The HOSTS Survey for Exozodiacal Dust: Observational Results from the Complete Survey
Steve Ertel, Denis Defrère, Philip M. Hinz, Bertrand Mennesson, Grant M. Kennedy, W. C. Danchi, Christopher R. Gelino, John M. Hill, W. F. Hoffmann, Johan Mazoyer, G. H. Rieke, Andrew Shannon, Karl R. Stapelfeldt, Eckhart Spalding, Jordan Stone, A. Vaz, Alycia J. Weinberger, P. A. Willems, Olivier Absil, P. Arbo, Vanessa P. Bailey, Charles Beichman, G. Bryden, E. Downey, Olivier Durney, Simone Esposito, Andras Gáspár, Paul Grenz, C. Haniff, Jarron Leisenring, Lindsay Marion, Thomas J. McMahon, R. Millan‐Gabet, M. Montoya, Katie M. Morzinski, Saavidra Perera, Enrico Pinna, Jörg‐Uwe Pott, J. Power, Alfio Puglisi, Aki Roberge, Eugene Serabyn, Andrew Skemer, K. Y. L. Su, Vidhya Vaitheeswaran, M. C. Wyatt
Abstract
Abstract The Large Binocular Telescope Interferometer (LBTI) enables nulling interferometric observations across the N band (8 to 13 μ m) to suppress a star’s bright light and probe for faint circumstellar emission. We present and statistically analyze the results from the LBTI/Hunt for Observable Signatures of Terrestrial Systems survey for exozodiacal dust. By comparing our measurements to model predictions based on the solar zodiacal dust in the N band, we estimate a 1 σ median sensitivity of 23 zodis times the solar system dust surface density in its habitable zone (HZ; 23 zodis) for early-type stars and 48 zodis for Sun-like stars, where 1 zodi is the surface density of HZ dust in the solar system. Of the 38 stars observed, 10 show significant excess. A clear correlation of our detections with the presence of cold dust in the systems was found, but none with the stellar spectral type or age. The majority of Sun-like stars have relatively low HZ dust levels (best-fit median: 3 zodis, 1 σ upper limit: 9 zodis, 95% confidence: 27 zodis based on our N band measurements), while ∼20% are significantly more dusty. The solar system’s HZ dust content is consistent with being typical. Our median HZ dust level would not be a major limitation to the direct imaging search for Earth-like exoplanets, but more precise constraints are still required, in particular to evaluate the impact of exozodiacal dust for the spectroscopic characterization of imaged exo-Earth candidates.