Contributed Talk - Splinter Exoplanets

Tuesday, 13 September 2022, 15:00   (SFG 1010 / virtual Exo)

Imaging pursuit of an elusive planet, epsilon Indi Ab, in the near to mid-infrared

Gayathri Viswanath(1), Markus Janson(1), Carl-Henrik Dahlqvist(2), Dominique Petit dit de la Roche(3), Matthias Samland(1), Julien Girard(4), Prashant Pathak(3), Markus Kasper(3), Fabo Feng(5), Michael Meyer(6), Anna Boehle(7), Sascha P. Quanz(7), Hugh R. A. Jones(8), Olivier Absil(2), Wolfgang Brandner(9), Anna-Lise Maire, Ralf Siebenmorgen(2), Michael Sterzik(3), Eric Pantin(10)
(1)Stockholm University, Sweden (2)STAR Institute/Université de Liège,Beligum (3)European Southern Observatory, Germany (4)Space Telescope Science Institute, USA (5)Department of Terrestrial Magnetism/Carnegie Institution of Washington, USA (6)University of Michigan, USA (7)ETH Zurich, Switzerland (8)Centre for Astrophysics Research/University of Hertfordshire, UK (9)Max Planck Institute for Astronomy, Germany (10)AIM/CEA/ CNRS/ Université Paris-Saclay/ Université Paris Diderot, France

Developments in theoretical knowledge as well as instrumentation have, in the past decade, pushed the boundaries of what high-contrast imaging can achieve, both in terms of detection sensitivity and constraining planet properties. Direct imaging surveys in the near-infrared (NIR) and longward wavelengths have proven particularly useful in detecting younger giant planets at wide orbital separations. The scientific work outlined in this talk is one such result of an imaging pursuit of a young giant planet which has long eluded NIR imaging surveys in the past, yet revealing its existence via radial velocity trends and astrometry of its Sun-like, parent star, epsilon Ind A, which is near enough to be visible to the naked eye in the night sky. I present results from its observations using both the NaCo (L’) and NEAR (10–12.5 microns) instruments at VLT, derive brightness limits from the non-detection of the companion with both instruments, and interpret the corresponding sensitivity in mass based on both cloudy and cloud-free atmospheric and evolutionary models. We arrive at unprecedented sensitivities close to the bright star (200-300 K) and constrain the age of the system to atleast 2 Gyr from our analysis. NaCo offers the highest sensitivity to the planetary companion but the combination with NEAR wavelength range adds a considerable degree of robustness against uncertainties in the atmospheric models. This underlines the benefits of including a broad set of wavelengths for the detection and characterisation of exoplanets in direct imaging studies. The new constraints for epsilon Indi Ab derived in this work set a firm foundation for further MIR imaging surveys for the planet, especially with upcoming more sensitive, advanced instruments in the latter half of the decade, giving hope for a possible detection of this elusive giant in the near future.