JWST COMPASS: NIRSpec/G395H Transmission Observations of TOI-776 c, a 2 R⊕ M Dwarf Planet
The atmospheres of planets between the size of Earth and Neptune at short orbital periods have been under intense scrutiny. Of the approximately dozen planets in this regime with atmospheres studied so far, a few appear to have prominent molecular features, while others appear relatively void of det...
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IOP Publishing
2025-01-01
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| Online Access: | https://doi.org/10.3847/1538-3881/adb975 |
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| author | Johanna Teske Natasha E. Batalha Nicole L. Wallack James Kirk Nicholas F. Wogan Tyler A. Gordon Munazza K. Alam Artyom Aguichine Angie Wolfgang Hannah R. Wakeford Nicholas Scarsdale Jea Adams Redai Sarah E. Moran Mercedes López-Morales Annabella Meech Peter Gao Natalie M. Batalha Lili Alderson Anna Gagnebin |
| author_facet | Johanna Teske Natasha E. Batalha Nicole L. Wallack James Kirk Nicholas F. Wogan Tyler A. Gordon Munazza K. Alam Artyom Aguichine Angie Wolfgang Hannah R. Wakeford Nicholas Scarsdale Jea Adams Redai Sarah E. Moran Mercedes López-Morales Annabella Meech Peter Gao Natalie M. Batalha Lili Alderson Anna Gagnebin |
| author_sort | Johanna Teske |
| collection | DOAJ |
| description | The atmospheres of planets between the size of Earth and Neptune at short orbital periods have been under intense scrutiny. Of the approximately dozen planets in this regime with atmospheres studied so far, a few appear to have prominent molecular features, while others appear relatively void of detectable atmospheres. Further work is therefore needed to understand the atmospheres of these planets, starting with observing a larger sample. To this end, we present the 3–5 μ m transmission spectrum of TOI-776 c, a warm ( T _eq ∼ 420 K), ∼2 R _⊕ , ∼7 M _⊕ planet orbiting an M1V star, measured with JWST NIRSpec/G395H. By combining two visits, we measure a median transit precision of ∼18 and ∼32 ppm in the NRS1 and NRS2 detectors, respectively. We compare the transmission spectrum to both nonphysical and physical models and find no strong evidence for molecular features. For cloud-top pressures larger than 10 ^−3 bars, we rule out atmospheric metallicities less than 180–240× solar (depending on the reduction and modeling technique), which corresponds to a mean molecular weight of ∼6–8 g mol ^−1 . However, we find that simple atmosphere mixture models (H _2 O + H _2 /He or CO _2 + H _2 /He) give more pessimistic constraints, and we caution that mean molecular weight inferences are model dependent. We compare TOI-776 c to the similar planet TOI-270 d and discuss possible options for further constraining TOI-776 c’s atmospheric composition. Overall, we suggest that these TOI-776 c observations may represent a combination of planetary and stellar parameters that fall just below the threshold of detectable features in small-planet spectra; finding this boundary is one of the main goals of the COMPASS program. |
| format | Article |
| id | doaj-art-82baaa2219da4ce3b72e3c5dcea368ff |
| institution | OA Journals |
| issn | 1538-3881 |
| language | English |
| publishDate | 2025-01-01 |
| publisher | IOP Publishing |
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| series | The Astronomical Journal |
| spelling | doaj-art-82baaa2219da4ce3b72e3c5dcea368ff2025-08-20T02:16:14ZengIOP PublishingThe Astronomical Journal1538-38812025-01-01169524910.3847/1538-3881/adb975JWST COMPASS: NIRSpec/G395H Transmission Observations of TOI-776 c, a 2 R⊕ M Dwarf PlanetJohanna Teske0https://orcid.org/0009-0008-2801-5040Natasha E. Batalha1https://orcid.org/0000-0003-1240-6844Nicole L. Wallack2https://orcid.org/0000-0003-0354-0187James Kirk3https://orcid.org/0000-0002-4207-6615Nicholas F. Wogan4https://orcid.org/0000-0002-0413-3308Tyler A. Gordon5https://orcid.org/0000-0001-5253-1987Munazza K. Alam6https://orcid.org/0000-0003-4157-832XArtyom Aguichine7https://orcid.org/0000-0002-8949-5956Angie Wolfgang8https://orcid.org/0000-0003-2862-6278Hannah R. Wakeford9https://orcid.org/0000-0003-4328-3867Nicholas Scarsdale10https://orcid.org/0000-0003-3623-7280Jea Adams Redai11https://orcid.org/0000-0002-4489-3168Sarah E. Moran12https://orcid.org/0000-0002-6721-3284Mercedes López-Morales13https://orcid.org/0000-0003-3204-8183Annabella Meech14https://orcid.org/0000-0002-7500-7173Peter Gao15https://orcid.org/0000-0002-8518-9601Natalie M. Batalha16https://orcid.org/0000-0002-7030-9519Lili Alderson17https://orcid.org/0000-0001-8703-7751Anna Gagnebin18https://orcid.org/0009-0003-2576-9422Earth and Planets Laboratory, Carnegie Institution for Science , 5241 Broad Branch Road NW, Washington, DC 20015, USA; The Observatories of the Carnegie Institution for Science , 813 Santa Barbara Street, Pasadena, CA 91101, USANASA Ames Research Center , Moffett Field, CA 94035, USAEarth and Planets Laboratory, Carnegie Institution for Science , 5241 Broad Branch Road NW, Washington, DC 20015, USADepartment of Physics, Imperial College London , Prince Consort Road, London, SW7 2AZ, UKSpace Science Division, NASA Ames Research Center , Moffett Field, CA 94035, USADepartment of Astronomy and Astrophysics, University of California, Santa Cruz , Santa Cruz, CA 95064, USASpace Telescope Science Institute , 3700 San Martin Drive, Baltimore, MD 21218, USADepartment of Astronomy and Astrophysics, University of California, Santa Cruz , Santa Cruz, CA 95064, USAEureka Scientific Inc. , 2452 Delmer Street, Suite 100, Oakland, CA 94602-3017, USASchool of Physics, University of Bristol , HH Wills Physics Laboratory, Tyndall Avenue, Bristol BS8 1TL, UKDepartment of Astronomy and Astrophysics, University of California, Santa Cruz , Santa Cruz, CA 95064, USACenter for Astrophysics ∣ Harvard & Smithsonian , 60 Garden Street, Cambridge, MA 02138, USANASA Goddard Space Flight Center , 8800 Greenbelt Road, Greenbelt, MD 20771, USA; NHFP Sagan FellowSpace Telescope Science Institute , 3700 San Martin Drive, Baltimore, MD 21218, USACenter for Astrophysics ∣ Harvard & Smithsonian , 60 Garden Street, Cambridge, MA 02138, USAEarth and Planets Laboratory, Carnegie Institution for Science , 5241 Broad Branch Road NW, Washington, DC 20015, USADepartment of Astronomy and Astrophysics, University of California, Santa Cruz , Santa Cruz, CA 95064, USADepartment of Astronomy, Cornell University , 122 Sciences Drive, Ithaca, NY 14853, USADepartment of Astronomy and Astrophysics, University of California, Santa Cruz , Santa Cruz, CA 95064, USAThe atmospheres of planets between the size of Earth and Neptune at short orbital periods have been under intense scrutiny. Of the approximately dozen planets in this regime with atmospheres studied so far, a few appear to have prominent molecular features, while others appear relatively void of detectable atmospheres. Further work is therefore needed to understand the atmospheres of these planets, starting with observing a larger sample. To this end, we present the 3–5 μ m transmission spectrum of TOI-776 c, a warm ( T _eq ∼ 420 K), ∼2 R _⊕ , ∼7 M _⊕ planet orbiting an M1V star, measured with JWST NIRSpec/G395H. By combining two visits, we measure a median transit precision of ∼18 and ∼32 ppm in the NRS1 and NRS2 detectors, respectively. We compare the transmission spectrum to both nonphysical and physical models and find no strong evidence for molecular features. For cloud-top pressures larger than 10 ^−3 bars, we rule out atmospheric metallicities less than 180–240× solar (depending on the reduction and modeling technique), which corresponds to a mean molecular weight of ∼6–8 g mol ^−1 . However, we find that simple atmosphere mixture models (H _2 O + H _2 /He or CO _2 + H _2 /He) give more pessimistic constraints, and we caution that mean molecular weight inferences are model dependent. We compare TOI-776 c to the similar planet TOI-270 d and discuss possible options for further constraining TOI-776 c’s atmospheric composition. Overall, we suggest that these TOI-776 c observations may represent a combination of planetary and stellar parameters that fall just below the threshold of detectable features in small-planet spectra; finding this boundary is one of the main goals of the COMPASS program.https://doi.org/10.3847/1538-3881/adb975Exoplanet atmospheresJames Webb Space Telescope |
| spellingShingle | Johanna Teske Natasha E. Batalha Nicole L. Wallack James Kirk Nicholas F. Wogan Tyler A. Gordon Munazza K. Alam Artyom Aguichine Angie Wolfgang Hannah R. Wakeford Nicholas Scarsdale Jea Adams Redai Sarah E. Moran Mercedes López-Morales Annabella Meech Peter Gao Natalie M. Batalha Lili Alderson Anna Gagnebin JWST COMPASS: NIRSpec/G395H Transmission Observations of TOI-776 c, a 2 R⊕ M Dwarf Planet The Astronomical Journal Exoplanet atmospheres James Webb Space Telescope |
| title | JWST COMPASS: NIRSpec/G395H Transmission Observations of TOI-776 c, a 2 R⊕ M Dwarf Planet |
| title_full | JWST COMPASS: NIRSpec/G395H Transmission Observations of TOI-776 c, a 2 R⊕ M Dwarf Planet |
| title_fullStr | JWST COMPASS: NIRSpec/G395H Transmission Observations of TOI-776 c, a 2 R⊕ M Dwarf Planet |
| title_full_unstemmed | JWST COMPASS: NIRSpec/G395H Transmission Observations of TOI-776 c, a 2 R⊕ M Dwarf Planet |
| title_short | JWST COMPASS: NIRSpec/G395H Transmission Observations of TOI-776 c, a 2 R⊕ M Dwarf Planet |
| title_sort | jwst compass nirspec g395h transmission observations of toi 776 c a 2 r⊕ m dwarf planet |
| topic | Exoplanet atmospheres James Webb Space Telescope |
| url | https://doi.org/10.3847/1538-3881/adb975 |
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