Disentangling the Planet from the Star in Late-Type M Dwarfs: A Case Study of TRAPPIST-1g
© 2018. The American Astronomical Society. All rights reserved. The atmospheres of late M stars represent a significant challenge in the characterization of any transiting exoplanets because of the presence of strong molecular features in the stellar atmosphere. TRAPPIST-1 is an ultracool dwarf, hos...
| Main Authors: | , , , , , , , , , , , , |
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| Format: | Article |
| Language: | English |
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American Astronomical Society
2021
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| Online Access: | https://hdl.handle.net/1721.1/133773 |
| _version_ | 1811072078182350848 |
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| author | Wakeford, HR Lewis, NK Fowler, J Bruno, G Wilson, TJ Moran, SE Valenti, J Batalha, NE Filippazzo, J Bourrier, V Hörst, SM Lederer, SM de Wit, J |
| author_facet | Wakeford, HR Lewis, NK Fowler, J Bruno, G Wilson, TJ Moran, SE Valenti, J Batalha, NE Filippazzo, J Bourrier, V Hörst, SM Lederer, SM de Wit, J |
| author_sort | Wakeford, HR |
| collection | MIT |
| description | © 2018. The American Astronomical Society. All rights reserved. The atmospheres of late M stars represent a significant challenge in the characterization of any transiting exoplanets because of the presence of strong molecular features in the stellar atmosphere. TRAPPIST-1 is an ultracool dwarf, host to seven transiting planets, and contains its own molecular signatures that can potentially be imprinted on planetary transit lightcurves as a result of inhomogeneities in the occulted stellar photosphere. We present a case study on TRAPPIST-1g, the largest planet in the system, using a new observation together with previous data, to disentangle the atmospheric transmission of the planet from that of the star. We use the out-of-transit stellar spectra to reconstruct the stellar flux on the basis of one, two, and three temperature components. We find that TRAPPIST-1 is a 0.08 M ∗, 0.117 R ∗, M8V star with a photospheric effective temperature of 2400 K, with ∼35% 3000 K spot coverage and a very small fraction, <3%, of ∼5800 K hot spot. We calculate a planetary radius for TRAPPIST-1g to be R p = 1.124 R ⊕with a planetary density of ρ p = 0.8214 ρ ⊕. On the basis of the stellar reconstruction, there are 11 plausible scenarios for the combined stellar photosphere and planet transit geometry; in our analysis, we are able to rule out eight of the 11 scenarios. Using planetary models, we evaluate the remaining scenarios with respect to the transmission spectrum of TRAPPIST-1g. We conclude that the planetary transmission spectrum is likely not contaminated by any stellar spectral features and are able to rule out a clear solar H2/He-dominated atmosphere at greater than 3σ. |
| first_indexed | 2024-09-23T09:00:31Z |
| format | Article |
| id | mit-1721.1/133773 |
| institution | Massachusetts Institute of Technology |
| language | English |
| last_indexed | 2024-09-23T09:00:31Z |
| publishDate | 2021 |
| publisher | American Astronomical Society |
| record_format | dspace |
| spelling | mit-1721.1/1337732021-10-28T04:49:49Z Disentangling the Planet from the Star in Late-Type M Dwarfs: A Case Study of TRAPPIST-1g Wakeford, HR Lewis, NK Fowler, J Bruno, G Wilson, TJ Moran, SE Valenti, J Batalha, NE Filippazzo, J Bourrier, V Hörst, SM Lederer, SM de Wit, J © 2018. The American Astronomical Society. All rights reserved. The atmospheres of late M stars represent a significant challenge in the characterization of any transiting exoplanets because of the presence of strong molecular features in the stellar atmosphere. TRAPPIST-1 is an ultracool dwarf, host to seven transiting planets, and contains its own molecular signatures that can potentially be imprinted on planetary transit lightcurves as a result of inhomogeneities in the occulted stellar photosphere. We present a case study on TRAPPIST-1g, the largest planet in the system, using a new observation together with previous data, to disentangle the atmospheric transmission of the planet from that of the star. We use the out-of-transit stellar spectra to reconstruct the stellar flux on the basis of one, two, and three temperature components. We find that TRAPPIST-1 is a 0.08 M ∗, 0.117 R ∗, M8V star with a photospheric effective temperature of 2400 K, with ∼35% 3000 K spot coverage and a very small fraction, <3%, of ∼5800 K hot spot. We calculate a planetary radius for TRAPPIST-1g to be R p = 1.124 R ⊕with a planetary density of ρ p = 0.8214 ρ ⊕. On the basis of the stellar reconstruction, there are 11 plausible scenarios for the combined stellar photosphere and planet transit geometry; in our analysis, we are able to rule out eight of the 11 scenarios. Using planetary models, we evaluate the remaining scenarios with respect to the transmission spectrum of TRAPPIST-1g. We conclude that the planetary transmission spectrum is likely not contaminated by any stellar spectral features and are able to rule out a clear solar H2/He-dominated atmosphere at greater than 3σ. 2021-10-27T19:56:34Z 2021-10-27T19:56:34Z 2018 2021-09-14T18:00:45Z Article http://purl.org/eprint/type/JournalArticle https://hdl.handle.net/1721.1/133773 en 10.3847/1538-3881/AAF04D 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 |
| spellingShingle | Wakeford, HR Lewis, NK Fowler, J Bruno, G Wilson, TJ Moran, SE Valenti, J Batalha, NE Filippazzo, J Bourrier, V Hörst, SM Lederer, SM de Wit, J Disentangling the Planet from the Star in Late-Type M Dwarfs: A Case Study of TRAPPIST-1g |
| title | Disentangling the Planet from the Star in Late-Type M Dwarfs: A Case Study of TRAPPIST-1g |
| title_full | Disentangling the Planet from the Star in Late-Type M Dwarfs: A Case Study of TRAPPIST-1g |
| title_fullStr | Disentangling the Planet from the Star in Late-Type M Dwarfs: A Case Study of TRAPPIST-1g |
| title_full_unstemmed | Disentangling the Planet from the Star in Late-Type M Dwarfs: A Case Study of TRAPPIST-1g |
| title_short | Disentangling the Planet from the Star in Late-Type M Dwarfs: A Case Study of TRAPPIST-1g |
| title_sort | disentangling the planet from the star in late type m dwarfs a case study of trappist 1g |
| url | https://hdl.handle.net/1721.1/133773 |
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