Gaia Gaps and the Physics of Low-Mass Stars. I. The Fully Convective Boundary

Abstract

The Gaia M-dwarf gap is a significant under-density of stars observed near $M_G=10.2$ in a color-magnitude diagram for stars within 200 pc of the Sun. It has been proposed that the gap is the manifestation of structural instabilities within stellar interiors due to non-equilibrium ${}^3$He fusion prior to some stars becoming fully convective. To test this hypothesis, we use Dartmouth stellar evolution models, MARCS model atmospheres, and simple stellar population synthesis to create synthetic $M_G$-($G_{\mathrm{BP}}-G_{\mathrm{RP}})$ color-magnitude diagrams. We confirm that the proposed ${}^3$He instability is responsible for the appearance of the M-dwarf gap. Our synthetic gap shows qualitatively similar features to the observed gap including: its vertical extent in $M_G$, its slope in the color-magnitude diagram, and its relative prominence at bluer colors as compared to redder colors. Furthermore, corresponding over-densities of stars above the gap are reproduced by the models. While qualitatively similar, the synthetic gap is approximately 0.2 magnitudes bluer and, accounting for this color offset, 0.16 magnitudes brighter than the observed gap. Our results reveal that the Gaia M dwarf gap is sensitive to conditions within cores of M dwarf stars, making the gap a powerful tool for testing the physics of M dwarf stars and potentially using M dwarfs to understand the local star formation history.

arXiv comment20 pages, 8 figures, accepted for publication in ApJ, comments welcome

References in corpus (50)

• SciPy 1.0--Fundamental Algorithms for Scientific Computing in Python
• The NumPy array: a structure for efficient numerical computation
• The chemical composition of the Sun
• Galactic Stellar and Substellar Initial Mass Function
• Gaia Data Release 2. Summary of the contents and survey properties
• A grid of MARCS model atmospheres for late-type stars I. Methods and general properties
• Intrinsic Colors, Temperatures, and Bolometric Corrections of Pre-Main Sequence Stars
• The Dartmouth Stellar Evolution Database
• The Geneva-Copenhagen survey of the Solar neighbourhood: Ages, metallicities, and kinematic properties of 14,000 F and G dwarfs
• New evolutionary models for pre-main sequence and main sequence low-mass stars down to the hydrogen-burning limit
• Accurate masses and radii of normal stars: modern results and applications
• Solar Chemical Abundances Determined with a CO5BOLD 3D Model Atmosphere
• Gaia Data Release 2: Photometric content and validation
• How to Constrain Your M Dwarf: measuring effective temperature, bolometric luminosity, mass, and radius
• Improving PARSEC models for very low mass stars
• Element Diffusion in the Solar Interior
• Stellar Diameters and Temperatures II. Main Sequence K & M Stars
• Theory of Low-Mass Stars and Substellar Objects
• The Geneva-Copenhagen Survey of the Solar neighbourhood III. Improved distances, ages, and kinematics
• Model Atmospheres for M (Sub)Dwarfs: I. The base model grid
• Helioseismology and Solar Abundances
• Evolution of low-mass star and brown dwarf eclipsing binaries
• Metallicity and Temperature Indicators in M dwarf K band Spectra: Testing New & Updated Calibrations With Observations of 133 Solar Neighborhood M dwarfs
• How to Constrain Your M dwarf II: the mass-luminosity-metallicity relation from 0.075 to 0.70$M_{\odot }$
• Magnetic Inhibition of Convection and the Fundamental Properties of Low-Mass Stars. III. A Consistent 10 Myr Age for the Upper Scorpius OB Association
• On the Correlation between the Magnetic Activity Levels, the Metallicities and the Radii of Low-Mass Stars
• Helioseismological Implications of Recent Solar Abundance Determinations
• On the use of Gaia magnitudes and new tables of bolometric corrections
• Synthetic Stellar Photometry - I. General considerations and new transformations for broad-band systems
• The Effective Temperature Scale of M dwarfs
• The Solar Neighborhood XXXVII: The Mass-Luminosity Relation for Main Sequence M Dwarfs
• The radius discrepancy in low mass stars: single vs. binaries
• Prospecting in late-type dwarfs: a calibration of infrared and visible spectroscopic metallicities of late-K and M dwarfs spanning 1.5 dex
• Magnetic Inhibition of Convection and the Fundamental Properties of Low-Mass Stars. I. Stars with a Radiative Core
• Masses and Radii of Low-Mass Stars: Theory versus Observations
• The Ages of the Thin Disk, Thick Disk, and the Halo from Nearby White Dwarfs
• Older and Colder: The impact of starspots on pre-main sequence stellar evolution
• Reevaluating the Mass-Radius Relation for Low-Mass, Main Sequence Stars
• The Helium abundance and Delta Y / Delta Z in Lower Main Sequence stars
• Magnetic Inhibition of Convection and the Fundamental Properties of Low-Mass Stars. II. Fully Convective Main Sequence Stars
• Are pre-main-sequence stars older than we thought?
• Magnetic Inflation and Stellar Mass II: On the Radii of Single, Rapidly Rotating, Fully Convective M Dwarf Stars
• Helium abundance in a sample of cool stars: measurements from asteroseismology
• A Gap in the Lower Main Sequence Revealed by Gaia Data Release 2
• Temperatures and Metallicities of M dwarfs in the APOGEE Survey
• Pre-main-sequence isochrones -- I. The Pleiades benchmark
• A closer look at the transition between fully convective and partly radiative low mass stars
• Exploring the M-dwarf Luminosity--Temperature--Radius Relationships using Gaia DR2
• A He3 driven instability near the fully convective boundary
• An explanation for the gap in the Gaia HRD for M dwarfs

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• Stellar Characterization and Radius Inflation of Hyades M Dwarf Stars From the APOGEE Survey
• The LHS 1678 System: Two Earth-Sized Transiting Planets and an Astrometric Companion Orbiting an M Dwarf Near the Convective Boundary at 20 pc
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• Mind the Gap I: H$\alpha$ Activity of M Dwarfs Near the Partially/Fully Convective Boundary and a New H$\alpha$ Emission Deficiency Zone on the Main Sequence
• A discontinuity in the luminosity-mass relation and fluctuations in the evolutionary tracks of low-mass and low-metallicity stars at the Gaia M-dwarf gap
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• Updated High-Temperature Opacities for the Dartmouth Stellar Evolution Program and their Effect on the Jao Gap Location
• The emptiness inside: Finding gaps, valleys, and lacunae with geometric data analysis
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• Constraints on Evolutionary Timescales for M Dwarf Planets from Dynamical Stability Arguments
• JWST observations of 47 Tucanae: I. The low-mass main sequence down to the hydrogen-burning limit
• The M-dwarf Ultraviolet Spectroscopic Sample I. Determining Stellar Parameters for Field Stars