NOAO >   Observing Info >   Approved Programs >   2005A-0422

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Proposal Information for 2005A-0422


PI: Christopher M. Johns-Krull, Rice University, cmj@rice.edu
Address: Physics Department, 6100 Main St, MS-108, Houston, Texas 77005, USA

CoI: Catrina M. Hamilton, Mount Holyoke College

Title: Disk-Locking in the Young Cluster NGC 2264

Abstract: Magnetically controlled accretion onto a compact object is a common theme in astrophysics. In the case of young stars, the general model of magnetospheric accretion is firmly entrenched in the literature as the mechanism by which classical T Tauri stars (CTTS) accrete material from their circumstellar disks. Magnetospheric accretion theories make specific predictions relating stellar and accretion parameters; however, little work has been done to test these predictions. Recently, Johns- Krull and Gafford (2002) used existing data to perform such tests, finding that the general predictions of magnetospheric accretion models are not present in the data. Johns-Krull and Gafford proposed a simple extension of one accretion model (Ostriker & Shu 1995), and the data appear to support this revised model. However, the test of this extended model was done with a relatively small sample of stars for which mass accretion rates and stellar rotation rates (and other stellar parameters) are known. Recently, Hartmann (2002) has suggested that the time required for a star and its disk to settle to an equilibrium rotation rate is on the order of ~ 1-2 Myr. Therefore, it is important to test the result of Johns-Krull and Gafford in larger samples of stars, but also in samples at different ages. Here, we will observe the 3 Myr old cluster NGC 2264 where rotation periods have been measured for ~ 400 stars, but which do not have measured mass accretion rates. The data we will obtain with R-C CCD spectrometer on the 4-m Mayall telescope will be used to test the current crop of magnetospheric accretion theories in young stars.


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