A COMBINED SUBARU/VLT/MMT 1–5 μm STUDY OF PLANETS ORBITING HR 8799: IMPLICATIONS FOR ATMOSPHERIC PROPERTIES, MASSES, AND FORMATION

By T. Currie, Adam Burrows, Y. Itoh, S. Matsumura, M. Fukagawa, D. Apai, N. Madhusudhan, P. Hinz, T. Rodigas, M. Kasper and 2 more. 2011

196 citations recorded by the source corpus.

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 et al. Our VLT/NaCo data yield a detection of a fourth planet at a projected separation of ∼15 AU—“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, Teff = 900 K, while HR 8799c, d, and (by inference) e have log(g) = 4–4.5, Teff = 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 MJ, 7–10 MJ, 7–10 MJ, and 7–10 MJ. “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.

Subfields: Astronomy and Astrophysics, Instrumentation

View Paper: https://www.semanticscholar.org/paper/410c5df88ae06fd013855cc9976be74b4f0f4f0f

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In Astronomy and Astrophysics

1. Michael C. Liu
2. M. Marley
3. N. Madhusudhan
4. Jon Fortney
5. T. Dupuy
6. B. Bowler
7. A. Burgasser
8. Adam Burrows

In Instrumentation

1. Michael C. Liu
2. M. Marley
3. N. Madhusudhan
4. Jon Fortney
5. T. Dupuy
6. A. Burgasser
7. K. Luhman
8. B. Bowler

Citations in the corpus

• THE HAWAII INFRARED PARALLAX PROGRAM. II. YOUNG ULTRACOOL FIELD DWARFS (2016, background): “But the planets’ infrared photometry and spectra indicate the presence of very cloudy photospheres and weak methane, stemming from the lower surface gravity (Marois et al. 2008; Hinz et al. 2010; Bowler et al. 2010; Currie et al. 2011; Barman et al. 2011a; Skemer et al. 2012, 2014).”
• LkCa 15: A YOUNG EXOPLANET CAUGHT AT FORMATION? (2011, result): “The same result has been found for moderately older direct-imaged exoplanets, such as Beta Pic b (Lagrange et al. 2009; Quanz et al. 2010; Currie et al. 2011a) and HR 8799 bcde (Marois et al. 2008; Bowler et al. 2010; Marois et al. 2010; Currie et al. 2011b; Madhusudhan et al. 2011).”
• THE BROWN DWARF KINEMATICS PROJECT (BDKP). III. PARALLAXES FOR 70 ULTRACOOL DWARFS (2012, result): “A connection between youth and dust in the photospheres of T dwarfs is consistent with the L dwarf results discussed in sections 5.1 and 6 of this work as well as recent modeling work of young exoplanets (Barman et al. 2011, Currie et al. 2011).”
• NEGLECTED CLOUDS IN T AND Y DWARF ATMOSPHERES (2012, background): “Several studies of the HR 8799 planets have shown that the iron and silicate clouds play a significant role in their atmospheres (Marois et al. 2008; Barman et al. 2011; Galicher et al. 2011; Bowler et al. 2010; Currie et al. 2011; Madhusudhan et al. 2011; Marley et al. 2012).”
• On the Cool Side: Modeling the Atmospheres of Brown Dwarfs and Giant Planets (2014, unknown): “Examples of such ‘defined cloud’ models include the ‘unified’ models of Tsuji et al. (Tsuji 2002) and various cloud models employed by Burrows and collaborators (Burrows et al. 2002; Currie et al. 2011).”
• Combining high-dispersion spectroscopy with high contrast imaging : Probing rocky planets around our nearest neighbors (2015, background): “Broadband photometry have lead to estimates of planet effective temperatures and radii, and possible prevalance of clouds (e.g. Currie et al. 2011, Currie et al. 2013, Bonnefoy et al. 2013).”
• SPECTRAL AND PHOTOMETRIC DIAGNOSTICS OF GIANT PLANET FORMATION SCENARIOS (2011, background): “For instance, the planets found in the HR8799 system (Marois et al. 2008, 2010) appear to be inconsistent with classical “cold-start” models (Dodson-Robinson et al. 2009; Bowler et al. 2010; Janson et al. 2010; Currie et al. 2011; Madhusudhan et al. 2011).”
• MODEL ATMOSPHERES FOR MASSIVE GAS GIANTS WITH THICK CLOUDS: APPLICATION TO THE HR 8799 PLANETS AND PREDICTIONS FOR FUTURE DETECTIONS (2011, methodology): “…giant planets at large orbital distances, and, hence, with low stellar irradiation, could have been expected to have had similar spectral characteristics to low temperature brown dwarfs, recent observations are proving otherwise (Marois et al. 2008 & 2010, Bowler et al. 2010, Currie et al. 2011).”
• Adaptive Optics for Astronomy (2012, background): “A more rapid growth rate could be achieved if the surrounding disk were dynamically cool, which would require it to consist of Pluto-mass planetesimals (Currie et al. 2011).”
• CLOUDS AND CHEMISTRY IN THE ATMOSPHERE OF EXTRASOLAR PLANET HR8799b (2011, methodology): “While certainly not perfect, the model comparisons presented here are better representations of the observations than those presented by Bowler et al. (2010) and Currie et al. (2011).”
• SIMULTANEOUS DETECTION OF WATER, METHANE, AND CARBON MONOXIDE IN THE ATMOSPHERE OF EXOPLANET HR 8799 b (2015, methodology): “The current astrometric data indicate that all four planets are less than 13 MJup(Marois et al. 2010; Fabrycky & Murray-Clay 2010; Currie et al. 2011; Pueyo et al. 2014).”
• The Formation and Early Evolution of Low-Mass Stars and Brown Dwarfs (2012, background): “The presence of this common anomaly has been recognized for subsets of these objects (Bowler et al. 2010; Currie et al. 2011; Metchev, Marois & Zuckerman 2009; Skemer et al. 2011).”
• C/O RATIO AS A DIMENSION FOR CHARACTERIZING EXOPLANETARY ATMOSPHERES (2012, background): “…curves (Knutson et al. 2007, 2012; Showman et al. 2009; Cowan et al. 2012), and direct imaging (e.g. Marois et al. 2008,2010; Bowler et al. 2010; Currie et al. 2011; Janson et al. 1 Department of Physics and Department of Astronomy, Yale University, New Haven, CT 06511…”
• ORBITAL MOTION OF HR 8799 b, c, d USING HUBBLE SPACE TELESCOPE DATA FROM 1998: CONSTRAINTS ON INCLINATION, ECCENTRICITY, AND STABILITY (2011, background): “Currently the consensus mass ranges are: 6-7 MJup for b, and 7-10 MJup for c, d, and e (Marois et al. 2008, 2010b; Currie et al. 2011a).”
• MASSES, RADII, AND CLOUD PROPERTIES OF THE HR 8799 PLANETS (2012, methodology): “The J-band data were taken from Marois et al. (2008) and Currie et al. (2011).”
• Retrieving scattering clouds and disequilibrium chemistry in the atmosphere of HR 8799e (2020, methodology): “Since their discovery (Marois et al. 2008, 2010; Currie et al. 2011) the HR 8799 planets have been extensively studied.”
• THE TUCANA/HOROLOGIUM, COLUMBA, AB DORADUS, AND ARGUS ASSOCIATIONS: NEW MEMBERS AND DUSTY DEBRIS DISKS (2011, background): “The near-IR colors of the planets of HR 8799 differ from those of conventional (old) L- and T-type substellar objects, but are similar to that of the ∼6 Jupiter mass 2M1207b (Marois et al 2008; Patience et al. 2010; Currie et al 2011).”