A Second Planet Transiting LTT 1445A and a Determination of the Masses of Both Worlds
LTT 1445 is a hierarchical triple M-dwarf star system located at a distance of 6.86 pc. The primary star LTT 1445A (0.257 Me) is known to host the transiting planet LTT 1445Ab with an orbital period of 5.36 days, making it the second-closest known transiting exoplanet system, and the closest one f...
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| Other Authors: | |
| Format: | Article |
| Language: | English |
| Published: |
American Astronomical Society
2022
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| Online Access: | https://hdl.handle.net/1721.1/142260 |
| _version_ | 1826198383789867008 |
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| author | Vanderburg, Andrew |
| author2 | Massachusetts Institute of Technology. Department of Physics |
| author_facet | Massachusetts Institute of Technology. Department of Physics Vanderburg, Andrew |
| author_sort | Vanderburg, Andrew |
| collection | MIT |
| description | LTT 1445 is a hierarchical triple M-dwarf star system located at a distance of 6.86 pc. The primary star LTT 1445A
(0.257 Me) is known to host the transiting planet LTT 1445Ab with an orbital period of 5.36 days, making it the
second-closest known transiting exoplanet system, and the closest one for which the host is an M dwarf. Using
Transiting Exoplanet Survey Satellite data, we present the discovery of a second planet in the LTT 1445 system,
with an orbital period of 3.12 days. We combine radial-velocity measurements obtained from the five
spectrographs, Echelle Spectrograph for Rocky Exoplanets and Stable Spectroscopic Observations, High
Accuracy Radial Velocity Planet Searcher, High-Resolution Echelle Spectrometer, MAROON-X, and Planet
Finder Spectrograph to establish that the new world also orbits LTT 1445A. We determine the mass and radius of
LTT 1445Ab to be 2.87 ± 0.25 M⊕ and -
+
1.304 0.060
0.067 R⊕, consistent with an Earth-like composition. For the newly
discovered LTT 1445Ac, we measure a mass of -
+
1.54 0.19
0.20 M⊕ and a minimum radius of 1.15 R⊕, but we cannot
determine the radius directly as the signal-to-noise ratio of our light curve permits both grazing and nongrazing
configurations. Using MEarth photometry and ground-based spectroscopy, we establish that star C (0.161 Me) is
likely the source of the 1.4 day rotation period, and star B (0.215 Me) has a likely rotation period of 6.7 days. We
estimate a probable rotation period of 85 days for LTT 1445A. Thus, this triple M-dwarf system appears to be in a
special evolutionary stage where the most massive M dwarf has spun down, the intermediate mass M dwarf is in
the process of spinning down, while the least massive stellar component has not yet begun to spin down |
| first_indexed | 2024-09-23T11:04:01Z |
| format | Article |
| id | mit-1721.1/142260 |
| institution | Massachusetts Institute of Technology |
| language | English |
| last_indexed | 2024-09-23T11:04:01Z |
| publishDate | 2022 |
| publisher | American Astronomical Society |
| record_format | dspace |
| spelling | mit-1721.1/1422602023-07-28T20:41:22Z A Second Planet Transiting LTT 1445A and a Determination of the Masses of Both Worlds Vanderburg, Andrew Massachusetts Institute of Technology. Department of Physics MIT Kavli Institute for Astrophysics and Space Research LTT 1445 is a hierarchical triple M-dwarf star system located at a distance of 6.86 pc. The primary star LTT 1445A (0.257 Me) is known to host the transiting planet LTT 1445Ab with an orbital period of 5.36 days, making it the second-closest known transiting exoplanet system, and the closest one for which the host is an M dwarf. Using Transiting Exoplanet Survey Satellite data, we present the discovery of a second planet in the LTT 1445 system, with an orbital period of 3.12 days. We combine radial-velocity measurements obtained from the five spectrographs, Echelle Spectrograph for Rocky Exoplanets and Stable Spectroscopic Observations, High Accuracy Radial Velocity Planet Searcher, High-Resolution Echelle Spectrometer, MAROON-X, and Planet Finder Spectrograph to establish that the new world also orbits LTT 1445A. We determine the mass and radius of LTT 1445Ab to be 2.87 ± 0.25 M⊕ and - + 1.304 0.060 0.067 R⊕, consistent with an Earth-like composition. For the newly discovered LTT 1445Ac, we measure a mass of - + 1.54 0.19 0.20 M⊕ and a minimum radius of 1.15 R⊕, but we cannot determine the radius directly as the signal-to-noise ratio of our light curve permits both grazing and nongrazing configurations. Using MEarth photometry and ground-based spectroscopy, we establish that star C (0.161 Me) is likely the source of the 1.4 day rotation period, and star B (0.215 Me) has a likely rotation period of 6.7 days. We estimate a probable rotation period of 85 days for LTT 1445A. Thus, this triple M-dwarf system appears to be in a special evolutionary stage where the most massive M dwarf has spun down, the intermediate mass M dwarf is in the process of spinning down, while the least massive stellar component has not yet begun to spin down 2022-05-03T18:31:12Z 2022-05-03T18:31:12Z 2022-04-01 2022-05-03T18:22:37Z Article http://purl.org/eprint/type/JournalArticle https://hdl.handle.net/1721.1/142260 Vanderburg, Andrew. 2022. "A Second Planet Transiting LTT 1445A and a Determination of the Masses of Both Worlds." The Astronomical Journal, 163 (4). en 10.3847/1538-3881/ac50a9 The Astronomical Journal Creative Commons Attribution 4.0 International License https://creativecommons.org/licenses/by/4.0 application/pdf American Astronomical Society American Astronomical Society |
| spellingShingle | Vanderburg, Andrew A Second Planet Transiting LTT 1445A and a Determination of the Masses of Both Worlds |
| title | A Second Planet Transiting LTT 1445A and a Determination of the Masses of Both Worlds |
| title_full | A Second Planet Transiting LTT 1445A and a Determination of the Masses of Both Worlds |
| title_fullStr | A Second Planet Transiting LTT 1445A and a Determination of the Masses of Both Worlds |
| title_full_unstemmed | A Second Planet Transiting LTT 1445A and a Determination of the Masses of Both Worlds |
| title_short | A Second Planet Transiting LTT 1445A and a Determination of the Masses of Both Worlds |
| title_sort | second planet transiting ltt 1445a and a determination of the masses of both worlds |
| url | https://hdl.handle.net/1721.1/142260 |
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