A MAGELLAN MIKE AND SPITZER MIPS STUDY OF 1.5-1.0 M⊙ STARS IN SCORPIUS-CENTAURUS

We obtained Spitzer Space Telescope Multiband Imaging Photometer for Spitzer (MIPS) 24 mu m and 70 mu m observations of 182 nearby, Hipparcos F-and G-type common proper motion single and binary systems in the nearest OB association, Scorpius-Centaurus. We also obtained Magellan/MIKE R similar to 50,000 visual spectra at 3500-10500 angstrom for 181 candidate ScoCen stars in single and binary systems. Combining our MIPS observations with those of other ScoCen stars in the literature, we estimate 24 mu mF+G-type disk fractions of 9/27 (33% +/- 11%), 21/67 (31% +/- 7%), and 25/71 (35% +/- 7%) for Upper Scorpius (similar to 10 Myr), Upper Centaurus Lupus (similar to 15 Myr), and Lower Centaurus Crux (similar to 17 Myr), respectively. We confirm previous IRAS and MIPS excess detections and present new discoveries of 41 protoplanetary and debris disk systems, with fractional infrared luminosities ranging from L-IR/L-* = 10(-5) to 10(-2) and grain temperatures ranging from T-gr = 40-300 K. We searched for an increase in 24 mu m excess at an age of 15-20 Myr, consistent with the onset of debris production predicted by coagulation N-body simulations of outer planetary systems. We found such an increase around 1.5M(circle dot) stars but discovered a decrease in the 24 mu m excess around 1.0 M-circle dot stars. We additionally discovered that the 24 mu m excess around 1.0 M-circle dot stars is larger than predicted by self-stirred models. Finally, we found a weak anti-correlation between fractional infrared luminosity (L-IR/L-*) and chromospheric activity (R'(HK)), that may be the result of differences in stellar properties, such as mass, luminosity, and/or winds.