THE GEMINI PLANET-FINDING CAMPAIGN: THE FREQUENCY OF GIANT PLANETS AROUND DEBRIS DISK STARS

Journal Article · Tue Aug 20 00:00:00 EDT 2013 · Astrophysical Journal

DOI:https://doi.org/10.1088/0004-637X/773/2/179· OSTI ID:22130949

Wahhaj, Zahed ^[1]; Liu, Michael C.; Nielsen, Eric L.; Ftaclas, Christ; Chun, Mark ^[2]; Biller, Beth A. ^[3]; Hayward, Thomas L. ^[4]; Close, Laird M.; Males, Jared R.; Skemer, Andrew ^[5]; Thatte, Niranjan; Tecza, Matthias ^[6]; Shkolnik, Evgenya L. ^[7]; Kuchner, Marc ^[8]; Reid, I. Neill ^[9]; Gregorio-Hetem, Jane ^[10]; Alencar, Silvia H. P. ^[11]; Boss, Alan ^[12]; Lin, Douglas N. C. ^[13]; others, and

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1. European Southern Observatory, Alonso de Cordova 3107, Vitacura, Casilla 19001, Santiago (Chile)
2. Institute for Astronomy, University of Hawaii, 2680 Woodlawn Drive, Honolulu, HI 96822 (United States)
3. Max-Planck-Institut fuer Astronomie, Koenigstuhl 17, D-69117 Heidelberg (Germany)
4. Gemini Observatory, Southern Operations Center, c/o AURA, Casilla 603, La Serena (Chile)
5. Steward Observatory, University of Arizona, 933 North Cherry Avenue, Tucson, AZ 85721 (United States)
6. Department of Astronomy, University of Oxford, DWB, Keble Road, Oxford OX1 3RH (United Kingdom)
7. Lowell Observatory, 1400 West Mars Hill Road, Flagstaff, AZ 86001 (United States)
8. NASA Goddard Space Flight Center, Exoplanets and Stellar Astrophysics Laboratory, Greenbelt, MD 20771 (United States)
9. Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218 (United States)
10. Departamento de Astronomia, Universidade de Sao Paulo, IAG/USP, Rua do Matao 1226, 05508-900 Sao Paulo, SP (Brazil)
11. Departamento de Fisica-ICEx-UFMG, Av. Antonio Carlos 6627, 30270-901 Belo Horizonte, MG (Brazil)
12. Department of Terrestrial Magnetism, Carnegie Institution of Washington, 5241 Broad Branch Road, NW, Washington, DC 20015 (United States)
13. Department of Astronomy and Astrophysics, University of California, Santa Cruz, CA (United States)

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 {beta} Pictoris and the HR 8799 planets. Our results show at 95% confidence that <13% of debris disk stars have a {>=}5 M{sub Jup} planet beyond 80 AU, and <21% of debris disk stars have a {>=}3 M{sub Jup} planet outside of 40 AU, based on hot-start evolutionary models. We model the population of directly imaged planets as d {sup 2} N/dMda{proportional_to}m {sup {alpha}} a {sup {beta}}, where m is planet mass and a is orbital semi-major axis (with a maximum value of a{sub max}). We find that {beta} < -0.8 and/or {alpha} > 1.7. Likewise, we find that {beta} < -0.8 and/or a{sub max} < 200 AU. For the case where the planet frequency rises sharply with mass ({alpha} > 1.7), this occurs because all the planets detected to date have masses above 5 M{sub Jup}, but planets of lower mass could easily have been detected by our search. If we ignore the {beta} 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{sub Jup} planet beyond 10 AU, and {beta} < -0.8 and/or {alpha} < -1.5. Likewise, {beta} < -0.8 and/or a{sub 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{sub Jup} do not carve the central holes in these disks.

• OSTI ID: 22130949
• Journal Information: Astrophysical Journal, Vol. 773, Issue 2; Other Information: Country of input: International Atomic Energy Agency (IAEA); ISSN 0004-637X
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTROPHYSICS
COSMOLOGY AND ASTRONOMY
LIMITING VALUES
MASS
PLANETS
STARS