Structural composition and atmospheric analysis of two planetary systems : TOI-270 and TOI-776
4 affiliations
- 1Gauhati University Department of Physics, , Jhalukbari, Guwahati 781014 ,
- 2Forensic Science Laboratory Uttar Pradesh , Ghaziabad 201204 ,
- 3Inter University Centre for Astronomy and Astrophysics , Pune 411007 ,
- 4NASA Goddard Space Flight Center , 8800 Greenbelt Road, Greenbelt, MD 20771 ,
Abstract
Investigating the bulk interior and atmosphere of exoplanets has become a crucial component in understanding the birth and formation history of planetary systems. The presence of different chemical species in the core and atmosphere of the planets hint at different birth location of exoplanets in the same planetary system. In this work, we investigate the bulk structure of two planetary systems : TOI-270 & TOI-776 and explore their atmospheric properties. We provide a detailed spectroscopic and photometric estimates of the fundamental properties of the two host stars using optical spectra from HARPS, ESPRESSO and photometric data from Gaia, Pan-STARRS1, 2MASS and WISE. We employ machine learning models to estimate the radius and mass fractions of the different interior layers of the exoplanets. The results highlight that the outer planets of TOI-270 system- TOI-270 c & d - are likely formed beyond the ice line, accreting sufficient volatiles, while the inner planet - TOI-270 b - exhibits a dry and rocky composition. The interior modeling of TOI-776 system suggests a predominantly rocky composition for both its planets, consistent with their location in the radius valley. The massloss models also indicate that the four planets - TOI-270 c & d and TOI-776 b & c - retain a modest gaseous envelope contributing to their total mass. Finally, we performed atmospheric retrieval of the HST-WFC3 transit spectra of TOI-270 c which resulted in tentative detection of H2O in its atmosphere along with partial cloud coverage, consistent with the limited SNR of the data. Some amount of metal hydrides are also detected in the retrieval, but their consistency needs to be verified by future observations.
Related
- Incorporation of atmospheric components in planetary magma oceans through bubble–metal compounds
- Effect of tidal gravity and planetary rotation on the retrieved atmospheric abundances of close-in exoplanets
- Effect of tidal gravity and planetary rotation on the retrieved atmospheric abundances of close-in exoplanets
- No statistically significant evidence for a correlation between stellar and planetary composition
- Quantitative Links between Formation and Atmospheric Composition for Giant Planets
BibTeX
@article{deb2026structural,
title = {{Structural composition and atmospheric analysis of two planetary systems : TOI-270 and TOI-776}},
author = {Sushmita Deb and Kaushal Sharma and Ravi Kumar Kopparapu and Biman Jyoti Medhi},
journal = {Monthly Notices of the Royal Astronomical Society},
year = {2026},
month = nov,
doi = {10.1093/mnras/stag2095},
url = {https://academic.oup.com/mnras/advance-article/doi/10.1093/mnras/stag2095/9011259},
note = {CC BY 4.0},
}
RIS
TY - JOUR
TI - Structural composition and atmospheric analysis of two planetary systems : TOI-270 and TOI-776
AU - Sushmita Deb
AU - Kaushal Sharma
AU - Ravi Kumar Kopparapu
AU - Biman Jyoti Medhi
PY - 2026
DA - 2026/11/03
JO - Monthly Notices of the Royal Astronomical Society
DO - 10.1093/mnras/stag2095
UR - https://academic.oup.com/mnras/advance-article/doi/10.1093/mnras/stag2095/9011259
AB - Investigating the bulk interior and atmosphere of exoplanets has become a crucial component in understanding the birth and formation history of planetary systems. The presence of different chemical species in the core and atmosphere of the planets hint at different birth location of exoplanets in the same planetary system. In this work, we investigate the bulk structure of two planetary systems : TOI-270 & TOI-776 and explore their atmospheric properties. We provide a detailed spectroscopic and photometric estimates of the fundamental properties of the two host stars using optical spectra from HARPS, ESPRESSO and photometric data from Gaia, Pan-STARRS1, 2MASS and WISE. We employ machine learning models to estimate the radius and mass fractions of the different interior layers of the exoplanets. The results highlight that the outer planets of TOI-270 system- TOI-270 c & d - are likely formed beyond the ice line, accreting sufficient volatiles, while the inner planet - TOI-270 b - exhibits a dry and rocky composition. The interior modeling of TOI-776 system suggests a predominantly rocky composition for both its planets, consistent with their location in the radius valley. The massloss models also indicate that the four planets - TOI-270 c & d and TOI-776 b & c - retain a modest gaseous envelope contributing to their total mass. Finally, we performed atmospheric retrieval of the HST-WFC3 transit spectra of TOI-270 c which resulted in tentative detection of H2O in its atmosphere along with partial cloud coverage, consistent with the limited SNR of the data. Some amount of metal hydrides are also detected in the retrieval, but their consistency needs to be verified by future observations.
SN - 0035-8711
SN - 1365-2966
ER -