Near-Infrared Spectral Classification of Late M and L Dwarfs

By I. Neill Reid, A. Burgasser, Kelle Cruz, J. D. Kirkpatrick, J. Gizis. 2000

153 citations recorded by the source corpus.

We present near-infrared (1–2.5 μm), low-resolution spectroscopy of 11 ultracool dwarfs, with spectral types ranging from M7 to L8. Combining our observations with data published by Leggett et al. in 2001, we have measured equivalent widths for the strongest atomic features and constructed narrowband indices to gauge the strength of the strongest molecular features. Those measurements show that the behavior at near-infrared wavelengths is well correlated with spectral type, where the latter is defined from observations between 6300 and 10000 Å. In particular, four indices designed to measure absorption in the wings of the 1.4 and 1.85 μm steam bands exhibit a linear, monotonic correlation with spectral type on the Kirkpatrick et al. system (published in 1999), allowing consistent calibration from both optical and near-infrared spectroscopy.

Subfields: Astronomy and Astrophysics, Instrumentation

View Paper: https://www.semanticscholar.org/paper/04bf0566b1d24d6066caeb7183c966d260ca516d

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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 Instrumentation

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

Citations in the corpus

• 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.”
• Dust in the Photospheric Environment: Unified Cloudy Models of M, L, and T Dwarfs (2002, methodology): “More recently, classification of L dwarfs was extended with the use of the near infrared spectra (e.g. Reid et al. 2001; Testi et al. 2001).”
• Astrometry and Photometry for Cool Dwarfs and Brown Dwarfs (2002, methodology): “This formula predicts values for BC that are 0.1 mag larger than calculated by Leggett et al. (2002a) and 0.3 mag smaller than calculated by Reid et al. (2001a) for L7.”
• The UKIRT Infrared Deep Sky Survey ZY JHK photometric system: passbands and synthetic colours (2006, unknown): “…Skrutskie (1997), Kirkpatrick et al. (1999b), Kirkpatrick et al. (2000), Knapp et al. (2004), Leggett et al. (2000; 2001; 2002a; 2002b), Liebert et al. (2000), McLean et al. (2003), Reid et al. (2001), Schultz et al. (1998), Strauss et al. (1999), Tinney et al. (1998), and Tsvetanov et al. (2000).”
• 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): “It is interesting to note that in Reid et al. (2001) an HST/WFPC2 survey of 20 L stars found four binaries and a similar BF of 10%–20%.”
• Subtle Signatures of Multiplicity in Late-type Dwarf Spectra: The Unresolved M8.5 + T5 Binary 2MASS J03202839–0446358 (2008, background): “The similarities to 2MASS J1439+1929 suggests an L1 near-infrared spectral type for 2MASS J0320−0446, which is confirmed by examination of the spectral indices and index/spectral type relations defined by Reid et al. (2001a) and Geballe et al. (2002).”
• Infrared Photometry of Late-M, L, and T Dwarfs (2001, background): “2MASSI J0746]20AB consists of a pair of similar early L dwarfs, and 2MASSs J0850]10AB consists of an L dwarf and probably a T dwarf (Reid et al. 2001b).”
• New spectral types L and T (2005, background): “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).”
• A NEAR-INFRARED SPECTROSCOPIC STUDY OF YOUNG FIELD ULTRACOOL DWARFS (2013, background): “Previous near-IR studies have shown that the H2O absorption bands, as measured by flux ratios (indices), are well-correlated with optical spectral type (e.g., Reid et al. 2001; Geballe et al. 2002; McLean et al. 2003).”
• 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.…”
• M dwarfs: effective temperatures, radii and metallicities (2008, methodology): “J−H plane is confirmed by similar plot using dwarfs much cooler than we have here (e.g. Reid et al. 2001; Burgasser et al. 2007).”
• The Spectroscopically Determined Substellar Mass Function of the Orion Nebula Cluster (2004, methodology): “The exceptions are the NaI lines which increase in strength until late M stars and then disappear quickly by early L (see also McLean et al. 2003, 2000 and Reid et al. 2001).”
• The Initial Mass Function in the Taurus Star-forming Region (2002, unknown): “5 (Reid et al. 2001).”
• The Field Substellar Mass Function Based on the Full-sky 20 pc Census of 525 L, T, and Y Dwarfs (2020, methodology): “Reid et al. (2001b) confirmed this hypothesis with imaging from HST and verified common proper motion of the components using earlier observations from the W. M. Keck Observatory.”
• DISCOVERIES FROM A NEAR-INFRARED PROPER MOTION SURVEY USING MULTI-EPOCH TWO MICRON ALL-SKY SURVEY DATA (2010, background): “Previous near-infrared classifications, such as those in Reid et al. (2001), Geballe et al. (2002), and McLean et al. (2003), have relied on comparing a target object’s spectral ratios with those same ratios derived for an object of known optical type.”
• SpeX SPECTROSCOPY OF UNRESOLVED VERY LOW MASS BINARIES. I. IDENTIFICATION OF 17 CANDIDATE BINARIES STRADDLING THE L DWARF/T DWARF TRANSITION (2009, background): “However, many L dwarfs have never been typed in the near-infrared, and those with nearinfrared types have been classified following different schemes (e.g., Reid et al. 2001a; Testi et al. 2001; McLean et al. 2003; Nakajima et al. 2004; Burgasser 2007a).”
• Global Climate and Atmospheric Composition of the Ultra-hot Jupiter WASP-103b from HST and Spitzer Phase Curve Observations (2018, background): “…been defined to characterize features in brown dwarf spectra, and these indices have revealed trends in the amplitude of a range of spectral features (water, sodium, potassium, VO, and FeH) with surface gravity and effective temperature (Reid et al. 2001; Geballe et al. 2002; McLean et al. 2003).”
• An Infrared Spectroscopic Sequence of M, L, and T Dwarfs (2004, background): “…have been numerous near-infrared spectroscopic studies of M, L, and T dwarfs (e.g., Jones et al. 1994; Ali et al. 1995; Leggett et al. 1996, 2001; Reid et al. 2001; Burgasser et al. 2000, 2002b), but the majority of the published spectra have low spectral resolving powers (R k= kP500) and a…”