# M Dwarfs

## Summary

Spectra of stars with known spectral class M

## Finding Targets

An object whose APOGEE_TARGET1 value includes one or more of the bitmasks in the following table was targeted for spectroscopy as part of this ancillary target program. See SDSS bitmasks to learn how to use these values to identify objects in this ancillary target program.

APOGEE_TARGET1
bit name
Bit Target Description
APOGEE_MDWARF 19 M dwarf star

## Description

M dwarfs make excellent candidates for planet searches due to both their ubiquity and the increased RV signal of a planet in the Habitable Zone (HZ; Kasting et al. 1993), relative to the same planet around an F, G, or K star. However, the coming generation of NIR precision-RV planet surveys, such as HPF (Mahadevan et al. 2010) and CARMENES (Quirrenbach et al. 2010), will be able to search efficiently around hundreds of nearby M dwarfs. The primary goals of this ancillary program are to constrain the rotational velocities and compositions of ~ 1400 M dwarfs and to detect their low mass companions through RV variability measurements. By using metallicity-sensitive H-band features, including some blended K and Ca lines (Terrien et al. 2012), we can derive metallicities for these M dwarfs, a measurement notoriously difficult to make directly because of their complex spectra. Finally, the multiplicity of M dwarfs and the rate of both brown dwarf and high-mass giant planet companions to M dwarfs can be probed via RV variability (along with direct K-band imaging), particularly in the subset of M dwarfs that will have ~ 12 APOGEE epochs, with time baselines beginning years before dedicated NIR RV planet searches come online.

## Primary contacts

Penn State University
suvrath -at- astro.psu.edu
Cullen Blake
Princeton University
cblake -at- astro.princeton.edu

## Other contacts

Chad Bender, Joleen Carlberg, Justin Crepp, Rohit Deshpande, Fred Hearty, David Nidever, Don Schneider, Ryan Terrien

## Target Selection Details

Targets are drawn from two primary sources: the LSPM-North catalog of nearby stars (Lépine & Shara 2005) and the Lépine & Gaidos (2011) catalog of nearby M dwarfs, which are both proper motion-selected catalogs. The LSPM-N sample required a simple color cut of (V-K) > 4 to select dwarfs of subtype M4 and later; the LG11 catalog already includes extensive color and reduced proper motion cuts aimed at selecting M dwarfs. For calibration, several targets are included that are known planet hosts, RV standards, and/or have previous vsin(i) or [Fe/H] estimates. We also include five M dwarfs that are Kepler objects of interest (Borucki et al. 2010), and three L dwarfs (Wilson et al. 2003; Phan-Bao et al. 2008).

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