H$\alpha$ Emission From Active Equal-mass, Wide M Dwarf Binaries

Abstract

We identify a sample of near-equal mass wide binary M dwarf systems from the SLoWPoKES catalog of common proper-motion binaries and obtain follow-up observations of their chromospheric activity as measured by the H$\alpha$ emission line. We present optical spectra for both components of 48 candidate M dwarf binaries, confirming their mid-M spectral types. Of those 48 coeval pairs, we find eight with H$\alpha$ emission from both components, three with weak emission in one component and no emission in the other, and 37 with two inactive components. We find that of the eleven pairs with at least one active component, only three follow the net trend of decreasing activity strength $L_{\mathrm{H}\alpha }/L_{\mathrm{bol}}$ with later spectral type. The difference in quiescent activity strength between the A and B components is larger than what would be expected based on the small differences in color (mass). For five binaries with two active components, we present 47 hours of time-resolved spectroscopy, observed on the ARC 3.5-m over twelve different nights. For four of the five pairs, the slightly redder (B) component exhibits a higher level of H$\alpha$ emission during the majority of the observations and the redder objects are the only components to flare. The full range of H$\alpha$ emission observed on these variable mid-M dwarfs is comparable to the scatter in H$\alpha$ emission found in single-epoch surveys of mid-M dwarfs, indicating that variability could be a major factor in the spread of observed activity strengths. We also find that variability is independent of both activity strength and spectral type.

10 pages, 6 figures, accepted for publication in PASP

References in corpus (5)

• Constraining the Age-Activity Relation for Cool Stars: The SDSS DR5 Low-Mass Star Spectroscopic Sample
• Stellar SEDs from 0.3-2.5 Microns: Tracing the Stellar Locus and Searching for Color Outliers in SDSS and 2MASS
• Magnetic field generation in fully convective rotating spheres
• The Effect of Binarity on Stellar Rotation - Beyond the Reach of Tides
• Chi Values for Blue Emission Lines in M Dwarfs

Cited by in corpus (2)

• Stellar flares from blended and neighbouring stars in Kepler short cadence observations
• Activity and Rotation of Nearby Field M Dwarfs in the TESS Southern Continuous Viewing Zone