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| DOI | 10.1051/0004-6361/201936613 |
| Hybrid star HD 81817 accompanied by brown dwarf or substellar companion | |
| Bang, Tae-Yang1; Lee, Byeong-Cheol2,3; Perdelwitz, Volker4; Jeong, Gwanghui2,3; Han, Inwoo2,3; Oh, Hyeong-Il1,2; Park, Myeong-Gu1 | |
| 通讯作者 | Park, Myeong-Gu |
| 来源期刊 | ASTRONOMY & ASTROPHYSICS
 |
| ISSN | 0004-6361 |
| EISSN | 1432-0746 |
| 出版年 | 2020 |
| 卷号 | 638 |
| 英文摘要 | HD 81817 is known as a hybrid star. Hybrid stars have both cool stellar wind properties and Ultraviolet (UV) or even X-ray emission features of highly ionized atoms in their spectra. A white dwarf companion has been suggested as the source of UV or X-ray features. HD 81817 has been observed since 2004 as a part of a radial velocity (RV) survey program to search for exoplanets around K giant stars using the Bohyunsan Observatory Echelle Spectrograph at the 1.8 m telescope of Bohyunsan Optical Astronomy Observatory in Korea. We obtained 85 RV measurements between 2004 and 2019 for HD 81817 and found two periodic RV variations. The amplitudes of RV variations are around 200 m s(-1), which are significantly lower than that expected from a closely orbiting white dwarf companion. Photometric data and relevant spectral lines were also analyzed to help determine the origin of the periodic RV variations. We conclude that 627.4-day RV variations are caused by intrinsic stellar activities such as long-term pulsations or rotational modulations of surface activities based on H-alpha equivalent width variations of a similar period. On the other hand, 1047.1-day periodic RV variations are likely to be caused by a brown dwarf or substellar companion, which is corroborated by a recent Gaia proper motion anomaly for HD 81817. The Keplerian fit yields a minimum mass of 27.1 M-Jup, a semimajor axis of 3.3 AU, and an eccentricity of 0.17 for the stellar mass of 4.3 M-circle dot for HD 81817. The inferred mass puts HD 81817 b in the brown dwarf desert. |
| 英文关键词 | stars: individual: HD 81817 |
| 类型 | Article |
| 语种 | 英语 |
| 国家 | South Korea ; Germany |
| 开放获取类型 | Green Submitted |
| 收录类别 | SCI-E |
| WOS记录号 | WOS:000547485300001 |
| WOS关键词 | RADIAL-VELOCITIES ; PARAMETERS ; CORONAE |
| WOS类目 | Astronomy & Astrophysics |
| WOS研究方向 | Astronomy & Astrophysics |
| 资源类型 | 期刊论文 |
| 条目标识符 | http://119.78.100.177/qdio/handle/2XILL650/319419 |
| 作者单位 | 1.Kyungpook Natl Univ, Dept Astron & Atmospher Sci, 80 Daehakro, Daegu 41566, South Korea; 2.Korea Astron & Space Sci Inst, 776 Daedukdae Ro, Daejeon 34055, South Korea; 3.Korea Univ Sci & Technol, 217 Gajeong Ro, Daejeon 34113, South Korea; 4.Hamburger Sternwarte, Gojenbergsweg 112, D-21029 Hamburg, Germany |
| 推荐引用方式 GB/T 7714 | Bang, Tae-Yang,Lee, Byeong-Cheol,Perdelwitz, Volker,et al. Hybrid star HD 81817 accompanied by brown dwarf or substellar companion[J],2020,638. |
| APA | Bang, Tae-Yang.,Lee, Byeong-Cheol.,Perdelwitz, Volker.,Jeong, Gwanghui.,Han, Inwoo.,...&Park, Myeong-Gu.(2020).Hybrid star HD 81817 accompanied by brown dwarf or substellar companion.ASTRONOMY & ASTROPHYSICS,638. |
| MLA | Bang, Tae-Yang,et al."Hybrid star HD 81817 accompanied by brown dwarf or substellar companion".ASTRONOMY & ASTROPHYSICS 638(2020). |
| 条目包含的文件 | 条目无相关文件。 | |||||
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