Spectroscopic Direct Detection of Reflected Light from Extrasolar Planets
At optical wavelengths, an exoplanet’s signature is essentially reflected light from the host star – several orders of magnitude fainter. Since it is superimposed on the star spectrum its detection has been a difficult observational challenge.
However, the development of a new generation of instruments like ESPRESSO and next generation telescopes like the E-ELT put us in a privileged position to detect these planets’ reflected light as we will have access to extremely high signal-to-noise ratio spectra. With this work, we propose an alternative approach for the direct detection of the reflected light of an exoplanet. We simulated observations with ESPRESSO@VLT and HIRES@E-ELT of several star+planet systems, encompassing 10h of the most favourable orbital phases.
To the simulated spectra we applied the Cross Correlation Function to operate in a much higher signal-to-noise ratio domain than when compared with the spectra. The use of the Cross-Correlation Function permitted us to recover the simulated the planet signals at a level above 3 \sigma_{noise} significance on several prototypical (e.g., Neptune type planet with a 2 days orbit with the VLT at 4.4 \sigma_{noise} significance) and real planetary systems (e.g., 55 Cnc e with the E-ELT at 4.9 \sigma_{noise} significance).
Even by using a more pessimistic approach to the noise level estimation, where systematics in the spectra increase the noise 2-3 times, the detection of the reflected light from large close-orbit planets is possible. We have also shown that this kind of study is currently within reach of current instruments and telescopes (e.g., 51 Peg b with the VLT at 5.2 \sigma_{noise} significance), although at the limit of their capabilities.
Jorge H. C. Martins, Pedro Figueira, Nuno Santos, Christophe Lovis (Submitted on 29 Aug 2013)
Comments: Accepted for Publication on MNRAS, 5 Figures, 11 pages
Subjects: Earth and Planetary Astrophysics (astro-ph.EP); Instrumentation and Methods for Astrophysics (astro-ph.IM)
Cite as: arXiv:1308.6516 [astro-ph.EP]
(or arXiv:1308.6516v1 [astro-ph.EP] for this version) Submission history From: Jorge Martins [v1] Thu, 29 Aug 2013 16:44:16 GMT (8143kb,D)
