High Tide or Riptide on the Cosmic Shoreline? A Water-Rich Atmosphere or Stellar Contamination for the Warm Super-Earth GJ~486b from JWST Observations
Fuente:
arXiv
Saved in:
| Main Authors: | , , , , , , , , , , , , , , , , , , , , , , , |
|---|---|
| Format: | Preprint |
| Published: |
2023
|
| Subjects: | |
| Online Access: | |
| Tags: |
Add Tag
No Tags, Be the first to tag this record!
|
| _version_ | 1866910041185976320 |
|---|---|
| author | Moran, Sarah E. Stevenson, Kevin B. Sing, David K. MacDonald, Ryan J. Kirk, James Lustig-Yaeger, Jacob Peacock, Sarah Mayorga, L. C. Bennett, Katherine A. López-Morales, Mercedes May, E. M. Rustamkulov, Zafar Valenti, Jeff A. Redai, Jéa I. Adams Alam, Munazza K. Batalha, Natasha E. Fu, Guangwei Gonzalez-Quiles, Junellie Highland, Alicia N. Kruse, Ethan Lothringer, Joshua D. Ceballos, Kevin N. Ortiz Sotzen, Kristin S. Wakeford, Hannah R. |
| author_facet | Moran, Sarah E. Stevenson, Kevin B. Sing, David K. MacDonald, Ryan J. Kirk, James Lustig-Yaeger, Jacob Peacock, Sarah Mayorga, L. C. Bennett, Katherine A. López-Morales, Mercedes May, E. M. Rustamkulov, Zafar Valenti, Jeff A. Redai, Jéa I. Adams Alam, Munazza K. Batalha, Natasha E. Fu, Guangwei Gonzalez-Quiles, Junellie Highland, Alicia N. Kruse, Ethan Lothringer, Joshua D. Ceballos, Kevin N. Ortiz Sotzen, Kristin S. Wakeford, Hannah R. |
| contents | Planets orbiting M-dwarf stars are prime targets in the search for rocky exoplanet atmospheres. The small size of M dwarfs renders their planets exceptional targets for transmission spectroscopy, facilitating atmospheric characterization. However, it remains unknown whether their host stars' highly variable extreme-UV radiation environments allow atmospheres to persist. With JWST, we have begun to determine whether or not the most favorable rocky worlds orbiting M dwarfs have detectable atmospheres. Here, we present a 2.8-5.2 micron JWST NIRSpec/G395H transmission spectrum of the warm (700 K, 40.3x Earth's insolation) super-Earth GJ 486b (1.3 R$_{\oplus}$ and 3.0 M$_{\oplus}$). The measured spectrum from our two transits of GJ 486b deviates from a flat line at 2.2 - 3.3 $σ$, based on three independent reductions. Through a combination of forward and retrieval models, we determine that GJ 486b either has a water-rich atmosphere (with the most stringent constraint on the retrieved water abundance of H2O > 10% to 2$σ$) or the transmission spectrum is contaminated by water present in cool unocculted starspots. We also find that the measured stellar spectrum is best fit by a stellar model with cool starspots and hot faculae. While both retrieval scenarios provide equal quality fits ($χ^2_ν$ = 1.0) to our NIRSpec/G395H observations, shorter wavelength observations can break this degeneracy and reveal if GJ 486b sustains a water-rich atmosphere. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2305_00868 |
| institution | arXiv |
| publishDate | 2023 |
| record_format | arxiv |
| spellingShingle | High Tide or Riptide on the Cosmic Shoreline? A Water-Rich Atmosphere or Stellar Contamination for the Warm Super-Earth GJ~486b from JWST Observations Moran, Sarah E. Stevenson, Kevin B. Sing, David K. MacDonald, Ryan J. Kirk, James Lustig-Yaeger, Jacob Peacock, Sarah Mayorga, L. C. Bennett, Katherine A. López-Morales, Mercedes May, E. M. Rustamkulov, Zafar Valenti, Jeff A. Redai, Jéa I. Adams Alam, Munazza K. Batalha, Natasha E. Fu, Guangwei Gonzalez-Quiles, Junellie Highland, Alicia N. Kruse, Ethan Lothringer, Joshua D. Ceballos, Kevin N. Ortiz Sotzen, Kristin S. Wakeford, Hannah R. Earth and Planetary Astrophysics Solar and Stellar Astrophysics Planets orbiting M-dwarf stars are prime targets in the search for rocky exoplanet atmospheres. The small size of M dwarfs renders their planets exceptional targets for transmission spectroscopy, facilitating atmospheric characterization. However, it remains unknown whether their host stars' highly variable extreme-UV radiation environments allow atmospheres to persist. With JWST, we have begun to determine whether or not the most favorable rocky worlds orbiting M dwarfs have detectable atmospheres. Here, we present a 2.8-5.2 micron JWST NIRSpec/G395H transmission spectrum of the warm (700 K, 40.3x Earth's insolation) super-Earth GJ 486b (1.3 R$_{\oplus}$ and 3.0 M$_{\oplus}$). The measured spectrum from our two transits of GJ 486b deviates from a flat line at 2.2 - 3.3 $σ$, based on three independent reductions. Through a combination of forward and retrieval models, we determine that GJ 486b either has a water-rich atmosphere (with the most stringent constraint on the retrieved water abundance of H2O > 10% to 2$σ$) or the transmission spectrum is contaminated by water present in cool unocculted starspots. We also find that the measured stellar spectrum is best fit by a stellar model with cool starspots and hot faculae. While both retrieval scenarios provide equal quality fits ($χ^2_ν$ = 1.0) to our NIRSpec/G395H observations, shorter wavelength observations can break this degeneracy and reveal if GJ 486b sustains a water-rich atmosphere. |
| title | High Tide or Riptide on the Cosmic Shoreline? A Water-Rich Atmosphere or Stellar Contamination for the Warm Super-Earth GJ~486b from JWST Observations |
| topic | Earth and Planetary Astrophysics Solar and Stellar Astrophysics |
| url | https://arxiv.org/abs/2305.00868 |