Direct-imaging Discovery of a Substellar Companion Orbiting the Accelerating Variable Star, HIP 39017
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2024
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| author | Tobin, Taylor L. Currie, Thayne Li, Yiting Chilcote, Jeffrey Brandt, Timothy D. Lacy, Brianna Kuzuhara, Masayuki Vincent, Maria Morsy, Mona El Deo, Vincent Williams, Jonathan P. Guyon, Olivier Lozi, Julien Vievard, Sebastien Skaf, Nour Ahn, Kyohoon Groff, Tyler Kasdin, N. Jeremy Uyama, Taichi Tamura, Motohide Gibbs, Aidan Lewis, Briley L. Bowens-Rubin, Rachel Salama, Maïssa An, Qier Chen, Minghan |
| author_facet | Tobin, Taylor L. Currie, Thayne Li, Yiting Chilcote, Jeffrey Brandt, Timothy D. Lacy, Brianna Kuzuhara, Masayuki Vincent, Maria Morsy, Mona El Deo, Vincent Williams, Jonathan P. Guyon, Olivier Lozi, Julien Vievard, Sebastien Skaf, Nour Ahn, Kyohoon Groff, Tyler Kasdin, N. Jeremy Uyama, Taichi Tamura, Motohide Gibbs, Aidan Lewis, Briley L. Bowens-Rubin, Rachel Salama, Maïssa An, Qier Chen, Minghan |
| contents | We present the direct-imaging discovery of a substellar companion (a massive planet or low-mass brown dwarf) to the young, $γ$ Doradus-type variable star, HIP 39017 (HD 65526). The companion's SCExAO/CHARIS JHK ($1.1-2.4μ$m) spectrum and Keck/NIRC2 L$^{\prime}$ photometry indicate that it is an L/T transition object. A comparison of the JHK+L$^{\prime}$ spectrum to several atmospheric model grids finds a significantly better fit to cloudy models than cloudless models. Orbit modeling with relative astrometry and precision stellar astrometry from Hipparcos and Gaia yields a semi-major axis of $23.8^{+8.7}_{-6.1}$ au, a dynamical companion mass of $30^{+31}_{-12}$~M$_J$, and a mass ratio of $\sim$1.9\%, properties most consistent with low-mass brown dwarfs. However, its mass estimated from luminosity models is a lower $\sim$13.8 $M_{\rm J}$ due to an estimated young age ($\lesssim$ 115 Myr); using a weighted posterior distribution informed by conservative mass constraints from luminosity evolutionary models yields a lower dynamical mass of $23.6_{-7.4}^{+9.1}$~M$_J$ and a mass ratio of $\sim$1.4\%. Analysis of the host star's multi-frequency $γ$ Dor-type pulsations, astrometric monitoring of HIP 39017b, and Gaia Data Release 4 astrometry of the star will clarify the system age and better constrain the mass and orbit of the companion. This discovery further reinforces the improved efficiency of targeted direct-imaging campaigns informed by long-baseline, precision stellar astrometry. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2403_04000 |
| institution | arXiv |
| publishDate | 2024 |
| record_format | arxiv |
| spellingShingle | Direct-imaging Discovery of a Substellar Companion Orbiting the Accelerating Variable Star, HIP 39017 Tobin, Taylor L. Currie, Thayne Li, Yiting Chilcote, Jeffrey Brandt, Timothy D. Lacy, Brianna Kuzuhara, Masayuki Vincent, Maria Morsy, Mona El Deo, Vincent Williams, Jonathan P. Guyon, Olivier Lozi, Julien Vievard, Sebastien Skaf, Nour Ahn, Kyohoon Groff, Tyler Kasdin, N. Jeremy Uyama, Taichi Tamura, Motohide Gibbs, Aidan Lewis, Briley L. Bowens-Rubin, Rachel Salama, Maïssa An, Qier Chen, Minghan Solar and Stellar Astrophysics Earth and Planetary Astrophysics We present the direct-imaging discovery of a substellar companion (a massive planet or low-mass brown dwarf) to the young, $γ$ Doradus-type variable star, HIP 39017 (HD 65526). The companion's SCExAO/CHARIS JHK ($1.1-2.4μ$m) spectrum and Keck/NIRC2 L$^{\prime}$ photometry indicate that it is an L/T transition object. A comparison of the JHK+L$^{\prime}$ spectrum to several atmospheric model grids finds a significantly better fit to cloudy models than cloudless models. Orbit modeling with relative astrometry and precision stellar astrometry from Hipparcos and Gaia yields a semi-major axis of $23.8^{+8.7}_{-6.1}$ au, a dynamical companion mass of $30^{+31}_{-12}$~M$_J$, and a mass ratio of $\sim$1.9\%, properties most consistent with low-mass brown dwarfs. However, its mass estimated from luminosity models is a lower $\sim$13.8 $M_{\rm J}$ due to an estimated young age ($\lesssim$ 115 Myr); using a weighted posterior distribution informed by conservative mass constraints from luminosity evolutionary models yields a lower dynamical mass of $23.6_{-7.4}^{+9.1}$~M$_J$ and a mass ratio of $\sim$1.4\%. Analysis of the host star's multi-frequency $γ$ Dor-type pulsations, astrometric monitoring of HIP 39017b, and Gaia Data Release 4 astrometry of the star will clarify the system age and better constrain the mass and orbit of the companion. This discovery further reinforces the improved efficiency of targeted direct-imaging campaigns informed by long-baseline, precision stellar astrometry. |
| title | Direct-imaging Discovery of a Substellar Companion Orbiting the Accelerating Variable Star, HIP 39017 |
| topic | Solar and Stellar Astrophysics Earth and Planetary Astrophysics |
| url | https://arxiv.org/abs/2403.04000 |