The Diversity of Cold Worlds: Age and Characterization of the Exoplanet COCONUTS-2b
Fuente:
arXiv
Saved in:
| Main Authors: | , , , , , , , , , , , , , , , , , , , , , |
|---|---|
| Format: | Preprint |
| Published: |
2025
|
| Subjects: | |
| Online Access: | |
| Tags: |
Add Tag
No Tags, Be the first to tag this record!
|
| _version_ | 1866911287339909120 |
|---|---|
| author | Kiman, Rocio Beichman, Charles A. Diaz, Azul Ruiz Faherty, Jacqueline K. Lacy, Brianna Suarez, Genaro Marocco, Federico Kirkpatrick, J. Davy Gagne, Jonathan Copeland, Jessica Burningham, Ben Whiteford, Niall Rowland, Melanie J. Gagliuffi, Daniella C. Bardalez Vos, Johanna M. Schneider, Adam C. Gonzales, Eileen C. Merchan, Sherelyn Alejandro Rothermich, Austin Smart, Richard Costa, Edgardo Mendez, Rene A. |
| author_facet | Kiman, Rocio Beichman, Charles A. Diaz, Azul Ruiz Faherty, Jacqueline K. Lacy, Brianna Suarez, Genaro Marocco, Federico Kirkpatrick, J. Davy Gagne, Jonathan Copeland, Jessica Burningham, Ben Whiteford, Niall Rowland, Melanie J. Gagliuffi, Daniella C. Bardalez Vos, Johanna M. Schneider, Adam C. Gonzales, Eileen C. Merchan, Sherelyn Alejandro Rothermich, Austin Smart, Richard Costa, Edgardo Mendez, Rene A. |
| contents | Studying cold brown dwarfs is key to understanding the diverse characteristics of cold giant exoplanets atmospheres. COCONUTS-2, is a wide binary system composed of a T9 brown dwarf and an M3 star, which presents a unique opportunity to characterize a cold benchmark brown dwarf. As part of a JWST program to study the range of physical and atmospheric properties of the coldest brown dwarfs, we obtained NIRSpec G395H spectra (R~2700, 2.87-5.13 um) and MIRI F1000W, F1280W, and F1800W photometry for COCONUTS-2b. In this work, we find a 99% probability of the system belonging to the Corona of Ursa Major (414+/-23 Myr) using BANYAN Sigma and its full kinematics. We also re-estimate the astrometry of COCONUTS-2b using the MIRI data. We support the membership with a comparison of rotation period, metallicity and C/O ratio of the group with those of the COCONUTS-2 system. We also calculate its bolometric luminosity, which combined with our age estimation, allows us to derive its mass, effective temperature, surface gravity, and radius with high precision. As a result of our analysis, we support the conclusion that COCONUTS-2b is a planetary mass object (7.5+/-0.4 MJup) which was likely formed via the same mechanism as stars. In addition we compare the JWST spectrum to another object in the sample, J082507.35+280548.5 (0825+2805), a Y0.5 brown dwarf, which is a candidate member of the same moving group, but has a lower mass (3.7+/-0.2 MJup). We identify absorption feature differences which could indicate that 0825+2805 has stronger vertical mixing. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2511_20923 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | The Diversity of Cold Worlds: Age and Characterization of the Exoplanet COCONUTS-2b Kiman, Rocio Beichman, Charles A. Diaz, Azul Ruiz Faherty, Jacqueline K. Lacy, Brianna Suarez, Genaro Marocco, Federico Kirkpatrick, J. Davy Gagne, Jonathan Copeland, Jessica Burningham, Ben Whiteford, Niall Rowland, Melanie J. Gagliuffi, Daniella C. Bardalez Vos, Johanna M. Schneider, Adam C. Gonzales, Eileen C. Merchan, Sherelyn Alejandro Rothermich, Austin Smart, Richard Costa, Edgardo Mendez, Rene A. Earth and Planetary Astrophysics Solar and Stellar Astrophysics Studying cold brown dwarfs is key to understanding the diverse characteristics of cold giant exoplanets atmospheres. COCONUTS-2, is a wide binary system composed of a T9 brown dwarf and an M3 star, which presents a unique opportunity to characterize a cold benchmark brown dwarf. As part of a JWST program to study the range of physical and atmospheric properties of the coldest brown dwarfs, we obtained NIRSpec G395H spectra (R~2700, 2.87-5.13 um) and MIRI F1000W, F1280W, and F1800W photometry for COCONUTS-2b. In this work, we find a 99% probability of the system belonging to the Corona of Ursa Major (414+/-23 Myr) using BANYAN Sigma and its full kinematics. We also re-estimate the astrometry of COCONUTS-2b using the MIRI data. We support the membership with a comparison of rotation period, metallicity and C/O ratio of the group with those of the COCONUTS-2 system. We also calculate its bolometric luminosity, which combined with our age estimation, allows us to derive its mass, effective temperature, surface gravity, and radius with high precision. As a result of our analysis, we support the conclusion that COCONUTS-2b is a planetary mass object (7.5+/-0.4 MJup) which was likely formed via the same mechanism as stars. In addition we compare the JWST spectrum to another object in the sample, J082507.35+280548.5 (0825+2805), a Y0.5 brown dwarf, which is a candidate member of the same moving group, but has a lower mass (3.7+/-0.2 MJup). We identify absorption feature differences which could indicate that 0825+2805 has stronger vertical mixing. |
| title | The Diversity of Cold Worlds: Age and Characterization of the Exoplanet COCONUTS-2b |
| topic | Earth and Planetary Astrophysics Solar and Stellar Astrophysics |
| url | https://arxiv.org/abs/2511.20923 |