Apparent Non-Coevality among the Stars in Upper Scorpio: Resolving the Problem using a Model of Magnetic Inhibition of Convection

Abstract

Two eclipsing binaries in the USco association have recently yielded precise values of masses and radii for 4 low-mass members of the association. Standard evolution models would require these dM4.5 - dM5 stars to have ages which are younger than the ages of more massive stars in the association by factors which appear (in extreme cases) to be as large as ~3. Are the stars in the association therefore non-coeval? We suggest that the answer is No: by incorporating the effects of magnetic inhibition of convective onset, we show that the stars in USco can be restored to coevality provided that the 4 low-mass member stars have vertical surface fields in the range 200 - 700 G. Fields of such magnitude have already been measured on the surface of certain solar-type stars in other young clusters.

References in corpus (30)

• Accurate masses and radii of normal stars: modern results and applications
• Models of Stars, Brown Dwarfs and Exoplanets
• A Revised Age for Upper Scorpius and The Star-Formation History Among the F-Type Members of the Scorpius-Centaurus OB Association
• Absolute dimensions of the M-type eclipsing binary YY Geminorum (Castor C): a challenge to evolutionary models in the lower main-sequence
• Large-scale magnetic topologies of late M dwarfs
• Evolution of low-mass star and brown dwarf eclipsing binaries
• Magnetic Inhibition of Convection and the Fundamental Properties of Low-Mass Stars. III. A Consistent 10 Myr Age for the Upper Scorpius OB Association
• Trumpeting M Dwarfs with CONCH-SHELL: a Catalog of Nearby Cool Host-Stars for Habitable ExopLanets and Life
• Episodic accretion at early stages of evolution of low mass stars and brown dwarfs: a solution for the observed luminosity spread in HR diagrams?
• The Effective Temperature Scale of M dwarfs
• Effect of episodic accretion on the structure and the lithium depletion of low-mass stars and planet-hosting stars
• The evolution of surface magnetic fields in young solar-type stars I: the first 250 Myr
• Absolute properties of the low-mass eclipsing binary CM Draconis
• Magnetic Inhibition of Convection and the Fundamental Properties of Low-Mass Stars. I. Stars with a Radiative Core
• The 0.4-Mo Eclipsing Binary CU Cancri: Absolute Dimensions, Comparison with Evolutionary Models and Possible Evidence for a Circumstellar Dust Disk
• Explaining the coexistence of large-scale and small-scale magnetic fields in fully convective stars
• A Survey for Low-mass Stars and Brown Dwarfs in the Upper-Scorpius OB Association
• On the magnetic topology of partially and fully convective stars
• Empirical Isochrones for Low Mass Stars in Nearby Young Associations
• A Surprising Reversal of Temperatures in the Brown-Dwarf Eclipsing Binary 2MASS J05352184-0546085
• Self-Consistent Magnetic Stellar Evolution Models of the Detached, Solar-Type Eclipsing Binary EF Aquarii
• Precision modeling of M dwarf stars: the magnetic components of CM Draconis
• K2 Discovery of Young Eclipsing Binaries in Upper Scorpius: Direct Mass and Radius Determinations for the Lowest Mass Stars and Initial Characterization of an Eclipsing Brown Dwarf Binary
• Dynamical Masses of Young Stars I: Discordant Model Ages of Upper Scorpius
• The radii of M-dwarfs in the young open cluster NGC 2516
• Magneto-Convection and Lithium Age Estimates of the βPictoris Moving Group
• Magnetic effects and oversized M dwarfs in the young open cluster NGC 2516
• A new method for the inversion of atmospheric parameters of A/Am stars
• M dwarf luminosity, radius, and $\alpha$-enrichment from $I$-band spectral features
• Discovery of an M4 Spectroscopic Binary in Upper Scorpius: A Calibration Point for Young Low-Mass Evolutionary Models

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