Discovery of the Exceptionally Short Period Ultracool Dwarf Binary LP 413-53AB
We report the detection of large-amplitude, rapid radial velocity (RV) variations and line-splitting in high-resolution Keck/NIRSPEC spectra of the M9 dwarf LP 413-53. We attribute these features to binary motion. Analyzing data spanning 15 yr, we infer a preliminary orbital period of 0.7106156 ± 0....
| Main Authors: | , , |
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| Format: | Article |
| Language: | English |
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IOP Publishing
2023-01-01
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| Series: | The Astrophysical Journal Letters |
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| Online Access: | https://doi.org/10.3847/2041-8213/acba8c |
| _version_ | 1797701443466035200 |
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| author | Chih-Chun Hsu Adam J. Burgasser Christopher A. Theissen |
| author_facet | Chih-Chun Hsu Adam J. Burgasser Christopher A. Theissen |
| author_sort | Chih-Chun Hsu |
| collection | DOAJ |
| description | We report the detection of large-amplitude, rapid radial velocity (RV) variations and line-splitting in high-resolution Keck/NIRSPEC spectra of the M9 dwarf LP 413-53. We attribute these features to binary motion. Analyzing data spanning 15 yr, we infer a preliminary orbital period of 0.7106156 ± 0.0000002 days, an eccentricity of 0.0088 ± 0.0017, a primary RV semiamplitude of 23.70 ± 0.05 km s ^−1 , and a secondary RV semiamplitude of 28.41 ± 0.06 km s ^−1 , implying a system mass ratio M _secondary / M _primary = 0.8340 ± 0.0017. These measurements identify LP 413-53 as the shortest-period ultracool binary discovered to date, and one of the smallest separation main-sequence binaries known. The position and velocity of the system rule out previously reported membership in the Hyades Moving Group, and indicate that this is likely a pair of evolved (age ≳1 Gyr), very-low-mass stars. Assuming masses consistent with evolved late-M and L dwarfs, we estimate an orbital separation of 0.0081–0.0084 au or 17–19 stellar radii, and an orbital inclination angle of 24°, making it unlikely that this system exhibits eclipse events. The larger radii of these stars at young ages would have put them near contact at the system’s current separation, and we speculate that this system has undergone dynamical evolution, either through orbital angular momentum loss or ejection of a third component followed by tidal circularization. While further observations are needed to fully constrain the orbital and physical parameters of LP 413-53, this ultra-short-period ultracool dwarf binary system serves as a new test bed for formation and dynamical evolution models of very-low-mass multiples. |
| first_indexed | 2024-03-12T04:35:34Z |
| format | Article |
| id | doaj.art-288164f093c14a01ade1fb29b2982b39 |
| institution | Directory Open Access Journal |
| issn | 2041-8205 |
| language | English |
| last_indexed | 2024-03-12T04:35:34Z |
| publishDate | 2023-01-01 |
| publisher | IOP Publishing |
| record_format | Article |
| series | The Astrophysical Journal Letters |
| spelling | doaj.art-288164f093c14a01ade1fb29b2982b392023-09-03T09:55:28ZengIOP PublishingThe Astrophysical Journal Letters2041-82052023-01-019451L610.3847/2041-8213/acba8cDiscovery of the Exceptionally Short Period Ultracool Dwarf Binary LP 413-53ABChih-Chun Hsu0https://orcid.org/0000-0002-5370-7494Adam J. Burgasser1https://orcid.org/0000-0002-6523-9536Christopher A. Theissen2https://orcid.org/0000-0002-9807-5435Center for Interdisciplinary Exploration and Research in Astrophysics (CIERA), Northwestern University , 1800 Sherman, Evanston, IL 60201, USA chsu@northwestern.edu; Center for Astrophysics and Space Science, University of California San Diego , La Jolla, CA 92093, USACenter for Astrophysics and Space Science, University of California San Diego , La Jolla, CA 92093, USACenter for Astrophysics and Space Science, University of California San Diego , La Jolla, CA 92093, USAWe report the detection of large-amplitude, rapid radial velocity (RV) variations and line-splitting in high-resolution Keck/NIRSPEC spectra of the M9 dwarf LP 413-53. We attribute these features to binary motion. Analyzing data spanning 15 yr, we infer a preliminary orbital period of 0.7106156 ± 0.0000002 days, an eccentricity of 0.0088 ± 0.0017, a primary RV semiamplitude of 23.70 ± 0.05 km s ^−1 , and a secondary RV semiamplitude of 28.41 ± 0.06 km s ^−1 , implying a system mass ratio M _secondary / M _primary = 0.8340 ± 0.0017. These measurements identify LP 413-53 as the shortest-period ultracool binary discovered to date, and one of the smallest separation main-sequence binaries known. The position and velocity of the system rule out previously reported membership in the Hyades Moving Group, and indicate that this is likely a pair of evolved (age ≳1 Gyr), very-low-mass stars. Assuming masses consistent with evolved late-M and L dwarfs, we estimate an orbital separation of 0.0081–0.0084 au or 17–19 stellar radii, and an orbital inclination angle of 24°, making it unlikely that this system exhibits eclipse events. The larger radii of these stars at young ages would have put them near contact at the system’s current separation, and we speculate that this system has undergone dynamical evolution, either through orbital angular momentum loss or ejection of a third component followed by tidal circularization. While further observations are needed to fully constrain the orbital and physical parameters of LP 413-53, this ultra-short-period ultracool dwarf binary system serves as a new test bed for formation and dynamical evolution models of very-low-mass multiples.https://doi.org/10.3847/2041-8213/acba8cClose binary starsM dwarf starsSpectroscopic binary starsLow mass starsHigh resolution spectroscopy |
| spellingShingle | Chih-Chun Hsu Adam J. Burgasser Christopher A. Theissen Discovery of the Exceptionally Short Period Ultracool Dwarf Binary LP 413-53AB The Astrophysical Journal Letters Close binary stars M dwarf stars Spectroscopic binary stars Low mass stars High resolution spectroscopy |
| title | Discovery of the Exceptionally Short Period Ultracool Dwarf Binary LP 413-53AB |
| title_full | Discovery of the Exceptionally Short Period Ultracool Dwarf Binary LP 413-53AB |
| title_fullStr | Discovery of the Exceptionally Short Period Ultracool Dwarf Binary LP 413-53AB |
| title_full_unstemmed | Discovery of the Exceptionally Short Period Ultracool Dwarf Binary LP 413-53AB |
| title_short | Discovery of the Exceptionally Short Period Ultracool Dwarf Binary LP 413-53AB |
| title_sort | discovery of the exceptionally short period ultracool dwarf binary lp 413 53ab |
| topic | Close binary stars M dwarf stars Spectroscopic binary stars Low mass stars High resolution spectroscopy |
| url | https://doi.org/10.3847/2041-8213/acba8c |
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