2017ApJ...834..151R


C.D.S. - SIMBAD4 rel 1.7 - 2021.05.18CEST04:51:03

2017ApJ...834..151R - Astrophys. J., 834, 151-151 (2017/January-2)

ACCESS I: an optical transmission spectrum of GJ 1214b reveals a heterogeneous stellar photosphere.

RACKHAM B., ESPINOZA N., APAI D., LOPEZ-MORALES M., JORDAN A., OSIP D.J., LEWIS N.K., RODLER F., FRAINE J.D., MORLEY C.V. and FORTNEY J.J.

Abstract (from CDS):

GJ 1214b is the most studied sub-Neptune exoplanet to date. Recent measurements have shown its near-infrared transmission spectrum to be flat, pointing to a high-altitude opacity source in the exoplanet's atmosphere, either equilibrium condensate clouds or photochemical hazes. Many photometric observations have been reported in the optical by different groups, though simultaneous measurements spanning the entire optical regime are lacking. We present an optical transmission spectrum (4500-9260 A) of GJ 1214b in 14 bins, measured with Magellan/IMACS repeatedly over three transits. We measure a mean planet-to-star radius ratio of Rp/Rs=0.1146±2×10–4 and mean uncertainty of σ(Rp/Rs)=8.7×10–4 in the spectral bins. The optical transit depths are shallower on average than observed in the near-infrared. We present a model for jointly incorporating the effects of a composite photosphere and atmospheric transmission through the exoplanet's limb (the CPAT model), and use it to examine the cases of absorber and temperature heterogeneities in the stellar photosphere. We find the optical and near-infrared measurements are best explained by the combination of (1) photochemical haze in the exoplanetary atmosphere with a mode particle size r = 0.1 µm and haze-forming efficiency fhaze=10 % and (2) faculae in the unocculted stellar disk with a temperature contrast ΔT=354–46+46 K, assuming 3.2% surface coverage. The CPAT model can be used to assess potential contributions of heterogeneous stellar photospheres to observations of exoplanet transmission spectra, which will be important for searches for spectral features in the optical.

Abstract Copyright: © 2017. The American Astronomical Society. All rights reserved.

Journal keyword(s): methods: observational - planets and satellites: atmospheres - planets and satellites: individual: GJ 1214b - stars: activity - techniques: spectroscopic - techniques: spectroscopic

Simbad objects: 6

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Number of rows : 6

N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2021
#notes
1 CD-38 3220b Pl 07 10 24.0606039387 -39 05 50.570553937           ~ 142 0
2 NAME L 320-124b Pl 10 14 51.7783473599 -47 09 24.189733387           ~ 101 0
3 G 139-21 PM* 17 15 18.9337265994 +04 57 50.064695682       14.394   M4.5V 256 1
4 NAME G 139-21b Pl 17 15 18.9337265994 +04 57 50.064695682           ~ 574 1
5 G 24-16 Er* 20 29 48.3179167836 +09 41 20.590506834       12.728   M4.5V 141 0
6 WASP-6b Pl 23 12 37.7368657624 -22 40 26.277489164           ~ 106 1

    Equat.    Gal    SGal    Ecl

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2021.05.18-04:51:03

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