A CLOSE COMPANION SEARCH AROUND L DWARFS USING APERTURE MASKING INTERFEROMETRY AND PALOMAR LASER GUIDE STAR ADAPTIVE OPTICS

作者：Bernat David^*; Bouchez Antonin H; Ireland Michael; Tuthill Peter; Martinache Frantz; Angione John; Burruss Rick S; Cromer John L; Dekany Richard G; Guiwits Stephen R; Henning John R; Hickey Jeff; Kibblewhite Edward; McKenna Daniel L; Moore Anna M; Petrie Harold L; Roberts Jennifer; Shelton J Chris; Thicksten Robert P; Trinh Thang; Tripathi Renu; Troy Mitchell; Truong Tuan; Velur Viswa; Lloyd James P

来源：Astrophysical Journal, 2010, 715(2): 724-735.

DOI：10.1088/0004-637X/715/2/724

• binaries: general
• brown dwarfs
• stars: low-mass
• techniques: high angular resolution

We present a close companion search around 16 known early L dwarfs using aperture masking interferometry with Palomar laser guide star adaptive optics (LGS AO). The use of aperture masking allows the detection of close binaries, corresponding to projected physical separations of 0.6-10.0 AU for the targets of our survey. This survey achieved median contrast limits of Delta K similar to 2.3 for separations between 1.2 lambda/D-4 lambda/D and Delta K similar to 1.4 at 23 lambda/D. We present four candidate binaries detected with moderate-to- high confidence (90%-98%). Two have projected physical separations less than 1.5 AU. This may indicate that tight-separation binaries contribute more significantly to the binary fraction than currently assumed, consistent with spectroscopic and photometric overluminosity studies. Ten targets of this survey have previously been observed with the Hubble Space Telescope as part of companion searches. We use the increased resolution of aperture masking to search for close or dim companions that would be obscured by full aperture imaging, finding two candidate binaries. This survey is the first application of aperture masking with LGS AO at Palomar. Several new techniques for the analysis of aperture masking data in the low signal-to-noise regime are explored.

• 出版日期2010-6-1
• 单位中国科学院国家天文台