A partially stripped massive star in a Be binary at low metallicity: A missing link towards Be X-ray binaries and double neutron star mergers
| Autor: | Ramachandran, V., Klencki, J., Sander, A. A. C., Pauli, D., Shenar, T., Oskinova, L. M., Hamann, W. -R. |
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| Rok vydání: | 2023 |
| Předmět: | |
| Zdroj: | A&A 674, L12 (2023) |
| Druh dokumentu: | Working Paper |
| DOI: | 10.1051/0004-6361/202346818 |
| Popis: | Standard binary evolutionary models predict a significant population of core helium-burning stars that lost their hydrogen-rich envelope after mass transfer via Roche-lobe overflow. However, there is a scarcity of observations of such stripped stars in the intermediate mass regime (~1.5 - 8$ M_{\odot}$), which are thought to be prominent progenitors of SN Ib/c. Especially at low metallicity, a significant fraction of these stars is expected to be only partially stripped, retaining a significant amount of hydrogen on their surfaces. For the first time, we discovered a partially stripped massive star in a binary with a Be-type companion located in the Small Magellanic Cloud (SMC) using a detailed spectroscopic analysis. The stripped-star nature of the primary is revealed by the extreme CNO abundance pattern and very high luminosity-to-mass ratio, which suggest that the primary is likely shell-hydrogen burning. Our target SMCSGS-FS 69 is the most luminous and most massive system among the known stripped star + Be binaries, with Mstripped ~3$ M_{\odot}$ and MBe ~17$ M_{\odot}$. Binary evolutionary tracks suggest an initial mass of Mini $\gtrsim 12 M_{\odot}$ for the stripped star and predict it to be in a transition phase towards a hot compact He star, which will eventually produce a stripped-envelope supernova. Our target marks the first representative of a so-far missing evolutionary stage in the formation pathway of Be X-ray binaries and double neutron star mergers. Comment: Accepted for publication as A&A Letter to the Editor |
| Databáze: | arXiv |
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