2012A&A...543L...4L


C.D.S. - SIMBAD4 rel 1.7 - 2020.10.20CEST08:15:24

2012A&A...543L...4L - Astronomy and Astrophysics, volume 543, L4-4 (2012/7-1)

Temporal variations in the evaporating atmosphere of the exoplanet HD 189733b.

LECAVELIER DES ETANGS A., BOURRIER V., WHEATLEY P.J., DUPUY H., EHRENREICH D., VIDAL-MADJAR A., HEBRARD G., BALLESTER G.E., DESERT J.-M., FERLET R. and SING D.K.

Abstract (from CDS):

Atmospheric escape has been detected from the exoplanet HD209458b through transit observations of the hydrogen Lyman-α line. Here we present spectrally resolved Lyman-α transit observations of the exoplanet HD189733b at two different epochs. These HST/STIS observations show for the first time that there are significant temporal variations in the physical conditions of an evaporating planetary atmosphere. While atmospheric hydrogen is not detected in the first epoch observations, it is observed at the second epoch, producing a transit absorption depth of 14.4±3.6% between velocities of -230 to -140km/s. Contrary to HD209458b, these high velocities cannot arise from radiation pressure alone and require an additional acceleration mechanism, such as interactions with stellar wind protons. The observed absorption can be explained by an atmospheric escape rate of neutral hydrogen atoms of about 109g/s, a stellar wind with a velocity of 190km/s and a temperature of ∼105K. An X-ray flare from the active star seen with Swift/XRT 8h before the second-epoch observation supports the idea that the observed changes within the upper atmosphere of the planet can be caused by variations in the stellar wind properties, or by variations in the stellar energy input to the planetary escaping gas (or a mix of the two effects). These observations provide the first indication of interaction between the exoplanet's atmosphere and stellar variations.

Abstract Copyright:

Journal keyword(s): planetary systems - stars: individual: HD189733 - techniques: spectroscopic - planets and satellites: atmospheres - stars: flare

Simbad objects: 5

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Number of rows : 5

N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2020
#notes
1 UCAC3 226-217434 PM* 20 00 42.9779742728 +22 42 34.178579623       14.67   M4V 14 0
2 HD 189733b Pl 20 00 43.7130382888 +22 42 39.071811263           ~ 1105 1
3 HD 189733 BY* 20 00 43.7130382888 +22 42 39.071811263 9.241 8.578 7.648 7.126 6.68 K2V 729 1
4 HD 209458 V* 22 03 10.7729598762 +18 53 03.548248479   8.21 7.63     F9V 999 1
5 HD 209458b Pl 22 03 10.7729598762 +18 53 03.548248479           ~ 1503 1

    Equat.    Gal    SGal    Ecl

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2020.10.20-08:15:24

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