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HV2112, a Thorne-A >> ytkow object or a super asymptotic giant branch star

Tout, Christopher A.; Zytkow, Anna N.; Church, Ross LU ; Lau, Herbert H. B.; Doherty, Carolyn L. and Izzard, Robert G. (2014) In Monthly Notices of the Royal Astronomical Society 445(1). p.36-40
Abstract
The very bright red star HV2112 in the Small Magellanic Cloud could be a massive Thorne-A >> ytkow object (TA >> O), a supergiant-like star with a degenerate neutron core. With a luminosity of over 10(5) L-aS (TM), it could also be a super asymptotic giant branch (SAGB) star, a star with an oxygen/neon core supported by electron degeneracy and undergoing thermal pulses with third dredge up. Both TA >> Os and SAGB stars are expected to be rare. Abundances of heavy elements in HV2112's atmosphere, as observed to date, do not allow us to distinguish between the two possibilities based on the latest models. Molybdenum and rubidium can be enhanced by both the irp-process in a TA >> O or by the s-process in SAGB stars.... (More)
The very bright red star HV2112 in the Small Magellanic Cloud could be a massive Thorne-A >> ytkow object (TA >> O), a supergiant-like star with a degenerate neutron core. With a luminosity of over 10(5) L-aS (TM), it could also be a super asymptotic giant branch (SAGB) star, a star with an oxygen/neon core supported by electron degeneracy and undergoing thermal pulses with third dredge up. Both TA >> Os and SAGB stars are expected to be rare. Abundances of heavy elements in HV2112's atmosphere, as observed to date, do not allow us to distinguish between the two possibilities based on the latest models. Molybdenum and rubidium can be enhanced by both the irp-process in a TA >> O or by the s-process in SAGB stars. Lithium can be generated by hot bottom burning at the base of the convective envelope in either. HV2112's enhanced calcium could thus be the key determinant. Neither SAGB stars nor TA >> Os are known to be able to synthesize their own calcium but it may be possible to produce it in the final stages of the process that forms a TA >> O, when the degenerate electron core of a giant star is tidally disrupted by a neutron star. Hence, it is more likely, on a fine balance, that HV2112 is indeed a genuine TA >> O. (Less)
Please use this url to cite or link to this publication:
author
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
stars: abundances, stars: AGB and post-AGB, binaries: close, stars:, evolution, stars: individual: HV2112
in
Monthly Notices of the Royal Astronomical Society
volume
445
issue
1
pages
36 - 40
publisher
Wiley-Blackwell
external identifiers
  • wos:000344231000008
  • scopus:84930834673
ISSN
1365-2966
DOI
10.1093/mnrasl/slu131
language
English
LU publication?
yes
id
e076f50e-5f5f-4cd2-85d1-6b9c2c430e78 (old id 4874982)
date added to LUP
2014-12-30 15:29:10
date last changed
2017-03-19 03:21:47
@article{e076f50e-5f5f-4cd2-85d1-6b9c2c430e78,
  abstract     = {The very bright red star HV2112 in the Small Magellanic Cloud could be a massive Thorne-A >> ytkow object (TA >> O), a supergiant-like star with a degenerate neutron core. With a luminosity of over 10(5) L-aS (TM), it could also be a super asymptotic giant branch (SAGB) star, a star with an oxygen/neon core supported by electron degeneracy and undergoing thermal pulses with third dredge up. Both TA >> Os and SAGB stars are expected to be rare. Abundances of heavy elements in HV2112's atmosphere, as observed to date, do not allow us to distinguish between the two possibilities based on the latest models. Molybdenum and rubidium can be enhanced by both the irp-process in a TA >> O or by the s-process in SAGB stars. Lithium can be generated by hot bottom burning at the base of the convective envelope in either. HV2112's enhanced calcium could thus be the key determinant. Neither SAGB stars nor TA >> Os are known to be able to synthesize their own calcium but it may be possible to produce it in the final stages of the process that forms a TA >> O, when the degenerate electron core of a giant star is tidally disrupted by a neutron star. Hence, it is more likely, on a fine balance, that HV2112 is indeed a genuine TA >> O.},
  author       = {Tout, Christopher A. and Zytkow, Anna N. and Church, Ross and Lau, Herbert H. B. and Doherty, Carolyn L. and Izzard, Robert G.},
  issn         = {1365-2966},
  keyword      = {stars: abundances,stars: AGB and post-AGB,binaries: close,stars:,evolution,stars: individual: HV2112},
  language     = {eng},
  number       = {1},
  pages        = {36--40},
  publisher    = {Wiley-Blackwell},
  series       = {Monthly Notices of the Royal Astronomical Society},
  title        = {HV2112, a Thorne-A >> ytkow object or a super asymptotic giant branch star},
  url          = {http://dx.doi.org/10.1093/mnrasl/slu131},
  volume       = {445},
  year         = {2014},
}