Models of very-low-mass stars, brown dwarfs and exoplanets

By F. Allard, Derek Homeier, Bernd Freytag. 2011

749 citations recorded by the source corpus.

Within the next few years, GAIA and several instruments aiming to image extrasolar planets will be ready. In parallel, low-mass planets are being sought around red dwarfs, which offer more favourable conditions, for both radial velocity detection and transit studies, than solar-type stars. In this paper, the authors of a model atmosphere code that has allowed the detection of water vapour in the atmosphere of hot Jupiters review recent advances in modelling the stellar to substellar transition. The revised solar oxygen abundances and cloud model allow the photometric and spectroscopic properties of this transition to be reproduced for the first time. Also presented are highlight results of a model atmosphere grid for stars, brown dwarfs and extrasolar planets.

Subfields: Astronomy and Astrophysics

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Citations in the corpus

REVISED STELLAR PROPERTIES OF KEPLER TARGETS FOR THE QUARTER 1–16 TRANSIT DETECTION RUN (2013, methodology): “To characterize these stars, we fit second to fourth order polynomials between colors, temperatures, gravities, and radii to > 2Gyr BT-Settl isochrones (Allard et al. 2012) with temperatures between 2000 − 3400K.”
The star formation history and accretion-disc fraction among the K-type members of the Scorpius–Centaurus OB association (2016, methodology): “This Teff and BCV scale was derived by fitting the spectral energy distributions of members of young, nearby moving groups to the BT-Settl theoretical atmospheric models (Allard et al. 2012).”
Global Climate and Atmospheric Composition of the Ultra-hot Jupiter WASP-103b from HST and Spitzer Phase Curve Observations (2018, methodology): “To calculate the best fit blackbody model, we assumed a planet-to-star radius ratio of 0.1146 and used a NextGen stellar spectrum interpolated to an effective temperature of 6110 K (Allard et al. 2012).”
WEATHER ON OTHER WORLDS. II. SURVEY RESULTS: SPOTS ARE UBIQUITOUS ON L AND T DWARFS (2014, background): “…et al. 2001), the more nuanced picture of photospheric condensate cloud formation (Ackerman & Marley 2001; Cooper et al. 2003; Helling et al. 2006; Allard et al. 2012) provides a more accurate representation of the spectra, colors, and chemical compositions across the L and T dwarf sequence…”
Revised Stellar Properties of Kepler Targets for the Q1-17 (DR25) Transit Detection Run (2016, methodology): “For this small sample of stars, distances and extinctions are not given and their provenance is BTSL since the parameters were estimated from polynomial fits to low-mass BT-Settl models (Allard et al. 2012).”
WIYN OPEN CLUSTER STUDY. LXII. COMPARISON OF ISOCHRONE SYSTEMS USING DEEP MULTI-BAND PHOTOMETRY OF M35 (2014, methodology): “BT-Settl atmospheres, using solar abundances from Asplund et al. (2009), were used in this work, differing from the ATLAS9 solar metallicity values of Grevesse & Sauval (1998).”
COSMOS2020: A Panchromatic View of the Universe to z ∼ 10 from Two Complementary Catalogs (2021, methodology): “By default, EAZY uses a set of theoretical PHOENIX BT-Settl stellar templates (Allard et al. 2012) spanning a range of effective temperatures and calculates the χ2 goodness of fit for each template individually (i.e., not as linear combinations).”
THE HAWAII INFRARED PARALLAX PROGRAM. II. YOUNG ULTRACOOL FIELD DWARFS (2016, methodology): “We also examine BT-Settl evolutionary model isochrones (Baraffe et al. 2015; Allard et al. 2015, in preparation) that adopt a particular prescription for the formation and sedimentation of clouds as objects age (Allard et al. 2012).”
A Population Study of Gaseous Exoplanets (2017, methodology): “…observed limb darkening coefficients are, for the cooler stars, stellar activity (e.g. Csizmadia et al. 2013) or inaccurate chemical models (e.g. Allard et al. 2012), and, for the hotter stars, the use of a plane-parallel approximation rather than full spherical geometry (Hayek et al. 2012;…”
Imaging Extrasolar Giant Planets (2016, background): “…(Chabrier et al. 2007; Helled et al. 2013; Chabrier et al. 2014; Helling et al. 2014), atmospheric models (Marley et al. 2007a; Helling et al. 2008, Allard et al. 2012; Marley & Robinson 2015), evolutionary models, (Burrows et al. 2001; Fortney & Nettelmann 2009), observational results (Absil &…”
The Updated BaSTI Stellar Evolution Models and Isochrones. I. Solar-scaled Calculations (2018, methodology): “Therefore for the VLM model calculations we employed boundary conditions (pressure and temperature at a Rosseland optical depth τ=100) taken from the PHOENIX model atmosphere library3 (Allard et al. 2012, and references therein), more precisely the BT-Settl model set.”
INTRINSIC COLORS, TEMPERATURES, AND BOLOMETRIC CORRECTIONS OF PRE-MAIN-SEQUENCE STARS (2013, methodology): “…R d = 10−0.2A We fit the observed photometry to synthetic photometry from two different libraries of synthetic spectra: the BT-Settl models8 of Allard et al. (2012) with the Asplund et al. (2009) solar composition and the ATLAS9 models9 of Castelli & Kurucz (2004) with the Grevesse…”
HUBBLE SPACE TELESCOPE NEAR-IR TRANSMISSION SPECTROSCOPY OF THE SUPER-EARTH HD 97658B (2014, methodology): “We calculate our limb-darkening coefficients using a PHOENIX stellar atmosphere model(Allard et al. 2012), where we take the flux-weighted average of the stellar intensity profile across the band and then fit for the limb-darkening coefficients.”
Disentangling the Planet from the Star in Late-Type M Dwarfs: A Case Study of TRAPPIST-1g (2018, methodology): “Late Corresponding author: Hannah R. Wakeford hwakeford@stsci.edu type M dwarfs (M5-M8) present particular challenges as they can contain molecules like water vapor and form aerosols in their atmospheres (Allard et al. 2012), which are key features of cooler planetary atmospheres.”