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, Dániel; Madhusudhan, Nikku; Hinz, Philip M.; Rodigas, Timothy J.; Kasper, Markus; Pyo, Tae‐Soo; Ogino, Satoshi

doi:10.1088/0004-637x/729/2/128

Cited by 286 publications

(455 citation statements)

References 83 publications

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“…Dynamical stability studies of the planetary system that orbits HR 8799 provide additional indirect evidence for a young system age. An older stellar age implied larger planet masses that would lead to a dynamically unstable system (Currie et al 2011;Sudol & Haghighipour 2012;Esposito et al 2013). Therefore, we adopt a value of 30 Myr for Tucana, Columba, and Carina and 45 Myr for Argus (the mean between isochrone and lithium depletion boundary ages).…”

Section: Tucana Columba Carina and Argusmentioning

confidence: 99%

The VLT/NaCo large program to probe the occurrence of exoplanets and brown dwarfs in wide orbits

Desidera

Covino

Messina

et al. 2015

A&A

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Context. Young, close stars are ideal targets for searching planets using the direct imaging technique. The determination of stellar parameters is crucial for the interpretation of imaging survey results, particularly since the luminosity of substellar objects has a strong dependence on system age. Aims. We have conducted a large program with NaCo at the VLT to search for planets and brown dwarfs in wide orbits around 86 stars. A large fraction of the targets observed with NaCo were poorly investigated in the literature. We performed a study to characterize the fundamental properties (age, distance, and mass) of the stars in our sample. To improve target age determinations, we compiled and analyzed a complete set of age diagnostics. Methods. We measured spectroscopic parameters and age diagnostics using dedicated observations acquired with FEROS and CORALIE spectrographs at La Silla Observatory. We also made extensive use of archival spectroscopic data and the results that are available in the literature. Additionally, we exploited photometric time-series, which are available in ASAS and Super-WASP archives, to derive a rotational period for a large fraction of our program stars. Results. We provided updated characterization of all the targets observed in the VLT NaCo Large program, a survey designed to probe the occurrence of exoplanets and brown dwarfs in wide orbits. The median distance and age of our program stars are 64 pc and 100 Myr, respectively. Nearly all the stars have masses between 0.70 and 1.50 M , with a median value of 1.01 M . The typical metallicity is close to solar with a dispersion that is smaller than that of samples usually observed in radial velocity surveys. Several stars are confirmed or proposed here to be members of close young moving groups. Eight spectroscopic binaries are identified.

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Section: Tucana Columba Carina and Argusmentioning

confidence: 99%

The VLT/NaCo large program to probe the occurrence of exoplanets and brown dwarfs in wide orbits

Desidera

Covino

Messina

et al. 2015

A&A

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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%

“…We first tested the predictions of Goździewski & Migaszewski (2014) with respect to the astrometric measurements presented in this paper. We gathered all the relative astrometric measurements available in the literature (Marois et al 2008(Marois et al , 2010bLafrenière et al 2009;Fukagawa et al 2009;Metchev et al 2009;Hinz et al 2010;Currie et al 2011Currie et al , 2012Currie et al , 2014Bergfors et al 2011;Galicher et al 2011;Soummer et al 2011;Esposito et al 2013;Pueyo et al 2015) and included the LEECH measurements (Table 2) to represent Fig. 3.…”

Section: Orbital Architecturementioning

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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“…So far, studies of the atmospheres of HR8799 bcde were conducted using mostly photometric measurements in the infrared (1−5 µm; Marois et al 2008Marois et al , 2010Lafrenière et al 2009;Hinz et al 2010;Janson et al 2010;Currie et al 2011a;Galicher et al 2011;Skemer et al 2012;Esposito et al 2013;Skemer et al 2014;Currie et al 2014). The measurements indicate that the four planets add to the restrained list of young companions at the L/T transition.…”

Section: Introductionmentioning

confidence: 99%

First light of the VLT planet finder SPHERE

Bonnefoy¹,

Zurlo²,

Baudino³

et al. 2016

A&A

129

104

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Context. The system of four planets discovered around the intermediate-mass star HR8799 offers a unique opportunity to test planet formation theories at large orbital radii and to probe the physics and chemistry at play in the atmospheres of self-luminous young (∼30 Myr) planets. We recently obtained new photometry of the four planets and low-resolution (R ∼ 30) spectra of HR8799 d and e with the SPHERE instrument (Paper III). Aims. In this paper (Paper IV), we aim to use these spectra and available photometry to determine how they compare to known objects, what the planet physical properties are, and how their atmospheres work. Methods. We compare the available spectra, photometry, and spectral energy distribution (SED) of the planets to field dwarfs and young companions. In addition, we use the extinction from corundum, silicate (enstatite and forsterite), or iron grains likely to form in the atmosphere of the planets to try to better understand empirically the peculiarity of their spectrophotometric properties. To conclude, we use three sets of atmospheric models (BT-SETTL14, Cloud-AE60, Exo-REM) to determine which ingredients are critically needed in the models to represent the SED of the objects, and to constrain their atmospheric parameters (T eff , log g, M/H). Results. We find that HR8799d and e properties are well reproduced by those of L6-L8 dusty dwarfs discovered in the field, among which some are candidate members of young nearby associations. No known object reproduces well the properties of planets b and c. Nevertheless, we find that the spectra and WISE photometry of peculiar and/or young early-T dwarfs reddened by submicron grains made of corundum, iron, enstatite, or forsterite successfully reproduce the SED of these planets. Our analysis confirms that only the Exo-REM models with thick clouds fit (within 2σ) the whole set of spectrophotometric datapoints available for HR8799 d and e for T eff = 1200 K, log g in the range 3.0−4.5, and M/H = +0.5. The models still fail to reproduce the SED of HR8799c and b. The determination of the metallicity, log g, and cloud thickness are degenerate. Conclusions. Our empirical analysis and atmospheric modelling show that an enhanced content in dust and decreased CIA of H 2 is certainly responsible for the deviation of the properties of the planet with respect to field dwarfs. The analysis suggests in addition that HR8799c and b have later spectral types than the two other planets, and therefore could both have lower masses.

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

Cited by 286 publications

References 83 publications

The VLT/NaCo large program to probe the occurrence of exoplanets and brown dwarfs in wide orbits

The VLT/NaCo large program to probe the occurrence of exoplanets and brown dwarfs in wide orbits

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

First light of the VLT planet finder SPHERE

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