A combined subaru/VLT/MMT 1-5 μm study of planets orbiting HR 8799: Implications for atmospheric properties, masses, and formation

Thayne Currie, Adam Burrows, Yoichi Itoh, Soko Matsumura, Misato Fukagawa, Daniel Apai, Nikku Madhusudhan, Philip M. Hinz, T. J. Rodigas, Markus Kasper, T.-S. Pyo, Satoshi Ogino

    Research output: Contribution to journalArticle

    138 Citations (Scopus)

    Abstract

    We present new 1-1.25 µm (z and J band) Subaru/IRCS and 2 µm (K band) VLT/NaCo data for HR 8799 and a re-reduction of the 3-5 µm MMT/Clio data first presented by Hinz etal. Our VLT/NaCo data yield a detection of a fourth planet at a projected separation of 15AU - "HR 8799e." We also report new, albeit weak detections of HR 8799b at 1.03 µm and 3.3 µm. Empirical comparisons to field brown dwarfs show that at least HR 8799b and HR 8799c, and possibly HR 8799d, have near-to-mid-IR colors/magnitudes significantly discrepant from the L/T dwarf sequence. Standard cloud deck atmosphere models appropriate for brown dwarfs provide only (marginally) statistically meaningful fits to HR 8799b and c for physically implausible small radii. Models with thicker cloud layers not present in brown dwarfs reproduce the planets' spectral energy distributions far more accurately and without the need for rescaling the planets' radii. Our preliminary modeling suggests that HR 8799b has log(g) = 4-4.5, T = 900 K, while HR 8799c, d, and (by inference) e have log(g) = 4-4.5, T = 1000-1200 K. Combining results from planet evolution models and new dynamical stability limits implies that the masses of HR 8799b, c, d, and e are 6-7 M , 7-10 M , 7-10 M , and 7-10 M . "Patchy" cloud prescriptions may provide even better fits to the data and may lower the estimated surface gravities and masses. Finally, contrary to some recent claims, forming the HR 8799 planets by core accretion is still plausible, although such systems are likely rare.
    Original languageEnglish
    Article number128
    JournalAstrophysical Journal
    Volume729
    Issue number2
    DOIs
    Publication statusPublished - 10 Mar 2011

    Fingerprint

    planets
    planet
    radii
    spectral energy distribution
    extremely high frequencies
    inference
    accretion
    gravity
    gravitation
    color
    atmospheres
    atmosphere
    modeling
    energy
    detection

    Keywords

    • brown dwarfs
    • Instrumentation
    • Adaptive optics
    • planetary systems
    • stars: individual (HR 8799)
    • techniques
    • Image processing

    Cite this

    Currie, Thayne ; Burrows, Adam ; Itoh, Yoichi ; Matsumura, Soko ; Fukagawa, Misato ; Apai, Daniel ; Madhusudhan, Nikku ; Hinz, Philip M. ; Rodigas, T. J. ; Kasper, Markus ; Pyo, T.-S. ; Ogino, Satoshi. / A combined subaru/VLT/MMT 1-5 μm study of planets orbiting HR 8799 : Implications for atmospheric properties, masses, and formation. In: Astrophysical Journal. 2011 ; Vol. 729, No. 2.
    @article{b2f4c4e034fb445495873bcd09ad78bd,
    title = "A combined subaru/VLT/MMT 1-5 μm study of planets orbiting HR 8799: Implications for atmospheric properties, masses, and formation",
    abstract = "We present new 1-1.25 µm (z and J band) Subaru/IRCS and 2 µm (K band) VLT/NaCo data for HR 8799 and a re-reduction of the 3-5 µm MMT/Clio data first presented by Hinz etal. Our VLT/NaCo data yield a detection of a fourth planet at a projected separation of 15AU - {"}HR 8799e.{"} We also report new, albeit weak detections of HR 8799b at 1.03 µm and 3.3 µm. Empirical comparisons to field brown dwarfs show that at least HR 8799b and HR 8799c, and possibly HR 8799d, have near-to-mid-IR colors/magnitudes significantly discrepant from the L/T dwarf sequence. Standard cloud deck atmosphere models appropriate for brown dwarfs provide only (marginally) statistically meaningful fits to HR 8799b and c for physically implausible small radii. Models with thicker cloud layers not present in brown dwarfs reproduce the planets' spectral energy distributions far more accurately and without the need for rescaling the planets' radii. Our preliminary modeling suggests that HR 8799b has log(g) = 4-4.5, T = 900 K, while HR 8799c, d, and (by inference) e have log(g) = 4-4.5, T = 1000-1200 K. Combining results from planet evolution models and new dynamical stability limits implies that the masses of HR 8799b, c, d, and e are 6-7 M , 7-10 M , 7-10 M , and 7-10 M . {"}Patchy{"} cloud prescriptions may provide even better fits to the data and may lower the estimated surface gravities and masses. Finally, contrary to some recent claims, forming the HR 8799 planets by core accretion is still plausible, although such systems are likely rare.",
    keywords = "brown dwarfs, Instrumentation, Adaptive optics, planetary systems, stars: individual (HR 8799), techniques, Image processing",
    author = "Thayne Currie and Adam Burrows and Yoichi Itoh and Soko Matsumura and Misato Fukagawa and Daniel Apai and Nikku Madhusudhan and Hinz, {Philip M.} and Rodigas, {T. J.} and Markus Kasper and T.-S. Pyo and Satoshi Ogino",
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    Currie, T, Burrows, A, Itoh, Y, Matsumura, S, Fukagawa, M, Apai, D, Madhusudhan, N, Hinz, PM, Rodigas, TJ, Kasper, M, Pyo, T-S & Ogino, S 2011, 'A combined subaru/VLT/MMT 1-5 μm study of planets orbiting HR 8799: Implications for atmospheric properties, masses, and formation', Astrophysical Journal, vol. 729, no. 2, 128. https://doi.org/10.1088/0004-637X/729/2/128

    A combined subaru/VLT/MMT 1-5 μm study of planets orbiting HR 8799 : Implications for atmospheric properties, masses, and formation. / Currie, Thayne; Burrows, Adam; Itoh, Yoichi; Matsumura, Soko; Fukagawa, Misato; Apai, Daniel; Madhusudhan, Nikku; Hinz, Philip M.; Rodigas, T. J.; Kasper, Markus; Pyo, T.-S.; Ogino, Satoshi.

    In: Astrophysical Journal, Vol. 729, No. 2, 128, 10.03.2011.

    Research output: Contribution to journalArticle

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    T1 - A combined subaru/VLT/MMT 1-5 μm study of planets orbiting HR 8799

    T2 - Implications for atmospheric properties, masses, and formation

    AU - Currie, Thayne

    AU - Burrows, Adam

    AU - Itoh, Yoichi

    AU - Matsumura, Soko

    AU - Fukagawa, Misato

    AU - Apai, Daniel

    AU - Madhusudhan, Nikku

    AU - Hinz, Philip M.

    AU - Rodigas, T. J.

    AU - Kasper, Markus

    AU - Pyo, T.-S.

    AU - Ogino, Satoshi

    PY - 2011/3/10

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    AB - We present new 1-1.25 µm (z and J band) Subaru/IRCS and 2 µm (K band) VLT/NaCo data for HR 8799 and a re-reduction of the 3-5 µm MMT/Clio data first presented by Hinz etal. Our VLT/NaCo data yield a detection of a fourth planet at a projected separation of 15AU - "HR 8799e." We also report new, albeit weak detections of HR 8799b at 1.03 µm and 3.3 µm. Empirical comparisons to field brown dwarfs show that at least HR 8799b and HR 8799c, and possibly HR 8799d, have near-to-mid-IR colors/magnitudes significantly discrepant from the L/T dwarf sequence. Standard cloud deck atmosphere models appropriate for brown dwarfs provide only (marginally) statistically meaningful fits to HR 8799b and c for physically implausible small radii. Models with thicker cloud layers not present in brown dwarfs reproduce the planets' spectral energy distributions far more accurately and without the need for rescaling the planets' radii. Our preliminary modeling suggests that HR 8799b has log(g) = 4-4.5, T = 900 K, while HR 8799c, d, and (by inference) e have log(g) = 4-4.5, T = 1000-1200 K. Combining results from planet evolution models and new dynamical stability limits implies that the masses of HR 8799b, c, d, and e are 6-7 M , 7-10 M , 7-10 M , and 7-10 M . "Patchy" cloud prescriptions may provide even better fits to the data and may lower the estimated surface gravities and masses. Finally, contrary to some recent claims, forming the HR 8799 planets by core accretion is still plausible, although such systems are likely rare.

    KW - brown dwarfs

    KW - Instrumentation

    KW - Adaptive optics

    KW - planetary systems

    KW - stars: individual (HR 8799)

    KW - techniques

    KW - Image processing

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