The Gemini/Nici Planet-Finding Campaign: The Frequency of Planets Around Young Moving Group Stars

Abstract

We report results of a direct imaging survey for giant planets around 80 members of the β 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 CH 4 narrowband ADI+SDI 0 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 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 comoving 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, Biller et al. 2010) , CD -35 2722B (31±8 M Jup , 67±4 AU, Wahhaj et al. 2011), 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 VLT/NaCo large program to probe the occurrence of exoplanets and brown dwarfs in wide orbits

“…For HD 61005, we adopt membership in Argus (40 Myr) while Wahhaj et al (2013) adopt an age of 100 Myr without assigning membership to any known group. Finally, HIP 71908 is included in the Her-Lyr membership in Biller et al (2013), while we claim it is a significantly older star with similar kinematics. While we are convinced of our adopted choices, this comparison is a further indication of the challenges represented by the age determination of young stars.…”

“…However, some of them were included independently in NICI imaging surveys Biller et al 2013). For the seven stars in common, we obtained identical ages for one member of AB Dor MG (HIP 14684) and one of HerLyr (HD 139664).…”

Performance of the VLT Planet Finder SPHERE

“…The main objectives of these surveys were to populate the mass vs. semi-major axis diagram at large separations, and to clarify the mechanisms of planetary formation. Among the most recent of these surveys we can cite the NACO-Large Program at the Very Large Telescope (Desidera et al 2014;Chauvin et al 2014), the Strategic Exploration of Exoplanets and Disk with Subaru (SEEDS) at the Subaru Telescope (Janson et al 2013;Brandt et al 2014), the Near-Infrared Coronagraphic Imager (NICI) campaign at the Gemini South Telescope (Nielsen et al 2013;Biller et al 2013), the International Deep Planet Survey (Vigan et al 2012) at the Very Large Telescope (VLT) and Gemini North, and a survey of young, nearby, and dusty stars to understand the formation of wide-orbit giant planets (Rameau et al 2013b) at VLT.…”

49 new T dwarfs identified using methane imaging

“…Methane imaging has already proved a valuable technique for detecting T dwarfs. It has been used in the search for T dwarfs in star forming regions (e.g., Burgess et al 2009;Parker & Tinney 2013), in the field (e.g., Tinney et al 2005) and in search of planetary companions (e.g., Biller et al 2013). In this work we describe our use of methane filters to perform a spectral classification of T dwarfs selected from the UKIDSS Large Area Survey (LAS).…”