Ultraviolet spectroscopy reveals a hot and luminous companion to the Be star plus black hole candidate MWC 656
文献类型：期刊论文
| 作者 | Müller, Johanna1,2; Ramachandran, Varsha3; El, Kareem1,4; Sander, Andreas A. C.3,5; Bodensteiner, Julia6; Gies, Douglas R.7; Götberg, Ylva8; Rivinius, Thomas9; Shenar, Tomer10; Schösser, Elisa C.3 |
| 刊名 | ASTRONOMY & ASTROPHYSICS
 |
| 出版日期 | 2026-04-08 |
| 卷号 | 708 |
| 关键词 | binaries: spectroscopic stars: black holes stars: emission-line, Be stars: individual: MWC 656 stars: individual: MWC 656 |
| ISSN号 | 0004-6361 |
| DOI | 10.1051/0004-6361/202557960 |
| 产权排序 | 第11完成单位 |
| 文献子类 | Article |
| 英文摘要 | The Galactic Be star binary MWC 656 was long considered the only known Be star+black hole (BH) system, making it a critical benchmark for models of massive binary evolution and for the expected X-ray emission of Be+BH binaries. However, recent dynamical measurements cast doubt on the presence of a BH companion. We present new multi-epoch ultraviolet spectroscopy from the Hubble Space Telescope, combined with high-resolution optical spectra, to reassess the nature of the companion. The far-ultraviolet spectra reveal high-ionisation features - including prominent N V and He II lines - which are absent in the spectra of normal Be stars and are indicative of a hot, luminous companion. Spectral modelling shows that these features cannot originate from the Be star or from an accretion disc around a compact object. Instead, we find that the data are best explained by a hot (T-eff approximate to 85 kK), compact, hydrogen-deficient star with strong wind signatures, consistent with an intermediate-mass stripped star. Our revised orbital solution and composite spectroscopic modelling yield a companion mass of M-2 = 1.48(-0.46)(+0.55) M-circle dot, definitively ruling out a BH and disfavouring a white dwarf. MWC 656 thus joins the growing class of Be + stripped star binaries. The system's unusual properties - including a high companion temperature and wind strength - extend the known parameter space of such binaries. The continued absence of confirmed OBe+BH binaries in the Galaxy highlights a growing tension with population synthesis models. |
| 学科主题 | 天文学 ; 天文学 ; 恒星与银河系 |
| URL标识 | 查看原文 |
| 出版地 | 17, AVE DU HOGGAR, PA COURTABOEUF, BP 112, F-91944 LES ULIS CEDEX A, FRANCE |
| WOS关键词 | ULLYSES MASSIVE STARS ; BLANKETED MODEL ATMOSPHERES ; MAIN-SEQUENCE STARS ; WOLF-RAYET BINARY ; LOW METALLICITY ; CONVECTIVE BOUNDARIES ; ECLIPSING BINARY ; STELLAR WINDS ; HELIUM STARS ; WN STARS |
| 资助项目 | N/A |
| WOS研究方向 | Astronomy & Astrophysics |
| 语种 | 英语 |
| WOS记录号 | WOS:001736053800001 |
| 出版者 | EDP SCIENCES S A |
| 资助机构 | [01054731] ; [445674056] ; [50 OR 2509] ; [50 OR 2306] ; [0603225041] ; [101164755] |
| 版本 | 出版稿 |
| 源URL | [http://ir.ynao.ac.cn/handle/114a53/29127]  |
| 专题 | 云南天文台_大样本恒星演化研究组 |
| 通讯作者 | Müller, Johanna |
| 作者单位 | 1.Max-Planck-Institut für Astronomie, Königstuhl 17, 69117 Heidelberg, Germany; 2.Fakultät für Physik und Astronomie, Universität Heidelberg, Im Neuenheimer Feld 226, 69120 Heidelberg, Germany; 3.Zentrum für Astronomie der Universität Heidelberg, Astronomisches Rechen-Institut, Mönchhofstr. 12-14, 69120 Heidelberg, Germany; 4.Department of Astronomy, California Institute of Technology, Pasadena, CA 91125, USA; 5.Interdisziplinäres Zentrum für Wissenschaftliches Rechnen, Universität Heidelberg, Im Neuenheimer Feld 225, 69120 Heidelberg, Germany; 6.Anton Pannekoek Institute for Astronomy, University of Amsterdam, Science Park 904, 1098 XH, Amsterdam, The Netherlands; 7.Center for High Angular Resolution Astronomy and Department of Physics and Astronomy, Georgia State University, PO Box 5060 Atlanta, GA 30302-5060, USA; 8.Institute of Science and Technology Austria (ISTA), Am Campus 1, 3400 Klosterneuburg, Austria; 9.European Organisation for Astronomical Research in the Southern Hemisphere (ESO), Casilla 19001 Santiago 19, Chile; 10.School of Physics and Astronomy, Tel Aviv University, Tel Aviv, 6997801, Israel; |
| 推荐引用方式 GB/T 7714 | Müller, Johanna,Ramachandran, Varsha,El, Kareem,et al. Ultraviolet spectroscopy reveals a hot and luminous companion to the Be star plus black hole candidate MWC 656[J]. ASTRONOMY & ASTROPHYSICS,2026,708. |
| APA | Müller, Johanna.,Ramachandran, Varsha.,El, Kareem.,Sander, Andreas A. C..,Bodensteiner, Julia.,...&Latham, David W..(2026).Ultraviolet spectroscopy reveals a hot and luminous companion to the Be star plus black hole candidate MWC 656.ASTRONOMY & ASTROPHYSICS,708. |
| MLA | Müller, Johanna,et al."Ultraviolet spectroscopy reveals a hot and luminous companion to the Be star plus black hole candidate MWC 656".ASTRONOMY & ASTROPHYSICS 708(2026). |
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来源：云南天文台
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