THE BROWN DWARF KINEMATICS PROJECT I. PROPER MOTIONS AND TANGENTIAL VELOCITIES FOR A LARGE SAMPLE OF LATE-TYPE M, L, AND T DWARFS

By Jacqueline K. Faherty, A. Burgasser, Kelle Cruz, M. Shara, F. Walter, C. Gelino. 2008

249 citations recorded by the source corpus.

We report proper-motion measurements for 427 late-type M, L, and T dwarfs, 332 of which have been measured for the first time. Combining these new proper motions with previously published measurements yields a sample of 841 M7-T8 dwarfs. We combined parallax measurements or calculated spectrophotometric distances, and computed tangential velocities for the entire sample. We find that kinematics for the full and volume-limited 20 pc samples are consistent with those expected for the Galactic thin disk, with no significant differences between late-type M, L, and T dwarfs. Applying an age–velocity relation we conclude that the average kinematic age of the 20 pc sample of ultracool dwarfs is older than recent kinematic estimates and more consistent with age results calculated with population synthesis models. There is a statistically distinct population of high tangential velocity sources (Vtan > 100 km s−1) whose kinematics suggest an even older population of ultracool dwarfs belonging to either the Galactic thick disk or halo. We isolate subsets of the entire sample, including low surface gravity dwarfs, unusually blue L dwarfs, and photometric outliers in J − Ks color and investigate their kinematics. We find that the spectroscopically distinct class of unusually blue L dwarfs has kinematics clearly consistent with old age, implying that high surface gravity and/or low metallicity may be relevant to their spectral properties. The low surface gravity dwarfs are kinematically younger than the overall population, and the kinematics of the red and blue ultracool dwarfs suggest ages that are younger and older than the full sample, respectively. We also present a reduced proper-motion diagram at 2MASS (Two Micron All Sky Survey) Ks for the entire population and find that a limit of > 18 excludes M dwarfs from the L and T dwarf population regardless of near-infrared color, potentially enabling the identification of the coldest brown dwarfs in the absence of color information.

Subfields: Astronomy and Astrophysics, Computational Mechanics, Instrumentation

View Paper: https://www.semanticscholar.org/paper/555b1d90cba232c51c86bc684fc3867e13ba3a3a

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Citations in the corpus

THE BROWN DWARF KINEMATICS PROJECT (BDKP). III. PARALLAXES FOR 70 ULTRACOOL DWARFS (2012, methodology): “…outliers, whose photometric properties might be attributable to dust, subtle variations in age or metallicity, or photometric variability (Knapp et al. 2004, Burgasser et al. 2008b, Faherty et al. 2009, Schmidt et al. 2010, Kirkpatrick et al. 2010,Looper et al. 2008b, Radigan et al. in prep).”
The Formation and Early Evolution of Low-Mass Stars and Brown Dwarfs (2012, background): “However, beyond a spectral type of ∼M9, young objects become redder than their older counterparts in J − K (Allers et al. 2010; Bihain et al. 2010; Briceño et al. 2002; Cruz, Kirkpatrick & Burgasser 2009; Faherty et al. 2009; Kirkpatrick et al. 2006, 2008; Schmidt et al. 2010).”
THE HAWAII INFRARED PARALLAX PROGRAM. I. ULTRACOOL BINARIES AND THE L/T TRANSITION, (2012, methodology): “Its offset from typical field (J −KS)2MASS colors is indeed small in an absolute sense (1.04 mag vs. 1.75 mag for field L6 dwarfs from Faherty et al. 2009).”
CLOUDS AND CHEMISTRY IN THE ATMOSPHERE OF EXTRASOLAR PLANET HR8799b (2011, background): “5 and a T1) are redder than the mean JKs for T0 to T2 (vertical dotted lines, values taken from Faherty et al. 2009).”
LOW-MASS TERTIARY COMPANIONS TO SPECTROSCOPIC BINARIES. I. COMMON PROPER MOTION SURVEY FOR WIDE COMPANIONS USING 2MASS (2009, background): “Also note that Faherty et al. (2009) has found that the typical proper motion of ≥M7 dwarfs with distances around 15 pc − 30 pc is ≥0.”
FUNDAMENTAL PARAMETERS AND SPECTRAL ENERGY DISTRIBUTIONS OF YOUNG AND FIELD AGE OBJECTS WITH MASSES SPANNING THE STELLAR TO PLANETARY REGIME (2015, background): “Since it is well documented that the colors of ultracool dwarfs are sensitive to age (Kirkpatrick et al. 2006, 2008; Cruz et al. 2009; Faherty et al. 2009; Allers et al. 2010; Bihain et al. 2010; Faherty et al. 2012; Schmidt et al. 2010), we derived one polynomial for the field age objects (MFLD)…”
COLORS AND KINEMATICS OF L DWARFS FROM THE SLOAN DIGITAL SKY SURVEY (2010, background): “Both the z−KS and J −KS color redden until mid-L types, then turn over and become more blue into the late-T (H02; Knapp et al. 2004; Chiu et al. 2006; Faherty et al. 2009).”
SpeX SPECTROSCOPY OF UNRESOLVED VERY LOW MASS BINARIES. I. IDENTIFICATION OF 17 CANDIDATE BINARIES STRADDLING THE L DWARF/T DWARF TRANSITION (2009, background): “Both Chiu et al. (2006) and Faherty et al. (2009) note this source as being unusually red for its spectral type, and the former attempted (unsuccessfully) to reproduce its spectrum as a binary.”
THE NIRSPEC ULTRACOOL DWARF RADIAL VELOCITY SURVEY (2010, methodology): “Coordinates, magnitudes, and spectral types of the targets in our sample as gathered from http://www.dwarfarchives.com and cross checked against the database of UCDs recently published by Faherty et al. (2009).”