TY - JOUR
T1 - Deep thermal infrared imaging of hr 8799 bcde
T2 - New atmospheric constraints and limits on a fifth planet
AU - Currie, Thayne
AU - Burrows, Adam S.
AU - Girard, Julien H.
AU - Cloutier, Ryan
AU - Fukagawa, Misato
AU - Sorahana, Satoko
AU - Kuchner, Marc
AU - Kenyon, Scott J.
AU - Madhusudhan, Nikku
AU - Itoh, Yoichi
AU - Jayawardhana, Ray
AU - Matsumura, Soko
AU - Pyo, Tae Soo
N1 - Publisher Copyright:
© 2014. The American Astronomical Society. All rights reserved..
PY - 2014/11/10
Y1 - 2014/11/10
N2 - We present new L′ (3.8 μm) and Brα (4.05 μm) data and reprocessed archival L′ data for the young, planet-hosting star HR 8799 obtained with Keck/NIRC2, VLT/NaCo, and Subaru/IRCS. We detect all four HR 8799 planets in each data set at a moderate to high signal-to-noise ratio (S/N ≳ 6-15). We fail to identify a fifth planet, "HR 8799 f," at r < 15 AU at a 5σ confidence level: one suggestive, marginally significant residual at 0.″2 is most likely a point-spread function artifact. Assuming companion ages of 30 Myr and the Baraffe planet cooling models, we rule out an HR 8799 f with a mass of 5 MJ (7 MJ ), 7 MJ (10 MJ ), or 12 MJ (13 MJ ) at r proj 12 AU, 9 AU, and 5 AU, respectively. All four HR 8799 planets have red early T dwarf-like L′-[4.05] colors, suggesting that their spectral energy distributions peak in between the L′ and M′ broadband filters. We find no statistically significant difference in HR 8799 cde's color. Atmosphere models assuming thick, patchy clouds appear to better match HR 8799 bcde's photometry than models assuming a uniform cloud layer. While non-equilibrium carbon chemistry is required to explain HR 8799 b and c's photometry/spectra, evidence for it from HR 8799 d and e's photometry is weaker. Future, deep-IR spectroscopy/spectrophotometry with the Gemini Planet Imager, SCExAO/CHARIS, and other facilities may clarify whether the planets are chemically similar or heterogeneous.
AB - We present new L′ (3.8 μm) and Brα (4.05 μm) data and reprocessed archival L′ data for the young, planet-hosting star HR 8799 obtained with Keck/NIRC2, VLT/NaCo, and Subaru/IRCS. We detect all four HR 8799 planets in each data set at a moderate to high signal-to-noise ratio (S/N ≳ 6-15). We fail to identify a fifth planet, "HR 8799 f," at r < 15 AU at a 5σ confidence level: one suggestive, marginally significant residual at 0.″2 is most likely a point-spread function artifact. Assuming companion ages of 30 Myr and the Baraffe planet cooling models, we rule out an HR 8799 f with a mass of 5 MJ (7 MJ ), 7 MJ (10 MJ ), or 12 MJ (13 MJ ) at r proj 12 AU, 9 AU, and 5 AU, respectively. All four HR 8799 planets have red early T dwarf-like L′-[4.05] colors, suggesting that their spectral energy distributions peak in between the L′ and M′ broadband filters. We find no statistically significant difference in HR 8799 cde's color. Atmosphere models assuming thick, patchy clouds appear to better match HR 8799 bcde's photometry than models assuming a uniform cloud layer. While non-equilibrium carbon chemistry is required to explain HR 8799 b and c's photometry/spectra, evidence for it from HR 8799 d and e's photometry is weaker. Future, deep-IR spectroscopy/spectrophotometry with the Gemini Planet Imager, SCExAO/CHARIS, and other facilities may clarify whether the planets are chemically similar or heterogeneous.
KW - planetary systems
KW - planets and satellites: atmospheres
KW - planets and satellites: composition
KW - stars: early-type
KW - stars: individual (HR 8799)
KW - techniques: high angular resolution
KW - techniques: image processing
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U2 - 10.1088/0004-637X/795/2/133
DO - 10.1088/0004-637X/795/2/133
M3 - Article
AN - SCOPUS:84908396162
SN - 0004-637X
VL - 795
JO - Astrophysical Journal
JF - Astrophysical Journal
IS - 2
M1 - 133
ER -