The Spectra of T Dwarfs. II. Red Optical Data

By A. Burgasser, J. D. Kirkpatrick, J. Liebert, Adam Burrows. 2003

137 citations recorded by the source corpus.

We present 6300-10100 Å spectra for a sample of 13 T dwarfs observed using LRIS mountedtpdel 99 on the Keck I 10 m Telescope. A variety of features are identified and analyzed, including pressure-broadened K I and Na I doublets; narrow Cs I and Rb I lines; weak CaH, CrH, and FeH bands; strong H2O absorption; and a possible weak CH4 band. Hα emission is detected in three of the T dwarfs, strong in the previously reported active T dwarf 2MASS 1237+6526 and weak in SDSS 1254-0122 and 2MASS 1047+2124. None of the T dwarfs exhibit Li I absorption. Guided by the evolution of optical spectral features with near-infrared spectral type, we derive a parallel optical classification scheme, focusing on spectral types T5 to T8, anchored to select spectral standards. We find general agreement between optical and near-infrared types for nearly all the T dwarfs so far observed, including two earlier type T dwarfs, within our classification uncertainties (~1 subtype). These results suggest that competing gravity and temperature effects compensate for each other over the 0.6-2.5 μm spectral region. We identify one possible means of disentangling these effects by comparing the strength of the K I red wing to the 9250 Å H2O band. One of our objects, 2MASS 0937+2931, exhibits a peculiar spectrum with a substantial red slope and relatively strong FeH absorption, both consequences of a metal-deficient atmosphere. On the basis of its near-infrared properties and substantial space motion, this object may be a thick disk or halo brown dwarf.

Subfields: Astronomy and Astrophysics, Instrumentation, Spectroscopy

View Paper: https://www.semanticscholar.org/paper/91685ee5ba347157dc1f5dea2f90145d3ec54ef6

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In Astronomy and Astrophysics

1. A. Burgasser
2. Michael C. Liu
3. J. D. Kirkpatrick
4. T. Dupuy
5. K. Luhman
6. M. Marley
7. Kelle Cruz
8. D. Saumon

In Instrumentation

1. A. Burgasser
2. Michael C. Liu
3. J. D. Kirkpatrick
4. T. Dupuy
5. Kelle Cruz
6. K. Luhman
7. M. Marley
8. K. Allers

In Spectroscopy

1. A. Burgasser
2. J. D. Kirkpatrick
3. Michael C. Liu
4. T. Dupuy
5. K. Luhman
6. Kelle Cruz
7. M. Cushing
8. M. Marley

Citations in the corpus

• FUNDAMENTAL PARAMETERS AND SPECTRAL ENERGY DISTRIBUTIONS OF YOUNG AND FIELD AGE OBJECTS WITH MASSES SPANNING THE STELLAR TO PLANETARY REGIME (2015, unknown): “…(100) Liebert et al. (1979), (101) Gizis (1997), (102) Lépine and Shara (2005), (103) Burgasser et al. (2000a), (104) Tinney et al. (1992), (105) Burgasser et al. (2003a), (106) Kirkpatrick et al. (1994), (107) Albert et al. (2011), (108) Burgasser et al. (2006c), (109) Strauss et al. (1999),…”
• Near-Infrared Photometry and Spectroscopy of L and T Dwarfs: The Effects of Temperature, Clouds, and Gravity (2004, background): “Burgasser et al. (2003a) identified a late L dwarf (2MASS J05325346+8246465) whose extremely blue nearinfrared colors are similar to those of the mid T types.”
• SpeX SPECTROSCOPY OF UNRESOLVED VERY LOW MASS BINARIES. I. IDENTIFICATION OF 17 CANDIDATE BINARIES STRADDLING THE L DWARF/T DWARF TRANSITION (2009, background): “…al. (1999); (26) Siegler et al. (2007); (27) Burgasser et al. (2003b); (28) Burgasser (2007a); (29) Cruz et al. (2003); (30) Looper et al. (2007); (31) Burgasser et al. (2003d); (32) Burgasser et al. (2000a); (33) Reid et al. (2008); (34) Wilson et al. (2003); (35) Gizis (2002); (36) Burgasser et…”
• The UKIRT Infrared Deep Sky Survey ZY JHK photometric system: passbands and synthetic colours (2006, methodology): “Colours of 30 L dwarfs and 22 T dwarfs have been computed from spectra covering the wavelength range i to K, collated from the following references: Burgasser et al. (2003), Chiu et al. (2006), Cruz et al. (2003), Fan et al. (2000a), Geballe et al. (1996), Geballe et al. (2001), Geballe et al…”
• Meeting the Cool Neighbors. IX. The Luminosity Function of M7-L8 Ultracool Dwarfs in the Field (2006, background): “Burgasser et al. (2003a) and Burgasser et al. (2006a) found evidence that condensate formation was inhibited in L subdwarf atmospheres due to the persistence of TiO molecular bands and Ti I and Ca I lines in their optical spectra.”
• New spectral types L and T (2005, methodology): “…1 0 SOri 71 Zapatero Osorio et al. 2002 0 1 SOri 70 Scholz & Meusinger 2002 1 0 SSSPM J0829 − 1309 Liebert et al. 2003 1 0 2MASSI J0144353 − 071614 Burgasser et al. 2003c 0 1 2MASS J15031961 + 2525196 Scholz et al. 2003 0 1 Ind B Salim et al. 2003 1 0 LSR 0602 + 3910 Gizis et al. 2003 3 0…”
• Hubble Space Telescope NICMOS Observations of T Dwarfs: Brown Dwarf Multiplicity and New Probes of the L/T Transition (2006, methodology): “Hα emission from T dwarfs is rare; only three other T dwarfs have been detected in emission (Burgasser et al. 2003a), one of which, 2MASS J12373919+6526148 (Burgasser et al. 1999), is unusually active and is speculated to be a very tight (ρ ∼ 0.1 R⊙) interacting binary system (Burgasser et al.…”
• The Field Substellar Mass Function Based on the Full-sky 20 pc Census of 525 L, T, and Y Dwarfs (2020, background): “…al. 2019, (192) Luhman et al. 2007, (193) Looper et al. 2008a, (194) Liebert, & Gizis 2006, (195) Ellis et al. 2005, (196) Kellogg et al. 2015, (197) Burgasser et al. 2003d, (198) Liu et al. 2016, (199) Smart et al. 2018, (200) NPARSEC unpublished (Smart, priv. comm.), (201) Gizis et al. 2015,…”
• Binaries and the L Dwarf/T Dwarf Transition (2006, methodology): “…from high-resolution imaging studies using the Hubble Space Telescope (HST ) and ground-based adaptive optics instrumentation (Martı́n et al. 1999a; Reid et al. 2001b, 2006a; Bouy et al. 2003; Burgasser et al. 2003c, 2006c; Close et al. 2003; Gizis et al. 2003; Liu&Leggett 2005;Gelino et al. 2006).”
• An Infrared Spectroscopic Sequence of M, L, and T Dwarfs (2004, background): “…0.95 m and typically have resolutions ranging from 9 to 18 8 (R ¼ 890 444), are from Kirkpatrick et al. (1991, 1999b, 2000), Tinney & Reid (1998), Martı́n et al. (1999), Fan et al. (2000), Gizis et al. (2000), Reid et al. (2000), Burgasser et al. (2003), and T. Henry (2004, private communication).”
• A Spitzer Infrared Spectrograph Spectral Sequence of M, L, and T Dwarfs (2004, background): “The red-optical spectra are from Kirkpatrick et al. (1991), (Fan et al. 2000), and Burgasser et al. (2003) and the near-infrared spectra are from Cushing et al. (2005) and J. T. Rayner et al. (in preparation).”
• THE FIRST HUNDRED BROWN DWARFS DISCOVERED BY THE WIDE-FIELD INFRARED SURVEY EXPLORER (WISE) (2011, methodology): “This latter spectrum is unusual in that it has stronger 8800-9200 Å CH4, stronger 9250-9400 Å H2O bands of the 3(ν1,ν3) transition, and stronger 9450-9800 Å H2O bands of the 2(ν1,ν3) + 2(ν2) transition than the latest T dwarf optical standard, the To8 dwarf 2MASS J04151954−0935066 (Burgasser et a”
• Spitzer IRAC Photometry of M, L, and T Dwarfs (2006, background): “…SDS 0423 0414, 2MA 0746+2000,GJ337CD,SDS0926+5847,SDS1021 0304,Kelu-1, 2MA1225 2739, 2MA1534 2952, 2MA1553+1532, and 2MA 1728+3948 (Reid et al. 2001; Burgasser et al. 2003b, 2005a, 2005b, 2006b; Gizis et al. 2003; Bouy et al. 2004; Golimowski et al. 2004b; Vrba et al. 2004; Liu&Leggett 2005).”
• DISCOVERIES FROM A NEAR-INFRARED PROPER MOTION SURVEY USING MULTI-EPOCH TWO MICRON ALL-SKY SURVEY DATA (2010, background): “Each spectrum has been normalized to one at 8250 Å and overplotted on a suite of like-normalized LRIS spectra of primary M, L, and T optical spectral standards from Kirkpatrick et al. (1991), Kirkpatrick et al. (1999), and Burgasser et al. (2003).”
• Meeting the Cool Neighbors. V. A 2MASS-Selected Sample of Ultracool Dwarfs (2003, background): “This issue is discussed in Burgasser et al. (2003) and will be addressed in detail in a future paper (Kirkpatrick et al. 2003).”
• THE HAWAII INFRARED PARALLAX PROGRAM. I. ULTRACOOL BINARIES AND THE L/T TRANSITION, (2012, background): “…al. 2010); (3) Allers et al. (2009); (4) Andrei et al. (2011); (5) Artigau et al. (2010); (6) Benedict et al. (1999); (7) Bowler et al. (2010a); (8) Burgasser et al. (2003a); (9) Burgasser et al. (2006b); (10) Burgasser et al. (2007); (11) Burgasser et al. (2008a); (12) Burgasser et al. (2008b);…”
• ATMOSPHERIC CHEMISTRY IN GIANT PLANETS, BROWN DWARFS, AND LOW-MASS DWARF STARS. III. IRON, MAGNESIUM, AND SILICON (2010, background): “The presence of monatomic Na gas in brown dwarfs (Kirkpatrick et al. 1999; Burgasser et al. 2003; McLean et al. 2003; Cushing et al. 2005) also suggests Al and Si removal, because albite (NaAlSi3O8) condensation would otherwise effectively remove Na from the observable atmosphere.”
• Individual Dynamical Masses of Ultracool Dwarfs (2017, unknown): “— Burg03b = Burgasser et al. (2003b); Burg06b = Burgasser et al. (2006b); Burg11 = Burgasser et al. (2011); Chiu06 = Chiu et al. (2006); Clos03 = Close et al. (2003); Cutr03 = Cutri et al. (2003); Dupu09a = Dupuy et al. (2009a); Dupu09b = Dupuy et al. (2009b); Dupu09c = Dupuy et al. (2009c); Dupu10…”