MID-INFRARED PHOTOMETRY OF COLD BROWN DWARFS: DIVERSITY IN AGE, MASS, AND METALLICITY

By S. Leggett, B. Burningham, D. Saumon, M. Marley, Stephen J. Warren, R. Smart, H. Jones, P. Lucas, D. Pinfield, Motohide Tamura. 2010

134 citations recorded by the source corpus.

We present new Spitzer Infrared Array Camera (IRAC) photometry of 12 very late-type T dwarfs: nine have [3.6], [4.5], [5.8], and [8.0] photometry and three have [3.6] and [4.5] photometry only. Combining this with previously published photometry, we investigate trends with type and color that are useful for both the planning and interpretation of infrared surveys designed to discover the coldest T or Y dwarfs. The online appendix provides a collation of MKO-system YJHKL′M′ and IRAC photometry for a sample of M, L, and T dwarfs. Brown dwarfs with effective temperature (T eff) below 700 K emit more than half their flux at wavelengths longer than 3 μm, and the ratio of the mid-infrared flux to the near-infrared flux becomes very sensitive to T eff at these low temperatures. We confirm that the color H (1.6 μm) – [4.5] is a good indicator of T eff with a relatively weak dependence on metallicity and gravity. Conversely, the colors H – K (2.2 μm) and [4.5] – [5.8] are sensitive to metallicity and gravity. Thus, near- and mid-infrared photometry provide useful indicators of the fundamental properties of brown dwarfs, and if temperature and gravity are known, then mass and age can be reliably determined from evolutionary models. There are 12 dwarfs currently known with H– [4.5] >3.0, and 500 K ≲ T eff ≲800 K, which we examine in detail. The ages of the dwarfs in the sample range from very young (0.1-1.0 Gyr) to relatively old (3-12 Gyr). The mass range is possibly as low as 5 Jupiter masses to up to 70 Jupiter masses, i.e., near the hydrogen burning limit. The metallicities also span a large range, from [m/H] = –0.3 to [m/H] = +0.3. The small number of T8-T9 dwarfs found in the UK Infrared Telescope Infrared Deep Sky Survey to date appear to be predominantly young low-mass dwarfs. Accurate mid-infrared photometry of cold brown dwarfs is essentially impossible from the ground, and extensions to the mid-infrared space missions, warm-Spitzer and Wide-Field Infrared Survey Explorer, are desirable in order to obtain the vital mid-infrared data for cold brown dwarfs, and to discover more of these rare objects.

Subfields: Archeology, Astronomy and Astrophysics, Geochemistry and Petrology

View Paper: https://www.semanticscholar.org/paper/00568b36069df0ad4c5c766db013dd31dd6a5d85

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In Astronomy and Astrophysics

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

In Geochemistry and Petrology

1. M. Marley
2. R. Freedman
3. Th. Henning
4. Jon Fortney

Citations in the corpus

• FURTHER DEFINING SPECTRAL TYPE “Y” AND EXPLORING THE LOW-MASS END OF THE FIELD BROWN DWARF MASS FUNCTION (2012, background): “J color in the mid- to late-T dwarf regime – was noted by Leggett et al. (2010) and Burningham et al. (2010) and ascribed to a brightening of the Y -band peak due to reduced absorption by the wings of the K I as atomic potassium begins to form into KCl at cooler temperatures (Lodders 1999).”
• MODEL ATMOSPHERES FOR MASSIVE GAS GIANTS WITH THICK CLOUDS: APPLICATION TO THE HR 8799 PLANETS AND PREDICTIONS FOR FUTURE DETECTIONS (2011, methodology): “For empirical comparisons, we primarily use the L/T dwarf sample compiled by Leggett et al. (2010).”
• THE DISCOVERY OF Y DWARFS USING DATA FROM THE WIDE-FIELD INFRARED SURVEY EXPLORER (WISE) (2011, background): “This is consistent with the blueward trend in the Y − J color of latetype T dwarfs (Leggett et al. 2010; Burningham et al. 2010) which Burningham et al. (2010) ascribed to the weakening of the strong resonance K I doublet (7665, 7699 Å) as K condenses into KCl. Finally, since the spectrum of WISEP…”
• NEAR-INFRARED SPECTROSCOPY OF THE EXTRASOLAR PLANET HR 8799 b (2010, methodology): “KMKO TO KS CONVERSION We converted KMKO-band to KS-band magnitudes for our sample of L and T dwarfs from Leggett et al. (2010) by performing synthetic photometry to objects in the SpeX Prism Spectral Libraries and fitting a fifth-order polynomial to the differential magnitudes (Figure 23).”
• A COMBINED SUBARU/VLT/MMT 1–5 μm STUDY OF PLANETS ORBITING HR 8799: IMPLICATIONS FOR ATMOSPHERIC PROPERTIES, MASSES, AND FORMATION (2011, methodology): “Methodology To compare the near-to-mid IR properties of the HR 8799 planets with those for other cool, substellar objects, we primarily use the sample of L/T dwarfs compiled by Leggett et al. (2010).”
• THE FIRST HUNDRED BROWN DWARFS DISCOVERED BY THE WIDE-FIELD INFRARED SURVEY EXPLORER (WISE) (2011, methodology): “The upper righthand panel of Figure 5 of Leggett et al. 2010 shows the trend of J −H color versus spectral type using the – 10 – MKO filter system, and there we find that J −H .”
• 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).”
• THE HAWAII INFRARED PARALLAX PROGRAM. I. ULTRACOOL BINARIES AND THE L/T TRANSITION, (2012, methodology): “…(2000); (92) Leggett et al. (2001); (93) Leggett et al. (2002a); (94) Leggett et al. (2002b); (95) Leggett et al. (2007); (96) Leggett et al. (2009); (97) Leggett et al. (2010); (98) Leggett et al. (2012); (99) Leinert et al. (2000); (100) Lépine et al. (2003a); (101) Lépine et al. (2003b);…”
• 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. (2003), (2) Leggett et al. (2002a), (3) Knapp et al. (2004), (4) Leggett et al. (2010), (5) Naud et al. (2014), (6) Leggett et al. (1998), (7) Chiu et al. (2006), (8) Leggett et al. (2000), (9) Hewett et al. (2006), (10) Leggett et al. (2002b), (11) Lawrence et al. (2007), (12)…”
• DIRECT IMAGING OF A COLD JOVIAN EXOPLANET IN ORBIT AROUND THE SUN-LIKE STAR GJ 504 (2013, methodology): “For this purpose, it has been placed on color– magnitude diagrams (Figure 11) along with LT-type field brown dwarfs (Leggett et al. 2010) and HR 8799 bcde (Marois et al. 2010; Metchev et al. 2009; Skemer et al. 2012), Kappa And b (Carson et al. 2013), 1RXS J1609 b (Lafrenière et al. 2008), 2M 1207…”
• DISCOVERY OF A BINARY BROWN DWARF AT 2 pc FROM THE SUN (2013, background): “For comparison, I have included a sample of known M, L, and T dwarfs (Leggett et al. 2010; Kirkpatrick et al. 2011, 2012, http://DwarfArchives.org).”