تقرير
The VLT-FLAMES survey of massive stars. NGC2004#115: A triple system hosting a possible short period B+BH binary
| العنوان: | The VLT-FLAMES survey of massive stars. NGC2004#115: A triple system hosting a possible short period B+BH binary |
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| المؤلفون: | Lennon, D. J., Dufton, P. L., Villaseñor, J. I., Evans, C. J., Langer, N., Saxton, R., Monageng, I. M., Toonen, S. |
| المصدر: | A&A 665, A80 (2022) |
| سنة النشر: | 2021 |
| المجموعة: | Astrophysics |
| مصطلحات موضوعية: | Astrophysics - Solar and Stellar Astrophysics |
| الوصف: | The star NGC2004#115 in the LMC, originally classified as an (SB1) Be spectroscopic binary, bears some morphological resemblance to the Galactic systems LB-1 and HR 6819, both of which are proposed as either Be+black hole (BH) or Be+stripped He-star systems. Two data-sets (ESO/VLT and SALT) of multi-epoch optical spectra of NGC 2004#115, separated by baseline of $\sim$20 years, lead us conclude it is a triple system hosting an inner binary with a period of 2.92 d, eccentricity $\sim$0.0 and mass function $\sim$0.07 $M_\odot$. The inner binary harbours a B-type star (the primary) with projected rotational velocity of 10km/s, and luminosity $\log L/L_\odot$=3.87, contributing $\sim$60% of the V-band light to the system. The secondary is not detected, while the tertiary, which contributes 40% of the light, is tentatively identified as a less luminous B-type star with high projected rotational velocity. No ellipsoidal light variability is detected, with stringent limits being set by MACHO and Gaia data. Assuming the primary to be a main sequence star yields a mass of 8.6$ M_\odot$, while the additional assumption of synchronous rotation constrains the inclination to be almost pole-on with i~9 degrees, implying the secondary is a BH with a mass of $\sim$25 $M_\odot$. A low mass stripped star with similar luminosity is ruled out as a potential solution as its mass implies a Roche radius that is substantially smaller than the stellar radius. The outer period likely exceeds 120 days and, while the disk-like emission is variable (it is almost absent in the SALT dataset), it may be associated with the inner binary rather than the rapidly rotating tertiary. XMM-Newton provides an upper limit of 5x$10^{33}$ ergs/s on the X-ray flux, consistent with, though not constraining of, the system hosting a quiescent B+BH binary. A number of caveats to this scenario are discussed in the paper. Comment: 19 pages, 21 figures. Accepted for publication in Astronomy and Astrophysics Version 2 |
| نوع الوثيقة: | Working Paper |
| DOI: | 10.1051/0004-6361/202142413 |
| URL الوصول: | http://arxiv.org/abs/2111.12173 |
| رقم الأكسشن: | edsarx.2111.12173 |
| قاعدة البيانات: | arXiv |
| DOI: | 10.1051/0004-6361/202142413 |
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