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تسجيل مستخدم جديدThe Gemini NICI Planet-Finding Campaign: The Orbit of the Young Exoplanet beta Pictoris b
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Eric L. Nielsen
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We present new astrometry for the young (12--21 Myr) exoplanet beta 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 beta 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 (+5.3, -0.5) 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 planets projected separation is currently decreasing. With unsaturated data of the entire beta Pic system (primary star, planet, and disk) obtained thanks to NICIs 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 (PA) of nodes for the planets orbit (211.8 +/- 0.3 degrees) is 7.4 sigma greater than the PA of the spine of the outer disk and 3.2 sigma less than the warped inner disk PA, indicating the disk is not collisionally relaxed. Finally, for the first time we are able to dynamically constrain the mass of the primary star beta Pic to 1.76 (+0.18, -0.17) solar masses.
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Our team is carrying out a multi-year observing program to directly image and characterize young extrasolar planets using the Near-Infrared Coronagraphic Imager (NICI) on the Gemini-South 8.1-meter telescope. NICI is the first instrument on a large t
elescope designed from the outset for high-contrast imaging, comprising a high-performance curvature adaptive optics system with a simultaneous dual-channel coronagraphic imager. Combined with state-of-the-art observing methods and data processing, NICI typically achieves ~2 magnitudes better contrast compared to previous ground-based or space-based programs, at separations inside of ~2 arcsec. In preparation for the Campaign, we carried out efforts to identify previously unrecognized young stars, to rigorously construct our observing strategy, and to optimize the combination of angular and spectral differential imaging. The Planet-Finding Campaign is in its second year, with first-epoch imaging of 174 stars already obtained out of a total sample of 300 stars. We describe the Campaigns goals, design, implementation, performance, and preliminary results. The NICI Campaign represents the largest and most sensitive imaging survey to date for massive (~1 Mjup) planets around other stars. Upon completion, the Campaign will establish the best measurements to date on the properties of young gas-giant planets at ~5-10 AU separations. Finally, Campaign discoveries will be well-suited to long-term orbital monitoring and detailed spectrophotometric followup with next-generation planet-finding instruments.
We have carried out high contrast imaging of 70 young, nearby B and A stars to search for brown dwarf and planetary companions as part of the Gemini NICI Planet-Finding Campaign. Our survey represents the largest, deepest survey for planets around hi
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