Biosignatures & Paleobiology

Spectroscopic Direct Detection of Reflected Light from Extrasolar Planets

By Keith Cowing
August 29, 2013
Filed under
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)

Explorers Club Fellow, ex-NASA Space Station Payload manager/space biologist, Away Teams, Journalist, Lapsed climber, Synaesthete, Na’Vi-Jedi-Freman-Buddhist-mix, ASL, Devon Island and Everest Base Camp veteran, (he/him) 🖖🏻