Probing the mass-loss history of the unusual Mira variable R Hya through its infrared CO wind
Decin, L ; Blomme, L ; Reyniers, M ; Ryde, Nils LU
and Hinkle, K H
(2008)
In Astronomy & Astrophysics
484(2).
p.55-401
- Abstract
- Context. The unusual Mira variable R Hya is well known for its declining period between AD 1770 and 1950, which is possibly attributed to a recent thermal pulse.
Aims. The goal of this study is to probe the circumstellar envelope (CSE) around R Hya and to check for a correlation between the derived density structure and the declining period.
Methods. We investigate the CSE around R Hya by performing an in-depth analysis of (1.) the photospheric light scattered by three vibration-rotation transitions in the fundamental band of CO at 4.6 $mu$m; and (2.) the pure rotational CO J = 1-0 through 6-5 emission lines excited in the CSE. The vibrational-rotational lines trace the inner CSE within 3.5´´, whereas the pure rotational... (More) - Context. The unusual Mira variable R Hya is well known for its declining period between AD 1770 and 1950, which is possibly attributed to a recent thermal pulse.
Aims. The goal of this study is to probe the circumstellar envelope (CSE) around R Hya and to check for a correlation between the derived density structure and the declining period.
Methods. We investigate the CSE around R Hya by performing an in-depth analysis of (1.) the photospheric light scattered by three vibration-rotation transitions in the fundamental band of CO at 4.6 $mu$m; and (2.) the pure rotational CO J = 1-0 through 6-5 emission lines excited in the CSE. The vibrational-rotational lines trace the inner CSE within 3.5´´, whereas the pure rotational CO lines are sensitive probes of the cooler gas further out in the CSE.
Results. The combined analysis bear evidence of a change in mass-loss rate some 220 yr ago (at ~150 $R_{star}$ or ~1.9 arcsec from the star). While the mass-loss rate before AD 1770 is estimated to be ~ $2 imes 10^$ $M_{odot}$/yr, the present day mass-loss rate is a factor of ~20 lower. The derived mass-loss history nicely agrees with the mass-loss rate estimates by Zijlstra et al. (2002) on the basis of the period decline. Moreover, the recent detection of an AGB-ISM bow shock around R Hya at 100 arcsec to the west by Wareing et al. (2006) shows that the detached shell seen in the 60 $mu$m IRAS images can be explained by a slowing-down of the stellar wind by surrounding matter and that no extra mass-loss modulation around 1-2 arcmin needs to be invoked.
Conclusions. Our results give empirical evidence to the thermal-pulse model, which is capable of explaining both the period evolution and the mass-loss history of R Hya . (Less)
Please use this url to cite or link to this publication:
https://lup.lub.lu.se/record/945387
- author
- Decin, L
; Blomme, L
; Reyniers, M
; Ryde, Nils
LU
and Hinkle, K H
- organization
- publishing date
- 2008
- type
- Contribution to journal
- publication status
- published
- subject
- keywords
- stars: mass-loss, stars: circumstellar matter, stars: AGB and post-AGB, line: profiles, radiative transfer, stars: individual: R Hya
- in
- Astronomy & Astrophysics
- volume
- 484
- issue
- 2
- pages
- 55 - 401
- publisher
- EDP Sciences
- external identifiers
-
- wos:000256309700014
- scopus:44449141960
- ISSN
- 0004-6361
- DOI
- 10.1051/0004-6361:20079312
- language
- English
- LU publication?
- yes
- id
- ec6585c2-fcda-446f-9e1c-4ee5c7e19840 (old id 945387)
- date added to LUP
- 2016-04-01 13:10:56
- date last changed
- 2024-04-10 01:41:18
@article{ec6585c2-fcda-446f-9e1c-4ee5c7e19840,
abstract = {{Context. The unusual Mira variable R Hya is well known for its declining period between AD 1770 and 1950, which is possibly attributed to a recent thermal pulse.<br/><br>
Aims. The goal of this study is to probe the circumstellar envelope (CSE) around R Hya and to check for a correlation between the derived density structure and the declining period.<br/><br>
Methods. We investigate the CSE around R Hya by performing an in-depth analysis of (1.) the photospheric light scattered by three vibration-rotation transitions in the fundamental band of CO at 4.6 $mu$m; and (2.) the pure rotational CO J = 1-0 through 6-5 emission lines excited in the CSE. The vibrational-rotational lines trace the inner CSE within 3.5´´, whereas the pure rotational CO lines are sensitive probes of the cooler gas further out in the CSE.<br/><br>
Results. The combined analysis bear evidence of a change in mass-loss rate some 220 yr ago (at ~150 $R_{star}$ or ~1.9 arcsec from the star). While the mass-loss rate before AD 1770 is estimated to be ~ $2 imes 10^$ $M_{odot}$/yr, the present day mass-loss rate is a factor of ~20 lower. The derived mass-loss history nicely agrees with the mass-loss rate estimates by Zijlstra et al. (2002) on the basis of the period decline. Moreover, the recent detection of an AGB-ISM bow shock around R Hya at 100 arcsec to the west by Wareing et al. (2006) shows that the detached shell seen in the 60 $mu$m IRAS images can be explained by a slowing-down of the stellar wind by surrounding matter and that no extra mass-loss modulation around 1-2 arcmin needs to be invoked.<br/><br>
Conclusions. Our results give empirical evidence to the thermal-pulse model, which is capable of explaining both the period evolution and the mass-loss history of R Hya .}},
author = {{Decin, L and Blomme, L and Reyniers, M and Ryde, Nils and Hinkle, K H}},
issn = {{0004-6361}},
keywords = {{stars: mass-loss; stars: circumstellar matter; stars: AGB and post-AGB; line: profiles; radiative transfer; stars: individual: R Hya}},
language = {{eng}},
number = {{2}},
pages = {{55--401}},
publisher = {{EDP Sciences}},
series = {{Astronomy & Astrophysics}},
title = {{Probing the mass-loss history of the unusual Mira variable R Hya through its infrared CO wind}},
url = {{http://dx.doi.org/10.1051/0004-6361:20079312}},
doi = {{10.1051/0004-6361:20079312}},
volume = {{484}},
year = {{2008}},
}