Site Map

M Dwarfs


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-III bitmasks to learn how to use these values to identify objects in this ancillary target program.

bit name
Bit Target Description
APOGEE_MDWARF 19 M dwarf star


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

Suvrath Mahadevan
Penn State University
suvrath -at-
Cullen Blake
Princeton University
cblake -at-

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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