Exoplanets with ELTMETIS. I. Estimating the direct imaging exoplanet yield around stars within 6.5 parsecs
Abstract
Direct imaging is a powerful exoplanet discovery technique that is complementary to other techniques and offers great promise in the era of 30 m class telescopes. Spacebased transit surveys have revolutionized our understanding of the frequency of planets at small orbital radii around Sunlike stars. The next generation of extremely large groundbased telescopes will have the angular resolution and sensitivity to directly image planets with R < 4 R_{⊕} around the very nearest stars. Here, we predict yields from a direct imaging survey of a volumelimited sample of Sunlike stars with the MidInfrared ELT Imager and Spectrograph (METIS) instrument, planned for the 39 m European Southern Observatory Extremely Large Telescope (ELT) that is expected to be operational towards the end of the decade. Using Kepler occurrence rates, a sample of stars with spectral types AK within 6.5 pc, and simulated contrast curves based on an advanced model of what is achievable from coronagraphic imaging with adaptive optics, we estimated the expected yield from METIS using Monte Carlo simulations. We find the METIS expected yield of planets in the N2 band (10.10−12.40 μm) is 1.14 planets, which is greater than comparable observations in the L (3.70−3.95 μm) and M (4.70−4.90 μm) bands. We also determined a 24.6% chance of detecting at least one Jovian planet in the background limited regime assuming a 1 h integration. We calculated the yield per star and estimate optimal observing revisit times to increase the yield. We also analyzed a northern hemisphere version of this survey and found there are additional targets worth considering. In conclusion, we present an observing strategy aimed to maximize the possible yield for limited telescope time, resulting in 1.48 expected planets in the N2 band.
 Publication:

Astronomy and Astrophysics
 Pub Date:
 September 2021
 DOI:
 10.1051/00046361/202141109
 arXiv:
 arXiv:2107.06375
 Bibcode:
 2021A&A...653A...8B
 Keywords:

 infrared: planetary systems;
 planets and satellites: detection;
 instrumentation: detectors;
 Astrophysics  Earth and Planetary Astrophysics;
 Astrophysics  Instrumentation and Methods for Astrophysics
 EPrint:
 11 pages, 6 Figures, 4 Tables, A&