The 2MASS Wide-Field T Dwarf Search. III. Seven New T Dwarfs and Other Cool Dwarf Discoveries

By A. Burgasser, M. McElwain, J. D. Kirkpatrick, Kelle Cruz, C. Tinney, I. Neill Reid. 2004

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We present the discovery of seven new T dwarfs identified in the Two Micron All Sky Survey. Low-resolution (R ∼ 150) 0.8–2.5 μm spectroscopy obtained with the Infrared Telescope Facility (IRTF) SpeX instrument reveals the characteristic H2O and CH4 bands in the spectra of these brown dwarfs. Comparison with spectral standards observed with the same instrument enables us to derive classifications of T3 to T7 for the objects in this sample. Moderate-resolution (R ∼ 1200) near-infrared spectroscopy for a subset of these discoveries reveal K I line strengths consistent with previously observed trends with spectral type. Follow-up imaging observations provide proper-motion measurements for these sources, ranging from less than 0.″1 to 1.″55 yr-1. One object, 2MASS 0034+0523, has a spectrophotometric distance placing it within 10 pc of the Sun. This source also exhibits a depressed K-band peak reminiscent of the peculiar T dwarf 2MASS 0937+2931 and may be a metal-poor or old, high-mass brown dwarf. We also present low-resolution SpeX data for a set of M- and L-type dwarf, subdwarf, and giant comparison stars used to classify 59 additional candidates identified as background stars. These are primarily M5–M8.5 dwarfs, many exhibiting H I Paγ, but include three candidate ultracool M subdwarfs and one possible early-type L subdwarf.

Subfields: Astronomy and Astrophysics, Atomic and Molecular Physics, and Optics, Instrumentation

View Paper: https://www.semanticscholar.org/paper/8fd4d991d6b7b471aa9dc5b2ce6f8eeafc9f8dcb

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Citations in the corpus

THE HAWAII INFRARED PARALLAX PROGRAM. I. ULTRACOOL BINARIES AND THE L/T TRANSITION, (2012, methodology): “…for ultracool binaries were derived primarily from three magnitude-limited searches: the SDSS ultracool dwarf search (e.g., Knapp et al. 2004; Chiu et al. 2006), the 2MASS L dwarf search (e.g., Cruz et al. 2007; Reid et al. 2008b), and the 2MASS T dwarf search (e.g., Burgasser et al. 2004).”
PLANETS AROUND LOW-MASS STARS (PALMS). IV. THE OUTER ARCHITECTURE OF M DWARF PLANETARY SYSTEMS (2014, background): “Burgasser et al. (2004) obtained a low-resolution near-infrared spectrum of the companion, which does not show obvious signs of low gravity in the form of an angular H-band shape, supporting an age &100 Myr (e.g., Allers & Liu 2013).”
Hubble Space Telescope NICMOS Observations of T Dwarfs: Brown Dwarf Multiplicity and New Probes of the L/T Transition (2006, methodology): “Details on the acquisition, reduction and characteristics of these data are described in detail in Burgasser et al. (2004a, 2006a).”
Seventy-One New L and T Dwarfs from the Sloan Digital Sky Survey (2006, background): “Table 2 lists MKO JHK magnitudes for three 2MASS dwarfs (2MASS J0034+0523, 2MASS J1209 1004, and 2MASS J2101+ 1756), as well as UFTI Zmagnitudes for 2MASS J1209 1004 and seven previously published SDSS L and T dwarfs (Burgasser et al. 2004; K04).”
Subtle Signatures of Multiplicity in Late-type Dwarf Spectra: The Unresolved M8.5 + T5 Binary 2MASS J03202839–0446358 (2008, unknown): “The LEHPM15 12 See Burgasser et al. (2004, 2006a, 2007a); Cruz et al. (2004); Siegler et al. (2005); Burgasser, Burrows & Kirkpatrick (2007); Burgasser & McElwain (2006); Chiu et al. (2006); McElwain & Burgasser (2006); Reid et al. (2006b); Burgasser (2007a,b); Liebert & Burgasser (2007); Looper, Ki”
THE MOST LUMINOUS z ∼ 9–10 GALAXY CANDIDATES YET FOUND: THE LUMINOSITY FUNCTION, COSMIC STAR-FORMATION RATE, AND THE FIRST MASS DENSITY ESTIMATE AT 500 Myr (2013, methodology): “In addition to galaxy templates, we fit all four candidates with stellar templates including observed dwarf spectra from Burgasser et al. (2004).”
Discovery of 11 New T Dwarfs in the Two Micron All Sky Survey, Including a Possible L/T Transition Binary (2007, background): “%) and low incidence of T dwarfs in spectroscopic follow-up (∼11%, Burgasser et al. 2004b).”
DISCOVERY OF A BINARY BROWN DWARF AT 2 pc FROM THE SUN (2013, background): “Most brown dwarfs, on the other hand, have been found through their distinctive colors (e.g., Burgasser et al. 2004; Cruz et al. 2007; Burningham et al. 2010; Albert et al. 2011; Kirkpatrick et al. 2011) because wide-field infrared (IR) surveys initially offered limited data on proper motions.”
New spectral types L and T (2005, background): “5 dwarf SOri47 shows none of the signs of lower gravity as originally reported by Zapatero Osorio et al. (1999), and Burgasser et al. (2004b) argue that the T dwarf SOri70 is more likely a field object based on more careful analysis of the original data.”
Discovery of a Very Young Field L Dwarf, 2MASS J01415823–4633574 (2005, methodology): “Standard reductions were employed using the Spextool package version 3.2 (Cushing et al. 2004; Vacca et al. 2003) as described in Burgasser et al. (2004).”
A Unified Near-Infrared Spectral Classification Scheme for T Dwarfs (2005, methodology): “This phenomenon, cited extensively in the literature (Burgasser et al. 2002c, 2004a; Burgasser, Burrows & Kirkpatrick 2005; Leggett et al. 2002b; Golimowski et al. 2004; Knapp et al. 2004), is caused by variations in collision induced H2 absorption, which is particularly strong in the atmospheres…”
The Field Substellar Mass Function Based on the Full-sky 20 pc Census of 525 L, T, and Y Dwarfs (2020, background): “As discussed in Kirkpatrick et al. (2019), Burgasser et al. (2004) proposed that this object’s broad K I lines might indicate a higher gravity that is the consequence of lower metallicity.”
The Cosmic Energy Inventory (2004, background): “The IMF at substellar masses, m < 0.08m⊙, is more uncertain, but recent observations of T dwarfs in the solar neighbourhood indicate x < 0 (e.g., Burgasser et al. 2003; 2004).”