Astrometry and Photometry for Cool Dwarfs and Brown Dwarfs

By C. Dahn, H. Harris, F. Vrba, H. Guetter, B. Canzian, A. Henden, S. Levine, C. Luginbuhl, A. B. Monet, D. Monet and 8 more. 2002

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Trigonometric parallax determinations are presented for 28 late-type dwarfs and brown dwarfs, including eight M dwarfs with spectral types between M7 and M9.5, 17 L dwarfs with spectral types between L0 and L8, and three T dwarfs. Broadband photometry at CCD wavelengths (VRIz*) and/or near-IR wavelengths (JHK) is presented for these objects and for 24 additional late-type dwarfs. Supplemented with astrometry and photometry from the literature, including 10 L and two T dwarfs with parallaxes established by association with bright, usually Hipparcos primaries, this material forms the basis for studying various color-color and color–absolute magnitude relations. The I-J color is a good predictor of absolute magnitude for late M and L dwarfs. MJ becomes monotonically fainter with I-J color and with spectral type through late L dwarfs, then brightens for early T dwarfs. The combination of z*JK colors alone can be used to classify late M, early L, and T dwarfs accurately, as well as to predict their absolute magnitudes, but is less effective at untangling the scatter among mid- and late L dwarfs. The mean tangential velocity of these objects is found to be slightly less than that for dM stars in the solar neighborhood, consistent with a sample with a mean age of several Gyr. Using colors to estimate bolometric corrections and models to estimate stellar radii, effective temperatures are derived. The latest L dwarfs are found to have Teff ∼ 1360 K.

Subfields: Astronomy and Astrophysics, Computational Mechanics, Instrumentation

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Citations in the corpus

Detection of Nine M8.0-L0.5 Binaries: The Very Low Mass Binary Population and Its Implications for Brown Dwarf and Very Low Mass Star Formation (2003, methodology): “We do not have spatially resolved spectra of both components in any of these systems; consequently, we can only try to fit the MKs values in Table 3 to the relation SpT ¼ 3:97MKs 31:67, which is derived from the data set of Dahn et al. (2002) by Siegler et al. (2003).”
A STUDY OF THE DIVERSE T DWARF POPULATION REVEALED BY WISE (2013, background): “The extremely red objects shown in this paper do not show the “peakiness” associated with youth, but instead display a broader plateau in the H band, and are most similar to WISEP J0047+6803 and 2MASSW J2244316+204343 (Dahn et al. 2002; McLean et al. 2003; Looper et al. 2008).”
An Infrared Spectroscopic Sequence of M, L, and T Dwarfs (2004, background): “The effective temperatures of ultracool dwarfs are typically determined by combining observationally measured bolometric luminosities with theoretical stellar radii (e.g., Leggett et al. 1996, 2001, 2002; Dahn et al. 2002; Golimowski et al. 2004).”
A Spitzer Infrared Spectrograph Spectral Sequence of M, L, and T Dwarfs (2004, background): “Bolometric Luminosities The effective temperatures of ultracool dwarfs are typically determined by combining observed bolometric luminosities with theoretical radii (Leggett et al. 2001; Dahn et al. 2002; Golimowski et al. 2004).”
THE BROWN DWARF KINEMATICS PROJECT I. PROPER MOTIONS AND TANGENTIAL VELOCITIES FOR A LARGE SAMPLE OF LATE-TYPE M, L, AND T DWARFS (2008, methodology): “Dahn et al. (2002) and Vrba et al. (2004) both showed that MJ is well correlated with spectral type for late-type M, L, and T dwarfs (see alsoWest et al. 2005, and Covey et al. 2007).”
Meeting the Cool Neighbors. VIII. A Preliminary 20 Parsec Census from the NLTT Catalogue (2004, unknown): “Trigonometric parallax surveys, such as the USNO program (Monet et al, 1992; Dahn et al, 2002) and the CTIOPI survey (Henry et al, 2003), generally target the latter stars, providing more accurate distance measure- ments.”
Radio Observations of a Large Sample of Late M, L, and T Dwarfs: The Distribution of Magnetic Field Strengths (2006, background): “For the L dwarfs I deriveBCK ¼ 3:42þ 0:075(SP 4) for L0YL4 and BCK ¼ 3:42 0:075(SP 4) for L5YL9, with SP ¼ 0 for L0, from the samples of Dahn et al. (2002) and Nakajima et al. (2004).”
ERRATUM: “THE LUMINOSITY AND MASS FUNCTIONS OF LOW-MASS STARS IN THE GALACTIC DISK. II. THE FIELD” (2010, AJ, 139, 2679) (2010, unknown): “The studies of Dahn et al. (2002) and Vrba et al. (2004) supplemented the original sample and provided accurate parallaxes (σπ/π 0.1) of late M and L dwarfs.”
Spitzer IRAC Photometry of M, L, and T Dwarfs (2006, background): “…is the fact that other groups have been able to obtain accurate trigonometric parallaxes for a large number of these very cool dwarfs (e.g., Dahn et al. 2002; Tinney et al. 2003; Vrba et al. 2004) and to obtain dynamical masses for a significant sample of stars (e.g., Henry & McCarthy…”
Spectroscopy of New High Proper Motion Stars in the Northern Sky. I. New Nearby Stars, New High-Velocity Stars, and an Enhanced Classification Scheme for M Dwarfs (2002, background): “5 V whose parallaxes are given in Dahn et al. (2002).”
HST SPECTRAL MAPPING OF L/T TRANSITION BROWN DWARFS REVEALS CLOUD THICKNESS VARIATIONS (2013, background): “Transition objects are seen to show brighter J-band magnitudes with later spectral types before an eventual turn to the clear T-dwarf sequence (Dahn et al. 2002; Tinney et al. 2003; Vrba et al. 2004).”
MID-INFRARED PHOTOMETRY OF COLD BROWN DWARFS: DIVERSITY IN AGE, MASS, AND METALLICITY (2010, background): “These trends have been known for some time (e.g. Dahn et al. 2002) and have now been confirmed, through studies of binaries, to be an intrinsic part of brown dwarf evolution, and not due to for example differences in gravity or metallicity, or due to unresolved binarity (e.g. Liu et al. 2006,…”
THE HAWAII INFRARED PARALLAX PROGRAM. II. YOUNG ULTRACOOL FIELD DWARFS (2016, background): “Finally, 14 objects in our sample have published parallaxes in several other papers (Dahn et al. 2002; Vrba et al. 2004; Costa et al. 2006; Teixeira et al. 2008; Gatewood & Coban 2009; Andrei et al. 2011; Shkolnik et al. 2012; Weinberger et al. 2013; Ducourant et al. 2014; Gizis et al. 2015).”
INTRINSIC COLORS, TEMPERATURES, AND BOLOMETRIC CORRECTIONS OF PRE-MAIN-SEQUENCE STARS (2013, methodology): “For the M dwarfs, the BCV scale was estimated via V-Ks colors and the BCK results from Leggett et al. (2001), Dahn et al. (2002), and Golimowski et al. (2004), as well as the authors’ SEDF fits compiled in Table 7.”
Individual Dynamical Masses of Ultracool Dwarfs (2017, methodology): “2MASS J0746+2000AB has a remarkably precise parallax of 81.9±0.3 mas from the USNO optical program (Dahn et al. 2002).”