The high-energy environment in the super-Earth system CoRoT-7
Abstract
High-energy irradiation of exoplanets has been identified to be a key influence on the stability of these planets' atmospheres. So far, irradiation-driven mass-loss has been observed only in two Hot Jupiters, and the observational data remain even more sparse in the super-Earth regime. We present an investigation of the high-energy emission in the CoRoT-7 system, which hosts the first known transiting super-Earth. To characterize the high-energy XUV radiation field into which the rocky planets CoRoT-7b and CoRoT-7c are immersed, we analyzed a 25 ks XMM-Newton observation of the host star. Our analysis yields the first clear (3.5σ) X-ray detection of CoRoT-7. We determine a coronal temperature of ≈ 3 MK and an X-ray luminosity of 3 × 1028 erg s-1. The level of XUV irradiation on CoRoT-7b amounts to ≈37 000 erg cm-2 s-1. Current theories for planetary evaporation can only provide an order-of-magnitude estimate for the planetary mass loss; assuming that CoRoT-7b has formed as a rocky planet, we estimate that CoRoT-7b evaporates at a rate of about 1.3 × 1011 g s-1 and has lost ≈4-10 earth masses in total.
- Publication:
-
Astronomy and Astrophysics
- Pub Date:
- May 2012
- DOI:
- 10.1051/0004-6361/201118507
- arXiv:
- arXiv:1203.4080
- Bibcode:
- 2012A&A...541A..26P
- Keywords:
-
- stars: activity;
- planetary systems;
- planets and satellites: atmospheres;
- X-rays: stars;
- stars: coronae;
- X-rays: individuals: CoRoT-7;
- Astrophysics - Solar and Stellar Astrophysics;
- Astrophysics - High Energy Astrophysical Phenomena
- E-Print:
- 5 pages, accepted for publication by Astronomy &