TY - JOUR
T1 - Direct imaging discovery of a young brown dwarf companion to an A2V star
AU - Wagner, Kevin
AU - Apai, Dániel
AU - Kasper, Markus
AU - McClure, Melissa
AU - Robberto, Massimo
AU - Currie, Thayne
N1 - Funding Information:
The authors acknowledge and thank Kaitlin Kratter and Maxwell Moe for useful conversations regarding the plausible formation scenarios. Support for this work was provided by NASA through the NASA Hubble Fellowship grant HST-HF2-51472.001-A awarded by the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Incorporated, under NASA contract NAS5-26555. The results reported herein benefited from collaborations and/or information exchange within NASA’s Nexus for Exoplanet System Science (NExSS) research coordination network sponsored by NASA’s Science Mission Directorate.
Publisher Copyright:
© 2020. The American Astronomical Society. All rights reserved.
PY - 2020/10/10
Y1 - 2020/10/10
N2 - We present the discovery and spectroscopy of HIP 75056Ab, a companion directly imaged at a very small separation of 0 125 to an A2V star in the Scorpius–Centaurus OB2 association. Our observations utilized Very Large Telescope/Spectro-Polarimetric High-contrast Exoplanet Research Experiment between 2015 and 2019, enabling low-resolution spectroscopy (0.95–1.65 μm), dual-band imaging (2.1–2.25 μm), and relative astrometry over a four-year baseline. HIP 75056Ab is consistent with spectral types in the range of M6-L2 and Teff ∼ 2000–2600 K. A comparison of the companion’s brightness to evolutionary tracks suggests a mass of ∼20–30 MJup. The astrometric measurements are consistent with an orbital semimajor axis of ∼15–45 au and an inclination close to face-on (i ≲ 35°). In this range of mass and orbital separation, HIP 75056Ab is likely at the low-mass end of the distribution of companions formed via disk instability, although a formation of the companion via core accretion cannot be excluded. The orbital constraints are consistent with the modest eccentricity values predicted by disk instability, a scenario that can be confirmed by further astrometric monitoring. HIP 75056Ab may be utilized as a low-mass atmospheric comparison to older, higher-mass brown dwarfs, and also to young giant planets. Finally, the detection of HIP 75056Ab at 0 125 represents a milestone in detecting low-mass companions at separations corresponding to the habitable zones of nearby Sun-like stars.
AB - We present the discovery and spectroscopy of HIP 75056Ab, a companion directly imaged at a very small separation of 0 125 to an A2V star in the Scorpius–Centaurus OB2 association. Our observations utilized Very Large Telescope/Spectro-Polarimetric High-contrast Exoplanet Research Experiment between 2015 and 2019, enabling low-resolution spectroscopy (0.95–1.65 μm), dual-band imaging (2.1–2.25 μm), and relative astrometry over a four-year baseline. HIP 75056Ab is consistent with spectral types in the range of M6-L2 and Teff ∼ 2000–2600 K. A comparison of the companion’s brightness to evolutionary tracks suggests a mass of ∼20–30 MJup. The astrometric measurements are consistent with an orbital semimajor axis of ∼15–45 au and an inclination close to face-on (i ≲ 35°). In this range of mass and orbital separation, HIP 75056Ab is likely at the low-mass end of the distribution of companions formed via disk instability, although a formation of the companion via core accretion cannot be excluded. The orbital constraints are consistent with the modest eccentricity values predicted by disk instability, a scenario that can be confirmed by further astrometric monitoring. HIP 75056Ab may be utilized as a low-mass atmospheric comparison to older, higher-mass brown dwarfs, and also to young giant planets. Finally, the detection of HIP 75056Ab at 0 125 represents a milestone in detecting low-mass companions at separations corresponding to the habitable zones of nearby Sun-like stars.
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U2 - 10.3847/2041-8213/abb94e
DO - 10.3847/2041-8213/abb94e
M3 - Article
AN - SCOPUS:85093076709
VL - 902
JO - Astrophysical Journal Letters
JF - Astrophysical Journal Letters
SN - 2041-8205
IS - 1
M1 - L6
ER -