Model Atmospheres for Massive Gas Giants With Thick Clouds: Application to the Hr 8799 Planets and Predictions for Future Detections

Madhusudhan, Nikku; Burrows, Adam; Currie, Thayne

doi:10.1088/0004-637x/737/1/34

Cited by 199 publications

(346 citation statements)

References 55 publications

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“…Further deep imaging characterization should help us to more tightly constrain the orbital parameter space, once the planet has passed the quadrature (most probably in 2013). Further spectroscopic or multi-photometric observations should also help us to determine the underlying physics of this giant planet in the framework of current planetary atmosphere studies Janson et al 2010;Skemer et al 2011;Madhusudhan et al 2011;Barman et al 2011a, b). Therefore, much is to be expected from future extreme-AO instruments SCExAO/Subaru (Guyon 2010), GPI/Gemini , SPHERE/VLT (Beuzit et al 2008) in the coming years.…”

Section: Resultsmentioning

confidence: 99%

Orbital characterization of theβPictoris b giant planet

Chauvin¹,

Lagrange²,

Beust³

et al. 2012

A&A

153

221

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Context. In June 2010, we confirmed the existence of a giant planet in the disk of the young star β Pictoris located between 8 AU and 15 AU from the star. This young planet offers the rare opportunity to monitor a large fraction of the orbit using the imaging technique over a reasonably short timescale. It also offers the opportunity to study its atmospheric properties using spectroscopy and multi-band photometry, and possibly derive its dynamical mass by combining imaging with radial velocity data to set tight constraints on giant planet formation theories. Aims. We aim to measure the evolution of the planet's position relative to the star β Pictoris to determine the planetary orbital properties. Our ultimate goal is to relate both the planetary orbital configuration and physical properties to either the disk structure or the cometary activity observed for decades in the β Pictoris system. Methods. Using the NAOS-CONICA adaptive-optics instrument (NACO) at the Very Large Telescope (VLT), we obtained repeated follow-up images of the β Pictoris system in the K s and L filters at four new epochs in 2010 and 2011. Complementing these data with previous measurements, we conduct a homogeneous analysis, which covers more than eight yrs, to accurately monitor the β Pictoris b position relative to the star. We then carefully consider the various sources of uncertainties that may affect the orbital parameter determination. Results. On the basis of the evolution of the planet's relative position with time, we derive the best-fit orbital solutions for our measurements using two fitting methods, a least squares Levenberg-Marquardt algorithm and a Markov-chain Monte Carlo approach. More reliable results are found with the second approach as our measurements do not cover the complete planetary orbit, and are biased toward the most recent epochs since the planet recovery. The solutions favor a low-eccentricity orbit e < ∼ 0.17, with semi-major axis in the range 8-9 AU corresponding to orbital periods of 17-21 yrs. Our solutions favor a highly inclined solution with a peak around i = 88.5 ± 1.7 • , and a longitude of ascending node tightly constrained at Ω = −147.5 ± 1.5 • . These results indicate that the orbital plane of the planet is likely to be above the midplane of the main disk, and compatible with the warp component of the disk being tilted between 3.5 deg and 4.0 deg. This suggests that the planet plays a key role in the origin of the inner warped-disk morphology of the β Pic disk. Finally, these orbital parameters are consistent with the hypothesis that the planet is responsible for the transit-like event observed in November 1981, and also linked to the cometary activity observed in the β Pic system.

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Section: Resultsmentioning

confidence: 99%

Orbital characterization of theβPictoris b giant planet

Chauvin¹,

Lagrange²,

Beust³

et al. 2012

A&A

153

221

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“…models from Baraffe et al 2003;Madhusudhan et al 2011). For this reason, samples of stars scrutinized for low-mass companions through high-contrast imaging usually include a high fraction of presumably young stars.…”

Section: Discussionmentioning

confidence: 99%

“…Baraffe et al 2003;Madhusudhan et al 2011); spurious young stars might therefore lead to poorly classified companions. In this paper we present the case of such a spurious young star, along with an originally misidentified substellar candidate, found in the NACO Large Program (NACO-LP 1 ; Chauvin 2010).…”

Section: Introductionmentioning

confidence: 99%

Astrophysical false positives in direct imaging for exoplanets: a white dwarf close to a rejuvenated star

Zurlo

Vigan

Hagelberg

et al. 2013

A&A

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Context. As is the case for all techniques involved in the research for exoplanets, direct imaging has to take into account the probability of so-called astrophysical false positives, which are phenomena that mimic the signature of the objects we are seeking. Aims. In this work we present the case of a false positive found during a direct-imaging survey conducted with VLT/NACO. A promising exoplanet candidate was detected around the K2-type star HD 8049 in July 2010. Its contrast of ∆H = 7.05 at 1.57 arcsec allowed us to assume a 35 M Jup companion at 50 projected AU, for the nominal system age and heliocentric distance. Methods. To check whether it was gravitationally bound to the host star, as opposed to an unrelated background object, we re-observed the system one year later and concluded a high probability of a bound system. We also used radial velocity measurements of the host star, spanning a time range of ∼30 yr, to constrain the companion's mass and orbital properties, as well as to probe the host star's spectral age indicators and general spectral energy distribution. We also obtained U-band imaging with EFOSC and near-infrared spectroscopy for the companion. Results. Combining all these information we conclude that the companion of HD 8049 is a white dwarf (WD) with temperature T eff = 18 800 ± 2100 K and mass M WD = 0.56 ± 0.08 M . The significant radial velocity trend combined with the imaging data indicates that the most probable orbit has a semi-major axis of about 50 AU. The discrepancy between the age indicators speaks against a bona-fide young star. The moderately high level of chromospheric activity and fast rotation, mimicking the properties of a young star, might be induced by the exchange of mass with the progenitor of the WD. This example demonstrates some of the challenges in determining accurate age estimates and identifications of faint companions.

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“…However, constraints from the stellar properties (Marois et al 2008;Baines et al 2012), the mass of the disk (Su et al 2009), and models of dynamical stability of the four planets (Esposito et al 2013;Goździewski & Migaszewski 2014) suggest that the system is young. Other hints for small radii or low masses of the planets come from the fitting of their spectral energy distribution (e.g., Marois et al 2008;Bowler et al 2010;Currie et al 2011;Barman et al 2011;Madhusudhan et al 2011;Galicher et al 2011;Ingraham et al 2014), although there are uncertainties on the atmospheric composition and the physical processes governing their atmospheres assumed for the models (e.g., solar/non-solar metallicity, physics of the clouds, non-equilibrium chemistry).…”

Section: Constraints On the Properties Of A Fifth Planetmentioning

confidence: 99%

The LEECH Exoplanet Imaging Survey. Further constraints on the planet architecture of the HR 8799 system

Maire

Skemer

Hinz

et al. 2015

A&A

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Context. Astrometric monitoring of directly imaged exoplanets allows the study of their orbital parameters and system architectures. Because most directly imaged planets have long orbital periods (>20 AU), accurate astrometry is challenging when based on data acquired on timescales of a few years and usually with different instruments. The LMIRCam camera on the Large Binocular Telescope is being used for the LBT Exozodi Exoplanet Common Hunt (LEECH) survey to search for and characterize young and adolescent exoplanets in L band (3.8 µm), including their system architectures. Aims. We first aim to provide a good astrometric calibration of LMIRCam. Then, we derive new astrometry, test the predictions of the orbital model of 8:4:2:1 mean motion resonance proposed for the system, and perform new orbital fitting of the HR 8799 bcde planets. We also present deep limits on a putative fifth planet inside the known planets. Methods. We use observations of HR 8799 and the Θ 1 Ori C field obtained during the same run in October 2013. Results. We first characterize the distortion of LMIRCam. We determine a platescale and a true north orientation for the images of 10.707 ± 0.012 mas/pix and −0.430 ± 0.076 • , respectively. The errors on the platescale and true north orientation translate into astrometric accuracies at a separation of 1 of 1.1 mas and 1.3 mas, respectively. The measurements for all planets agree within 3σ with a predicted ephemeris. The orbital fitting based on the new astrometric measurements favors an architecture for the planetary system based on 8:4:2:1 mean motion resonance. The detection limits allow us to exclude a fifth planet slightly brighter or more massive than HR 8799 b at the location of the 2:1 resonance with HR 8799 e (∼9.5 AU) and about twice as bright as HR 8799 cde at the location of the 3:1 resonance with HR 8799 e (∼7.5 AU).

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Model Atmospheres for Massive Gas Giants With Thick Clouds: Application to the Hr 8799 Planets and Predictions for Future Detections

Cited by 199 publications

References 55 publications

Orbital characterization of theβPictoris b giant planet

Orbital characterization of theβPictoris b giant planet

Astrophysical false positives in direct imaging for exoplanets: a white dwarf close to a rejuvenated star

The LEECH Exoplanet Imaging Survey. Further constraints on the planet architecture of the HR 8799 system

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