THE BANANA PROJECT. IV. TWO ALIGNED STELLAR ROTATION AXES IN THE YOUNG ECCENTRIC BINARY SYSTEM EP CRUCIS: PRIMORDIAL ORIENTATION AND TIDAL ALIGNMENT
With observations of the EP Cru system, we continue our series of measurements of spin-orbit angles in eclipsing binary star systems, the BANANA project (Binaries Are Not Always Neatly Aligned). We find a close alignment between the sky projections of the rotational and orbital angular momentum vect...
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| Format: | Article |
| Language: | en_US |
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Institute of Physics Publishing
2014
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| Online Access: | http://hdl.handle.net/1721.1/88623 https://orcid.org/0000-0002-4265-047X |
| _version_ | 1826215177504161792 |
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| author | Albrecht, Simon H. Setiawan, Johny Torres, Guillermo Fabrycky, Daniel C. Winn, Joshua Nathan |
| author2 | Massachusetts Institute of Technology. Department of Physics |
| author_facet | Massachusetts Institute of Technology. Department of Physics Albrecht, Simon H. Setiawan, Johny Torres, Guillermo Fabrycky, Daniel C. Winn, Joshua Nathan |
| author_sort | Albrecht, Simon H. |
| collection | MIT |
| description | With observations of the EP Cru system, we continue our series of measurements of spin-orbit angles in eclipsing binary star systems, the BANANA project (Binaries Are Not Always Neatly Aligned). We find a close alignment between the sky projections of the rotational and orbital angular momentum vectors for both stars (βp = –1fdg8 ± 1fdg6 and |βs| < 17°). We also derive precise absolute dimensions and stellar ages for this system. The EP Cru and DI Her systems provide an interesting comparison: they have similar stellar types and orbital properties, but DI Her is younger and has major spin-orbit misalignments, raising the question of whether EP Cru also had a large misalignment at an earlier phase of evolution. We show that tidal dissipation is an unlikely explanation for the good alignment observed today, because realignment happens on the same timescale as spin-orbit synchronization, and the stars in EP Cru are far from synchronization (they are spinning nine times too quickly). Therefore it seems that some binaries form with aligned axes, while other superficially similar binaries are formed with misaligned axes. |
| first_indexed | 2024-09-23T16:18:48Z |
| format | Article |
| id | mit-1721.1/88623 |
| institution | Massachusetts Institute of Technology |
| language | en_US |
| last_indexed | 2024-09-23T16:18:48Z |
| publishDate | 2014 |
| publisher | Institute of Physics Publishing |
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| spelling | mit-1721.1/886232022-10-02T07:38:13Z THE BANANA PROJECT. IV. TWO ALIGNED STELLAR ROTATION AXES IN THE YOUNG ECCENTRIC BINARY SYSTEM EP CRUCIS: PRIMORDIAL ORIENTATION AND TIDAL ALIGNMENT Albrecht, Simon H. Setiawan, Johny Torres, Guillermo Fabrycky, Daniel C. Winn, Joshua Nathan Massachusetts Institute of Technology. Department of Physics MIT Kavli Institute for Astrophysics and Space Research Winn, Joshua Nathan Albrecht, Simon H. With observations of the EP Cru system, we continue our series of measurements of spin-orbit angles in eclipsing binary star systems, the BANANA project (Binaries Are Not Always Neatly Aligned). We find a close alignment between the sky projections of the rotational and orbital angular momentum vectors for both stars (βp = –1fdg8 ± 1fdg6 and |βs| < 17°). We also derive precise absolute dimensions and stellar ages for this system. The EP Cru and DI Her systems provide an interesting comparison: they have similar stellar types and orbital properties, but DI Her is younger and has major spin-orbit misalignments, raising the question of whether EP Cru also had a large misalignment at an earlier phase of evolution. We show that tidal dissipation is an unlikely explanation for the good alignment observed today, because realignment happens on the same timescale as spin-orbit synchronization, and the stars in EP Cru are far from synchronization (they are spinning nine times too quickly). Therefore it seems that some binaries form with aligned axes, while other superficially similar binaries are formed with misaligned axes. Space Telescope Science Institute (U.S.) (AURA under contract NAS 5-26555) United States. National Aeronautics and Space Administration (Hubble Fellowship grant HF-51272.01-A) United States. National Aeronautics and Space Administration (NASA Origins award NNX09AB33G ) National Science Foundation (U.S.) (NSF grant No.1108595) Netherlands Organization for Scientific Research (Rubicon fellowship) 2014-08-08T17:03:19Z 2014-08-08T17:03:19Z 2013-04 2012-08 Article http://purl.org/eprint/type/JournalArticle 0004-637X 1538-4357 http://hdl.handle.net/1721.1/88623 Albrecht, Simon, Johny Setiawan, Guillermo Torres, Daniel C. Fabrycky, and Joshua N. Winn. “The BANANA Project. IV. Two Aligned Stellar Rotation Axes in the Young Eccentric Binary System EP Crucis: Primordial Orientation and Tidal Alignment.” The Astrophysical Journal 767, no. 1 (March 22, 2013): 32. https://orcid.org/0000-0002-4265-047X en_US http://dx.doi.org/10.1088/0004-637x/767/1/32 Astrophysical Journal Creative Commons Attribution-Noncommercial-Share Alike http://creativecommons.org/licenses/by-nc-sa/4.0/ application/pdf Institute of Physics Publishing arXiv |
| spellingShingle | Albrecht, Simon H. Setiawan, Johny Torres, Guillermo Fabrycky, Daniel C. Winn, Joshua Nathan THE BANANA PROJECT. IV. TWO ALIGNED STELLAR ROTATION AXES IN THE YOUNG ECCENTRIC BINARY SYSTEM EP CRUCIS: PRIMORDIAL ORIENTATION AND TIDAL ALIGNMENT |
| title | THE BANANA PROJECT. IV. TWO ALIGNED STELLAR ROTATION AXES IN THE YOUNG ECCENTRIC BINARY SYSTEM EP CRUCIS: PRIMORDIAL ORIENTATION AND TIDAL ALIGNMENT |
| title_full | THE BANANA PROJECT. IV. TWO ALIGNED STELLAR ROTATION AXES IN THE YOUNG ECCENTRIC BINARY SYSTEM EP CRUCIS: PRIMORDIAL ORIENTATION AND TIDAL ALIGNMENT |
| title_fullStr | THE BANANA PROJECT. IV. TWO ALIGNED STELLAR ROTATION AXES IN THE YOUNG ECCENTRIC BINARY SYSTEM EP CRUCIS: PRIMORDIAL ORIENTATION AND TIDAL ALIGNMENT |
| title_full_unstemmed | THE BANANA PROJECT. IV. TWO ALIGNED STELLAR ROTATION AXES IN THE YOUNG ECCENTRIC BINARY SYSTEM EP CRUCIS: PRIMORDIAL ORIENTATION AND TIDAL ALIGNMENT |
| title_short | THE BANANA PROJECT. IV. TWO ALIGNED STELLAR ROTATION AXES IN THE YOUNG ECCENTRIC BINARY SYSTEM EP CRUCIS: PRIMORDIAL ORIENTATION AND TIDAL ALIGNMENT |
| title_sort | banana project iv two aligned stellar rotation axes in the young eccentric binary system ep crucis primordial orientation and tidal alignment |
| url | http://hdl.handle.net/1721.1/88623 https://orcid.org/0000-0002-4265-047X |
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