2MASS J04435686+3723033 B: A Young Companion at the Substellar Boundary with Potential Membership in the $\beta$ Pictoris Moving Group

Abstract

We present a detailed characterization of 2MASS J04435750+3723031, a low-mass companion orbiting the young M2 star, 2MASS J04435686+3723033, at 7.6 arcseconds (550 AU) with potential membership in the 23 Myr $\beta$ Pictoris moving group ($\beta$PMG). Using near-infrared spectroscopy of the companion from IRTF/SpeX we have found a spectral type of M6 $\pm$ 1 and indications of youth through age-sensitive absorption lines and a low surface gravity index (VL-G). A young age is supported by H$\alpha$ emission and lithium absorption in the host. We re-evaluate the membership of this system and find that it is a marginally consistent kinematic match to the $\beta$PMG using $Gaia$ parallaxes and new radial velocities for the host and companion. If this system does belong to the $\beta$PMG, it would be a kinematic outlier and the companion would be over-luminous compared to other similar ultracool objects like PZ Tel B; this would suggest 2M0443+3723 B could be a close brown dwarf binary ($\approx$52+52 M${}_{\mathrm{Jup}}$ if equal-flux, compared with 99 $\pm$ 5 M${}_{\mathrm{Jup}}$ if single), and would make it the sixth substellar companion in this group. To test this hypothesis, we acquired NIR AO images with Keck II/NIRC2, but they do not resolve the companion to be a binary down to the diffraction limit of $\sim$3 AU. If 2M0443+3723 AB does not belong to any moving group then its age is more uncertain. In this case it is still young ($\lesssim$30 Myr), and the implied mass of the companion would be between $\sim$30--110 M${}_{\mathrm{Jup}}$.

18 pages, 18 figures, Accepted to ApJ

References in corpus (21)

• Direct Imaging of Multiple Planets Orbiting the Star HR 8799
• The Gemini Planet Imager: First Light
• The Evolution of L and T Dwarfs in Color-Magnitude Diagrams
• On the age of the $\beta$ Pictoris moving group
• The Hawaii Infrared Parallax Program. II. Young Ultracool Field Dwarfs
• Planets Around Low-Mass Stars (PALMS). IV. The Outer Architecture of M Dwarf Planetary Systems
• A Stellar Census of the Tucana-Horologium Moving Group
• Subtle Signatures of Multiplicity in Late-type Dwarf Spectra: The Unresolved M8.5 + T5 Binary 2MASS J03202839-0446358
• New periodic variable stars coincident with ROSAT sources discovered using SuperWASP
• BANYAN. IV. Fundamental parameters of low-mass star candidates in nearby young stellar kinematic groups - Isochronal Age determination using Magnetic evolutionary models
• Characterizing 51 Eri b from 1-5 $\mu$m: a partly-cloudy exoplanet
• All-sky Co-moving Recovery Of Nearby Young Members. (ACRONYM) II: The Beta Pictoris Moving Group
• On-sky speckle nulling demonstration at small angular separation with SCExAO
• Zodiacal Exoplanets in Time (ZEIT) V: A Uniform Search for Transiting Planets in Young Clusters Observed by K2
• A Model-Independent Mass and Moderate Eccentricity for $\beta$ Pic b
• Performance of the Near-infrared coronagraphic imager on Gemini-South
• The Elusive Majority of Young Moving Groups. I. Young Binaries and Lithium-Rich Stars in the Solar Neighborhood
• The beta Pictoris association low-mass members: membership assessment, rotation period distribution, and dependence on multiplicity
• Dynamical Mass Measurement of the Young Spectroscopic Binary V343 Normae AaAb Resolved With the Gemini Planet Imager
• Effective Temperatures of Low-Mass Stars from High-Resolution H-band Spectroscopy
• Development of models for nearby young stellar moving groups: creation, revision, and finalisation of the models

Cited by in corpus (3)

• Gaia-based Isochronal, Kinematic, and Spatial Analysis of the $\epsilon$ Cha Association
• A Census of the 32 Ori Association with Gaia
• Dynamical Mass of the Young Brown Dwarf Companion PZ Tel B