Infrared Photometry of Late-M, L, and T Dwarfs

By S. Leggett, D. Golimowski, Xiaohui Fan, T. Geballe, G. Knapp, J. Brinkmann, István Csabai, James E. Gunn, S. Hawley, Todd J. Henry and 9 more. 2001

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We present ZJHKL′M′ photometry of a sample of 58 late M, L, and T dwarfs, most of which are identified from the Sloan Digital Sky Survey and the Two Micron All-Sky Survey. Near-infrared spectra and spectral classifications for most of this sample are presented in a companion paper by Geballe et al. We derive the luminosities of 18 dwarfs in the sample with known parallaxes, and the results imply that the effective temperature range for the L dwarfs in our sample is approximately 2200-1300 K and for the T dwarfs 1300-800 K. We obtained new photometric data at the United Kingdom Infrared Telescope for: 42 dwarfs at Z, 34 dwarfs at JHK, 21 dwarfs at L', as well as M' data for two L dwarfs and two T dwarfs. The M' data provide the first accurate photometry for L and T dwarfs in this bandpass—for a T2 and a T5 dwarf, we find K-M′ = 1.2 and 1.6, respectively. These colors are much bluer than predicted by published models, suggesting that CO may be more abundant in these objects than expected, as has been found for the T6 dwarf Gl 229B. We also find that K-L' increases monotonically through most of the M, L, and T subclasses, but it is approximately constant between types L6 and T5, restricting its usefulness as a temperature indicator. The degeneracy is probably due to the onset of CH4 absorption at the blue edge of the L' bandpass. The JHK colors of L dwarfs show significant scatter, suggesting that the fluxes in these bandpasses are sensitive to variations in photospheric dust properties. The H-K colors of the later T dwarfs also show some scatter, which we suggest is due to variations in pressure-induced H2 opacity, which is sensitive to gravity and metallicity.

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

View Paper: https://www.semanticscholar.org/paper/dcae6985b01c06ae2e3cd2bb9172f7520737ef3f

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Citations in the corpus

Evidence of Cloud Disruption in the L/T Dwarf Transition (2002, background): “Photometric studies of late-type L and T dwarfs also indicate far greater absorption in the 5mm band than predicted by chemical equilibrium models (Leggett et al. 2002; Reid & Cruz 2002), likely caused by enhanced CO abundances brought up by vertical flows.”
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).”
A Spitzer Infrared Spectrograph Spectral Sequence of M, L, and T Dwarfs (2004, background): “The majority of the observations consist of L′ and M ′-band photometry (Stephens et al. 2001; Leggett et al. 2002; Golimowski et al. 2004), although some spectroscopy has been performed at these wavelengths (Noll et al. 1997; Oppenheimer et al. 1998; Burgasser 2001; Noll et al. 2000; Cushing et al.…”
SpeX SPECTROSCOPY OF UNRESOLVED VERY LOW MASS BINARIES. I. IDENTIFICATION OF 17 CANDIDATE BINARIES STRADDLING THE L DWARF/T DWARF TRANSITION (2009, methodology): “This could indicate a 7Photometry shown in Figure 9 is based either on direct measurements (Geballe et al. 2002; Leggett et al. 2002; Knapp et al. 2004; Chiu et al. 2006) or synthetic filter corrections from 2MASS photometry as computed directly from the SpeX data; see Section 4.4.”
Binaries and the L Dwarf/T Dwarf Transition (2006, methodology): “The primary relation used in the simulations was 7 See Basri et al. (2000), Kirkpatrick et al. (2000), Burgasser et al. (2002b), Dahn et al. (2002), Leggett et al. (2002), Schweitzer et al. (2002), Golimowski et al. (2004), Nakajima et al. (2004), Vrba et al. (2004), and Burgasser et al. (2006a).”
Debris Disks around White Dwarfs: The DAZ Connection (2006, background): “If the observed near-infrared excess is due to a late type dwarf companion, this would correspond to MK 11:38 mag, an early L dwarf (Leggett et al. 2002).”
New spectral types L and T (2005, unknown): “K) have been published by Reid et al. (2001) and Leggett et al. (2001, 2002), but the most comprehensive attempt so far is that by Golimowski et al. (2004).”
Evolutionary models for cool brown dwarfs and extrasolar giant planets. The case of HD 209458 (2003, background): “The predictions of the COND models provide a general good agreement with observed near-IR photometry and spectra at wavelength > 1µm (Leggett et al. 2002b; Zapatero et al. 2002).”
The Stellar Populations of Praesepe and Coma Berenices (2007, methodology): “We estimated absolute bolometric magnitudes using the bolometric corrections of Leggett (1992) and Leggett et al. (2002).”
Spitzer IRAC Photometry of M, L, and T Dwarfs (2006, background): “…theMKO L0 andM 0 filters, as well as a model spectrum of a mid-T dwarf, are also shown to illustrate the relative band centers and bandwidths of filters in recent use to characterize the infrared colors of M, L, and T dwarfs (e.g., Leggett et al. 2002; Golimowski et al. 2004a; Knapp et al. 2004).”
A Unified Near-Infrared Spectral Classification Scheme for T Dwarfs (2005, background): “…identified trends of absolute brightness (Dahn et al. 2002; Tinney, Burgasser, & Kirkpatrick 2003; Vrba et al. 2004), color (Burgasser et al. 2002c; Leggett et al. 2002b; Knapp et al. 2004) and Teff (Golimowski et al. 2004; Vrba et al. 2004) as a function of spectral type remain effectively…”
An Infrared Spectroscopic Sequence of M, L, and T Dwarfs (2004, methodology): “…fluxes include the error due to the photometry used to flux-calibrate the spectra and an estimate of the systematic error introduced by assuming a Rayleigh-Jeans tail at k > 4:1 m. Leggett et al. (1996, 2001, 2002) have computed bolometric fluxes for 11 of the M and L dwarfs in our sample.”
Astrometry and Photometry for Cool Dwarfs and Brown Dwarfs (2002, methodology): “Simple models (e.g., Burrows et al. 2002; Marley et al. 2002) predict a sensitivity of colors for different surface gravity, metallicity, and dust precipitation, and the near-IR colors of L dwarfs (e.g., Leggett et al. 2002a) show little correlation with spectral type.”
Seventy-One New L and T Dwarfs from the Sloan Digital Sky Survey (2006, background): “…data to select L and T dwarf candidates and carry out follow-up observations of their photometric and spectroscopic properties (Strauss et al. 1999; Tsvetanov et al. 2000; Fan et al. 2000a; Leggett et al. 2000, 2002; Schneider et al. 2002; G02; Hawley et al. 2002; K04; Golimowski et al. 2004a).”