PROPERTIES OF CIRCUMSTELLAR DUST IN SYMBIOTIC MIRAS
D.
1
Kotnik-Karuza ,
T.
1
Jurkić ,
M.
2
Friedjung
1Physics
Dept., University of Rijeka, Rijeka, Croatia
2Institut d'Astrophysique de Paris, Université Pierre & Marie Curie, Paris, France
Abstract
Observational data and methods of analysis
Results
JHKL magnitudes of seven southern symbiotic stars, o Cet, KM Vel, V835 Cen, V366 Car, RR Tel, R Aqr and RX Pup, as
observed for at least 10 years at different epochs at SAAO, have been analysed. The magnitudes have been corrected for
interstellar reddening using visual extinctions Av given in Table 1. The light curves were corrected for Mira pulsations by an
approximate procedure to show only the long-term variations. RR Tel, R Aqr and RX Pup give evidence of marked
obscuration events.
Modeling of circumstellar properties of the dust shell around the cool Mira component was carried out by use of the numerical
code DUSTY, assuming spherical geometry, with Mira in the centre of the spherical dust shell. We used black body input
radiation from the Mira at a temperature between 2300 K and 2600 K depending on spectral class and in agreement with data
from the literature. Only  Cet stellar temperature could be modeled due to its high spectral class variability. As the Mira
component has strong stellar winds, envelope expansion is driven by radiation pressure on the dust grains. In the analytical
approximation for radiatively driven winds the number density h is a function of the scaled radius y =r/rin, of the initial vi and
final wind ve velocity, while rin is the inner dust shell radius (sublimation radius):
h
1
y2
Two-colour diagrams of seven southern symbiotic Miras with theoretical
models and extinctions at K (AK)
y
y  1   vi / ve 
We present a study of the properties of circumstellar dust in symbiotic Miras during sufficiently long
time intervals, including observed obscuration events. The published JHKL magnitudes of o Ceti, RX
Pup, KM Vel, V366 Car, V835 Cen, RR Tel, R Aqr have been collected. In order to follow the
evolution of their colours in time, we removed the Mira pulsations to correct their light curves.
Assuming spherical distribution of the dust in the close neighbourhood of the Mira, the DUSTY code
was used to solve the radiative transfer in order to determine the dust temperature and its properties in
each particular case.
The preliminary results of this systematic study of dust envelopes in symbiotic stars with Miras as cool
components provide information on nature of dust in these objects.
2
In the applied MRN dust grain size distribution n  a   a  q , ( amin  a  amax ), the minimum grain size of amin = 0.005 m
and q = 3.5 are taken as fixed input parameters, while maximum grain size amax is a free parameter determined by modeling.
Dust composition typical for Mira stars containing 100% warm silicates has been assumed. Outer dust shell radius is fixed to
20 rin, contrary to the inner dust shell radius rin which is obtained by fitting, together with the dust sublimation temperature
Tdust as a linked parameter.
Symbiotic Other name
Spectral class
Mira
et al. 1997, ApJ, 482, L175
HD 14386
Mira M2-7III Karovska
 Cet
Whitelock et al. 1988, IAUC 103, p. 47
MWC 35
Acker et al. 1988, A&AS, 73, 325
Mira M
KM Vel Hen 2-34
Whitelock et al. 1988, IAUC 103, p. 47
d
P
(kpc) (days)
0.01 0.12 331-333
3.2
9.0
370
V835 Cen Hen 2-106 Mira M  M5
Mira M6
V366 Car Hen 2-38
Hen 3-1811 Mira M6/M5
RR Tel
3.9
2.8
0.3
9.4
3.8
2.5
400
433
387
R Aqr
RX Pup
HD 222800 Mira M7, M8,
MWC 400
M4
HD 69190
Mira
Hen 3-138
M5.5/M5
Schulte-Ladbeck 1988, A&A, 189, 97
Muerset & Schmid 1999, A&AS, 137, 473
Allen 1980, MNRAS, 192, 521
Muerset & Schmid 1999, A&AS, 137, 473
Kenyon, 1986
Muerset & Schmid 1999, A&AS, 137, 473
Whitelock et al. 2000, MNRAS, 319, 728
Allen 1980, MNRAS, 192, 521
Muerset & Schmid 1999, A&AS, 137, 473
Av
0.01 0.27 383-386
2.0
3.0
580
Whitelock et al. 2000, MNRAS, 319, 728
Kholopov et al, 1985, GCVS, Nauka
Perryman et al. 1997, Hipp.Cat. ESA SP-1200
Feast et al. 1983a, MNRAS, 203, 373
Feast et al. 1983a, MNRAS, 203, 373
Feast et al. 1983a, MNRAS, 203, 373
Feast et al. 1983b, MNRAS, 202, 951
Penston et al. 1983, MNRAS, 202, 833
Kotnik-Karuza et al. 2006, A&A, 452, 503
Whitelock et al. 2000, MNRAS, 319, 728
Kholopov et al, 1985, GCVS, Nauka
Perryman et al. 1997, Hipp.Cat. ESA SP-1200
Whitelock et al. 1983, MNRAS, 203, 363
Feast et al. 1977, MNRAS, 179, 499
Mikolajewska et al. 1999, MNRAS, 205, 190
Light curves of seven southern symbiotics corrected for Mira pulsations
Obscuration
Minimum
Parameters
KM Vel
 Cet
TMira (K)
2600 (1)
2500 (2)
Tdust (K)
1100
1150
[1000 – 1150] [1050 – 1200]
0.15
0.10
amax (m)
[0.10 – 0.20] [0.05 – 0.15]
0.4 – 3.4
8.3 – 12.6
v
AK
0.04– 0.38
0.9 – 1.4
2.7 – 3.3
9.1 – 13.6
M (10-6 MSun/yr)
ve (km/s)
14.4 – 16.1
11.0 – 12.1
TMira (K)
Tdust (K)
amax (m)
Event(s)
Event III
(1994 –
1998)
v
AK
-6
M (10 MSun/yr)
ve (km/s)
TMira (K)
Tdust (K)
V835 Cen
2500 (2)
2500
950
[950 – 1000]
0.15
[0.15 – 0.20]
11.9 – 20.3
1.33 – 2.27
9.6 – 15.4
9.3 – 10.6
Symbiotic Miras
V366 Car
2500 (2)
1000
[900 – 1100]
0.15
[0.10 – 0.20]
1.3 – 5.4
0.15 – 0.65
4.6 – 9.7
17.4 – 20.9
2500
1000
[900 – 1100]
0.15
[0.10 – 0.20]
15.3
1.86
11.4
10.5
RR Tel*
2500 (3)
800
[600 – 850]
1.40
[1.20 – 1.80]
1.9 – 4.2
0.23 – 0.52
4.6 – 9.7
17.4 – 20.9
2500
750
[700 – 850]
0.85
[0.85 – 0.95]
4.6 – 9.5
0.56 – 1.16
9.7 – 17.3
12.0 – 15.7
amax (m)
v
AK
-6
M (10 MSun/yr)
ve (km/s)
(1)
RX Pup**
2300 (5)
700
[650 – 800]
1.70
[1.55 – 1.90]
3.2 – 5.3
0.36 – 0.60
8.7 – 13.8
13.9 – 16.0
2300
900
[850 – 900]
1.10
[1.10 – 1.15]
5.6 – 7.5
0.63 – 0.84
9.9 – 12.8
16.9 – 18.6
2300
700
[700 – 750]
2.00
[1.80 – 2.20]
2.5 – 5.1
0.28 – 0.57
7.0 – 13.9
13.9 – 16.8
fitted by the model
(2) fixed parameter defined by its spectral class and from Feast (1983a)
(3) fixed parameter defined by its spectral class and from Feast (1983b)
(4) fixed parameter defined by its spectral class and from Whitelock (2000) and Danchi (1994)
(5) fixed parameter defined by its spectral class and from Mikolajewska (1999)
* Obscuration events I, II and III
AK
M
Mira temperature
dust sublimation temperature
maximum grain size
visual optical depth
extinction at K
mass-loss rate
** Minimum obscuration 1980, 1986 and 1994; Obscuration events I and II
ve
terminal wind velocity
References
Danchi W. C. et al. 1994, AJ, 107, 1469
Ivezic Z., Elitzur M. 1997, MNRAS 287, 799
Ivezic Z. et al. 1999, User Manual for DUSTY, University of Kentucky Internal Report,
www.pa.uky.edu/ ~ moshe/dusty
Kotnik-Karuza D. et al. 2006, A&A, 452, 503
Mathis J.S., Rumpl W., Nordsieck K.H. 1977, ApJ, 217, 425
Mikolajewska J. 1999, in Optical and Infrared Spectroscopy of Circumstellar Matter, eds. E. W. Guenther, B.
Stecklum, S. Klose, ASP Conf. Ser. 188, 291
Ossenkopf V., Henning, Th., Mathis J.S. 1992, A&A, 261, 567
Whitelock P. A. 2002, in Symbiotic stars probing stellar evolution, eds. R. L. M. Corradi, J. Mikolajewska, T. J.
Mahoney, ASP Conf. Ser. 303, 41
TMira
Tdust
amax
R Aqr
2300 (4)
650
[630 – 670]
0.15
[0.13 – 0.17]
0.55 – 8.80
0.07 – 1.07
0.65 – 10.1
7.8 – 10.3
2300
650
[600 – 750]
0.15
[0.10 – 0.15]
10.9 – 21.4
1.3 – 2.6
12.3 – 23.0
6.3 – 7.4
v
Behaviour of parameters in transition from minimum to obscuration event:




generally v, AK, M , ve
R Aqr, V366 Car, V835 Cen  Tdust = const, amax (small grains) = const
RR Tel  Tdust = const, amax (large grains) 
RX Pup  Tdust, I, II , amax (large grains) 
Tdust, III < Tdust, I, II, amax, III > amax, I, II  fit less reliable, other processes contribute to colours
Sublimation temperature and small grains are in general not changed by obscuration, while large
grains tend to become smaller.