The HOSTS Survey—Exozodiacal Dust Measurements for 30 Stars

Journal
Date Issued
2018
Author(s)
Ertel, S.
•
Defrère, D.
•
Hinz, P.
•
Mennesson, B.
•
Kennedy, G. M.
•
Danchi, W. C.
•
Gelino, C.
•
Hill, J. M.
•
Hoffmann, W. F.
•
Rieke, G.
•
Shannon, A.
•
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.
•
•
Gaspar, A.
•
Grenz, P.
•
Haniff, C. A.
•
Leisenring, J. M.
•
Marion, L.
•
McMahon, T. J.
•
Millan-Gabet, R.
•
Montoya, M.
•
Morzinski, K. M.
•
•
Power, J.
•
•
Roberge, A.
•
Serabyn, E.
•
Skemer, A. J.
•
Stapelfeldt, K.
•
Su, K. Y. L.
•
Vaitheeswaran, V.
•
Wyatt, M. C.
DOI
Abstract
The Hunt for Observable Signatures of Terrestrial Systems survey searches for dust near the habitable zones (HZs) around nearby, bright main-sequence stars. We use nulling interferometry in the N band to suppress the bright stellar light and to probe for low levels of HZ dust around the 30 stars observed so far. Our overall detection rate is 18%, including four new detections, among which are the first three around Sun-like stars and the first two around stars without any previously known circumstellar dust. The inferred occurrence rates are comparable for early-type and Sun-like stars, but decrease from {60}-21+16% for stars with previously detected cold dust to {8}-3+10% for stars without such excess, confirming earlier results at higher sensitivity. For completed observations on individual stars, our sensitivity is five to ten times better than previous results. Assuming a lognormal excess luminosity function, we put upper limits on the median HZ dust level of 13 zodis (95% confidence) for a sample of stars without cold dust and of 26 zodis when focusing on Sun-like stars without cold dust. However, our data suggest that a more complex luminosity function may be more appropriate. For stars without detectable Large Binocular Telescope Interferometer (LBTI) excess, our upper limits are almost reduced by a factor of two, demonstrating the strength of LBTI target vetting for future exo-Earth imaging missions. Our statistics are limited so far, and extending the survey is critical to informing the design of future exo-Earth imaging surveys.
Volume
155
Issue
5
Start page
194
Uri
Url
Issn Identifier
0004-6256
Ads BibCode
2018AJ....155..194E
Rights
open.access
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