New constraints on the formation and settling of dust in the atmospheres of young M and L dwarfs

Manjavacas, Elena; Bonnefoy, M.; Schlieder, Joshua E.; Allard, F.; Rojo, P.; Goldman, B.; Chauvin, G.; Homeier, D.; Lodieu, N.; Henning, Th.

doi:10.1051/0004-6361/201323016

Cited by 51 publications

(62 citation statements)

References 146 publications

(260 reference statements)

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“…(2014) using the SED only and/or different atmospheric models. The T eff is also coherent with those derived for young objects at similar spectral types Manjavacas et al 2014). The dilution factors needed to adjust the model SED expressed in surface fluxes to the apparent fluxes of the planet correspond to a planetary radius of 1.5 ± 0.2 R Jup (see Bonnefoy et al 2013).…”

Section: Physical Properties and Initial Conditionssupporting

confidence: 76%

“…We compared the normalized spectrum of β Pic b with predictions from the PHOENIX-based (BT-SETTL10, BT-SETTL13, DRIFT-PHOENIX, described in Witte et al 2011;Bonnefoy et al 2013;Manjavacas et al 2014) and five grids of LESIA atmospheric models (see Appendix C and Baudino et al 2014) to derive updated T eff and log g estimates (Table 2). A similar analysis derived for the up-to-date SED is reported in Appendix D. The SED and spectra of β Pic b constrain the T eff to 1650 ± 150 K. The fits are less sensitive to log g and to the metallicity.…”

Section: Physical Properties and Initial Conditionsmentioning

confidence: 99%

“…Sample 2 is composed of spectra of M and L dwarfs with features indicative of low surface gravity (Allers & Liu 2013;Manjavacas et al 2014;Liu et al 2013;Schneider et al 2014). The third sample is made of spectra of members of 1−150 Myr old young moving groups and clusters (Lodieu et al 2008;Rice et al 2010;Bonnefoy et al 2014;Gagné et al 2014).…”

Section: Appendix A: Details On the Orbital Fitmentioning

confidence: 99%

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Physical and orbital properties ofβPictoris b

Bonnefoy

Marleau

Galicher

et al. 2014

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The intermediate-mass star β Pictoris is known to be surrounded by a structured edge-on debris disk within which a gas giant planet was discovered orbiting at 8−10 AU. The physical properties of β Pic b were previously inferred from broad-and narrow-band 0.9−4.8 µm photometry. We used commissioning data of the Gemini Planet Imager (GPI) to obtain new astrometry and a lowresolution (R ∼ 35−39) J-band (1.12−1.35 µm) spectrum of the planet. We find that the planet has passed the quadrature. We constrain its semi-major axis to ≤10 AU (90% prob.) with a peak at 8.9 +0.4 −0.6 AU. The joint fit of the planet astrometry and the most recent radial velocity measurements of the star yields a planet dynamical mass lower than 20 M Jup (≥96% prob.). The extracted spectrum of β Pic b is similar to those of young L1 +1 −1.5 dwarfs. We used the spectral type estimate to revise the planet luminosity to log(L/L ) = −3.90±0.07. The 0.9−4.8 µm photometry and spectrum are reproduced for T eff = 1650 ± 150 K and a log g ≤ 4.7 dex by 12 grids of PHOENIX-based and LESIA atmospheric models. For the most recent system age estimate (21 ± 4 Myr), the bolometric luminosity and the constraints on the dynamical mass of β Pic b are only reproduced by warm-and hot-start tracks with initial entropies S i > 10.5 k B /baryon. These initial conditions may result from an inefficient accretion shock and/or a planetesimal density at formation higher than in the classical core-accretion model. Considering a younger age for the system or a conservative formation time for β Pic b does not change these conclusions.

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Section: Physical Properties and Initial Conditionssupporting

confidence: 76%

Section: Physical Properties and Initial Conditionsmentioning

confidence: 99%

Section: Appendix A: Details On the Orbital Fitmentioning

confidence: 99%

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Physical and orbital properties ofβPictoris b

Bonnefoy

Marleau

Galicher

et al. 2014

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“…14), we did not find any significant, unambiguous spectral features of a (nonirradiated) low-mass dwarf star (e.g., Li et al 2014;Littlefair et al 2014;Manjavacas et al 2014). In this phase, the expected secondary's contribution to the composite spectrum of AA Dor is of the order of 0.1% in the NIR.…”

Section: Spectrum Of the Secondarymentioning

confidence: 61%

Search with UVES and X-Shooter for signatures of the low-mass secondary in the post common-envelope binary AA Doradus

Hoyer

Rauch

Werner

et al. 2015

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Context. AA Dor is a close, totally eclipsing, post common-envelope binary with an sdOB-type primary star and an extremely lowmass secondary star, located close to the mass limit of stable central hydrogen burning. Within error limits, it may either be a brown dwarf or a late M-type dwarf. Aims. We aim to extract the secondary's contribution to the phase-dependent composite spectra. The spectrum and identified lines of the secondary decide on its nature. Methods. In January 2014, we measured the phase-dependent spectrum of AA Dor with X-Shooter over one complete orbital period. Since the secondary's rotation is presumable synchronized with the orbital period, its surface strictly divides into a day and night side. Therefore, we may obtain the spectrum of its cool side during its transit and of its hot, irradiated side close to its occultation. We developed the Virtual Observatory (VO) tool TLISA to search for weak lines of a faint companion in a binary system. We successfully applied it to the observations of AA Dor. Results. We identified 53 spectral lines of the secondary in the ultraviolet-blue, visual, and near-infrared X-Shooter spectra that are strongest close to its occultation. We identified 57 (20 additional) lines in available Ultraviolet and Visual Echelle Spectrograph (UVES) spectra from 2001. The lines are mostly from C ii-iii and O ii, typical for a low-mass star that is irradiated and heated by the primary. We verified the orbital period of P = 22 597.033201 ± 0.00007 s and determined the orbital velocity K sec = 232.9 +16.6 −6.5 km s −1 of the secondary. The mass of the secondary is M sec = 0.081 +0.018 −0.010 M and, hence, it is not possible to reliably determine a brown dwarf or an M-type dwarf nature. Conclusions. Although we identified many emission lines of the secondary's irradiated surface, the resolution and signal-to-noise ratio of our UVES and X-Shooter spectra are not good enough to extract a good spectrum of the secondary's nonirradiated hemisphere.

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“…In addition, the models do not provide a good fit of the datapoints in the 3−4 µm regime while they are the only ones that account for non-equilibrium chemistry. Manjavacas et al (2014) suggested that the BT-SETTL models do not seem to produce naturally enough dust, especially at high altitude in the cloud. The problem could be emphasized here with the HR8799 planets.…”

Section: Resultsmentioning

confidence: 99%

First light of the VLT planet finder SPHERE

Bonnefoy¹,

Zurlo²,

Baudino³

et al. 2016

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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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New constraints on the formation and settling of dust in the atmospheres of young M and L dwarfs

Cited by 51 publications

References 146 publications

Physical and orbital properties ofβPictoris b

Physical and orbital properties ofβPictoris b

Search with UVES and X-Shooter for signatures of the low-mass secondary in the post common-envelope binary AA Doradus

First light of the VLT planet finder SPHERE

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