Constraints on CoRoT-7 b's exosphere

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Constraints on CoRoT-7 b's exosphere

Post by Sirius_Alpha on 28th September 2010, 8:54 pm

Constraints on the exosphere of CoRoT-7b
http://arxiv.org/abs/1009.5500

Context: The small radius and high density of CoRoT-7b implies that this transiting planet belongs to a different species than all transiting planets that have previously been found. Current models suggest that this is the first transiting rocky planet found outside the solar system. Given that the planet orbits a solar-like star at a distance of only 4.5 R*, it is expected that material from its surface is released which would then form an exosphere. AIMS: {Our aim is to constrain the properties of the exosphere by observing the planet in and out-of-transit. The detection of the exosphere of CoRoT-7b would for the first time allow to study the material originating from the surface of a rocky extrasolar planet. We survey the whole optical spectrum for any lines originating from the planet, particularly focusing on spectral-lines like those that have been detected in Mercury, and Io in our solar-system.} Methods: Given that it is expected that lines originating from the exosphere will be narrow, we observed CoRoT-7b at high-resolution with UVES on the VLT. By subtracting the two spectra from each other, we search for emission and absorption lines originating from the exosphere of CoRoT-7b. Results: In the first step we focus on Ca\,I, Ca\,II, Na, because these lines have been detected in Mercury. Since the S/N-ratio of the spectra is as high as 300, we derive firm upper limits in the range between 1.6E-18 and 3.2E-18 Wm-2. For CaO we find an upper limit of 1.0E-17 Wm-2. We also search for emission lines originating from the plasma torus fed by volcanic activity and derive upper limits for these lines as well. We finally search the whole spectrum for the presence of other lines originating from the planet. Conclusions: Except for CaO, the upper limits derived correspond to 2E-6 to 6E-6 L*. Our observations certainly rule out the extreme views of CoRoT-7b.

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Re: Constraints on CoRoT-7 b's exosphere

Post by Borislav on 5th October 2010, 8:30 am

I thought that a possible explanation for not finding the atmosphere in this article
http://solar-flux.forumandco.com/extrasolar-news-and-discoveries-f2/corot-results-t9-255.htm#4895

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