L′ and M′ photometry of ultracool dwarfs

D. A. Golimowski, S. K. Leggett, M. S. Marley, X. Fan, T. R. Geballe, G. R. Knapp, F. J. Vrba, A. A. Henden, C. B. Luginbuhl, H. H. Guetter, J. A. Munn, B. Canzian, W. Zheng, Zlatan Tsvetanov, K. Chiu, K. Glazebrook, E. A. Hoversten, D. P. Schneider, J. Brinkmann

Research output: Contribution to journalArticle

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Abstract

We have compiled L′ (3.4-4.1 μm) and M′ (4.6-4.8 μm) photometry of 63 single and binary M, L, and T dwarfs obtained at the United Kingdom Infrared Telescope using the Mauna Kea Observatory filter set. This compilation includes new L′ measurements of eight L dwarfs and 13 T dwarfs and new M′ measurements of seven L dwarfs, five T dwarfs, and the M1 dwarf G1 229A. These new data increase by factors of 0.6 and 1.6, respectively, the numbers of ultracool dwarfs (T eff ≲ 2400 K) for which L′ and M′ measurements have been reported. We compute L bol, BC K, and T eff for 42 dwarfs whose flux-calibrated JHK spectra, L′ photometry, and trigonometric parallaxes are available, and we estimate these quantities for nine other dwarfs whose parallaxes and flux-calibrated spectra have been obtained. BC K is a well-behaved function of near-infrared spectral type with a dispersion of ∼0.1 mag for types M6-T5; it is significantly more scattered for types T5-T9. T eff declines steeply and monotonically for types M6-L7 and T4-T9, but it is nearly constant at ∼1450 K for types L7-T4 with assumed ages of ∼3 Gyr. This constant T eff is evidenced by nearly unchanging values of L′-M′ between types L6 and T3. It also supports recent models that attribute the changing near-infrared luminosities and spectral features across the L-T transition to the rapid migration, disruption, and/or thinning of condensate clouds over a narrow range of J eff. The L′ and M′ luminosities of early-T dwarfs do not exhibit the pronounced humps or inflections previously noted in the I through K bands, but insufficient data exist for types L6-T5 to assert that M L′ and M M′ are strictly monotonic within this range of types. We compare the observed K, L′, and M′ luminosities of L and T dwarfs in our sample with those predicted by precipitating-cloud and cloud-free models for varying surface gravities and sedimentation efficiencies. The models indicate that the L3-T4.5 dwarfs generally have higher gravities (log g = 5.0-5.5) than the T6-T9 dwarfs (log g = 4.5-5.0). The predicted M′ luminosities of late-T dwarfs are 1.5-2.5 times larger than those derived empirically for the late-T dwarfs in our sample. This discrepancy is attributed to absorption at 4.5-4.9 μm by CO, which is not expected under the condition of thermochemical equilibrium assumed in the models. Our photometry and bolometric calculations indicate that the L3 dwarf Kelu-1 and the T0 dwarf SDSS J042348.57-041403.5 are probable binary systems. We compute log (L bol/L ) = -5.73 ± 0.05 and T eff= 600-750 K for the T9 dwarf 2MASSI J0415195-093506, which supplants Gl 570D as the least luminous and coolest brown dwarf presently known.

Original languageEnglish
Pages (from-to)3516-3536
Number of pages21
JournalAstronomical Journal
Volume127
Issue number6 1782
DOIs
Publication statusPublished - Jun 2004
Externally publishedYes

Fingerprint

photometry
luminosity
near infrared
gravity
high gravity environments
infrared telescopes
United Kingdom
extremely high frequencies
condensate
thinning
condensates
observatories
observatory
sedimentation
gravitation
filter
filters
estimates

Keywords

  • Infrared: stars
  • Stars: fundamental parameters
  • Stars: late-type
  • Stars: low-mass, brown dwarfs

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science

Cite this

Golimowski, D. A., Leggett, S. K., Marley, M. S., Fan, X., Geballe, T. R., Knapp, G. R., ... Brinkmann, J. (2004). L′ and M′ photometry of ultracool dwarfs. Astronomical Journal, 127(6 1782), 3516-3536. https://doi.org/10.1086/420709

L′ and M′ photometry of ultracool dwarfs. / Golimowski, D. A.; Leggett, S. K.; Marley, M. S.; Fan, X.; Geballe, T. R.; Knapp, G. R.; Vrba, F. J.; Henden, A. A.; Luginbuhl, C. B.; Guetter, H. H.; Munn, J. A.; Canzian, B.; Zheng, W.; Tsvetanov, Zlatan; Chiu, K.; Glazebrook, K.; Hoversten, E. A.; Schneider, D. P.; Brinkmann, J.

In: Astronomical Journal, Vol. 127, No. 6 1782, 06.2004, p. 3516-3536.

Research output: Contribution to journalArticle

Golimowski, DA, Leggett, SK, Marley, MS, Fan, X, Geballe, TR, Knapp, GR, Vrba, FJ, Henden, AA, Luginbuhl, CB, Guetter, HH, Munn, JA, Canzian, B, Zheng, W, Tsvetanov, Z, Chiu, K, Glazebrook, K, Hoversten, EA, Schneider, DP & Brinkmann, J 2004, 'L′ and M′ photometry of ultracool dwarfs', Astronomical Journal, vol. 127, no. 6 1782, pp. 3516-3536. https://doi.org/10.1086/420709
Golimowski DA, Leggett SK, Marley MS, Fan X, Geballe TR, Knapp GR et al. L′ and M′ photometry of ultracool dwarfs. Astronomical Journal. 2004 Jun;127(6 1782):3516-3536. https://doi.org/10.1086/420709
Golimowski, D. A. ; Leggett, S. K. ; Marley, M. S. ; Fan, X. ; Geballe, T. R. ; Knapp, G. R. ; Vrba, F. J. ; Henden, A. A. ; Luginbuhl, C. B. ; Guetter, H. H. ; Munn, J. A. ; Canzian, B. ; Zheng, W. ; Tsvetanov, Zlatan ; Chiu, K. ; Glazebrook, K. ; Hoversten, E. A. ; Schneider, D. P. ; Brinkmann, J. / L′ and M′ photometry of ultracool dwarfs. In: Astronomical Journal. 2004 ; Vol. 127, No. 6 1782. pp. 3516-3536.
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title = "L′ and M′ photometry of ultracool dwarfs",
abstract = "We have compiled L′ (3.4-4.1 μm) and M′ (4.6-4.8 μm) photometry of 63 single and binary M, L, and T dwarfs obtained at the United Kingdom Infrared Telescope using the Mauna Kea Observatory filter set. This compilation includes new L′ measurements of eight L dwarfs and 13 T dwarfs and new M′ measurements of seven L dwarfs, five T dwarfs, and the M1 dwarf G1 229A. These new data increase by factors of 0.6 and 1.6, respectively, the numbers of ultracool dwarfs (T eff ≲ 2400 K) for which L′ and M′ measurements have been reported. We compute L bol, BC K, and T eff for 42 dwarfs whose flux-calibrated JHK spectra, L′ photometry, and trigonometric parallaxes are available, and we estimate these quantities for nine other dwarfs whose parallaxes and flux-calibrated spectra have been obtained. BC K is a well-behaved function of near-infrared spectral type with a dispersion of ∼0.1 mag for types M6-T5; it is significantly more scattered for types T5-T9. T eff declines steeply and monotonically for types M6-L7 and T4-T9, but it is nearly constant at ∼1450 K for types L7-T4 with assumed ages of ∼3 Gyr. This constant T eff is evidenced by nearly unchanging values of L′-M′ between types L6 and T3. It also supports recent models that attribute the changing near-infrared luminosities and spectral features across the L-T transition to the rapid migration, disruption, and/or thinning of condensate clouds over a narrow range of J eff. The L′ and M′ luminosities of early-T dwarfs do not exhibit the pronounced humps or inflections previously noted in the I through K bands, but insufficient data exist for types L6-T5 to assert that M L′ and M M′ are strictly monotonic within this range of types. We compare the observed K, L′, and M′ luminosities of L and T dwarfs in our sample with those predicted by precipitating-cloud and cloud-free models for varying surface gravities and sedimentation efficiencies. The models indicate that the L3-T4.5 dwarfs generally have higher gravities (log g = 5.0-5.5) than the T6-T9 dwarfs (log g = 4.5-5.0). The predicted M′ luminosities of late-T dwarfs are 1.5-2.5 times larger than those derived empirically for the late-T dwarfs in our sample. This discrepancy is attributed to absorption at 4.5-4.9 μm by CO, which is not expected under the condition of thermochemical equilibrium assumed in the models. Our photometry and bolometric calculations indicate that the L3 dwarf Kelu-1 and the T0 dwarf SDSS J042348.57-041403.5 are probable binary systems. We compute log (L bol/L ⊙) = -5.73 ± 0.05 and T eff= 600-750 K for the T9 dwarf 2MASSI J0415195-093506, which supplants Gl 570D as the least luminous and coolest brown dwarf presently known.",
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TY - JOUR

T1 - L′ and M′ photometry of ultracool dwarfs

AU - Golimowski, D. A.

AU - Leggett, S. K.

AU - Marley, M. S.

AU - Fan, X.

AU - Geballe, T. R.

AU - Knapp, G. R.

AU - Vrba, F. J.

AU - Henden, A. A.

AU - Luginbuhl, C. B.

AU - Guetter, H. H.

AU - Munn, J. A.

AU - Canzian, B.

AU - Zheng, W.

AU - Tsvetanov, Zlatan

AU - Chiu, K.

AU - Glazebrook, K.

AU - Hoversten, E. A.

AU - Schneider, D. P.

AU - Brinkmann, J.

PY - 2004/6

Y1 - 2004/6

N2 - We have compiled L′ (3.4-4.1 μm) and M′ (4.6-4.8 μm) photometry of 63 single and binary M, L, and T dwarfs obtained at the United Kingdom Infrared Telescope using the Mauna Kea Observatory filter set. This compilation includes new L′ measurements of eight L dwarfs and 13 T dwarfs and new M′ measurements of seven L dwarfs, five T dwarfs, and the M1 dwarf G1 229A. These new data increase by factors of 0.6 and 1.6, respectively, the numbers of ultracool dwarfs (T eff ≲ 2400 K) for which L′ and M′ measurements have been reported. We compute L bol, BC K, and T eff for 42 dwarfs whose flux-calibrated JHK spectra, L′ photometry, and trigonometric parallaxes are available, and we estimate these quantities for nine other dwarfs whose parallaxes and flux-calibrated spectra have been obtained. BC K is a well-behaved function of near-infrared spectral type with a dispersion of ∼0.1 mag for types M6-T5; it is significantly more scattered for types T5-T9. T eff declines steeply and monotonically for types M6-L7 and T4-T9, but it is nearly constant at ∼1450 K for types L7-T4 with assumed ages of ∼3 Gyr. This constant T eff is evidenced by nearly unchanging values of L′-M′ between types L6 and T3. It also supports recent models that attribute the changing near-infrared luminosities and spectral features across the L-T transition to the rapid migration, disruption, and/or thinning of condensate clouds over a narrow range of J eff. The L′ and M′ luminosities of early-T dwarfs do not exhibit the pronounced humps or inflections previously noted in the I through K bands, but insufficient data exist for types L6-T5 to assert that M L′ and M M′ are strictly monotonic within this range of types. We compare the observed K, L′, and M′ luminosities of L and T dwarfs in our sample with those predicted by precipitating-cloud and cloud-free models for varying surface gravities and sedimentation efficiencies. The models indicate that the L3-T4.5 dwarfs generally have higher gravities (log g = 5.0-5.5) than the T6-T9 dwarfs (log g = 4.5-5.0). The predicted M′ luminosities of late-T dwarfs are 1.5-2.5 times larger than those derived empirically for the late-T dwarfs in our sample. This discrepancy is attributed to absorption at 4.5-4.9 μm by CO, which is not expected under the condition of thermochemical equilibrium assumed in the models. Our photometry and bolometric calculations indicate that the L3 dwarf Kelu-1 and the T0 dwarf SDSS J042348.57-041403.5 are probable binary systems. We compute log (L bol/L ⊙) = -5.73 ± 0.05 and T eff= 600-750 K for the T9 dwarf 2MASSI J0415195-093506, which supplants Gl 570D as the least luminous and coolest brown dwarf presently known.

AB - We have compiled L′ (3.4-4.1 μm) and M′ (4.6-4.8 μm) photometry of 63 single and binary M, L, and T dwarfs obtained at the United Kingdom Infrared Telescope using the Mauna Kea Observatory filter set. This compilation includes new L′ measurements of eight L dwarfs and 13 T dwarfs and new M′ measurements of seven L dwarfs, five T dwarfs, and the M1 dwarf G1 229A. These new data increase by factors of 0.6 and 1.6, respectively, the numbers of ultracool dwarfs (T eff ≲ 2400 K) for which L′ and M′ measurements have been reported. We compute L bol, BC K, and T eff for 42 dwarfs whose flux-calibrated JHK spectra, L′ photometry, and trigonometric parallaxes are available, and we estimate these quantities for nine other dwarfs whose parallaxes and flux-calibrated spectra have been obtained. BC K is a well-behaved function of near-infrared spectral type with a dispersion of ∼0.1 mag for types M6-T5; it is significantly more scattered for types T5-T9. T eff declines steeply and monotonically for types M6-L7 and T4-T9, but it is nearly constant at ∼1450 K for types L7-T4 with assumed ages of ∼3 Gyr. This constant T eff is evidenced by nearly unchanging values of L′-M′ between types L6 and T3. It also supports recent models that attribute the changing near-infrared luminosities and spectral features across the L-T transition to the rapid migration, disruption, and/or thinning of condensate clouds over a narrow range of J eff. The L′ and M′ luminosities of early-T dwarfs do not exhibit the pronounced humps or inflections previously noted in the I through K bands, but insufficient data exist for types L6-T5 to assert that M L′ and M M′ are strictly monotonic within this range of types. We compare the observed K, L′, and M′ luminosities of L and T dwarfs in our sample with those predicted by precipitating-cloud and cloud-free models for varying surface gravities and sedimentation efficiencies. The models indicate that the L3-T4.5 dwarfs generally have higher gravities (log g = 5.0-5.5) than the T6-T9 dwarfs (log g = 4.5-5.0). The predicted M′ luminosities of late-T dwarfs are 1.5-2.5 times larger than those derived empirically for the late-T dwarfs in our sample. This discrepancy is attributed to absorption at 4.5-4.9 μm by CO, which is not expected under the condition of thermochemical equilibrium assumed in the models. Our photometry and bolometric calculations indicate that the L3 dwarf Kelu-1 and the T0 dwarf SDSS J042348.57-041403.5 are probable binary systems. We compute log (L bol/L ⊙) = -5.73 ± 0.05 and T eff= 600-750 K for the T9 dwarf 2MASSI J0415195-093506, which supplants Gl 570D as the least luminous and coolest brown dwarf presently known.

KW - Infrared: stars

KW - Stars: fundamental parameters

KW - Stars: late-type

KW - Stars: low-mass, brown dwarfs

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