A SPITZER MIPS STUDY OF 2.5-2.0 M-circle dot STARS IN SCORPIUS-CENTAURUS

作者：Chen Christine H^*; Pecaut Mark; Mamajek Eric E; Su Kate Y L; Bitner Martin

来源：Astrophysical Journal, 2012, 756(2): 133.

DOI：10.1088/0004-637X/756/2/133

• circumstellar matter
• infrared: planetary systems
• infrared: stars
• open clusters and associations: individual (Upper Scorpius, Lower Centaurus Crux, Upper Centaurus-)
• planetary systems
• planets and satellites: formation

We have obtained Spitzer Space Telescope Multiband Imaging Photometer for Spitzer (MIPS) 24 mu m and 70 mu m observations of 215 nearby, Hipparcos B- and A-type common proper-motion single and binary systems in the nearest OB association, Scorpius-Centaurus. Combining our MIPS observations with those of other ScoCen stars in the literature, we estimate 24 mu m B+A-type disk fractions of 17/67 (25(5)(+6)%), 36/131 (27(-4)(+4)%), and 23/95 (24(-4)(+5)%) for Upper Scorpius (similar to 11 Myr), Upper Centaurus Lupus (similar to 15 Myr), and Lower Centaurus Crux (similar to 17 Myr), respectively, somewhat smaller disk fractions than previously obtained for F- and G-type members. We confirm previous IRAS excess detections and present new discoveries of 51 protoplanetary and debris disk systems, with fractional infrared luminosities ranging from L-IR/L-* = 10(-6) to 10(-2) and grain temperatures ranging from T-gr = 40 to 300 K. In addition, we confirm that the 24 mu m and 70 mu m excesses (or fractional infrared luminosities) around B+A-type stars are smaller than those measured toward F+G-type stars and hypothesize that the observed disk property dependence on stellar mass may be the result of a higher stellar companion fraction around B- and A-type stars at 10-200 AU. Finally, we note that the majority of the ScoCen 24 mu m excess sources also possess 12 mu m excess, indicating that Earth-like planets may be forming via collisions in the terrestrial planet zone at similar to 10-100 Myr.

• 出版日期2012-9-10