Disk Braking in young Stars: Probing Rotation in Chamaeleon i and Taurus-Auriga
2009 (English)In: Astrophysical Journal, ISSN 0004-637X, E-ISSN 1538-4357, Vol. 695, 1648-1656 p.Article in journal (Refereed) Published
We present a comprehensive study of rotation, disk, and accretion signatures for 144 T Tauri stars in the young (~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 vsin 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 ~0.16-3 M sun. This power law complements previous studies in Orion which estimated j vprop M 0.25 for lsim2 Myr stars in the same mass regime, and a sharp decline in j with decreasing mass for older stars (~10 Myr) with M < 2 M sun. Furthermore, the overall specific angular momentum of this ~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.
Place, publisher, year, edition, pages
2009. Vol. 695, 1648-1656 p.
accretion, accretion disks, circumstellar matter, stars: evolution, stars: formation, stars: pre-main sequence, stars: rotation, stars: statistics
Research subject Astronomy
IdentifiersURN: urn:nbn:se:su:diva-35865DOI: 10.1088/0004-637X/695/2/1648/ISI: 000265018300078ISBN: 0004-637XOAI: oai:DiVA.org:su-35865DiVA: diva2:288208