Dynamical masses of M-dwarf binaries in young moving groups: II - Toward empirical mass-luminosity isochrones

Abstract

Low-mass stars exhibit substantial pre-main sequence evolution during the first ~100 Myrs of their lives. Thus, young M-type stars are prime targets for isochronal dating, especially in young moving groups (YMGs), which contain large amounts of stars in this mass and age range. If the mass and luminosity of a star can both be directly determined, this allows for a particularly robust isochronal analysis. This motivates in-depth studies of low-mass binaries with spatially resolvable orbits, where dynamical masses can be derived. Here we present the results of an observing campaign dedicated to orbital monitoring of AB Dor Ba/Bb, which is a close M-dwarf pair within the quadruple AB Dor system. We have acquired eight astrometric epochs with the SPHERE/ZIMPOL and NACO instruments, which we combine with literature data to improve the robustness and precision for the orbital characterization of the pair. We find a system mass 0.66+/-0.12 Msun and bolometric luminosities in log(L/Lsun) of -2.02+/-0.02 and -2.11 +/- 0.02 for AB Dor Ba and Bb, respectively. These measurements are combined with other YMG pairs in the literature to start building a framework of empirical isochrones in mass-luminosity space. This can be used to calibrate theoretical isochrones and to provide a model-free basis for assessing relative stellar ages. We note a tentative emerging trend where the youngest moving group members are largely consistent with theoretical expectations, while stars in older associations such as the AB Dor moving group appear to be systematically underluminous relative to isochronal expectations.

arXiv comment10 pages, 5 figures, A&A 620, A33

References in corpus (39)

• Gaia Data Release 2. Summary of the contents and survey properties
• The Wide-field Infrared Survey Explorer (WISE): Mission Description and Initial On-orbit Performance
• The Gaia mission
• PARSEC: stellar tracks and isochrones with the PAdova and TRieste Stellar Evolution Code
• MESA Isochrones and Stellar Tracks (MIST). I: Solar-Scaled Models
• Direct Imaging of Multiple Planets Orbiting the Star HR 8799
• New evolutionary models for pre-main sequence and main sequence low-mass stars down to the hydrogen-burning limit
• Discovery and spectroscopy of the young Jovian planet 51 Eri b with the Gemini Planet Imager
• BANYAN. XI. The BANYAN $\Sigma$ multivariate Bayesian algorithm to identify members of young associations within 150 pc
• A self-consistent, absolute isochronal age scale for young moving groups in the solar neighbourhood
• Improving the Efficiency of Markov Chain Monte Carlo for Analyzing the Orbits of Extrasolar Planets
• Quantifying the Uncertainty in the Orbits of Extrasolar Planets
• BANYAN. II. Very Low Mass and Substellar Candidate Members to Nearby, Young Kinematic Groups With Previously Known Signs of Youth
• The AstraLux Large M-dwarf Multiplicity Survey
• Discovery of a warm, dusty giant planet around HIP65426
• The nearest young moving groups
• Orbital characterization of the βPictoris b giant planet
• Bayesian Ages for Early-Type Stars from Isochrones Including Rotation, and a Possible Old Age for the Hyades
• STIS Imaging of the HR 4796A Circumstellar Debris Ring
• Lucky Imaging survey for southern M dwarf binaries
• Sparse aperture masking at the VLT I. Faint companion detection limits for the two debris disk stars HD 92945 and HD 141569
• Imaging Discovery of the Debris Disk Around HIP 79977
• The AstraLux Multiplicity Survey: Extension to Late M-dwarfs
• The Ages of A-Stars I: Interferometric Observations and Age Estimates for Stars in the Ursa Major Moving Group
• New Photometry and Spectra of AB Doradus C: An Accurate Mass Determination of a Young Low-Mass Object with Theoretical Evolutionary Tracks
• SPHERE / ZIMPOL observations of the symbiotic system R Aqr. I. Imaging of the stellar binary and the innermost jet clouds
• Dynamical Masses of Young M Dwarfs: Masses and Orbital Parameters of GJ 3305 AB, the Wide Binary Companion to the Imaged Exoplanet Host 51 Eri
• Orbits and Masses in the T Tauri System
• Improved age constraints for the AB Dor quadruple system - The binary nature of AB Dor B
• Orbital Monitoring of the AstraLux Large M-dwarf Multiplicity Sample
• Binaries among low-mass stars in nearby young moving groups
• Dynamical Mass Measurement of the Young Spectroscopic Binary V343 Normae AaAb Resolved With the Gemini Planet Imager
• Direct imaging of the young spectroscopic binary HD 160934
• Orbits and Masses in the multiple system LHS 1070
• Dynamical masses of M-dwarf binaries in young moving groups: I - The case of TWA 22 and GJ 2060
• Dynamical masses of the low-mass stellar binary ABDoradusB
• Orbits and masses in the young triple system TWA 5
• The discrepancy between dynamical and theoretical mass in the triplet-system 2MASS J10364483+1521394
• Young, active radio stars in the AB Doradus moving group

Cited by in corpus (5)

• SPHERE: the exoplanet imager for the Very Large Telescope
• The Elusive Majority of Young Moving Groups. I. Young Binaries and Lithium-Rich Stars in the Solar Neighborhood
• Addressing Systematics in the Traceback Age of the $\beta$ Pictoris Moving Group
• Evidence of a substellar companion to AB Dor C
• Direct Imaging Explorations for Companions around Mid-Late M Stars from the Subaru/IRD Strategic Program