Abstract
We present a comprehensive study of rotation, disk, and accretion signatures for 144 T Tauri stars in the young (similar to 2 Myr old) Chamaeleon I and Taurus-Auriga star-forming regions based on multi-epoch high-resolution optical spectra from the Magellan Clay 6.5 m telescope supplemented by mid-infrared photometry from the Spitzer Space Telescope. In contrast to previous studies in the Orion Nebula Cluster and NGC 2264, we do not see a clear signature of disk braking in Tau-Aur and Cha I. We find that both accretors and non-accretors have similar distributions of v sin i. This result could be due to different initial conditions, insufficient time for disk braking, or a significant age spread within the regions. The rotational velocities in both regions show a clear mass dependence, with F-K stars rotating on average about twice as fast as M stars, consistent with results reported for other clusters of similar age. Similarly, we find the upper envelope of the observed values of specific angular momentum j varies as M(0.5) for our sample which spans a mass range of similar to 0.16-3 M(circle dot). This power law complements previous studies in Orion which estimated j proportional to M(0.25) for less than or similar to 2 Myr stars in the same mass regime, and a sharp decline in j with decreasing mass for older stars (similar to 10 Myr) with M <2 M(circle dot). Furthermore, the overall specific angular momentum of this similar to 10 Myr population is five times lower than that of non-accretors in our sample, and implies a stellar braking mechanism other than disk braking could be at work. For a subsample of 67 objects with mid-infrared photometry, we examine the connection between accretion signatures and dusty disks: in the vast majority of cases (63/67), the two properties correlate well, which suggests that the timescale of gas accretion is similar to the lifetime of inner disks.
Original language | English |
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Pages (from-to) | 1648-1656 |
Number of pages | 9 |
Journal | Astrophysical Journal |
Volume | 695 |
Issue number | 2 |
DOIs | |
Publication status | Published - 20 Apr 2009 |
Keywords
- MAIN-SEQUENCE STARS
- stars: evolution
- ORION NEBULA CLUSTER
- stars: formation
- stars: pre-main sequence
- STELLAR ROTATION
- SPITZER OBSERVATIONS
- EMISSION-LINE DIAGNOSTICS
- stars: statistics
- LOW-MASS STARS
- ANGULAR-MOMENTUM EVOLUTION
- accretion, accretion disks
- BROWN DWARFS
- MAGNETOSPHERIC ACCRETION
- REGULATION PARADIGM
- circumstellar matter
- stars: rotation