Sanz-Forcada, J.; Ribas, I.; Micela, G.; Pollock, A. M. T.; García-Álvarez, D.; Solano, E.; Eiroa, C.
Bibliographical reference
Astronomy and Astrophysics, Volume 511, id.L8
Advertised on:
2
2010
Journal
Citations
69
Refereed citations
55
Description
Context. According to theory, high-energy emission from the coronae of
cool stars can severely erode the atmospheres of orbiting planets. No
observational tests of the long-term erosion effects have been made yet.
Aims: We analyze the current distribution of planetary mass with
X-ray irradiation of the atmospheres to make an observational assessment
of the consequences of erosion by coronal radiation. Methods: We
studied a large sample of planet-hosting stars with XMM-Newton, Chandra,
and ROSAT, carefully identified the X-ray counterparts, and fit their
spectra to accurately measure the stellar X-ray flux. Results:
The distribution of the planetary masses with X-ray flux suggests that
erosion has taken place. Most surviving massive planets (Mp
sin i > 1.5 MJ) have been exposed to lower accumulated
irradiation. Heavy erosion during the initial stages of stellar
evolution is followed by a phase of much weaker erosion. A line dividing
these two phases could be present, showing a strong dependence on planet
mass. Although a larger sample will be required to establish a
well-defined erosion line, the distribution found is very suggestive.
Conclusions: The distribution of planetary mass with X-ray flux
is consistent with a scenario in which planet atmospheres have suffered
the effects of erosion by coronal X-ray and EUV emission. The erosion
line is an observational constraint for models of atmospheric erosion.
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