Exoplanets with ELT-METIS

Abstract

Direct imaging is a powerful exoplanet discovery technique that is complementary to other techniques and offers great promise in the era of 30 meter class telescopes. Space-based transit surveys have revolutionized our understanding of the frequency of planets at small orbital radii around Sun-like stars. The next generation of extremely large ground-based telescopes will have the angular resolution and sensitivity to directly image planets with R < 4R ⊕ around the very nearest stars. Here, we predict yields from a direct imaging survey of a volume-limited sample of Sun-like stars with the Mid-Infrared ELT Imager and Spectrograph (METIS) instrument, planned for the 39 m European Southern Observatory (ESO) 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 A-K 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 hour 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.

Planet populations inferred from debris discs

“…Further ahead, the Mid-infrared E-ELT Imager and Spectrograph (METIS; Brandl et al 2018) should detect planets down to several Earth masses at small angular separations (Quanz et al 2015), thanks to its 39 m mirror that increases angular resolution by a factor of ∼4-5 compared to current telescopes. The expected background-limited magnitude for a one-hour observation in L with METIS is 21.2 mag (Bowens et al 2021), which is several orders of magnitude deeper than current NaCo limits (∼16-17 mag, Launhardt et al 2020). Taken together, many of our predicted planets should be observable by upcoming instrumentation.…”

Large Interferometer For Exoplanets (LIFE)

“…Due to their unprecedented spatial resolution and sensitivity, the upcoming 30-40 m ground-based extremely large telescopes (ELTs) will be powerful enough to directly detect small planets around the nearest stars. Instruments working at mid-infrared (MIR) wavelengths, such as the Mid-infrared ELT Imager and Spectrograph (METIS; Brandl et al 2018Brandl et al , 2021, will detect the thermal emission of the planets (Quanz et al 2015;Bowens et al 2021). Instruments working at optical or near-infrared (NIR) wavelengths and featuring high-resolution spectrographs coupled with adaptive optics systems, such as the Planetary Camera and Spectrograph (PCS; Kasper et al 2021) and the High Resolution Spectrograph (HIRES; Marconi 2020), aim at detection in reflected light.…”

An Integrative Analysis of the Rich Planetary System of the Nearby Star e Eridani: Ideal Targets for Exoplanet Imaging and Biosignature Searches

“…Furthermore, future thermal infrared imagers at the Very Large Telescope-perhaps building on the NEAR concept (e.g., Kasper et al 2017;Wagner et al 2021)-may also be able to detect some of the planets close to the habitable zone of e Eridani. In fact, e Eridani has also been identified among the highest-priority targets for the high-resolution thermal infrared imaging with the E-ELT's METIS instrument (Bowens et al 2021).…”