Infrared Spectra and Spectral Energy Distributions of Late M and L Dwarfs

By S. Leggett, F. Allard, T. Geballe, Peter Hauschildt, A. Schweitzer. 2000

239 citations recorded by the source corpus.

We have obtained 1.0-2.5 μm spectra at R ~ 600 of 14 disk dwarfs with spectral types M6-L7. For four of the dwarfs, we have also obtained infrared spectra at R ~ 3000 in several narrow intervals. In addition, we present new L' photometry for four of the dwarfs in the sample, which allows improved determinations of their bolometric luminosities. While obtaining the photometry we resolved the L dwarf Denis-P J0205-1159 into an identical pair of objects separated by 0.″35. The spectra together with the published energy distribution for one other L5 dwarf are compared to synthetic spectra generated by upgraded model atmospheres. Good matches are found for 2200 K ≥ Teff ≥ 1900 K (spectral types around M9-L3), but discrepancies exist at Teff ≥ 2300 K (M8) and Teff ≤ 1800 K (L4-L7). At the higher temperatures the mismatches are due to incompleteness in the water vapor opacity line list. At the lower temperatures the disagreement is probably due to our treatment of dust; we assume a photospheric distribution in equilibrium with the gas phase and neglect any diffusion mechanisms. We derive effective temperatures for the sample from the comparison with synthetic spectra and also by comparing our observed total intrinsic luminosities to structural model calculations (which are mostly independent of the atmosphere but are dependent on the unknown masses and ages of the targets). The two derivations agree to about 200 K except for the faintest object in the sample, where the discrepancy is larger. Agreement with other temperature determinations is also ±~200 K, except for the L7 dwarf.

Subfields: Astronomy and Astrophysics, Atmospheric Science, Spectroscopy

View Paper: https://www.semanticscholar.org/paper/6f237a3a0faa3ea85abbefe53012a648e59a0342

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In Astronomy and Astrophysics

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

In Atmospheric Science

1. A. Burgasser
2. J. D. Kirkpatrick
3. Adam Burrows
4. M. Marley
5. Michael C. Liu
6. K. Luhman
7. K. Allers
8. M. Cushing

In Spectroscopy

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

Citations in the corpus

• MID-INFRARED PHOTOMETRY OF COLD BROWN DWARFS: DIVERSITY IN AGE, MASS, AND METALLICITY (2010, methodology): “MKO-system L′M ′ photometry is included where available (although not used in this study), from Geballe et al. (2001); Golimowski et al. (2004a); Jones et al. (1996); Leggett (1992); Leggett et al. (1998, 2001, 2002b, 2007); Reid & Cruz (2002).”
• Near-Infrared Photometry and Spectroscopy of L and T Dwarfs: The Effects of Temperature, Clouds, and Gravity (2004, methodology): “These known binaries are DENIS-P J0205 1159AB (Koerner et al. 1999; Leggett et al. 2001; Bouy et al. 2003); DENIS-P J1228 1547AB (Koerner et al. 1999; Martı́n et al. 1999a; Bouy et al. 2003); 2MASS J0746+2000AB and 2MASS J0850+1057AB (Reid et al. 2001; Bouy et al. 2003); 2MASS J1225 2739AB and…”
• X-Ray-emitting Young Stars in the Orion Nebula (2002, methodology): “The bolometric luminosity values used in the final column are estimated from logLbol ’ 0:4ðM ;bol MK BCKÞ þ logL ;bol ergs s 1 ; ð10Þ where BCK ’ 2:9 for a dwarf star with spectral type M7 (Leggett 1992; Leggett et al. 2001).”
• M dwarfs: effective temperatures, radii and metallicities (2008, methodology): “The interested reader can find e.g. in Leggett et al. (2000, 2001) and Burgasser et al. (2007) a thorough discussion of the comparison and pitfalls between observed and modelled spectra for M dwarfs and subdwarfs.”
• Astrometry and Photometry for Cool Dwarfs and Brown Dwarfs (2002, methodology): “The tempera- tures derived here are hotter for late M and early L dwarfs and cooler for late L dwarfs than those derived in some other studies (Basri et al. 2000; Leggett et al. 2001; Schweitzer et al. 2001, 2002; Chabrier 2002) using fitting of model atmospheres to spectroscopic data.”
• The HARPS search for southern extra-solar planets. X. A m sin i = 11 M_â planet around the nearby spotted M dwarf GJ 674 (2007, background): “GJ 674’s J−K color (= 0.86 – Cutri et al. 2003) and the Leggett et al. (2001) color-bolometric relation result in a K-band bolometric correction of BCK = 2.67, and in a 0.016 L luminosity.”
• Binaries and the L Dwarf/T Dwarf Transition (2006, background): “There have been several studies on the TeA/spectral type scale for field L and T dwarfs; 7 however, all of these rely on an assumed radius (or distribution of radii) or spectral modeling, and deviations between thesemethods have been noted (Leggett et al. 2001; Smith et al. 2003).”
• Dust in brown dwarfs - III. Formation and structure of quasi-static cloud layers (2004, unknown): “The latter result, an increasingly metal-poor gas for lower Teff, has been suggested as explanation for the disappearance of certain molecular features (like TiO and FeH) in the observed spectra of L dwarfs in comparison to M dwarfs (e.g. Leggett et al. 2001).”
• The First Substellar Subdwarf? Discovery of a Metal-poor L Dwarf with Halo Kinematics (2003, background): “Solar-metallicity mid- to late-type L dwarfs have temperatures 1400dTeffd1800 K (Kirkpatrick et al. 1999; Basri et al. 2000; Pavlenko, Zapatero Osorio, & Rebolo 2000; Leggett et al. 2001; Stephens et al. 2001; Burgasser et al. 2002; Dahn et al. 2002).”
• FUNDAMENTAL PARAMETERS AND SPECTRAL ENERGY DISTRIBUTIONS OF YOUNG AND FIELD AGE OBJECTS WITH MASSES SPANNING THE STELLAR TO PLANETARY REGIME (2015, background): “…of Lbol from direct integration of distance-scaled SEDs without the use of model atmosphere grids has been done in the past by Tinney et al. (1993), Leggett et al. (2001), Dahn et al. (2002), Golimowski et al. (2004), and Cushing et al. (2005b) however these samples only had spectral and…”
• Multiplicity of Nearby Free-floating Ultracool Dwarfs: A Hubble Space Telescope WFPC2 Search for Companions (2003, methodology): “Our results on the separation of the system are in good agreement with the one given by Leggett et al. (2001) within the uncertainties but do not agree with the one given by Koerner et al. (1999).”
• Toward Spectral Classification of L and T Dwarfs: Infrared and Optical Spectroscopy and Analysis (2001, background): “5 km region et al. 1999b, hereafter M99; K99 ; Kirk-(Mart• n patrick et al. 2000, hereafter K00 ; Leggett et al. 2001).”
• The UKIRT Infrared Deep Sky Survey ZY JHK photometric system: passbands and synthetic colours (2006, background): “…covering the wavelength range i to K, collated from the following references: Geballe et al. (2002), Hawley, Gizis & Reid (1996), Henry, Kirkpatrick & Simons (1996), Kirkpatrick, Henry & Simons (1995), Leggett et al. (2000a; 2001; 2002a), McLean et al. (2003), and Reid, Hawley & Gizis (1995).”
• Direct Imaging and Spectroscopy of a Planetary-Mass Candidate Companion to a Young Solar Analog (2008, background): “Uncertainties in the model opacities could account for the mismatch on the red side of theH-band for low gravities, and thus this should not be taken as evidence of high gravity (Leggett et al. 2001).”
• Characterizing Young Brown Dwarfs Using Low-Resolution Near-Infrared Spectra (2006, methodology): “5]; Luhman2004; Luhman et al. 2004), three field dwarfs (Gl 406 [M6V], LHS2065 [M9V], andKelu 1 [L2V]; Leggett et al. 2001, 2002), and a late-type giant (Br 1219 1336 [M9 III]; Kirkpatrick et al. 1997).”
• AN EMPIRICAL UBV RI JHK COLOR–TEMPERATURE CALIBRATION FOR STARS (2006, methodology): “For cool dwarfs, we adopt the K-band (UKIRT IRCAM3 system) BCs of Leggett et al. (2001).”
• Flaring up All Over—Radio Activity in Rapidly Rotating Late M and L Dwarfs (2001, methodology): “Based on 1−2.5 µm spectroscopy, and synthetic spectra fitting, Leggett et al. (2001) find log(Lbol/L⊙) ≈ −3.65 andT ≈ 2200 K for this source.”
• The Spectra of T Dwarfs. I. Near-Infrared Data and Spectral Classification (2001, methodology): “We have also included data for M, L, and T dwarfs obtained from the literature (Geballe et al. 1996; Strauss et al. 1999; Tsvetanov et al. 2000; Leggett et al. 2000, 2001; Reid et al. 2001, hereafter CGS4 data).”
• A Spitzer Census of the IC 348 Nebula (2007, background): “These bands are the primary spectral classification diagnostics for late-type objects (Kirkpatrick et al. 1991; Leggett et al. 2001; Reid et al. 2001) and are broad enough to be easily detected at the low resolution of our data.”