Imaging search for the unseen companion to Eps Ind A -- Improving the detection limits with 4 micron observations

Abstract

Eps Ind A is one of the nearest sun-like stars, located only 3.6 pc away. It is known to host a binary brown dwarf companion, Eps Ind Ba/Bb, at a large projected separation of 6.7", but radial velocity measurements imply that an additional, yet unseen component is present in the system, much closer to Eps Ind A. Previous direct imaging has excluded the presence of any stellar or high-mass brown dwarf companion at small separations, indicating that the unseen companion may be a low-mass brown dwarf or high-mass planet. We present the results of a deep high-contrast imaging search for the companion, using active angular differential imaging (aADI) at 4 micron, a particularly powerful technique for planet searches around nearby and relatively old stars. We also develop an additional PSF reference subtraction scheme based on locally optimized combination of images (LOCI) to further enhance the detection limits. No companion is seen in the images, although we are sensitive to significantly lower masses than previously achieved. Combining the imaging data with the known radial velocity trend, we constrain the properties of the companion to within approximately 5-20 Mjup, 10-20 AU, and i > 20 deg, unless it is an exotic stellar remnant. The results also imply that the system is probably older than the frequently assumed age of ~1 Gyr.

10 pages, 6 figures, accepted for publication in MNRAS

References in corpus (9)

• Direct Imaging of Multiple Planets Orbiting the Star HR 8799
• Optical Images of an Exosolar Planet 25 Light Years from Earth
• Nearby debris disk systems with high fractional luminosity reconsidered
• HST/NICMOS detection of HR 8799 b in 1998
• A comprehensive examination of the Eps Eri system -- Verification of a 4 micron narrow-band high-contrast imaging approach for planet searches
• Thermal Infrared Constraint to a Planetary Companion of Vega with the MMT Adaptive Optics System
• NACO-SDI direct imaging search for the exoplanet Eps Eri b
• The very nearby M/T dwarf binary SCR 1845-6357
• A direct and differential imaging search for sub-stellar companions to epsilon Indi A

Cited by in corpus (16)

• Stellar and substellar companions of nearby stars from Gaia DR2 - Binarity from proper motion anomaly
• Imaging Extrasolar Giant Planets
• Testing a Predictive Theoretical Model for the Mass Loss Rates of Cool Stars
• Spatially resolved spectroscopy of the exoplanet HR 8799 c
• High-contrast Imaging Search for Planets and Brown Dwarfs around the Most Massive Stars in the Solar Neighborhood
• Discovery of a Highly Unequal-Mass Binary T Dwarf with Keck Laser Guide Star Adaptive Optics: A Coevality Test of Substellar Theoretical Models and Effective Temperatures
• The Star-Planet Connection I: Using Stellar Composition to Observationally Constrain Planetary Mineralogy for the Ten Closest Stars
• The planet search programme at the ESO CES and HARPS. IV. The search for Jupiter analogues around solar-like stars
• Detection of the nearest Jupiter analog in radial velocity and astrometry data
• A temperate super-Jupiter imaged with JWST in the mid-infrared
• Direct Imaging Constraints on the Putative Exoplanet 14 Her c
• High contrast imaging at 10 microns, a search for exoplanets around: Eps Indi A, Eps Eri, Tau Ceti, Sirius A and Sirius B
• A New Method for Target Selection in Direct Imaging Programs with COPAINS
• MagAO Imaging of Long-period Objects (MILO). I. A Benchmark M Dwarf Companion Exciting a Massive Planet around the Sun-like Star HD 7449
• Piercing the Glare: Direct Imaging Search for Planets in the Sirius System
• Constraints on the nearby exoplanet $\epsilon$ Ind Ab from deep near/mid-infrared imaging limits