2004A&A...420..217E


C.D.S. - SIMBAD4 rel 1.7 - 2021.01.22CET20:55:19

2004A&A...420..217E - Astronomy and Astrophysics, volume 420, 217-223 (2004/6-2)

OH spectral evolution of oxygen-rich late-type stars.

ETOKA S. and LE SQUEREN A.M.

Abstract (from CDS):

We investigated the main-line spectral evolution with shell thickness of oxygen rich AGB stars. The study is based on a sample of 30 sources distributed along the IRAS colour-colour diagram. The sources were chosen to trace the Miras with thick shells and the whole range of OH/IR stars. The Miras exhibit a 1665MHz emission strength comparable to that at 1667MHz. Even though the Miras of the study have quite thick shells, their spectral characteristics in both main lines attest to a strong heterogeneity in their OH shell with, in particular, the presence of significant turbulence and acceleration. The expansion velocity has been found to be about the same at 1665 and 1667MHz, taking into account a possible velocity turbulence of 1-2km/s at the location of the main-line maser emission. An increase in the intensity ratio 1667/1665 with shell thickness has been found. A plausible explanation for such a phenomenon is that competitive gain in favour of the 1667MHz line increases when the shell is getting thicker. There is an evolution in the spectral profile shape with the appearance of a substantial inter-peak signal when the shell is getting thicker. Also, inter-peak components are found and can be as strong as the external standard peaks when the shell is very thick. This trend for an increase of the signal in between the two main peaks is thought to be the result of an increase of the saturation with shell thickness. All sources but two - a Mira and an OH/IR star from the lower part of the colour-colour diagram - are weakly polarized. The strong polarization observed for those two particular objects is thought to be the result of perturbations in their shells.

Abstract Copyright:

Journal keyword(s): stars: AGB and post-AGB - stars: circumstellar matter - masers - line: profiles - stars: mass-loss - evolution stars:

Simbad objects: 30

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Number of rows : 30

N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2021
#notes
1 V* V372 Lup Mi* 15 25 47.5600580359 -36 13 54.257158918     12.63     M8.5 21 0
2 V* MW Ser Mi* 15 28 43.6873984337 +03 49 42.981302411     14     M7/9 52 0
3 IRAS 17220-2448 OH* 17 25 07.2 -24 51 03           ~ 6 0
4 OH 354.88 -0.54 OH* 17 35 02.72 -33 33 29.4           ~ 66 1
5 IRAS 17385-3332 pA* 17 41 52.2828274827 -33 33 40.575162432           ~ 26 0
6 IRAS 17392-3319 OH* 17 42 33.73320 -33 20 59.8020           ~ 11 0
7 RAFGL 5379 OH* 17 44 24.0038735481 -31 55 35.428622508           ~ 83 0
8 OH 1.3 +1.0 OH* 17 44 58.73040 -27 14 42.8316           ~ 32 0
9 OH 1.1 -0.8 OH* 17 51 26.777 -28 25 37.13           O-rich 39 1
10 OH 358.497 -2.952 OH* 17 53 47.47 -31 44 26.2           ~ 13 0
11 OH 7.96 +1.45 OH* 17 58 04.9 -21 21 07           ~ 23 0
12 OH 9.055 -0.156 OH* 18 06 22.626 -21 11 27.39           ~ 8 0
13 OH 15.7 +0.8 OH* 18 16 25.376 -14 55 15.66           ~ 72 0
14 GLMP 765 Mas 18 22 43.1 -12 47 41           ~ 31 0
15 OH 21.5 +0.5 OH* 18 28 30.937 -09 58 14.32           ~ 87 0
16 OH 26.5 +0.6 OH* 18 37 32.50920 -05 23 59.1936           ~ 286 0
17 OH 30.7 +0.4 OH* 18 45 52.39728 -01 46 42.4776           ~ 64 1
18 OH 30.1 -0.7 OH* 18 48 41.949 -02 50 28.85           ~ 93 0
19 OH 32.0 -0.5 OH* 18 51 26.222 -01 03 52.31           ~ 64 0
20 GLMP 876 Mas 19 08 58.8 +08 37 45           ~ 28 0
21 RAFGL 2333 C* 19 09 56.859 +09 26 51.43           C-rich 28 0
22 RAFGL 2362 OH* 19 18 14.67 +23 49 27.9           ~ 51 0
23 IRAS 19190+1128 * 19 21 26.7 +11 33 59           ~ 14 0
24 IRC +10420 pA* 19 26 48.0981288433 +11 21 16.756524951   13.98 11.66     F8Ia+e 455 0
25 OH 51.8 -0.1 OH* 19 27 42.04 +16 37 24.0           ~ 38 1
26 RAFGL 5408S * 19 37 24.00 +20 36 57.8           ~ 23 0
27 V* XX Aqr Mi* 20 42 18.8943874535 -08 15 30.738526728   13.53 11.96     M4 13 0
28 V* U Equ pA* 20 57 16.2826997638 +02 58 44.538087517           ~ 55 0
29 NSV 25875 OH* 22 19 27.48 +59 51 21.7           ~ 134 0
30 V* MY Cep s*r 22 54 31.6975860144 +60 49 38.970114015           M7.5I 79 0

    Equat.    Gal    SGal    Ecl

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2021.01.22-20:55:19

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