The Gemini NICI planet-finding campaign: the orbit of the young exoplanet β Pictoris b

Journal Article · Mon Oct 20 00:00:00 EDT 2014 · Astrophysical Journal

DOI:https://doi.org/10.1088/0004-637X/794/2/158· OSTI ID:22370362

Nielsen, Eric L.; Liu, Michael C.; Chun, Mark; Ftaclas, Christ ^[1]; Wahhaj, Zahed ^[2]; Biller, Beth A. ^[3]; Hayward, Thomas L. ^[4]; Males, Jared R.; Close, Laird M.; Morzinski, Katie M.; Skemer, Andrew J.; Hinz, Philip M. ^[5]; Kuchner, Marc J. ^[6]; Rodigas, Timothy J. ^[7]; Toomey, Douglas W. ^[8]

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1. Institute for Astronomy, University of Hawaii, 2680 Woodlawn Drive, Honolulu, HI 96822 (United States)
2. European Southern Observatory, Alonso de Cordova 3107, Vitacura, Casilla 19001, Santiago (Chile)
3. Institute for Astronomy, The University of Edinburgh, Royal Observatory, Blackford Hill, Edinburgh EH9 3HJ (United Kingdom)
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. Goddard Space Flight Center, Code 667, Greenbelt, MD 20771 (United States)
7. Department of Terrestrial Magnetism, Carnegie Institute of Washington, 5241 Broad Branch Road, NW, Washington, DC 20015 (United States)
8. Mauna Kea Infrared, LLC, 21 Pookela Street, Hilo, HI 96720 (United States)

We present new astrometry for the young (12-21 Myr) exoplanet β Pictoris b taken with the Gemini/NICI and Magellan/MagAO instruments between 2009 and 2012. The high dynamic range of our observations allows us to measure the relative position of β Pic b with respect to its primary star with greater accuracy than previous observations. Based on a Markov Chain Monte Carlo analysis, we find the planet has an orbital semi-major axis of 9.1{sub −0.5}{sup +5.3} AU and orbital eccentricity <0.15 at 68% confidence (with 95% confidence intervals of 8.2-48 AU and 0.00-0.82 for semi-major axis and eccentricity, respectively, due to a long narrow degenerate tail between the two). We find that the planet has reached its maximum projected elongation, enabling higher precision determination of the orbital parameters than previously possible, and that the planet's projected separation is currently decreasing. With unsaturated data of the entire β Pic system (primary star, planet, and disk) obtained thanks to NICI's semi-transparent focal plane mask, we are able to tightly constrain the relative orientation of the circumstellar components. We find the orbital plane of the planet lies between the inner and outer disks: the position angle (P.A.) of nodes for the planet's orbit (211.8 ± 0.°3) is 7.4σ greater than the P.A. of the spine of the outer disk and 3.2σ less than the warped inner disk P.A., indicating the disk is not collisionally relaxed. Finally, for the first time we are able to dynamically constrain the mass of the primary star β Pic to 1.76{sub −0.17}{sup +0.18} M {sub ☉}.

• OSTI ID: 22370362
• Journal Information: Astrophysical Journal, Vol. 794, 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
ACCURACY
DETECTION
ELONGATION
INTERACTIONS
MARKOV PROCESS
MASS
MONTE CARLO METHOD
ORBITS
PLANETS
SATELLITES
STARS
VERTEBRAE