학술논문
VLTI/GRAVITY Provides Evidence the Young, Substellar Companion HD 136164 Ab formed like a 'Failed Star'
Document Type
Working Paper
Author
Balmer, William O.; Pueyo, L.; Lacour, S.; Wang, J. J.; Stolker, T.; Kammerer, J.; Pourré, N.; Nowak, M.; Rickman, E.; Blunt, S.; Sivaramakrishnan, A.; Sing, D.; Wagner, K.; Marleau, G. -D.; Lagrange, A. -M.; Abuter, R.; Amorim, A.; Asensio-Torres, R.; Berger, J. -P.; Beust, H.; Boccaletti, A.; Bohn, A.; Bonnefoy, M.; Bonnet, H.; Bordoni, M. S.; Bourdarot, G.; Brandner, W.; Cantalloube, F.; Caselli, P.; Charnay, B.; Chauvin, G.; Chavez, A.; Choquet, E.; Christiaens, V.; Clénet, Y.; Foresto, V. Coudé du; Cridland, A.; Davies, R.; Dembet, R.; Drescher, A.; Duvert, G.; Eckart, A.; Eisenhauer, F.; Schreiber, N. M. F"orster; Garcia, P.; Lopez, R. Garcia; Gendron, E.; Genzel, R.; Gillessen, S.; Girard, J. H.; Grant, S.; Haubois, X.; Heißel, G.; Henning, Th.; Hinkley, S.; Hippler, S.; Houllé, M.; Hubert, Z.; Jocou, L.; Keppler, M.; Kervella, P.; Kreidberg, L.; Kurtovic, N. T.; Lapeyrère, V.; Bouquin, J. -B. Le; Léna, P.; Lutz, D.; Maire, A. -L.; Mang, F.; Mérand, A.; Mollière, P.; Mordasini, C.; Mouillet, D.; Nasedkin, E.; Ott, T.; Otten, G. P. P. L.; Paladini, C.; Paumard, T.; Perraut, K.; Perrin, G.; Pfuhl, O.; Ribeiro, D. C.; Rodet, L.; Rustamkulov, Z.; Shangguan, J.; Shimizu, T.; Straubmeier, C.; Sturm, E.; Tacconi, L. J.; Vigan, A.; Vincent, F.; Ward-Duong, K.; Widmann, F.; Winterhalder, T.; Woillez, J.; Yazici, S.
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Subject
Language
Abstract
Young, low-mass Brown Dwarfs orbiting early-type stars, with low mass ratios ($q\lesssim0.01$), appear intrinsically rare and present a formation dilemma: could a handful of these objects be the highest mass outcomes of ``planetary" formation channels (bottom up within a protoplanetary disk), or are they more representative of the lowest mass ``failed binaries" (formed via disk fragmentation, or core fragmentation)? Additionally, their orbits can yield model-independent dynamical masses, and when paired with wide wavelength coverage and accurate system age estimates, can constrain evolutionary models in a regime where the models have a wide dispersion depending on initial conditions. We present new interferometric observations of the $16\,\mathrm{Myr}$ substellar companion HD~136164~Ab (HIP~75056~Ab) with VLTI/GRAVITY and an updated orbit fit including proper motion measurements from the Hipparcos-Gaia Catalogue of Accelerations. We estimate a dynamical mass of $35\pm10\,\mathrm{M_J}$ ($q\sim0.02$), making HD~136164~Ab the youngest substellar companion with a dynamical mass estimate. The new mass and newly constrained orbital eccentricity ($e=0.44\pm0.03$) and separation ($22.5\pm1\,\mathrm{au}$) could indicate that the companion formed via the low-mass tail of the Initial Mass Function. Our atmospheric fit to the \texttt{SPHINX} M-dwarf model grid suggests a sub-solar C/O ratio of $0.45$, and $3\times$ solar metallicity, which could indicate formation in the circumstellar disk via disk fragmentation. Either way, the revised mass estimate likely excludes ``bottom-up" formation via core accretion in the circumstellar disk. HD~136164~Ab joins a select group of young substellar objects with dynamical mass estimates; epoch astrometry from future \textit{Gaia} data releases will constrain the dynamical mass of this crucial object further.
Comment: Accepted for publication in The Astronomical Journal. 9 figures, 3 tables
Comment: Accepted for publication in The Astronomical Journal. 9 figures, 3 tables