학술논문
The HOSTS Survey-Exozodiacal Dust Measurements for 30 Stars
Document Type
Report
Author
Ertel, S; Defrere, 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; 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; Pinna, E; Power, J; Puglisi, A; Roberge, A; Serabyn, E; Skemer, A. J; Stapelfeldt, K; Su, K. Y. L; Vaitheeswaran, V; Wyatt, M. C
Source
Astronomical Journal. 155(5)
Subject
Language
English
ISSN
1538-3881
0004-6256
0004-6256
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(sup +16)(sub -21)% for stars with previously detected cold dust to 8(sup +10)(sub -3)% 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.