TOI-2155 b: A Massive Brown Dwarf or a Very Low-Mass Star?
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| Main Authors: | , , , , , , , , , , , , , , , , |
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| Format: | Preprint |
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2025
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| author | Ahmed, Md Redyan Daylan, Tansu Carmichael, Theron W. Casewell, Sarah L. Hafner, Anita Alvarado-Montes, Jaime A. Bieryla, Allyson Quinn, Samuel N. Calkins, Michael Collins, Karen A. Watkins, Cristilyn N. Stassun, Keivan G. Safonov, Boris S. Goliguzova, Maria V. Marino, Giuseppe Conti, Dennis M. Tuthill, Peter |
| author_facet | Ahmed, Md Redyan Daylan, Tansu Carmichael, Theron W. Casewell, Sarah L. Hafner, Anita Alvarado-Montes, Jaime A. Bieryla, Allyson Quinn, Samuel N. Calkins, Michael Collins, Karen A. Watkins, Cristilyn N. Stassun, Keivan G. Safonov, Boris S. Goliguzova, Maria V. Marino, Giuseppe Conti, Dennis M. Tuthill, Peter |
| contents | We present TOI-2155\,b, a massive transiting companion, discovered using data from NASA's Transiting Exoplanet Survey Satellite (TESS) mission and confirmed with ground-based RV measurements from the Tillinghast Reflector Echelle Spectrograph (TRES). We also analyze ground-based follow-up photometric data from the Wendelstein Observatory (WST), Las Cumbres Observatory Global Telescope (LCOGT), and Wild Boar Remote Observatory (WBR). TOI-2155\,b is a short-period companion with {$P= 3.7246950 \pm{0.0000014}$}~days. The radius and mass of TOI-2155\,b are found to be $R_b = 0.972^{+0.009}_{-0.008} \,\mathrm{R_J}$ and $M_b = 80.6^{+1.0}_{-1.1} \,\mathrm{M_J}$, respectively, corresponding to a density of {$ρ_b= 109^{+3.1}_{-3.3}$ g cm$^{-3}$}. The F-type subgiant host star has an effective temperature of $T_{\rm eff} = 6085\pm 78$ K, a radius $R_{\thinstar} = 1.705^{+0.066}_{-0.064}$ $\mathrm{R_\odot}$ and a mass $M_\star = 1.33 \pm 0.008$~M$_\odot$. With a mass close to the hydrogen-burning minimum mass, TOI-2155\,b lies at the boundary between brown dwarfs and low-mass stars. Its measured mass, radius, and density place it in a transitional region, where distinguishing between a massive brown dwarf and a very low-mass star is not straightforward. TOI-2155\,b therefore provides a valuable benchmark for testing evolutionary models of stellar and substellar structure near the hydrogen-burning limit. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2509_18503 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | TOI-2155 b: A Massive Brown Dwarf or a Very Low-Mass Star? Ahmed, Md Redyan Daylan, Tansu Carmichael, Theron W. Casewell, Sarah L. Hafner, Anita Alvarado-Montes, Jaime A. Bieryla, Allyson Quinn, Samuel N. Calkins, Michael Collins, Karen A. Watkins, Cristilyn N. Stassun, Keivan G. Safonov, Boris S. Goliguzova, Maria V. Marino, Giuseppe Conti, Dennis M. Tuthill, Peter Earth and Planetary Astrophysics Solar and Stellar Astrophysics We present TOI-2155\,b, a massive transiting companion, discovered using data from NASA's Transiting Exoplanet Survey Satellite (TESS) mission and confirmed with ground-based RV measurements from the Tillinghast Reflector Echelle Spectrograph (TRES). We also analyze ground-based follow-up photometric data from the Wendelstein Observatory (WST), Las Cumbres Observatory Global Telescope (LCOGT), and Wild Boar Remote Observatory (WBR). TOI-2155\,b is a short-period companion with {$P= 3.7246950 \pm{0.0000014}$}~days. The radius and mass of TOI-2155\,b are found to be $R_b = 0.972^{+0.009}_{-0.008} \,\mathrm{R_J}$ and $M_b = 80.6^{+1.0}_{-1.1} \,\mathrm{M_J}$, respectively, corresponding to a density of {$ρ_b= 109^{+3.1}_{-3.3}$ g cm$^{-3}$}. The F-type subgiant host star has an effective temperature of $T_{\rm eff} = 6085\pm 78$ K, a radius $R_{\thinstar} = 1.705^{+0.066}_{-0.064}$ $\mathrm{R_\odot}$ and a mass $M_\star = 1.33 \pm 0.008$~M$_\odot$. With a mass close to the hydrogen-burning minimum mass, TOI-2155\,b lies at the boundary between brown dwarfs and low-mass stars. Its measured mass, radius, and density place it in a transitional region, where distinguishing between a massive brown dwarf and a very low-mass star is not straightforward. TOI-2155\,b therefore provides a valuable benchmark for testing evolutionary models of stellar and substellar structure near the hydrogen-burning limit. |
| title | TOI-2155 b: A Massive Brown Dwarf or a Very Low-Mass Star? |
| topic | Earth and Planetary Astrophysics Solar and Stellar Astrophysics |
| url | https://arxiv.org/abs/2509.18503 |