Spectral analysis of two directly imaged benchmark L dwarf companions at the stellar-substellar boundary

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Auteurs principaux: Ceva, William, Matthews, Elisabeth C., Rickman, Emily L., Ségransan, Damien, Vigan, Arthur, Bowler, Brendan P., Forveille, Thierry, Franson, Kyle, Hagelberg, Janis, Udry, Stéphane
Format: Preprint
Publié: 2025
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author Ceva, William
Matthews, Elisabeth C.
Rickman, Emily L.
Ségransan, Damien
Vigan, Arthur
Bowler, Brendan P.
Forveille, Thierry
Franson, Kyle
Hagelberg, Janis
Udry, Stéphane
author_facet Ceva, William
Matthews, Elisabeth C.
Rickman, Emily L.
Ségransan, Damien
Vigan, Arthur
Bowler, Brendan P.
Forveille, Thierry
Franson, Kyle
Hagelberg, Janis
Udry, Stéphane
contents We used multiple epochs of high-contrast imaging spectrophotometric observations to determine the atmospheric characteristics and thermal evolution of two previously detected benchmark L dwarf companions, HD 112863 B and HD 206505 B. We analyzed IRDIS and IFS data from VLT/SPHERE of each companion, both of which have dynamical masses near the stellar-substellar boundary. We compared each companion with empirical spectral standards, as well as constrained their physical properties through atmospheric model fits. From these analyses, we estimate that HD 112863 B is spectral type $\rm{L}3\pm1$ and that HD 206505 B is spectral type $\rm{L}2\pm1$. Using the BT-Settl atmospheric model grids, we find a bimodal solution for the atmospheric model fit of HD 112863 B, such that $T_{\rm{eff}}=1757^{+37}_{-36}$ K or $2002^{+23}_{-24}$ K and $\log{g}=4.973^{+0.057}_{-0.063}$ or $5.253^{+0.037}_{-0.033}$, while for HD 206505 B, $T_{\rm{eff}}=1754^{+13}_{-13}$ K and $\log{g}=4.919^{+0.031}_{-0.029}$. Comparing the bolometric luminosities of both companions with evolutionary models imply that both companions are likely above the hydrogen burning limit.
format Preprint
id arxiv_https___arxiv_org_abs_2507_08654
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Spectral analysis of two directly imaged benchmark L dwarf companions at the stellar-substellar boundary
Ceva, William
Matthews, Elisabeth C.
Rickman, Emily L.
Ségransan, Damien
Vigan, Arthur
Bowler, Brendan P.
Forveille, Thierry
Franson, Kyle
Hagelberg, Janis
Udry, Stéphane
Earth and Planetary Astrophysics
Solar and Stellar Astrophysics
We used multiple epochs of high-contrast imaging spectrophotometric observations to determine the atmospheric characteristics and thermal evolution of two previously detected benchmark L dwarf companions, HD 112863 B and HD 206505 B. We analyzed IRDIS and IFS data from VLT/SPHERE of each companion, both of which have dynamical masses near the stellar-substellar boundary. We compared each companion with empirical spectral standards, as well as constrained their physical properties through atmospheric model fits. From these analyses, we estimate that HD 112863 B is spectral type $\rm{L}3\pm1$ and that HD 206505 B is spectral type $\rm{L}2\pm1$. Using the BT-Settl atmospheric model grids, we find a bimodal solution for the atmospheric model fit of HD 112863 B, such that $T_{\rm{eff}}=1757^{+37}_{-36}$ K or $2002^{+23}_{-24}$ K and $\log{g}=4.973^{+0.057}_{-0.063}$ or $5.253^{+0.037}_{-0.033}$, while for HD 206505 B, $T_{\rm{eff}}=1754^{+13}_{-13}$ K and $\log{g}=4.919^{+0.031}_{-0.029}$. Comparing the bolometric luminosities of both companions with evolutionary models imply that both companions are likely above the hydrogen burning limit.
title Spectral analysis of two directly imaged benchmark L dwarf companions at the stellar-substellar boundary
topic Earth and Planetary Astrophysics
Solar and Stellar Astrophysics
url https://arxiv.org/abs/2507.08654