Eric L. Nielsen

THE GEMINI/NICI PLANET-FINDING CAMPAIGN: THE FREQUENCY OF PLANETS AROUND YOUNG MOVING GROUP STARS ∗

We report results of a direct imaging survey for giant planets around 80 members of the ? Pic, TW Hya, Tucana-Horologium, AB Dor, and Hercules-Lyra moving groups, observed as part of the Gemini/NICI Planet-Finding Campaign. For this sample, we obtained median contrasts of ?H = 13.9 mag at 1 in combined CH4 narrowband ADI+SDI mode and median contrasts of ?H = 15.1 mag at 2 in H-band ADI mode. We found numerous (>70) candidate companions in our survey images. Some of these candidates were rejected as common-proper motion companions using archival data; we reobserved with Near-Infrared Coronagraphic Imager (NICI) all other candidates that lay within 400?AU of the star and were not in dense stellar fields. The vast majority of candidate companions were confirmed as background objects from archival observations and/or dedicated NICI Campaign followup. Four co-moving companions of brown dwarf or stellar mass were discovered in this moving group sample: PZ Tel B (36 ? 6 M Jup, 16.4 ? 1.0?AU), CD?35 2722B (31 ? 8 M Jup, 67 ? 4?AU), HD?12894B (0.46?? 0.08 M ?, 15.7 ? 1.0?AU), and BD+07 1919C (0.20 ? 0.03 M ?, 12.5 ? 1.4?AU). From a Bayesian analysis of the achieved H band ADI and ASDI contrasts, using power-law models of planet distributions and hot-start evolutionary models, we restrict the frequency of 1-20 M Jup companions at semi-major axes from 10-150?AU to <18% at a 95.4% confidence level using DUSTY models and to <6% at a 95.4% using COND models. Our results strongly constrain the frequency of planets within semi-major axes of 50?AU as well. We restrict the frequency of 1-20 M Jup companions at semi-major axes from 10-50?AU to <21% at a 95.4% confidence level using DUSTY models and to <7% at a 95.4% using COND models. This survey is the deepest search to date for giant planets around young moving group stars.

THE GEMINI NICI PLANET-FINDING CAMPAIGN: THE FREQUENCY OF GIANT PLANETS AROUND YOUNG B AND A STARS

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 high-mass stars (1.5-2.5 M ☉) conducted to date and includes the planet hosts β Pic and Fomalhaut. We obtained follow-up astrometry of all candidate companions within 400xa0AU projected separation for stars in uncrowded fields and identified new low-mass companions to HDxa01160 and HIPxa079797. We have found that the previously known young brown dwarf companion to HIPxa079797 is itself a tight (3xa0AU) binary, composed of brown dwarfs with masses 58 M Jup and 55 M Jup, making this system one of the rare substellar binaries in orbit around a star. Considering the contrast limits of our NICI data and the fact that we did not detect any planets, we use high-fidelity Monte Carlo simulations to show that fewer than 20% of 2 M ☉ stars can have giant planets greater than 4 M Jup between 59 and 460xa0AU at 95% confidence, and fewer than 10% of these stars can have a planet more massive than 10 M Jup between 38 and 650xa0AU. Overall, we find that large-separation giant planets are not common around B and A stars: fewer than 10% of B and A stars can have an analog to the HRxa08799 b (7 M Jup, 68xa0AU) planet at 95% confidence. We also describe a new Bayesian technique for determining the ages of field B and A stars from photometry and theoretical isochrones. Our method produces more plausible ages for high-mass stars than previous age-dating techniques, which tend to underestimate stellar ages and their uncertainties.

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

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 5MJup planet beyond 80 AU, and 3MJup planet outside of 40 AU, based on hot-start evolutionary models. We model the population of directly-imaged planets as d^2N/dMda ~ m^alpha a^beta, where m is planet mass and a is orbital semi-major axis (with a maximum value of amax). We find that beta 1.7. Likewise, we find that beta 3MJup planet beyond 10 AU, and beta 40 AU and planet masses > 3 MJup do not carve the central holes in these disks.

MAGELLAN ADAPTIVE OPTICS FIRST-LIGHT OBSERVATIONS OF THE EXOPLANET β PIC b. I. DIRECT IMAGING IN THE FAR-RED OPTICAL WITH MagAO+VisAO AND IN THE NEAR-IR WITH NICI* , **

We present the first ground-based CCD (

The Gemini NICI Planet-Finding Campaign: Discovery of a Multiple System Orbiting the Young A Star HD?1160

lambda < 1mu

THE GEMINI NICI PLANET-FINDING CAMPAIGN: THE COMPANION DETECTION PIPELINE*

m) image of an extrasolar planet. Using MagAOs VisAO camera we detected the extrasolar giant planet (EGP)

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

beta

The Gemini NICI Planet-Finding Campaign: The Offset Ring of HR 4796 A

Pictoris b in

Improving signal-to-noise in the direct imaging of exoplanets and circumstellar disks with MLOCI

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Astrometric Calibration of the Gemini NICI Planet-Finding Campaign

-short (