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Beasor, ER, Davies, B, Cabrera-Ziri, I and Hurst, G (2018) A critical re-evaluation of the Thorne-Zytkow object candidate HV 2112. Monthly Notices of the Royal Astronomical Society, 479 (3). pp. 3101-3105. ISSN 0035-8711
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A critical re-evaluation of the Thorne–Żytkow object candidate HV 2112.pdf - Published Version Download (1MB) | Preview |
Abstract
It has been argued in the literature that the star HV 2112 in the Small Magellanic Cloud (SMC) is the first known example of a Thorne–Żytkow object (TŻO), a red supergiant with a degenerate neutron core. This claim is based on the star having a high luminosity (log (L/L⊙) ≳ 5), an extremely cool effective temperature, and a surface enriched in in lithium, calcium, and various irp-process elements. In this paper we re-examine this evidence, and present new measurements of the stellar properties. By compiling archival photometry from blue to mid-infrared for HV 2112 and integrating under its spectral energy distribution, we find a bolometric luminosity in the range of log (L/L⊙) = 4.70–4.91, lower than that found in previous work and comparable to bright asymptotic giant branch (AGB) stars. We compare a VLT+XSHOOTER spectrum of HV 2112 to other late-type, luminous SMC stars, finding no evidence for enhancements in Rb, Ca, or K, though there does seem to be an enrichment in Li. We therefore conclude that a much more likely explanation for HV 2112 is that it is an intermediate mass (∼5 M⊙) AGB star. However, from our sample of comparison stars we identify a new TŻO candidate, HV 11417, which seems to be enriched in Rb but for which we cannot determine a Li abundance.
| Item Type: | Article |
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| Additional Information: | This article has been accepted for publication in Monthly Notices of the Royal Astronomical Society ©: 2018 The Authors Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved. |
| Uncontrolled Keywords: | 0201 Astronomical And Space Sciences |
| Subjects: | Q Science > QB Astronomy Q Science > QC Physics |
| Divisions: | Astrophysics Research Institute |
| Publisher: | Oxford University Press |
| Related URLs: | |
| Date Deposited: | 16 Oct 2018 12:11 |
| Last Modified: | 04 Sep 2021 02:19 |
| DOI or ID number: | 10.1093/mnras/sty1744 |
| URI: | https://researchonline.ljmu.ac.uk/id/eprint/9489 |
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