Disk Census in the Star-forming Regions of the Orion OB Associations
First Author:
Jesus Hernandez
Email: hernandj AT umich.edu
U. Michigan
500 Church Street, 830 Dennison Building
Ann Arbor, Mi-48109
Coauthors:
Calvet, Nuria,
Hartmann, Lee,
Briceno, Cesar,
Vivas, Katherine,
Muzerolle, James,
Gutermuth, Rob,
Megeath, Tom,
Jeffries, Rob,
Stauffer, John,
Allen, Lori,
Abstract
Combining optical/2MASS data with IRAC/MIPS photometry, we are carrying out a systematic study to identify and characterize disk populations in star-forming regions of the Orion OB associations, including the sigma Orionis cluster, the lambda Orionis cluster, a subregion of the OB1b sub-association, and the 25 Orionis stellar aggregate in Ori OB1a, which range in age from ~3 to ~10 Myr. Our samples are optimal for studying disk evolution; for one thing, observations and theoretical studies indicate that key process in the evolution of protoplanetary disks take place in the 3-10 Myrage range. In addition, the samples are relatively near (<500 pc), allowing us to probe a wide range of stellar masses, from intermediate masses down to the substellar regime. Finally, these populations most likely share a common origin from the same giant molecular cloud, minimizing evolutionary effects due to differences in initial environments. In this comparative study we address issues as the mass-dependence and age-dependence of the frequency of primordial disks. We also quantify the decrease of near infrared emission and the clearing of the inner regions of primordial disks with age, and how these interrelate to the appearance of the debris disk phenomena. We compare our observation with predictions of detailed models of primordial and debris disks, to identify the main agents guiding the evolution and the transition from primordial to debris dust.
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