An Infrared Spectroscopic Sequence of M, L, and T Dwarfs

By M. Cushing, J. Rayner, W. Vacca. 2004

533 citations recorded by the source corpus.

We present a 0.6-4.1 μm spectroscopic sequence of M, L, and T dwarfs. The spectra have R ≡ λ/Δλ ≈ 2000 from 0.9 to 2.4 μm and R = 2500-200 from 2.9 to 4.1 μm. These new data nearly double the number of L and T dwarfs that have reported L-band spectra. The near-infrared spectra are combined with previously published red-optical spectra to extend the wavelength coverage to ~0.6 μm. Prominent atomic and molecular absorption features are identified including neutral lines of Al, Fe, Mg, Ca, Ti, Na, and K and 19 new weak CH4 absorption features in the H-band spectra of mid- to late-type T dwarfs. In addition, we detect for the first time the 0-0 band of the A 4Π-X 4Σ- transition of VO at ~1.06 μm in the spectra of L dwarfs and the P- and R-branches of the ν3 band of CH4 in the spectrum of a T dwarf. The equivalent widths of the refractory atomic features all decrease with increasing spectral type and are absent by a spectral type of ~L0, except for the 1.189 μm Fe I line, which persists to at least ~L3. We compute the bolometric luminosities of the dwarfs in our sample with measured parallaxes and find good agreement with previously published results that use L'-band photometry to account for the flux emitted from 2.5 to 3.6 μm. Finally, 2MASS J2224381-0158521 (L4.5) has an anomalously red spectrum and the strongest Δν = +2 CO bands in our sample. This may be indicative of unusually thick condensate clouds and/or low surface gravity.

Subfields: Astronomy and Astrophysics, Education, Instrumentation

View Paper: https://www.semanticscholar.org/paper/7c14e557b727c6dcfe7774d510b43785206b0876

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Citations in the corpus

Line and Mean Opacities for Ultracool Dwarfs and Extrasolar Planets (2007, background): “The line list for FeH is known to be incomplete in the near-infrared (Cushing et al. 2005).”
Discovery of a Very Young Field L Dwarf, 2MASS J01415823–4633574 (2005, unknown): “The SpeX near-infrared spectrum of 2MASS 0141−4633 is shown in Figure 5 along with SpeX spectra of normal field late-M and early-L dwarfs from Cushing et al. (2005).”
SpeX SPECTROSCOPY OF UNRESOLVED VERY LOW MASS BINARIES. I. IDENTIFICATION OF 17 CANDIDATE BINARIES STRADDLING THE L DWARF/T DWARF TRANSITION (2009, methodology): “For the composites, synthetic MKO JHK and HST/NICMOS F110W and F170M photometry were computed directly from the fluxcalibrated SpeX data by integrating these and a Kurucz model spectrum of Vega with the respective filter profiles (see Cushing et al. 2005).”
Binaries and the L Dwarf/T Dwarf Transition (2006, methodology): “Once the template spectra were scaled to their respective absolute magnitudes following standard techniques (cf. Cushing et al. 2005), composite spectra were created by adding the templates that bracketed the assigned spectral types of the binary components, weighted accordingly.10 Examples of…”
SPECTRO-THERMOMETRY OF M DWARFS AND THEIR CANDIDATE PLANETS: TOO HOT, TOO COOL, OR JUST RIGHT? (2013, background): “5 dwarf HD 36395 from the IRTF spectral library (Cushing et al. 2005; Rayner et al. 2009).”
THE HAWAII INFRARED PARALLAX PROGRAM. II. YOUNG ULTRACOOL FIELD DWARFS (2016, background): “Cushing et al. (2005) first noted that 2MASS J2224−0158 has abnormally red colors for its spectral type ((J −KS)2MASS = 2.03 ± 0.04mag), thus we assign a “p” designation to denote this spectral peculiarity.”
ATMOSPHERIC CHEMISTRY IN GIANT PLANETS, BROWN DWARFS, AND LOW-MASS DWARF STARS. III. IRON, MAGNESIUM, AND SILICON (2010, background): “The most prominent FeH feature is the band located at 0.9896 µm, which weakens throughout the L dwarf spectral sequence and in early T dwarfs (McLean et al. 2003; Nakajima et al. 2004; Cushing et al. 2005), consistent with the removal of iron into a cloud located deeper and deeper in the atmosphere.”
UV-extended E-MILES stellar population models: young components in massive early-type galaxies (2016, methodology): “However since the stars of the IRTF library are mostly bright, nearby stars of around solar metallicity, these models are most accurate in the metallicity range −0.40 [Fe/H] +0.20 for ages above 1.5Gyr.”
Direct Imaging and Spectroscopy of a Planetary-Mass Candidate Companion to a Young Solar Analog (2008, methodology): “1, alongside template spectra of known BDs in Upper Scorpius3 (Lodieu et al. 2008), field dwarfs4 (Cushing et al. 2005) and synthetic spectra from the DUSTY models (Chabrier et al. 2000).”
Spitzer IRAC Photometry of M, L, and T Dwarfs (2006, background): “—Noted as having an anomalously red spectrum, possibly indicative of an unusually thick condensate cloud or of low surface gravity (Cushing et al. 2005).”
Discovery of Two Nearby Peculiar L Dwarfs from the 2MASS Proper-Motion Survey: Young or Metal-Rich? (2008, methodology): “2MASS J1821+1414 (L5 pec) We compare the IRTF-SpeX cross-dispersed spectrum (R∼1200) of 2MASS J1821+1414 to a spectral sequence of normal, late-type L field dwarfs from Cushing et al. (2005) in Figure 5.”
THE 0.8–14.5 μm SPECTRA OF MID-L TO MID-T DWARFS: DIAGNOSTICS OF EFFECTIVE TEMPERATURE, GRAIN SEDIMENTATION, GAS TRANSPORT, AND SURFACE GRAVITY (2009, methodology): “Cushing et al. (2005) obtained high-resolution (λ/∆λ ≈ 1200 or 2000), 0.9–2.4 µm spectra of these dwarfs with the SpeX instrument (Rayner et al. 2003) at NASA’s Infrared Telescope Facility.”
UNVEILING THE STRUCTURE OF PRE-TRANSITIONAL DISKS (2010, methodology): “The spectra of corresponding template stars were obtained from the IRTF Spectral Library (Cushing et al. 2005; Rayner et al. 2009)13.”
Characterizing Young Brown Dwarfs Using Low-Resolution Near-Infrared Spectra (2006, methodology): “The spectral energy distributions (SEDs) of lateM-type objects peak in the near-IR (Cushing et al. 2005), making them, particularly in the presence of foreground reddening, easier to observe in the near-IR than in the optical.”
DETECTING PLANETS AROUND VERY LOW MASS STARS WITH THE RADIAL VELOCITY METHOD (2009, methodology): “The spectra reproduce the data shown by McLean et al. (2003) and Cushing et al. (2005) reasonably well when degraded to low-resolution.”
CHARACTERIZING THE COOL KOIs. III. KOI 961: A SMALL STAR WITH LARGE PROPER MOTION AND THREE SMALL PLANETS (2012, background): “Notice the strong agreement in line depths (we identified the lines using Cushing et al. 2005), and the similar spectral shape inH and K bands.”
NEAR-INFRARED METALLICITIES, RADIAL VELOCITIES, AND SPECTRAL TYPES FOR 447 NEARBY M DWARFS (2013, methodology): “We indicated the FeH bands identified in Cushing et al. (2005) with dashed lines, though the FIG.”