Spitzer IRAC Photometry of M, L, and T Dwarfs

By B. Patten, J. Stauffer, Adam Burrows, M. Marengo, J. Hora, K. Luhman, S. Sonnett, T. Henry, D. Raghavan, S. Megeath and 2 more. 2006

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We present the results of a program to acquire photometry for 86 late M, L, and T dwarfs using the Infrared Array Camera (IRAC) on the Spitzer Space Telescope. We examine the behavior of these cool dwarfs in various color-color and color-magnitude diagrams composed of near-IR and IRAC data. The T dwarfs exhibit the most distinctive positions in these diagrams. In M5.8 versus [5.8]-[8.0], the IRAC data for T dwarfs are not monotonic in either magnitude or color, giving the clearest indication yet that the T dwarfs are not a one-parameter family in Teff. Because metallicity does not vary enough in the solar neighborhood to act as the second parameter, the most likely candidate then is gravity, which in turn translates to mass. Among objects with similar spectral type, the range of mass suggested by our sample is about a factor of 5 (~70MJ to ~15MJ), with the less massive objects making up the younger members of the sample. We also find the IRAC 4.5 μm fluxes to be lower than expected, from which we infer a stronger CO fundamental band at ~4.67 μm. This suggests that equilibrium CH4/CO chemistry underestimates the abundance of CO in T dwarf atmospheres, confirming earlier results based on M-band observations from the ground. In combining IRAC photometry with near-IR JHK photometry and parallax data, we find the combination of Ks, IRAC 3.6 μm, and 4.5 μm bands to provide the best color-color discrimination for a wide range of M, L, and T dwarfs. Also noteworthy is the M versus Ks-[4.5] relation, which shows a smooth progression over spectral type, and splits the M, L, and T types cleanly.

Subfields: Astronomy and Astrophysics, Instrumentation

View Paper: https://www.semanticscholar.org/paper/5d5bd91a9870620b8390d094622cd715b34891d3

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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): “(1) Cutri et al. (2012), (2) Patten et al. (2006), (3) Leggett et al. (1998), (4) Cushing et al. (2008a), (5) Luhman et al. (2009), (6) Leggett et al. (2002a), (7) Leggett et al. (2010), (8) Golimowski et al. (2004), (9) Cutri et al. (2014), (10) Leggett et al. (2001), (11) Burgasser et al.…”
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): “This last question is motivated by the mid-infrared colors of T dwarfs measured from the ground (Noll et al. 1997; Golimowski et al. 2004a) and by Spitzer’s Infrared Array Camera (IRAC, Fazio et al. 2004; Patten et al. 2006; Leggett et al. 2007).”
THE FIRST HUNDRED BROWN DWARFS DISCOVERED BY THE WIDE-FIELD INFRARED SURVEY EXPLORER (WISE) (2011, background): “Figure 11 shows the trend of ch1-ch2 color versus spectral type for early-M through late- T dwarfs taken from Patten et al. (2006), Leggett et al. (2009), and Leggett et al. (2010).”
MID-INFRARED PHOTOMETRY OF COLD BROWN DWARFS: DIVERSITY IN AGE, MASS, AND METALLICITY (2010, background): “Previously published IRAC photometry for a reference sample of late-type M, L and T dwarfs was taken from Burgasser et al. (2008b); Burningham et al. (2008); Leggett et al. (2007b); Luhman et al. (2007); Patten et al. (2006); Warren et al. (2007).”
CEERS Key Paper. I. An Early Look into the First 500 Myr of Galaxy Formation with JWST (2022, methodology): “The colors imply a very late spectral type of T5, which corresponds to an absolute magnitude of K= 16.1 AB mag (Patten et al. 2006).”
THE BROWN DWARF KINEMATICS PROJECT (BDKP). III. PARALLAXES FOR 70 ULTRACOOL DWARFS (2012, background): “The models disagree as to which parameter has the largest effect on the emergent spectra and color trends, and small numbers of objects with independently measured secondary parameters has hindered progress (Knapp et al. 2004; Patten et al. 2006; Leggett et al. 2010).”
CLOUDS AND CHEMISTRY IN THE ATMOSPHERE OF EXTRASOLAR PLANET HR8799b (2011, background): “…brown dwarfs (Noll et al. 1997; Saumon et al. 2000, 2006; Geballe et al. 2009) along with weaker than predicted fluxes from ∼ 4.5 µm ground and space-based photometry (Patten et al. 2006; Leggett et al. 2007) have established disequilibrium CO mole fractions as a common occurrence in brown dwarfs.”
A comparison of chemistry and dust cloud formation in ultracool dwarf model atmospheres (2008, methodology): “Journal compilation C© 2008 RAS, MNRAS 391, 1854–1873 Downloaded from https://academic.oup.com/mnras/article-abstract/391/4/1854/1747427 by guest on 29 July 2018 with the Patten et al. (2006) data occur for [5.8]-[8.0], Ks-[3.6] and J-[4.5].”
THE HAWAII INFRARED PARALLAX PROGRAM. I. ULTRACOOL BINARIES AND THE L/T TRANSITION, (2012, methodology): “…et al. (2007); (75) Luhman et al. (2012); (76) Marocco et al. (2010); (77) Monet et al. (1992); (78) Murray et al. (2011); (79) Patience et al. (2010); (80) Patten et al. (2006); (81) Pinfield et al. (2012); (82) Reid et al. (1995); (83) Reid et al. (2003a); (84) Reid et al. (2003b); (85) Reid et…”
Discovery of Two T Dwarf Companions with the Spitzer Space Telescope (2006, methodology): “The observing strategy and image reduction procedures were the same as those described by Patten et al. (2006a) for IRAC observations of M, L, and T dwarfs, except for the following modifications (Patten et al. 2006b).”
A Long Time Ago in a Galaxy Far, Far Away: A Candidate z ∼ 12 Galaxy in Early JWST CEERS Imaging (2022, methodology): “As these spectra end at 2.5 μm, we use the tabulated 2MASS photometry to link each SpeX model with Spitzer/IRAC photometry from Patten et al. (2006).”
THE SPITZER DEEP, WIDE-FIELD SURVEY (2009, background): “Their colors ([3.6] − [4.5] > 0.5) imply mid-T brown dwarf spectral types (Patten et al. 2006).”