de l’
Observatoiré, BP 89, F-33271 Floirac Cedex, France
(6) CNRS, UMR 5804, Laboratoire d’ Astrophysique de Bordeaux, 2 rue de l`
Observatoire, BP 89, F-33271 Floirac Cedex, France
HST observations of the exoplanet HD209458b have shown a broad absorption signature
about the Ly-alpha; stellar line during transit, suggesting the presence of a thick neutral hydrogen
cloud around the exoplanet. We present an improved flow model of HD 209458b and use stellar
wind values similar to those in our solar system. We find that the Energetic Neutral Atom (ENA)
production is high enough to explain the observations, and we show that using expected values
for the stellar wind and exosphere, the spatial and velocity distributions of ENAs would give
absorption in good agreement with the observations. We also study how the production of ENAs
depends on the exospheric parameters and establish an upper limit for the obstacle standoff
distance at approximately 4 - 10 planetary radii. Finally, we compare the results obtained for the
obstacle standoff distance with existing exomagnetospheric models and show how the magnetic
moment of HD 209458b can be estimated from ENA observations.
UV VIEW OF HMXRBS: ACTUAL STATE AND PRESPECTIVES FOR WSO-UV
Blay, P.
IPL - University of Valencia, Spain
High Mass X-Ray Binary systems (HMXRB) are composed by a compact object orbiting
around a massive star. The mass transfer which takes place within the system is the responsible
of the high energy emission observed in these systems (to which they owe the name of their
class). The presence of a compact object must exert a clear influence in the outer envelopes of
the massive star and, thus, must modify the formation and evolution of its stellar wind. Tidal
interactions, mass capture and high energy radiation pressure are among the possible ways in
which the compact companion will influence the stellar wind of the massive counterpart. The
status of the observations of such systems from previous UV missions will be reviewed, and
perspectives for the incoming WSO-UV will be reported.
GAP FORMATION IN A PROTOPLANETARY DISC AROUND BINARY STAR
Kaygorodov P.V., Bisikalo D.V., Fateeva A.M., Sytov A.Yu.
Institute of Astronomy RAS, Russia
We discuss a problem of gaps formation in protoplanetary discs around binary systems. it
is generally accepted that these gaps are formed due to resonances but the analysis of
observational data shows systematically underestimates of their linear sizes. We propose the idea
that the gap is formed by bow-shocks occurring due to the motion of the binary system
components in the gas of protoplanetary discs. We show results of 3D simulation, that prove a
significant role of the bow-shocks in the formation of the flow structure and, in particular, gaps
in protoplanetary discs around binary systems.
GROUND-BASED UV SPECTROSCOPY OF HOT STARS AT DIFFERENT
EVOLUTION STAGES
Klochkova Valentina1, Chentsov Eugene1, Panchuk Vladimir1, Kipper Tonu2, Tavolganskaya
Nonna1, Yushkin Maxim1
1 - SAO RAS, Russia
2 - Tartu observatory
We present an atlas of 4 B-, A-stars within the poor studied wavelength range 305452nm. The atlas is based on the high resolution (R=60000) spectra we taken with the 6-meter
telescope (Russia) in combination with the echelle spectrograph NES. Details of line
identifications and the atlas producing are described. Based on these spectral data, we studied in
detail velocity field within the expanded atmospheres and envelopes of hot evolved stars beta
Ori, alpha Cyg and extremely hydrogen deficient supergiant KSPer. The atlas in whole and a full
list of lines identification will be available in the SIMBAD database.
UV-CONTROLLED PHYSICAL AND CHEMICAL STRUCTURE OF
PROTOPLANETARY DISKS
Akimkin V.V.1, Pavlyuchenkov Ya.N.1, Vasyunin A.I.2, Wiebe D.S.1, Henning Th.2
1 – Institute of Astronomy RAS. Russia
2 – MPIA, Germany
The influence of UV radiation from a T~Tau star on the structure and appearance of a
protoplanetary disk surrounding the star is two-fold. First, this radiation heats up the disk, being
one of the two primary energy contributors, along with viscous heating, and, thus, defines its
shape and its spectral energy distribution. Second, it defines rates of photochemical reactions
and, thus, controls abundances of almost all chemical species, including those that are observed
in such disks. In this contribution we study details of UV radiation transfer in a protoplanetary
disk, paying attention to the influence of dust growth and sedimentation on the disk density and
temperature. Also, we show how the dust evolution may affect both column densities and spatial
distributions of key molecules, including CO, CS, water, and others.
SPECTRAL AND PHOTOMETRIC OBSERVATIONS OF TWO SYMBIOTIC HR 1105
AND V471 PER.
Kondratyeva L.., Rspaev F.
AFIF, Kazakhstan
New spectral and photometric observations of some symbiotic stars, carried out in the
Fessenkov Astrophysical Institute, are presented.
HR 1105 (BD Cam) is a symbiotic interacting system comprised of an S red giant and a
hot companion. It’s brightness was rather stable (V= 5m.00 - 5m.10, (B-V) = 1m.62 – 1m.63 until
2002, when significant decrease (V=8.732, (B-V)=1.138) was registered, giving evidence of the
falling of a red giant luminosity and increasing of a hot star contribution. In opposite to those
results our observations of HR 1105 in 2008 have shown the maximal values of star’s
brightness ever observed for this object: B=6m.60 V=4m.88. The high level of B magnitude is
kept till now, testifying that a hot star luminosity became much more. Recent appearance of HeI
lines in the spectrum of HR 1105 confirms this conclusion.
V471 Per –a symbiotic system, which consists of a hot star and a G2 giant. Our spectral
observations of this object were made from 1991 to 2009, but they are ranged rather randomly
in time. We have compiled available spectral data for this object all over ~ 40 years, and the
following changes were found out:
1. The gradual changes of the [OIII] line fluxes ratio R=F(4363)/F(4959+5007), which
may be caused by changes of electron density.
2. Variability of F(Hα)/F(Hβ) и F(Hγ)/F(Hβ), probably connected with an optical depth
in Balmer lines.
An analysis of spectral variability lead to conclusion that [OIII] and HI lines are formed
in quite independent zones, probably forbidden lines come from jets.
SYNCHRONOUS HIGH-SPEED UBVRI - PHOTOMETRY OF THE CLOSE BINARY
SYSTEM WZ SGE DURING ITS 2001 SUPEROUTBURST
Dmitrienko Elena S.
Sternberg Astronomical Institute of the MSU,Russia
Synchronous high-speed UBVRI - photometry of the close binary system WZ Sge during its
2001 superoutburst was performed at the Crimean Astrophysical Observatory with 1.25-m
telescope AZT-11. Analysis of our data revealed the essential distinctions between the
morphology of the light in the UV and the longer wavelengths of the spectrum at the various
stages of the superoutburst. The observed behavior of WZ Sge indicated its significant
structural and energetic changes with time and especially in the UV range. WZ Sge is a good
example of the need for the integrated approach of the study of the activity of close binary
stars. Observations of these objects in the UV region should be the important tasks of the
experimental astrophysics.
UV INSTRUMENTATION
WORLD SPACE OBSERVATORY-ULTRAVIOLET AMONG UV MISSIONS OF THE
COMING YEARS
B.Shustov, M.Sachkov, A.I.Gomez de Castro, K.Werner, N.Kappelmann, N.Steshenko and
WSO-UV team
Continuous access to the UV domain has been considered of importance to
astrophysicists and planetary scientists since mid-sixties.
However, the future of UV missions for the post-HST era is believed by significant part
of astronomical community to be less encouraging.
We argue that key science problems of the coming years will require further development
of the UV observational technologies. Among these hot astrophysical issues are: search for
missing baryons, the revealing the nature of astronomical engines; properties of atmospheres of
exoplanets as well as of the planets of the Solar System etc. We give a brief review of missions
to be put into orbit in coming decade(s) paying a special attention at the World Space
Observatory-Ultraviolet mission with 1.7 m UV-telescope onboard. The mission will allow us to
carry out high resolution/high sensitivity imaging and high/moderate resolution spectroscopy.
EARLY SCIENCE RESULTS FROM THE COSMIC ORIGINS SPECTROGRAPH
Cynthia Froning,
CASA, USA
The Cosmic Origins Spectrograph (COS), a sensitive ultraviolet spectrograph, was
successfully installed on the Hubble Space Telescope during Servicing Mission 4. COS covers
the 1150 -- 3200 A range with moderate spectral resolution (R 20,000) at sensitivities that are 2
to >10 times better than the previous capabilities on HST. In its low resolution FUV grating
(G140L), COS has spectral response down to the Lyman limit (900 A) at sensitivities that are
comparable to or significantly larger than those of the Far Ultraviolet Spectroscopic Explorer
over the same wavelength range. In this talk, I will present results from the first nine months of
COS science operations, focusing on observations obtained as part of the Guaranteed Time
Observations allocated to the COS science team. These include observations of the transiting
extrasolar planet, HD209458b; sightlines through the diffuse IGM and near dwarf galaxies; and
probes of the He II Gunn-Peterson effect using the extreme FUV (<1150 A) coverage of COS. In
presenting these data, I will highlight the on-orbit performance of COS and the expanded
scientific capabilities of HST enabled by this new instrument.
COSMIC ORIGINS SPECTROGRAPH: ON ORBIT PERFORMANCE AND LESSONS
LEARNED
Osterman, Steve N., University of Colorado
Green, James C., University of Colorado
The Cosmic Origins Spectrograph, installed in the Hubble Space Telescope in May, 2009 as part
of Servicing Mission 4, provided Hubble with a high sensitivity, medium and low resolution
spectrograph with sensitivity from below 90nm to 320nm. We present on-orbit instrument
performance and discuss design and development choices and their consequences.
TAUVEX: STATUS REPORT
Noah Brosch1, Jayant Murthy2
1 - Tel Aviv University, Israel
2 - Indian Institute of Astrophysics, India
I will review the original goals of the TAUVEX project and the solutions adopted to
achieve them. I will report on the various modification required by the changing platform and
will discuss the present status of the mission.
TAUVEX, FIRST INDIAN UV SPACE OBSERVATORY: CURRENT STATUS
Margarita Safonova
Indian Institute of Astrophysics, India
UV astronomy has benefited considerably in the last decades from a number of UV space
missions, each with its own unique capabilities. However, despite its importance to many areas
of astronomy, there have been no complete surveys of the UV sky since the TD-1 satellite in the
1970s, which had both low sensitivity and low spatial resolution. The need for a UV sky survey
has been recognized by NASA and the GALEX satellite was launched in 2005 with impressive
performance, however, it is avoiding low galactic latitudes and is limited to only two UV bands.
TAUVEX UV Space Observatory (joint Indo-Israeli mission) will not only complement
GALEX, but will be an ideal precursor for the upcoming multi-wavelength satellite
ASTROSAT. Unlike other UV missions, TAUVEX will observe from a geostationary orbit, well
above the radiation belts and without any intervention of the Earthglow. Rotating mounting
platform allows complete sky coverage from North to South Celestial Pole. The Observatory
consists of three co-aligned telescopes with three filters per telescope, offering a total of five
different UV bands for observation. The specific choice of TAUVEX filters cuts off the Lyman
lines of hydrogen. A simultaneous monitoring of a ~1 deg field of view in three different bands
will allow the accurate determination of UV fluxes and colours at high time resolution (~0.1
sec), while choosing the same filter on two telescopes will increase S/N ratio. A unique
possibility to study interstellar dust band at 217.4 nm is provided by two TAUVEX filters that
are centered on this wavelength but have different widths. The photometry capabilities (each
detected photon is time-tagged with a precision of ~128 ms) and the possibility of repeated scans
enables the recording of UV light curves of variable sources, and multi-wavelength follow-up
will be coordinated by the TAUVEX Science Team with ground-based observatories in India
(such as ARIES in Nainital and IAO in Hanle) and Israel (such as Wise Observatory). The first
few months of the mission will be dedicated to the performance verification, calibration and the
First Science Survey. I will review the current status of the Observatory and the present the
observational plan for the first year.
10 YEARS OF THE OPTICAL-UV MONITOR ON BOARD XMM-NEWTON
Antonio Talavera
ESA-Serco
The XMM-Newton X-ray observatory was launched at the end of 1999 and it is still
successfully operated. In addition to the X-ray instruments, the payload carries a small telescope,
the Optical Monitor, which provides simultaneous image and spectroscopic observations in the
optical and UV ranges. In this presentation we review the status of the OM and its main
achievements after 10 years of operations. We also introduce the XMM-OM Serendipitous
Ultraviolet Source Survey (SUSS) Catalogue.
PLATO AND POSSIBLE UV FOLLOW-UP
Pagano I., Piotto G., Ragazzoni R., Micela G., Catala, C.
PLATO (PLAnetary Transits and Oscillations of stars) is an ESA project currently under
definition study in the framework of the ESA Cosmic Vision 2015-2025 programme. We present
the PLATO science objectives and how the mission is implemented. We emphasize the main
peculiarities of PLATO with respect to other similar extrasolar planetary projects, highlighting
the role of UV follow-up of the PLATO extrasolar planetary systems.
NEW DEVELOPMENTS OF THE WORLD SPACE OBSERVATORY UV
SPECTROGRAPHS (WUVS)
N. Kappelmann1 and the WUVS Team
1 - University of Tuebingen, Germany
The World Space Observatory Ultraviolet (WSO/UV) S/C is a multilateral project led by
the Russian Federal Space Agency (Roscosmos). The WSO/UV consists of a 1.7 m reflective
telescope feeding UV spectrographs (WUVS) and UV imagers. Within the UV spectrographs the
102-310 nm spectral band is split to feed two spectrographs, the High Resolution Double Echelle
Spectrographs (HIRDES), covering the vacuum-UV range between 102-176 nm and the UV
range between 174–310 nm with high spectral resolution (R >50000). A third spectrograph
(Long Slit Spectrograph, LSS, spectral band: 102-310nm) with medium spectral resolution (R ≅
1000) allows observations with a spatial resolution of 1”. Each spectrograph comprises a CeSiC
optical bench structure with a fully redundant MCP detector system, the optomechanics and a
network of mechanisms. New development activities are described considering MCP cathodes,
anodes and new high speed front-end electronics. Performance aspects, design drivers and
related trade-offs are discussed.
A UV SPACE TELESCOPE BASED ON DIFFRACTION FOCUSING
Laurent Koechlin, Ana-Ines Gomez de Castro, Paul Deba, Truswin Raksasataya
We propose a new concept for data acquisition in UV astrophysics: diffraction focusing
with a thin opaque membrane. This membrane is punched with a large number of specially
shaped subapertures that cover approximately 50% of the total area. The global size will be 3 to
4 meters, It should provide diffraction limited and very high contrast images, and a 7%
efficiency at prime focus with a broad spectral coverage. It implies formation flying of two
spacecraft, but with relatively tolerant positioning.
This two-module concept has been validated from the ground on sky objects (in the
visible), and a prototype is being built for validation tests in the UV with lab sources.
We will briefly present the optical principle and the validation results obtained in the
visible with this diffractive optics imager (Sirius A-B, Mars satellites), and propose some science
cases that could be addressed in the UV (accretion disks, symbiotic binaries, etc.)
ISSIS AN INSTRUMENT FOR HIGH SENSITIVITY IMAGING IN THE UV
Ana I Gomez de Castro, Alejandro Brana, Jesus Maiz, Paola Sestito, Pablo Rodriguez, Maite
Gomez, Tomas Belenguer, Juan Larruquert, Jose A. Mendez
ISSIS (Imaging and Slitless Spectroscopy Instrument for Surveys), the camera system for the
WSO-UV mission, has been designed to satisfy the needs of the astronomical community at
large, with high resolution and sensitivity in the far UV as the main design driver. Slitless
spectroscopy is built in to allow a rapid and efficient characterization of astronomical sources
and redshift determination in Lyman break galaxies.
ISSIS is designed to have two acquisition channels: (1) the High Sensitivity Channel (HSC) with
an MCP-type detector to guarantee high sensitivity in the 1100-1800 Angstroms range and high
rejection of lower energy radiation and (2) the Channel for Surveys (CfS) with a large CCD
detector (4kx4k) able to obtain images from the far UV to the red (1200-8000 Angstroms). The
current status of ISSIS design will be presented.
WSO-UV MASTER CATALOGUE. EXPERIMENTAL VERIFICATION OF THE
PHOTOMETRIC SYSTEM
A.S. Shugarov, N.V. Chupina, A.E. Piskunov, N.V. Kharchenko
It is planned that the precise pointing and stabilization of T-170M telescope, the main
instrument of the World Space Observatory-Ultraviolet (WSO-UV), will be provided by Fine
Guidance Sensors (FGS) and dedicated guiding catalog (Master Catalog, MC). The MC
photometry, based on NIR data of 2MASS, is reduced to the optical system close to the FGS
range. To check the accuracy of the reduction we have carried out in a spectral band, close to the
FGS, the ground-based observations with CCD-camera. The observations show that the quality
of the reduction is sufficient to support the FGS operations. The mean difference between
observed and reduced magnitudes in the range 14- 17 mag is 0.23 mag, and its variation over the
sky does not exceed the factor of two. For 2% of stars this difference exceeds 2 mag. We find a
correlation between large magnitude deviations and photometric quality flags.
TIME ALLOCATION SCHEME FOR THE WSO-UV MISSION
Oleg Malkov1, Mikhail Sachkov1, Boris Shustov1, Pavel Kaigorodov1,Francisco Javier Yanez2,
Ana Ines Gomez de Castro2
Institute of Astronomy RAS, Moscow, Russia
Universidad Complutense de Madrid, Spain
The World Space Observatory --- Ultraviolet (WSO-UV) is an international space
observatory for observation in UV spectral range 100-350 nm. The WSO-UV consists of a 1.7 m
aperture telescope with instrumentation designed to carry out high resolution spectroscopy, longslit low resolution spectroscopy and direct sky imaging. The WSO-UV Ground Segment is under
development by Spain and Russia. They will coordinate the Mission and Science Operations and
provide the satellite tracking stations for the project.
The WSO-UV will work as a targeted scientific observatory. Three scientific programs
will be carried out at the observatory. Core Program of scientific observations, which deserves
large amounts of observing time, will be defined by the WSO-UV Science Committee to allow
the conduction of high impact or legacy scientific projects. Funding Bodies Program is the
guaranteed time granted to each one of the national bodies funding the WSO-UV project. Guest
observer program for everyone, or Open Program, consists of astronomical observations
obtained with the WSO-UV by astronomers who may or may not belong to the WSO-UV
international consortium. It is open to excellent scientific projects from the world-wide
community and occupies up to 40% of total observational time.
A brief summary of the algorithmic strategies analyzed for scheduling optimization is
also given in the presentation.
THE GALEX PUBLIC SCIENCE DATA ARCHIVE @ MAST
Alberto Conti (STScI), Luciana Bianchi (JHU), Bernie Shiao (STScI), et al.
The Galaxy Evolution Explorer (GALEX) was successfully launched on April 28, 2003.
Over the last 7 years, the GALEX mission has expanded our understanding of the process of star
formation and galaxy evolution.GALEX data, consisting of far-UV (1344-1786A) and near-UV
(1771-2831A) imaging over most of the sky, and grism spectroscopy, are available to the entire
astronomical community and to the general public via the Multi-mission Archive at Space
Telescope (MAST). The main characteristics and access tools to the large data archive (16TB)
are presented.
Recently our group has undertaken an ambitious project to conduct an all-sky search for
time-variable and transient sources within GALEX data; results and tools for variability searches
will also be made publicly available. GALEX extracted catalogs of unique sources (Bianchi et al
2010), with matches to surveys at other wavelengths (SDSS, GSC2, 2MASS, and others), will
also be online as High Level Science Products in MAST, to complement the already existing
catalogs.
PLANETARY ATMOSPHERES
PLANETARY ATMOSPHERES
Valery I. Shematovich
Institute of astronomy RAS
The state of art in the space observations in the ultraviolet (UV) wavelength range of the
planetary atmospheres is discussed. The main aeronomic systems on planets, satellites and
comets are briefly described. The UV observations together with the in situ mass-spectrometer
measurements allow us to determine the density and temperature height profiles of the
atmospheric species and to improve our understanding of the physical and chemical aeronomy of
the planetary atmospheres.
The following hot fields of the UV planetary astronomy are discussed:
- UV observations of the hot hydrogen and oxygen coronae of the terrestrial planets;
- auroras and hot hydrogen coronae of the giant planets;
- formation and morphology of the water vapour and oxygen atmospheres of the icy
satellites in the giant planet systems. Space distribution and evolution of the neutral clouds and
gas torii in the giant planet systems;
- UV observations of the cometary comae and exospheres of the KBOs;
- UV emissions in the extended upper atmospheres of the extrasolar planets.
The mathematical models such as the stochastic model of the hot planetary coronae,
Monte Carlo models of the high-energy electron, proton and heavy ion fluxes penetrating into
the planetary atmospheres are also discussed. These models are used for the interpretation of the
atmospheric UV emissions and are currently used to calculate the excitation rates of the UV
emissions for the astrophysical objects which are planned for the observations by the World
Space Observatory (WSO-UV).
ULTRAVIOLET DAYGLOW AND AURORA IN PLANETARY UPPER
ATMOSPHERES
Jean-Claude Gérard
LPAP, Université de Liège, Belgium
Planetary airglow ultraviolet emissions are produced by a series of atmospheric processes
resulting from direct and indirect interaction of solar FUV, EUV and X-ray radiation with the
constituents of the planetary atmospheres. In this presentation, we review some recent results
obtained from space platforms in Earth orbit and from planetary probes and we indicate how
some of these observations can further extended with future ultraviolet telescopes. Dayglow
FUV of Mars spectra collected with the SPICAM FUV spectrograph indicate a dependence of
the intensity and peak altitude of the CO Cameron bands and CO2 + doublet emissions on
latitude, local time and solar activity level. These have been investigated and compared with the
results of a FUV Mars dayglow model. Far and Extreme UV dayglow spectra of Venus have
been collected with the UVIS instrument during the flyby by Cassini. Their analysis shows the
presence of OI, OII, NI, CI, CO and CO2 + emissions, some of them not previously identified in
the Venus spectrum. Scans of the intensity variation of several EUV bright emissions across the
sunlit can be compared with predictions by a Venus dayglow model.
The near UV nightglow of terrestrial planets is dominated by gamma and delta bands of
NO between 190 and 270 nm are excited by radiative recombination of N and O atoms. These
emissions have been extensively observed with the SPICAV (SPICAM) spectrograph on board
Venus (Mars) Express. On Venus, the N and O atoms are transported to the night side by the
subsolar to antisolar global circulation in the thermosphere generated by the thermal contrast
between the two sides of the planet. The statistical shift of the NO airglow bright spots from
midnight suggests that zonal wind blow preferably dawnward. Auroral emissions are excited by
collisions between (primary and secondary) auroral electrons (with some proton contribution)
and atmospheric species. Observations of Jupiter’s and Saturn’s auroral performed with the
Hubble Space Telescope over nearly two decades have provided a large amount of information
on the morphology and dynamics of the aurora and the nature and energy of precipitating
particles. HST UV images have shown that the interaction of the solar wind with the
magnetospheres of the giant planets is different from that with the terrestrial magnetosphere in
several respects bearing consequences on the morphology and dynamics of the aurora. The size
and brightness of the Jovian main oval shows only a weak dependence on solar wind conditions.
By contrast, Saturn’s aurora is quite responsive to solar wind perturbations, as was observed
during campaigns of concurrent observations between HST and Cassini.
HST-COS OBSERVATIONS OF THE TRANSITING EXOPLANETARY SYSTEM
HD209458b
Kevin France, Jeffrey L. Linsky, John T. Stocke, and Cynthia S. Froning
We present the deepest ultraviolet observations of a transiting exoplanetary system ever
acquired. We used the Cosmic Origins Spectrograph (COS), recently installed on the Hubble
Space Telescope, to observe the HD209458 system at primary and secondary eclipse, as well as
both quadrature positions. The transit observations confirm the ~8% decrease in stellar flux at
the CII doublet, and we use the spectral resolving power of COS to characterize the velocity
distribution of the CII atmosphere. These data also reveal an 8% decrease from SiIII for the first
time. We use these results to constrain the mass-loss rate from the planet (3.2 x 1011 g/s),
consistent with an exoplanetary wind that fills its Roche Lobe, or that is distributed into a
cometary tail. We also present the first search for direct auroral emissions from an exoplanet.
We compare models of gas giant atmospheres to the observed quadrature spectra to place
constraints on the presence of a Jovian-like auroral system, and discuss implications for models
of hot Jupiters.
CHARACTERIZATION OF AURORAL FUV EMISSIONS : FROM JUPITER TO HOT
JUPITERS
Hélène Menager, Mathieu Barthélemy, Jean Lilensten
Laboratoire de Planétologie de Grenoble, France
Jupiter has bright aurorae due to particle precipitation in the upper atmosphere. In the
FUV, the brightest emissions are those of the H Lyman-α line and of the Lyman and Werner
bands of H2. These emissions provide information on the precipitating particles, which are still
poorly known, and on the atmospheric conditions, which are badly constrained in polar regions.
Auroral UV emissions of hot Jupiters, when detected, could similarly help constrain their
atmospheric conditions and magnetospheric environment.
We will start by discussing the FUV auroral emissions of Jupiter. We use a kinetic code
to describe the transport of the electrons which precipitate in the auroral atmosphere of this
planet. This code allows us to calculate the excitation rates of H and H2, and the ensuing FUV
emissions. Radiative transfer calculations are then carried out to calculate the intensity of the
lines which emerge from the atmosphere. We will present the results of a sensitivity study which
shows how the spectrum of H2 depends on the energy of the incident electrons and their angular
distribution. We will propose some variable parameters which can be used in the analysis of
observational spectra to constrain the auroral environment. We will then present how this
modeling is adapted to describe the environment of hot Jupiters. For these planets, a lot of issues
are still unresolved, like the presence of a magnetic field or the properties of incident particle
fluxes. These issues are crucial to auroral processes and could be addressed by studying auroral
emissions of the planets. France et al. (2010) used the COS instrument on HST to try to detect
H2 auroral FUV emissions from HD 209458b but made no unambiguous detection. Atmospheric
models of HD 209458b have been given by Yelle (2004) and Garcia-Muñoz (2007). They allow
us to evaluate the H Lyman-α dayglow of the planet. We also estimate H and H2 FUV planetary
emissions caused by the precipitation of particles, with and without an intrinsic magnetic field.
We make observing facility suggestions for a future detection.
References
R. V. Yelle, “Aeronomy of extra-solar giant planets at small orbital distances”, Icarus, vol 170,
pp.
167-179, 2004
A. Garcia Muñoz, “Physical and chemical aeronomy of HD 209458b”, Planetary and Space
Science, vol 55, pp. 1426-1455, 2007
K. France, J. T. Stocke, H. Yang, J. L. Linsky, B. C. Wolven, C. S. Froning, J. C. Green, S. N.
Osterman, Astrophysical Journal, vol 712, pp. 1277-1286, 2010
UV TRANSIT OBSERVATIONS OF M-DWARF EARTH-LIKE EXOPLANETS:
STUDING THE STAR-PLANET INTERACTION
Antoniadis J.1, Barentsen G.2, Bjerkeli P.3, Dorner B.4, Dumitrache C.5, Eybl V.6, Humberset B.7,
Jacimovic A.8, Kuutmann A.9, Lammer H.10, Moser H.11, Rotter T.12, Vinas Tió M.13, XiangGrüß M.14, Ygouf M.15
1 Greece, 2 Armagh Observatory, UK, 3 Onsala Space Observatory, Sweden, 4 CRAL Observatoire de Lyon, France, 5 University Politehnica of Bucharest, Romania, 6 University of
Vienna, Austria,
7 University of Bergen, Norway, 8 University College Utrecht, Netherlands, 9 Sweden, 10 Space
Research Institute, Austrian Academy of Sciences, Austria,
11 Luxembourg, 12 University of Graz, Austria, 13 Universitat Politècnica de Catalunya, Spain,
14 Christian-Albrechts-Universität zu Kiel, Germany, 15 Laboratoire d'Astrophysique de
Grenoble, France
The detection and investigation of extended hydrogen atmospheres around extrasolar
planets provide very promising insights into the interaction of the host star with the planet as
well as the evolution of these planets and their atmospheres.
There are different scenarios in the evolution of an Earth-like planet, during which
hydrogen coronae can occur. In the presence of strong stellar activity, the planetary exosphere
can be affected significantly leading to the production of highly energetic neutral atoms (ENA).
By measuring the size of the extended atmosphere and determining the velocities of hydrogen
atoms, conclusions can be drawn in respect to the origin of these features.
Due to the large number of M-type stars in our neighborhood and their comparably long
periods of strong stellar activity, M-type stars represent the most promising candidates for the
detection of ENAs and the subsequent study of the interaction between the host star and the
planets' atmosphere as well as the evolution of the planet. The low mass of M-type stars also
makes them preferable targets to observe extended hydrogen clouds around planets with a mass
as low as one Earth mass.
This method can be understood as a new approach for the research of star-planet
interaction and planet evolution.
MILKY WAY AND GALAXIES
UV RADIATION IN GALAXIES
Sil'chenko Olga K.
Sternberg Astronomical institute of the MSU,Russia
The nature of UV-radiation in galaxies of different morphological types will be reviewed.
The UV-excess in massive elliptical galaxies which have predominantly old stellar populations is
traditionally explained by the contribution of low-mass stars at very late, poorly known stages of
evolution -- by so called `AGB-manque' stars or by the populations of extended horizonthal
branch. However recent results from the GALEX survey for a rich sample of nearby ellipticals
have also demonstrated probable traces of recent star formation in a third of all ellipticals
observed. In spiral galaxies the extended UV-disks have been discovered by the GALEX; they
are certainly illuminated by the current star formation, but what has provoked star formation in
the area of very low gas density, beyond the distribution of older stars, is a puzzle yet. A separate
very interesting problem which can be solved only in the UV spectral range, is a search for
`missing baryons' -- for the warm gas which can be detected through the absorption lines of
highly ionized O and C in the spectra of background sources (quasars). Some results are already
reported, but even more remains to be done relating this topic.
INTERSTELLAR MEDIUM
Linsky Jeffrey
tbc
SYNTHESIS OF OLD STELLAR POPULATIONS AT UV WAVELENGTHS
M. Chavez, E. Bertone and A. Bressan
INAOE-Mexico
In this talk I will briefly address the main topics that, in my opinion, have substantially
motivated the development of the technique called evolutionary population synthesis and that, to
some extent, are still open. These are (a) the rising branch of the Far-UV energy distribution of
Elliptical Galaxies, (b) The age metallicity degeneracy and the UV spectrum as a
(complementary) tool to break it, (c) The UV properties of distant red galaxies and (d) the stellar
libraries currently used in the modeling of the integrated properties of evolved populations. In
addition to historical remarks in these four branches and an updated view of their current status, I
will comment on some recent investigations developed by our group that might help in
understanding the global UV properties of aged stellar populations.
POLARIZATION OF AGN IN UV SPECTRAL RANGE
Gnedin Yu.N.
Central Astronomical Observatory at Pulkovo, Russia
I present the review of basic methods of measurements of magnetic fields with
application to accreting supermassive black holes in UV spectral range/ The problem of
connection between t jet and accretion disk is discussed. The expected results of UV polarimetric
observations of QSO and AGN are presented in this talk. I consider the new aspects of UV
polarimetry of AGN: (a) the strong dependence of UV polarization on the rotation rate of a
supermassive black hole; (b) the principal possibility to use polarimetric observations for testing
cosmological models.
THE GALAXY EVOLUTION EXPLORER (GALEX): EXPLORING GALAXY
EVOLUTION AND THE UV UNIVERSE
Chris Martin
California Institute of Technology. USA
The Galaxy Evolution Explorer (GALEX) continues its surveys of the ultraviolet sky.
GALEX surveys have supported the following galaxy evolution investigations: calibrating UV as
a star formation rate tracer, using wide and deep surveys to measure star formation history,
studying the evolution of dust extinction and metallicity, selecting and analyzing galaxies in
transitory states, finding local analogs to Lyman Break Galaxies, probing and time-dating star
formation in a wide variety of physical regimes. Our continuing mission is focussed on relating
star formation history and galaxy evolution paths to the properties of dark matter halos and their
assembly history, and on beginning to relate the evolution of galaxies to that of black holes and
the intergalactic medium. GALEX has proven that the UV is an ideal band to find and map star
formation in low mass, low density objects, and potentially in primordial gas. GALEX has made
a number of new and exciting discoveries, including winds from AGB stars glowing in the UV,
extended star forming disks, analogs to high redshift galaxies, stellar tidal disruption flares from
otherwise inactive massive black holes, and supernova break-out shocks. With future UV
missions it may be possible to map emission from the intergalactic and circum-galactic medium,
and make a definitive connection between galaxy evolution and the cooling, accretion, heating,
and enrichment of gas in the cosmic web.
A UV-OPTICAL SURVEY OF THE NORTH CELESTIAL CAP
Evgeny Gorbikov and Noah Brosch
The Wise Observatory and the Raymond and Beverly Sackler School of Physics and Astronomy,
the Faculty of Exact Sciences, Tel Aviv University, Tel Aviv 69978, Israel
We present preliminary results of an optical two-colour CCD survey of the North
Celestial Cap (NCCS) combined with UV observations. The NCCS primary aim was to obtain
good photometric and astrometric data for the region from the Pole ( = 90 ) to  = 80 in
support of the TAUVEX mission. This region, at galactic latitudes from ~17 to ~37 , has poor
coverage in modern CCD-based surveys.
The observations are performed with the Wise Observatory one-meter reflector and with
a new mosaic CCD camera (LAIWO) that images in the Johnson-Cousins R and I bands a onesquare-degree field with sub-arcsec pixels. The images are treated using IRAF and SExtractor to
produce a final catalogue of sources. The astrometry, based on the USNO-A2.0 catalogue, is
good to . 1 arcsec and the photometry is good to ~0.1 mag for point sources brighter than R=20.2
or I=19.1 mag. The limiting magnitudes of the survey, defined at photometric errors smaller than
0.15 mag, are 20.7 mag (R) and 19.7 (I). We separate stars from non-stellar objects based on the
object shapes in the R and I bands, attempting to reproduce the SDSS star/galaxy dichotomy.
The completeness test indicates that the catalogue is complete to the limiting magnitudes stated
above. The NCCS sky coverage today is ~70% of the planned coverage. The expected total
number of distinct objects in NCCS is ~1, 500, 000.
Here we present preliminary results for ~10% of the survey area where our R and I
magnitudes are combined with GALEX FUV and NUV photometry. We discuss issues of the
galactic extinction and the galaxy clustering in the color-color diagrams.
TRACING THE SECULAR EVOLUTION OF EARLY-TYPE GALAXIES WITH
GALEX
Rampazzo R.1, Marino A2., Bianchi L.2, Annibali F.1, Bressan A1. Buson, L.M. 1 Clemens M. 1,
Panuzzo P3, Zeilinger, W. 4
1 - INAF-Osservatorio Padova, Italy
2 - . JHU, Baltimore, USA
3 - CEA, Saclay, France
4 - IfA, Univ. Wien, Austria
Early-type galaxies (ETGs) are considered the fossil evidence of the process of galaxy
evolution. However, evidence are accumulating that rejuvenation of the ETGs stellar populations
may be triggered both by accretion events and by the inner secular evolution.
We are performing a comprehensive, multi-wavelength study of 65 nearby ETGs, mostly
located in low density environments. Aimimg at improving our understanding of the evolution of
ETGs, we are extending the study of their spectral energy distribution to the far UV region,
sensitive to the presence of young stellar populations.
We present here the GALEX FUV and NUV study of 40 out of 65 ETGs in the original
sample. We present and model the secular evolution in ETGs with ring/arm-like structures
detected in the far UV. The Far UV data set is complemented by optical and Mid Infrared
(Spitzer-IRS) observations.
INTERGALACTIC DUST: PRO AND CONTRA
Yuri A. Shchekinov1, Biman B. Nath2
1 - Southern Federal University, Russia
2 - Raman Research Institute, Bangalore, India
The presence of metals in the intergalactic (IG) space suggests that dust particles may
also exist there. It is clear thought that the dust abundance in the IG mechanism is small as the
corresponding reported extinction is only E(B-V)~0.1. Even in this negligible amount dust grains
can considerably affect thermodynamics of the IG gas through photoelectric heating. The key
question is therefore what exact fraction of dust particles is expelled from galaxies under their
activity, what are dust properties when they reach true intergalactic medium. We discuss here
dust transport mechanism, destruction and survival of dust drains. We argue that intergalactic
dust is generally much lighter, i.e. they are smaller in size, then dust in galaxies.
GALAXY EVOLUTION STUDIES WITH THE SWIFT UV/OPTICAL TELESCOPE
Hoversten Erik (Penn State), Gronwall Caryl (Penn State), Vanden Berk Daniel (St. Vincent's
College), Roming Peter (Penn State)
The UV/Optical Telescope (UVOT) onboard the Swift Gamma-Ray Burst Explorer
satellite occupies a niche in UV parameter space (having a smaller PSF than GALEX while the
UVOT field of view is larger than those of HST instruments). It is ideally suited for studies of
galaxy evolution, two of which are described here. UVOT observed the Extended Chandra Deep
Field South for a total of 568,000 seconds split between the uvw2 (2030 A), uvm2 (2231 A),
uvw1 (2634 О‘) and u (3501 A) filters. Galaxy number counts cover a range of AB magnitudes
from 21 - 26 in uvw2 to 20 - 24.5 in u, bridging the gap between the GALEX NUV number
counts (Xu, et al. 2005) and HST STIS NUV number counts (Gardner, Brown, & Ferguson
2000) and are consistent with both suggesting evolution in the UV luminosity function of
galaxies. UVOT observed M81 and its companion galaxy, Holmberg IX. We combine UVOT
imaging in the uvw2, uvm2, and uvw1 filters is combined with imaging in the u, g, r, i, and z
bands from the Sloan Digital Sky Survey to extend the SED coverage of the star forming
regions. We show the colors and derived ages of individual star forming regions, UV surface
brightness profiles, and pixel by pixel fits of the properties of the stellar populations in M81 and
Homberg IX. These results are in agreement with an interaction between M81 and M82 200
Myr ago, a tidal dwarf origin for Holmberg IX, and a Milky Way extinction law for both
galaxies.
CARBON IONIZATION STATES AND THE COSMIC FAR-UV BACKGROUND WITH
HEII ABSORPTION
Vasiliev Evgenii1,Sethi Shiv K.2, Nath Biman B. 2
1 - Southern Federal University, Russia
2 - Raman Research Institute, Bangalore, India
We constrain the spectrum of the cosmic ultraviolet background radiation by fitting the observed
abundance ratios carbon ions at $z\sim 2\hbox{--}3$ with those expected from different models
of the background radiation. We use the recently calculated modulation of the background
radiation between 3 and 4 Ryd due to resonant line absorption by intergalactic HeII, and
determine the ratios of CIII to CIV expected at these redshifts, as functions of metallicity, gas
density and temperature. Our analysis of the observed ratios shows that 'delayed reionization'
models, which assume a large fraction of HeII at $z\sim3$, is not favoured by data. Our results
suggest that HeII reionization was inhomogeneous and extended to redshifts as low as
$z\sim2.5$.
THE BARYONS IN THE LOW Z UNIVERSE
Ivanchik Alexander V.1, Varshalovich Dmitry A. 1, Balashev Sergei A.1,Petitjean Patrick2
1 - Ioffe Physical-Technical Institute RAS, Russia
2 - IAP CNRS France
We discuss some possibilities of observations of the baryon content in the low Universe:
researches of the hot gas in the low Universe from a OVI-NeVIII survey and DLA-systems
survey for z<2.
SCATTERING OF LIGHT BY A COLLECTION OF DUST GRAINS: EFFECT OF
GRAIN SIZE DISTRIBUTION.
S.Chatterjee
Indian Institute of Astrophysics, Bangalore 560 034. INDIA
Astrophysical systems of various types are known to possess copious quantities of dust,
which differ in their chemical compositions and also in their morphology, both of which are
determined by the environment and the process by which the grain grows. While the light
absorption properties are largely determined by the composition, the scattering properties of
substances are determined also by the size of the grain and also by the roughness of the surface.
We will consider a model, in which the grain size distribution is described by a distribution
function of the type:
P(a) = 0 for a<a0
= Na-x exp[-(a/r0)y] , for a≥ a0 (1)
where N is a normalizing constant for the probability P(a)da that the grain has a radius,
lying between a and a+da. In the above distribution, a0 describes the minimum size of the grain,
i.e. the size of the critical nucleus and another length scale, r0 describes approximately the radius,
beyond which the probability approaches zero very rapidly. The factor a -x is chosen to account
for the scaling law kind of dependence that is found observationally. Thus a0 and r0 give the
typical range within which the grains of different radii can be found to exist. While the
probability P(a) tends to zero for a>>r0, the parameter y describes as to how fast does this fall to
zero take place. The four parameters, involved in the description of P(a) can be related to the
details of the grain formation and destruction process. From the theories of scattering it can be
shown that the scattering cross section for any wave vector of scattering ks is given by,
σ(ks) = [k4(nr2-1)2/ks6] ∫ [cos(ksa) – (ksa)sin(ksa)]2P(a)da (2)
where k = (2π/λ) , λ being the wave length of light. It can be seen from equations (1) and
(2) that σ(ks) involves two dimensionless quantities, (ksa0) and (ksr0) and can be expressed in
terms of confluent hypergeometric series involving the above dimensionless quantities for which
we present the asymptotic expansions. Computations for realistic situations will be presented, for
wave length of light being in the ultraviolet range. The result, it is clear will contain admixture of
Rayleigh and diffractive parts, which will be delineated for the purpose of inversion, as is needed
for extracting the values of the parameters a0, r0, x and y.
WFPC2 FUV IMAGING OF GALACTIC OPEN CLUSTERS
Jesus Maiz Apellaniz, Instituto de Astrofisica de Andalucia
WFPC2 was the last instrument aboard HST with FUV wide-field imaging capabilities
not subject to bright-object limits. Before the instrument was brought back to Earth by the SM4
astronauts in May 2009, we used it to observe five Galactic open clusters and H II regions in
multiple filters between the FUV and the I band. Those data represent the highest angularresolution images in the FUV ever obtained of objects of such type. We will present our first
results, including the first subarcsecond-resolution image of a Galactic reflection nebula in the
FUV.
UV PROPERTIES OF TYPE IA SUPERNOVA AND THEIR HOST GALAXIES
Brad Tucker, Mt. Stromlo Observatory, ANU
The use of type Ia supernova (SNe Ia) as standard candles has shifted from not just
simply testing whether the Universe is accelerating, but what in fact is the cause of the
mysterious dark energy. Determining the dark energy equation of state to better than 10% is the
aim in current supernova cosmology projects, as it will help to distinguish between various
cosmological models. However, we still lack a clear understanding of the SNe Ia progenitor
systems, and their use in cosmology has provide a variety of systematic problems. Recently
though, the use of ultraviolet photometry has helped us to eliminate possible progenitor system
models. Furthermore, the analyzing of the host galaxies of SNe Ia's has utilized UV photometry
to measure the dust content and star formation history of the host galaxy. I will present these
results from two new papers that without the ultraviolet, would not have been possible.
THE NEUTRINOS BACKGROUND AND ULTRAVIOLET
Mychelkin E.G., Denisyuk E.K.
Fesenkov Astrophysical Institute, Nat. Center of Space Researches&Technologies, Almaty
050020 Kazakhstan
Some theoretical and observational aspects of dark matter (DM) phenomenon in the
Universe are discussed in relation with the proposed tachyon neutrinos background as a realistic
approach to DM. Then the expected scale for galactic DM ‘haloes’ is about (0.3 – 3) Mpc to be
in concordance with empirical law of the surface mass-density constancy exposed recently for a
big array of spiral galaxies (Donato F. et al., arXiv: astro-ph/0904.4054 (2009)). To perform the
corresponding astronomical UV observations of widespread masses (including DM) around
galaxies the special long-slit spectrograph method is presented to be applied for measuring the
saturation effect of rotation curves in galaxies on the grounds of Ly-alpha emission line
registration.
THE STARFORMING CASCADE IN M17 AND ULTRAVIOLET
Dzhakusheva K.G., Mychelkin E.G.
Fesenkov Astrophysical Institute, Nat. Center of Space Researches&Technologies, Almaty
050020 Kazakhstan
The cascade process of star formation in M17 revealed by the world astronomical
practice is considered beginning from the pioneer study of some peculiar active domain of that
nebula executed in Fesenkov Astrophysical Institute. The different spectral and IR data including
those obtained by space-craft telescopes are reviewed in connection with universal shock-waves
mechanism of diffuse X-Rays and hard UV production exposed previously for M42
(Dzhakusheva K.G., Mychelkin E.G., in ‘UV Universe II, Moscow 2008’, P.294). The analogous
region in M17 with exited diffuse UV is expected to be found, and a justification of that is
performed on the grounds of related photometric and polarimetric data.
GALACTIC SPIRAL DENSITY WAVE PARAMETERS ON YOUNG OBJECTS
Bajkova Anisa.T., Bobylev Vadim.V., Stepanishchev Alexander. S.
Central (Pulkovo) Astronomical Observatory of RAS
Based on Bottlinger’s equations and currently available data on three-dimensional field of
space velocities of young (≤50 Myr) open star clusters and 28 masers having trigonometric
parallaxes we have found Galactic kinematics parameters. Fourier analysis of galactocentric
radial velocities V(R) of the masers allowed us to estimate amplitude fR=4.0±1.0 km/s and
wavelength λ=2.1±0.5 kpc of the density wave periodic perturbations, and phase of the Sun in
the density wave χo=–118.8o±10o, what proofs that the Sun is located in the inter-arm space close
to the Carina-Sagittarius arm. We revised the localization of the Perseus spiral arm and found its
pitch angle i=–5o±1o. The solutions for spiral density wave parameters obtained directly from
Bottlinger’s equations complemented by the terms in accordance with the density wave theory
(Lin and Shu, 1964, APJ, 140, 646) are as follows: fR=5.5±1.1, fθ=3.8±0.8, i=–5.1o±0.8o, χo=–
117.9o±11.7o, λ=2.2±0.3 kpc for data on young open star clusters.
NGC 4262: A VIRGO GALAXY WITH AN EXTENDED ULTRAVIOLLET RING
Buson Lucio
INAF, Italy
GALEX satellite has recently shown the presence of an extended, outer ring studded with UVbright HII regions surrounding the otherwise normal lenticular galaxy NGC 4262. Such a
structure is coupled with a ring of cold (HI) gas. Having structured UV-bright sources beyond
its optical disc, NGC 4262 can be classified as a Type I extended ultraviolet disc (XUV).
GRAVITATIONALLY LENSED QSOS IN THE ISSIS/WSO-UV ERA
Luis Goicoechea,
Universidad de Cantabria, Spain
QSOs at 1 ≤ z ≤ 2 play a key role in understanding the cosmic evolution of the innermost
parts of active galaxies. In this context, the gravitationally lensed QSO (GLQ) population is of
particular interest, since about 50% of all well-identified GLQs are situated at a redshift between
1 and 2, and these are magnified with respect to normal QSOs at similar redshifts. With respect
to studies of normal QSOs, GLQ programmes have several advantages. For example, a
monitoring of GLQs may lead to unambiguous detections of intrinsic and extrinsic variations,
accurate determinations of cosmological parameters, and valuable information on the structure
and composition of lensing galaxies at intermediate redshifts. We describe some observation
strategies to analyse the GLQ population at z ~ 1.5, using ISSIS (CfS) on board WSO-UV.
AN OBSCURED CLUSTER ASSOCIATED WITH THE HII REGION RCW173
Marco Amparo, Negueruela Ignacio
Universidad de Alicante, Spain
We present UBV photometry and spectroscopy of stars in the direction of the to HII
region RCW173, located at l=25.3 degrees, projected towards Galactic Bar. We find evindence
for several populations of early type stars at different distances. We identify the main ionization
source of the HII region as a heavily reddened O7 II supergiant, which belongs to an obscured
cluster that seems to be emerging from the molecular cloud associated with the bright nebulosity.
We find several O and early-B members of this newly identified cluster, which we name as
Alicante 6.
MOLECULE SUBLIMATION AND PHOTODISSOCIATION AROUND HII REGIONS
Kirsanova M., Wiebe D., Akimkin V.
Institute of Astronomy, RAS
Chemical composition of gas and dust mantles in a cold dense cloud during the expansion
of an HII region is studied with a chemo-dynamical model. We found that photoevaporation of
molecules, rather than thermal or cosmic ray evaporation, is the main way to bring species to the
gas phase from dust icy mantles. Sharp evaporation fronts are formed in a molecular cloud with
high initial gas density. They are close to each other and to the shock front, so in fact we have a
single evaporation front for various species. In a cloud with moderate gas density, desorption
from icy mantles occurs gradually rather than in a jump-like fashion. The distances between
evaporation fronts are significant in this case, so the overall distributions of various gas-phase
species in the cloud are also different. Various molecular components reside in regions with
different kinematics, which would result in different spectral signatures. Photoreactions are
another important factor determining the chemical composition in the vicinity of a young star.
Cross sections of these photoreactions are largest in the UV band. We discuss how important it is
to know accurate values of the cross sections.
AGN IN UV LIGHT: TESTING THE MODELS OF MATTER OUTFLOW
E.Y. Vilkoviskij and S.N. Yefimov
Fesenkov Astrophysical Institute, Almaty, Kazakhstan)
We present a theoretical model of the matter outflow from AGN. The model includes the
hot gas dynamics calculations, the calculation of dynamics of the cold clouds embedded in the
hot gas flow, and the radiation transfer calculations in the two-phase medium. The model permits
numerical simulations of the absorption spectra of AGN in the UV and X-ray bands. We used the
model for calculation of the ultraviolet spectrum of the quasars q1303+308. Our model
calculations permits to obtain some thin details seen in the observed absorption spectrum, which
confirms the validity of the main issues of our theory and model of the two-phase medium
dynamics in the radiation field for the sake of interpretation of the absorption spectra of the
matter outflow from AGN.
The WSO-UV mission provides us with the opportunities to further testing and
developing of this model.
VARIATION OF DUST SIZE DISTRIBUTION TRANSPORTED INTO IGM.
Shaginyan Alexey
Southern Federal University, Russia
Radiation pressure is thought to be an efficient mechanism of dust transport from galactic
disks through their halos into the intergalactic space. The forces governing dust motion are:
radiation pressure, gravitation, Lorentz force, friction through Coulomb and direct collisions.
While radiation pressure and friction in direct collisions are proportional to the square of dust
radius, gravitational force is proportional to the radius cube, and Lorentz and Coulomb forces
depend on dust charge. This therefore means that dust motion is selective, and when transported
into the intergalactic medium they change their size distribution: the heaviest particles are bound
to the gravitating (stellar and dark matter) disk, while the lightest are collisionally coupled to the
gaseous disk. As a results, the size distribution becomes narrower and flatter, however, depends
strongly on exact distribution of gravitational potential, gas density profile, and magnetic field
configuration. We show several examples of variations of the dust size spectrum.
DYNAMICS OF GALAXIES CLUSTER IN THE WSO-UV PROJECT
Chechin Leonid
AFIF, Kazakhstan
Number of space telescopes can detect hundreds of thousands galaxies that locate on sky
at distances about 10-12 billions light years of order. That is why one of the WSO-UV scientific
priorities is the processes of galaxies creation and their clusters searching for - that allowed to
lighting the dark matter phenomena, for example. It relates to the practically absence of such
searching due to deficiency of deep UV; images. They plan to realize by UV- cameras of WSOUV that allowed search galaxies at relatively small distances corresponded to, where - small
value. As example of such galaxy cluster is the cluster Abell 2218, that locates at distance about
three billions light years ( ) in Draco constellation. The theory of stationary galactic system on
the nonbaryonic matter background is presents. The basic kinetic equation for distribution
function of system gravitating galaxies with general potential was deduced for this Where - is the
density of gravitating baryonic substance, and - are the density and pressure of antigravitating
nonbaryonic substance. Some dynamical consequences of this equation for the spherical galaxies
distribution are discussed.