The HOSTS Survey for Exozodiacal Dust: Observational Results from the Complete Survey

April 2020 • 2020AJ....159..177E

Authors • Ertel, S. • Defrère, D. • Hinz, P. • Mennesson, B. • Kennedy, G. M. • Danchi, W. C. • Gelino, C. • Hill, J. M. • Hoffmann, W. F. • Mazoyer, J. • Rieke, G. • Shannon, A. • Stapelfeldt, K. • Spalding, E. • Stone, J. M. • Vaz, A. • Weinberger, A. J. • Willems, P. • Absil, O. • Arbo, P. • Bailey, V. P. • Beichman, C. • Bryden, G. • Downey, E. C. • Durney, O. • Esposito, S. • Gaspar, A. • Grenz, P. • Haniff, C. A. • Leisenring, J. M. • Marion, L. • McMahon, T. J. • Millan-Gabet, R. • Montoya, M. • Morzinski, K. M. • Perera, S. • Pinna, E. • Pott, J. -U. • Power, J. • Puglisi, A. • Roberge, A. • Serabyn, E. • Skemer, A. J. • Su, K. Y. L. • Vaitheeswaran, V. • Wyatt, M. C.

Abstract • The Large Binocular Telescope Interferometer (LBTI) enables nulling interferometric observations across the N band (8 to 13 μm) 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 1σ 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, 1σ 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.


IPAC Authors

Chris Gelino

Associate Scientist