The Leech exoplanet imaging survey

Characterization of the coldest directly imaged exoplanet, GJ 504 b, and evidence for superstellar metallicity

Andrew J. Skemer, Caroline V. Morley, Neil T. Zimmerman, Michael F. Skrutskie, Jarron Leisenring, Esther Buenzli, Mickael Bonnefoy, Vanessa Bailey, Philip Hinz, Denis Defrére, Simone Esposito, Dániel Apai, Beth Biller, Wolfgang Brandner, Laird Close, Justin R. Crepp, Robert J. De Rosa, Silvano Desidera, Josh Eisner, Jonathan Fortney & 22 others Richard Freedman, Thomas Henning, Karl Heinz Hofmann, Taisiya Kopytova, Roxana Lupu, Anne Lise Maire, Jared R. Males, Mark Marley, Katie Morzinski, Apurva Oza, Jennifer Patience, Abhijith Rajan, George Rieke, Dieter Schertl, Joshua Schlieder, Jordan Stone, Kate Su, Amali Vaz, Channon Visscher, Kimberly Ward-Duong, Gerd Weigelt, Charles E. Woodward

Research output: Contribution to journalReview article

22 Citations (Scopus)

Abstract

As gas giant planets and brown dwarfs radiate away the residual heat from their formation, they cool through a spectral type transition from L to T, which encompasses the dissipation of cloud opacity and the appearance of strong methane absorption. While there are hundreds of known T-type brown dwarfs, the first generation of directly imaged exoplanets were all L type. Recently, Kuzuhara et al. announced the discovery of GJ 504 b, the first T dwarf exoplanet. GJ 504 b provides a unique opportunity to study the atmosphere of a new type of exoplanet with a ∼500 K temperature that bridges the gap between the first directly imaged planets (∼1000 K) and our own solar system's Jupiter (∼130 K). We observed GJ 504 b in three narrow L-band filters (3.71, 3.88, and 4.00 μm), spanning the red end of the broad methane fundamental absorption feature (3.3 μm) as part of the LBTI Exozodi Exoplanet Common Hunt (LEECH) exoplanet imaging survey. By comparing our new photometry and literature photometry with a grid of custom model atmospheres, we were able to fit GJ 504 b's unusual spectral energy distribution for the first time. We find that GJ 504 b is well fit by models with the following parameters: Teff = 544 ± 10 K, g < 600 m s-2, [M/H] = 0.60 ± 0.12, cloud opacity parameter of fsed = 2-5, R = 0.96 ± 0.07 RJup, and log(L) = -6.13 ± 0.03 Lo, implying a hot start mass of 3-30 Mjup for a conservative age range of 0.1-6.5 Gyr. Of particular interest, our model fits suggest that GJ 504 b has a superstellar metallicity. Since planet formation can create objects with nonstellar metallicities, while binary star formation cannot, this result suggests that GJ 504 b formed like a planet, not like a binary companion.

Original languageEnglish (US)
Article number166
JournalAstrophysical Journal
Volume817
Issue number2
DOIs
StatePublished - Feb 1 2016

Fingerprint

leech
extrasolar planets
metallicity
planet
planets
opacity
methane
photometry
atmosphere
gas giant planets
atmospheres
Jupiter
solar system
binary stars
ultrahigh frequencies
dissipation
spectral energy distribution
Jupiter (planet)
star formation
filter

Keywords

  • planets and satellites: atmospheres
  • planets and satellites: composition
  • planets and satellites: gaseous planets
  • stars: individual (GJ 504)

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science

Cite this

Skemer, A. J., Morley, C. V., Zimmerman, N. T., Skrutskie, M. F., Leisenring, J., Buenzli, E., ... Woodward, C. E. (2016). The Leech exoplanet imaging survey: Characterization of the coldest directly imaged exoplanet, GJ 504 b, and evidence for superstellar metallicity. Astrophysical Journal, 817(2), [166]. https://doi.org/10.3847/0004-637X/817/2/166

The Leech exoplanet imaging survey : Characterization of the coldest directly imaged exoplanet, GJ 504 b, and evidence for superstellar metallicity. / Skemer, Andrew J.; Morley, Caroline V.; Zimmerman, Neil T.; Skrutskie, Michael F.; Leisenring, Jarron; Buenzli, Esther; Bonnefoy, Mickael; Bailey, Vanessa; Hinz, Philip; Defrére, Denis; Esposito, Simone; Apai, Dániel; Biller, Beth; Brandner, Wolfgang; Close, Laird; Crepp, Justin R.; De Rosa, Robert J.; Desidera, Silvano; Eisner, Josh; Fortney, Jonathan; Freedman, Richard; Henning, Thomas; Hofmann, Karl Heinz; Kopytova, Taisiya; Lupu, Roxana; Maire, Anne Lise; Males, Jared R.; Marley, Mark; Morzinski, Katie; Oza, Apurva; Patience, Jennifer; Rajan, Abhijith; Rieke, George; Schertl, Dieter; Schlieder, Joshua; Stone, Jordan; Su, Kate; Vaz, Amali; Visscher, Channon; Ward-Duong, Kimberly; Weigelt, Gerd; Woodward, Charles E.

In: Astrophysical Journal, Vol. 817, No. 2, 166, 01.02.2016.

Research output: Contribution to journalReview article

Skemer, AJ, Morley, CV, Zimmerman, NT, Skrutskie, MF, Leisenring, J, Buenzli, E, Bonnefoy, M, Bailey, V, Hinz, P, Defrére, D, Esposito, S, Apai, D, Biller, B, Brandner, W, Close, L, Crepp, JR, De Rosa, RJ, Desidera, S, Eisner, J, Fortney, J, Freedman, R, Henning, T, Hofmann, KH, Kopytova, T, Lupu, R, Maire, AL, Males, JR, Marley, M, Morzinski, K, Oza, A, Patience, J, Rajan, A, Rieke, G, Schertl, D, Schlieder, J, Stone, J, Su, K, Vaz, A, Visscher, C, Ward-Duong, K, Weigelt, G & Woodward, CE 2016, 'The Leech exoplanet imaging survey: Characterization of the coldest directly imaged exoplanet, GJ 504 b, and evidence for superstellar metallicity', Astrophysical Journal, vol. 817, no. 2, 166. https://doi.org/10.3847/0004-637X/817/2/166
Skemer, Andrew J. ; Morley, Caroline V. ; Zimmerman, Neil T. ; Skrutskie, Michael F. ; Leisenring, Jarron ; Buenzli, Esther ; Bonnefoy, Mickael ; Bailey, Vanessa ; Hinz, Philip ; Defrére, Denis ; Esposito, Simone ; Apai, Dániel ; Biller, Beth ; Brandner, Wolfgang ; Close, Laird ; Crepp, Justin R. ; De Rosa, Robert J. ; Desidera, Silvano ; Eisner, Josh ; Fortney, Jonathan ; Freedman, Richard ; Henning, Thomas ; Hofmann, Karl Heinz ; Kopytova, Taisiya ; Lupu, Roxana ; Maire, Anne Lise ; Males, Jared R. ; Marley, Mark ; Morzinski, Katie ; Oza, Apurva ; Patience, Jennifer ; Rajan, Abhijith ; Rieke, George ; Schertl, Dieter ; Schlieder, Joshua ; Stone, Jordan ; Su, Kate ; Vaz, Amali ; Visscher, Channon ; Ward-Duong, Kimberly ; Weigelt, Gerd ; Woodward, Charles E. / The Leech exoplanet imaging survey : Characterization of the coldest directly imaged exoplanet, GJ 504 b, and evidence for superstellar metallicity. In: Astrophysical Journal. 2016 ; Vol. 817, No. 2.
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abstract = "As gas giant planets and brown dwarfs radiate away the residual heat from their formation, they cool through a spectral type transition from L to T, which encompasses the dissipation of cloud opacity and the appearance of strong methane absorption. While there are hundreds of known T-type brown dwarfs, the first generation of directly imaged exoplanets were all L type. Recently, Kuzuhara et al. announced the discovery of GJ 504 b, the first T dwarf exoplanet. GJ 504 b provides a unique opportunity to study the atmosphere of a new type of exoplanet with a ∼500 K temperature that bridges the gap between the first directly imaged planets (∼1000 K) and our own solar system's Jupiter (∼130 K). We observed GJ 504 b in three narrow L-band filters (3.71, 3.88, and 4.00 μm), spanning the red end of the broad methane fundamental absorption feature (3.3 μm) as part of the LBTI Exozodi Exoplanet Common Hunt (LEECH) exoplanet imaging survey. By comparing our new photometry and literature photometry with a grid of custom model atmospheres, we were able to fit GJ 504 b's unusual spectral energy distribution for the first time. We find that GJ 504 b is well fit by models with the following parameters: Teff = 544 ± 10 K, g < 600 m s-2, [M/H] = 0.60 ± 0.12, cloud opacity parameter of fsed = 2-5, R = 0.96 ± 0.07 RJup, and log(L) = -6.13 ± 0.03 Lo, implying a hot start mass of 3-30 Mjup for a conservative age range of 0.1-6.5 Gyr. Of particular interest, our model fits suggest that GJ 504 b has a superstellar metallicity. Since planet formation can create objects with nonstellar metallicities, while binary star formation cannot, this result suggests that GJ 504 b formed like a planet, not like a binary companion.",
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AU - Morley, Caroline V.

AU - Zimmerman, Neil T.

AU - Skrutskie, Michael F.

AU - Leisenring, Jarron

AU - Buenzli, Esther

AU - Bonnefoy, Mickael

AU - Bailey, Vanessa

AU - Hinz, Philip

AU - Defrére, Denis

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AU - Crepp, Justin R.

AU - De Rosa, Robert J.

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AU - Males, Jared R.

AU - Marley, Mark

AU - Morzinski, Katie

AU - Oza, Apurva

AU - Patience, Jennifer

AU - Rajan, Abhijith

AU - Rieke, George

AU - Schertl, Dieter

AU - Schlieder, Joshua

AU - Stone, Jordan

AU - Su, Kate

AU - Vaz, Amali

AU - Visscher, Channon

AU - Ward-Duong, Kimberly

AU - Weigelt, Gerd

AU - Woodward, Charles E.

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N2 - As gas giant planets and brown dwarfs radiate away the residual heat from their formation, they cool through a spectral type transition from L to T, which encompasses the dissipation of cloud opacity and the appearance of strong methane absorption. While there are hundreds of known T-type brown dwarfs, the first generation of directly imaged exoplanets were all L type. Recently, Kuzuhara et al. announced the discovery of GJ 504 b, the first T dwarf exoplanet. GJ 504 b provides a unique opportunity to study the atmosphere of a new type of exoplanet with a ∼500 K temperature that bridges the gap between the first directly imaged planets (∼1000 K) and our own solar system's Jupiter (∼130 K). We observed GJ 504 b in three narrow L-band filters (3.71, 3.88, and 4.00 μm), spanning the red end of the broad methane fundamental absorption feature (3.3 μm) as part of the LBTI Exozodi Exoplanet Common Hunt (LEECH) exoplanet imaging survey. By comparing our new photometry and literature photometry with a grid of custom model atmospheres, we were able to fit GJ 504 b's unusual spectral energy distribution for the first time. We find that GJ 504 b is well fit by models with the following parameters: Teff = 544 ± 10 K, g < 600 m s-2, [M/H] = 0.60 ± 0.12, cloud opacity parameter of fsed = 2-5, R = 0.96 ± 0.07 RJup, and log(L) = -6.13 ± 0.03 Lo, implying a hot start mass of 3-30 Mjup for a conservative age range of 0.1-6.5 Gyr. Of particular interest, our model fits suggest that GJ 504 b has a superstellar metallicity. Since planet formation can create objects with nonstellar metallicities, while binary star formation cannot, this result suggests that GJ 504 b formed like a planet, not like a binary companion.

AB - As gas giant planets and brown dwarfs radiate away the residual heat from their formation, they cool through a spectral type transition from L to T, which encompasses the dissipation of cloud opacity and the appearance of strong methane absorption. While there are hundreds of known T-type brown dwarfs, the first generation of directly imaged exoplanets were all L type. Recently, Kuzuhara et al. announced the discovery of GJ 504 b, the first T dwarf exoplanet. GJ 504 b provides a unique opportunity to study the atmosphere of a new type of exoplanet with a ∼500 K temperature that bridges the gap between the first directly imaged planets (∼1000 K) and our own solar system's Jupiter (∼130 K). We observed GJ 504 b in three narrow L-band filters (3.71, 3.88, and 4.00 μm), spanning the red end of the broad methane fundamental absorption feature (3.3 μm) as part of the LBTI Exozodi Exoplanet Common Hunt (LEECH) exoplanet imaging survey. By comparing our new photometry and literature photometry with a grid of custom model atmospheres, we were able to fit GJ 504 b's unusual spectral energy distribution for the first time. We find that GJ 504 b is well fit by models with the following parameters: Teff = 544 ± 10 K, g < 600 m s-2, [M/H] = 0.60 ± 0.12, cloud opacity parameter of fsed = 2-5, R = 0.96 ± 0.07 RJup, and log(L) = -6.13 ± 0.03 Lo, implying a hot start mass of 3-30 Mjup for a conservative age range of 0.1-6.5 Gyr. Of particular interest, our model fits suggest that GJ 504 b has a superstellar metallicity. Since planet formation can create objects with nonstellar metallicities, while binary star formation cannot, this result suggests that GJ 504 b formed like a planet, not like a binary companion.

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KW - stars: individual (GJ 504)

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