DISK BRAKING IN YOUNG STARS: PROBING ROTATION IN CHAMAELEON I AND TAURUS-AURIGA

Duy Cuong Nguyen*, Ray Jayawardhana, Marten H. van Kerkwijk, Alexis Brandeker, Alexander Scholz, Ivana Damjanov

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

41 Citations (Scopus)

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 languageEnglish
Pages (from-to)1648-1656
Number of pages9
JournalAstrophysical Journal
Volume695
Issue number2
DOIs
Publication statusPublished - 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

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