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1811082153220374528
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MIT
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© 2020. The American Astronomical Society. All rights reserved. We report the discovery of a warm Neptune and a hot sub-Neptune transiting TOI-421 (BD-14 1137, TIC 94986319), a bright (V = 9.9) G9 dwarf star in a visual binary system observed by the Transiting Exoplanet Survey Satellite (TESS) space mission in Sectors 5 and 6. We performed ground-based follow-up observations - comprised of Las Cumbres Observatory Global Telescope transit photometry, NIRC2 adaptive optics imaging, and FIbre-fed Echellé Spectrograph, CORALIE, High Accuracy Radial velocity Planet Searcher, High Resolution chelle Spectrometer, and Planet Finder Spectrograph high-precision Doppler measurements - and confirmed the planetary nature of the 16 day transiting candidate announced by the TESS team. We discovered an additional radial velocity signal with a period of five days induced by the presence of a second planet in the system, which we also found to transit its host star. We found that the inner mini-Neptune, TOI-421 b, has an orbital period of P b = 5.19672 ± 0.00049 days, a mass of M b = 7.17 ± 0.66 M ⊕, and a radius of R b = 2.68-0.18+0.19 R ⊕, whereas the outer warm Neptune, TOI-421 c, has a period of P c = 16.06819 ± 0.00035 days, a mass of M c = 16.42-1.04+1.06 M ⊕, a radius of R c = 5.09-0.15+0.16 R ⊕, and a density of ρ c = 0.685-0.072+0.080 g cm-3. With its characteristics, the outer planet (ρ c = 0.685-0.072+0.080 g cm-3) is placed in the intriguing class of the super-puffy mini-Neptunes. TOI-421 b and TOI-421 c are found to be well-suited for atmospheric characterization. Our atmospheric simulations predict significant Lyα transit absorption, due to strong hydrogen escape in both planets, as well as the presence of detectable CH4 in the atmosphere of TOI-421 c if equilibrium chemistry is assumed.
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2024-09-23T11:58:25Z
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Article
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mit-1721.1/134321
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Massachusetts Institute of Technology
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English
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2024-09-23T11:58:25Z
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2021
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American Astronomical Society
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dspace
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mit-1721.1/1343212022-08-25T15:12:38Z The Multiplanet System TOI-421 © 2020. The American Astronomical Society. All rights reserved. We report the discovery of a warm Neptune and a hot sub-Neptune transiting TOI-421 (BD-14 1137, TIC 94986319), a bright (V = 9.9) G9 dwarf star in a visual binary system observed by the Transiting Exoplanet Survey Satellite (TESS) space mission in Sectors 5 and 6. We performed ground-based follow-up observations - comprised of Las Cumbres Observatory Global Telescope transit photometry, NIRC2 adaptive optics imaging, and FIbre-fed Echellé Spectrograph, CORALIE, High Accuracy Radial velocity Planet Searcher, High Resolution chelle Spectrometer, and Planet Finder Spectrograph high-precision Doppler measurements - and confirmed the planetary nature of the 16 day transiting candidate announced by the TESS team. We discovered an additional radial velocity signal with a period of five days induced by the presence of a second planet in the system, which we also found to transit its host star. We found that the inner mini-Neptune, TOI-421 b, has an orbital period of P b = 5.19672 ± 0.00049 days, a mass of M b = 7.17 ± 0.66 M ⊕, and a radius of R b = 2.68-0.18+0.19 R ⊕, whereas the outer warm Neptune, TOI-421 c, has a period of P c = 16.06819 ± 0.00035 days, a mass of M c = 16.42-1.04+1.06 M ⊕, a radius of R c = 5.09-0.15+0.16 R ⊕, and a density of ρ c = 0.685-0.072+0.080 g cm-3. With its characteristics, the outer planet (ρ c = 0.685-0.072+0.080 g cm-3) is placed in the intriguing class of the super-puffy mini-Neptunes. TOI-421 b and TOI-421 c are found to be well-suited for atmospheric characterization. Our atmospheric simulations predict significant Lyα transit absorption, due to strong hydrogen escape in both planets, as well as the presence of detectable CH4 in the atmosphere of TOI-421 c if equilibrium chemistry is assumed. 2021-10-27T20:04:27Z 2021-10-27T20:04:27Z 2020 2021-09-30T11:48:23Z Article http://purl.org/eprint/type/JournalArticle https://hdl.handle.net/1721.1/134321 en 10.3847/1538-3881/ABA124 Astronomical Journal Article is made available in accordance with the publisher's policy and may be subject to US copyright law. Please refer to the publisher's site for terms of use. application/pdf American Astronomical Society The American Astronomical Society
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| spellingShingle |
The Multiplanet System TOI-421
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| title |
The Multiplanet System TOI-421
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| title_full |
The Multiplanet System TOI-421
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| title_fullStr |
The Multiplanet System TOI-421
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| title_full_unstemmed |
The Multiplanet System TOI-421
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| title_short |
The Multiplanet System TOI-421
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| title_sort |
multiplanet system toi 421
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| url |
https://hdl.handle.net/1721.1/134321
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