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          Institute: MPI für Astronomie     Collection: Publikationen_mpia     Display Documents

ID: 693412.0, MPI für Astronomie / Publikationen_mpia
The Gemini Planet-finding Campaign: The frequency of giant planets around debris disk stars
Authors:Wahhaj, Z.; Liu, M. C.; Nielsen, E. L.; Biller, B. A.; Hayward, T. L.; Close, L. M.; Males, J. R.; Skemer, A.; Ftaclas, C.; Chun, M.; Thatte, N.; Tecza, M.; Shkolnik, E. L.; Kuchner, M.; Reid, I. N.; de Gouveia Dal Pino, E. M.; Alencar, S. H. P.; Gregorio-Hetem, J.; Boss, A.; Lin, D. N. C.; Toomey, D. W.
Date of Publication (YYYY-MM-DD):2013
Title of Journal:The Astrophysical Journal
Issue / Number:2
Start Page:id. 179 (30 pp)
Audience:Not Specified
Abstract / Description:We have completed a high-contrast direct imaging survey for giant planets around 57 debris disk stars as part of the Gemini NICI Planet-Finding Campaign. We achieved median H-band contrasts of 12.4 mag at 0.''5 and 14.1 mag at 1'' separation. Follow-up observations of the 66 candidates with projected separation <500 AU show that all of them are background objects. To establish statistical constraints on the underlying giant planet population based on our imaging data, we have developed a new Bayesian formalism that incorporates (1) non-detections, (2) single-epoch candidates, (3) astrometric and (4) photometric information, and (5) the possibility of multiple planets per star to constrain the planet population. Our formalism allows us to include in our analysis the previously known β Pictoris and the HR 8799 planets. Our results show at 95% confidence that <13% of debris disk stars have a >=5 M Jup planet beyond 80 AU, and <21% of debris disk stars have a >=3 M Jup planet outside of 40 AU, based on hot-start evolutionary models. We model the population of directly imaged planets as d 2 N/dMdavpropm α a β, where m is planet mass and a is orbital semi-major axis (with a maximum value of a max). We find that β < -0.8 and/or α > 1.7. Likewise, we find that β < -0.8 and/or a max < 200 AU. For the case where the planet frequency rises sharply with mass (α > 1.7), this occurs because all the planets detected to date have masses above 5 M Jup, but planets of lower mass could easily have been detected by our search. If we ignore the β Pic and HR 8799 planets (should they belong to a rare and distinct group), we find that <20% of debris disk stars have a >=3 M Jup planet beyond 10 AU, and β < -0.8 and/or α < -1.5. Likewise, β < -0.8 and/or a max < 125 AU. Our Bayesian constraints are not strong enough to reveal any dependence of the planet frequency on stellar host mass. Studies of transition disks have suggested that about 20% of stars are undergoing planet formation; our non-detections at large separations show that planets with orbital separation >40 AU and planet masses >3 M Jup do not carve the central holes in these disks. Based on observations obtained at the Gemini Observatory, which is operated by the Association of Universities for Research in Astronomy, Inc., under a cooperative agreement with the NSF on behalf of the Gemini partnership: the National Science Foundation (United States), the Science and Technology Facilities Council (United Kingdom), the National Research Council (Canada), CONICYT (Chile), the Australian Research Council (Australia), Ministério da Ciência e Tecnologia (Brazil) and Ministerio de Ciencia, Tecnología e Innovación Productiva (Argentina).
Free Keywords:brown dwarfs; circumstellar matter; infrared: planetary systems; instrumentation: adaptive optics; methods: statistical; planetary systems
External Publication Status:published
Document Type:Article
Communicated by:N. N.
Affiliations:MPI für Astronomie
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