81 research outputs found
Deep Thermal Infrared Imaging of HR 8799 bcde: New Atmospheric Constraints and Limits on a Fifth Planet
We present new (3.8 ) and Br- (4.05 ) data
and reprocessed archival 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 dataset at a moderate to high signal-to-noise (SNR
6-15). We fail to identify a fifth planet, "HR 8799 f", at 15
at a 5- confidence level: one suggestive, marginally significant
residual at 0.2" is most likely a PSF artifact. Assuming companion ages of 30
and the Baraffe (Spiegel \& Burrows) planet cooling models, we rule out
an HR 8799 f with mass of 5 (7 ), 7 (10 ), and 12
(13 ) at 12 , 9 , and 5 ,
respectively. All four HR 8799 planets have red early T dwarf-like -
[4.05] colors, suggesting that their SEDs peak in between the and
broadband filters. We find no statistically significant difference
in HR 8799 cde's colors. 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
bc's photometry/spectra, evidence for it from HR 8799 de'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.Comment: 18 pages, 6 Tables, and 9 Figures. Fig. 1a is the key figure.
Accepted for publication in Ap
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