Dust & Gas around Stars Young & Old, Near & Far
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Dust & Gas around Stars Young & Old, Near & Far Kathleen Kraemer ISR Scientific Collaborators Steve Price (BC) Greg Sloan (Cornell (formerly BC)) Don Mizuno (BC) Tom Kuchar (BC) Charles Engelke (BC) Bev Smith (ETSU) Joe Hora (CfA) Ciska Kemper (Acad. Sinica) Nick Wright (CfA) Paul Ruffle (U. Manchester) Joana Oliveira (Keele U.) Nicola Schneider (U. Paris) Sean Carey (Spitzer SciCtr, formerly BC) … Stellar Evolution protostar Supernova (SN) stellar nursery black hole protostar mass interstellar medium blue supergiant blue supergiant protostar blue supergiant black hole Type II SN blue giant protostar yellow giant red giant Type II SN neutron star Type Ia SN yellow dwarf (Sun) protostar protostar protostar red giant red dwarf brown dwarf planetary nebula red dwarf time white dwarf white dwarf brown dwarf Chart Credit: NASA IR Astronomy Surveys η Car – luminous blue variable & nebula IRAS 1983 MSX 1996 VISIBLE Spitzer 2005 Image credits: NASA, DSS, AFRL, NASA Spitzer Space Telescope Mapping Projects •Cygnus-X •MIPS 24 & 70 µm •IRAC 4-band •MIPSGAL •MIPS 24 & 70 µm Spectroscopy Projects •Small Magellanic Cloud •Large Magellanic Cloud •Local Group Galaxies •Cygnus-X Werner et al. 2004, Rieke et al. 2004, Fazio et al. 2004, Houck et al. 2004 •Infrared Spectrograph (IRS) •5.2-38 µm •Infrared Array Camera (IRAC) •3.6, 4.5, 5.8, 8.0 µm • Multiband Imaging Photometer for Spitzer (MIPS) •24, 70, 160 µm • Cryo: 2003-2009 Post-cryo: 2009-2014 Cygnus-X Massive Star Forming Region <2 kpc >103 OB stars > 104 protostars M>105 M Mtot>106 M •blue=3.6 µm ~stars •green=8 µm ~warm gas/dust •red=24 µm ~cool dust Hora et al. 2009 Infrared Dark Clouds IRDCs LDN 896 • discovered by MSX & ISO • very dense cold dust lanes • youngest, most deeply embedded YSOs near AFGL 2636 near G078.0+00.6 Cygnus-X Evolved Stars Evolved Object Type PNe WRs pAGBs C*s S*s SNRs Miras semi-reg Cepheids RR Lyr cont. bin Dw. Nov. other V*s # in # Det’d at Det’n 24µm Region 24µm Rate 7 9 2 52 6 10 4 4 4 1 19 3 85 5 9 2 51 5 ? 4 4 4 ? 4 1 61 71% 100% 100% 98% 83% ? 100% 100% 100% ? 21% 33% 72% Kraemer et al. 2010 Evolved Stars BD+43 3710 Carbon star with a bipolar outflow HBHA 4202-22 G79.29+0.46 Moving WolfRayet star with shell Luminous blue variable near IRDC Evolved Stars •He-shell flashes & dredge-ups create C, N etc. & move it out C/O>1 → carbon star molecule & dust formation, wind Adapted from Karakas & Lattanzio 2008 and Habing & Olofsson 2004 Evolved Stars: Models HBHA 4202-22 Line through peak: 30° Space motion: 31° Evolved Stars: Models HBHA 4202-22 Radiative transfer model with 3 carbon-rich dust shells thin shell & model thick shell & model MIPSGAL 24 µm Survey blue= 3.6 µm ~stars green=8 µm ~warm gas/dust red=24 µm ~cool dust Carey et al. 2009, Benjamin et al. 2003 Evolved Stars •Catalog of >400 disks & rings in MIPSGAL •Little or no emission at other wavelengths •~15% previously ID’d as evolved objects •Likely planetary nebulae or other evolved objects – missing population Mizuno et al. 2010, Flagey et al. 2009 Magellanic Clouds Image credit: ESO Visible Magellanic Clouds IRAS 100 µm The Small Magellanic Cloud • low metallicity: ~0.2xsolar • nearby: ~60 kpc • local surrogate for galaxies in the earlier Universe WISE • SKY model & LMC to predict object types for brightest MSX objects • Spitzer’s IRS spectra to verify SMC IRS Project The plan • The plan: observe several of each type of evolved star • These stars create: • dust – energy balance • C & N – planets, life • The result: many, many carbon stars! What happened Sloan et al. 2006 SMC IRS Project Carbon rich Oxygen rich silicates crystalline silicates silicates C2H2, HCN, CS, C3, CN oxides – Si, Al, Mg, Fe Extended IRS Projects Carbon rich •initial study: 36 objects •extending to other IRS programs •~250+ SMC •~1000+ LMC •~dozens Local Group C2H2, HCN, CS, C3, CN Sloan et al. 2012 Spectra for Calibration • Mid-IR selection, isolated, ~uniform sky coverage • Non-variable to <<10% at 12 & 25 µm (IRAS) • 600+ calibration stars, 1-35 µm spectral templates • Moderate spectral resolution & photometric accuracy • Limited actually measured spectra Spectra for Calibration • Upgrades current calibration network to improve: – absolute accuracy (MSX) – spectral resolution (ISO) – wavelength coverage (ISO, MSX, DIRBE, Tycho/Hip, Kurucz, Pickles) – dynamic range (ISO, MSX, Spitzer) – variability assessments (nearIR, visible) Price et al. 2004, Engelke et al. 2006, 2010 Variability Assessments 3500 4000 β UMi 3300 T Cep 3500 3100 3000 Flux (Jy) 2700 2500 2300 2100 2500 2000 1500 1000 1900 1.25 µm 1700 1.25 µm 500 0 1500 0 50 100 150 0 200 50 100 150 200 t (weeks) t (weeks) 80 12 Lomb-Scargle periodogram 10 6 Lomb-Scargle periodogram 70 60 Power 8 Power Flux (Jy) 2900 50 40 30 4 20 2 10 0 0 3 30 Period (weeks) 3 30 Period (weeks) Price et al. 2010 IR Periodogram Results “Expected” Variables IR Standards 16; 7% 12; 5% 17; 3% 1; 0% 199; 88% 589; 97% Control Sample IR Bright Variables; 266; 15% Candidates; 58; 3% 19; 33% Non-variables; 1457; 82% 36; 62% 3; 5% Kraemer et al. 2010 Visible assessment in-progress IR-Visible Phase Lags Vis-IR Lag (days) 120 100 80 Vis-IR Lag (days) Peak Matching 60 40 20 0 80 ∆T, shocks, molecular formation cause a lag between the visible peak & the IR peaks Miras C stars S stars SRs 70 Co 0 60 Miras C stars S stars SRs esu ts 200 X-Cor lag = 0.098P 400 IR + 8.15 IR Period (days) 600 50 40 30 20 10 Cross-correlation 0 0 200 400 IR Period (days) 600 TODAY: Last transit of Venus til 2117 I: 1st contact ~6:05pm II: 2nd contact ~6:23pm Sunset ~8:18pm Boston University & Harvard-Smithsonian observing from rooftops & other locations (incl. indoors if cloudy) www.bu.edu/astronomy/events/venustransit www.cfa.harvard.edu/events.mon.html NH Astro.Soc & McAuliffe-Shepard Disc.Ctr. nhastro.com/events/transit.php starhop.com/ ($) sunearthday.nasa.gov/2012/transit/webcast.php www.exploratorium.edu/venus/ Thanks!
