The Transformative Journey of HD 93521
| Autor: | Gies, Douglas R., Shepard, Katherine, Wysocki, Peter, Klement, Robert |
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| Rok vydání: | 2021 |
| Předmět: | |
| Druh dokumentu: | Working Paper |
| DOI: | 10.3847/1538-3881/ac43be |
| Popis: | HD 93521 is a massive, rapidly rotating star that is located about 1 kpc above the Galactic disk, and the evolutionary age for its estimated mass is much less than the time-of-flight if it was ejected from the disk. Here we present a re-assessment of both the evolutionary and kinematical timescales for HD 93521. We calculate a time-of-flight of 39 +/- 3 Myr based upon the distance and proper motions from Gaia EDR3 and a summary of radial velocity measurements. We then determine the stellar luminosity using a rotational model combined with the observed spectral energy distribution and distance. A comparison with evolutionary tracks for rotating stars from Brott et al. yields an evolutionary age of about 5 +/- 2 Myr. We propose that the solution to the timescale discrepancy is that HD 93521 is a stellar merger product. It was probably ejected from the Galactic disk as a close binary system of lower mass stars that eventually merged to create the rapidly rotating and single massive star we observe today. Comment: Accepted for AJ; 10 pages, 4 figures |
| Databáze: | arXiv |
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