Protostars and Planets VI, Heidelberg, July 15-20, 2013
Magnetically Active Stars in Taurus-Auriga
Grankin, Konstantin (Crimean Astrophysical Observatory)
A sample of 70 magnetically active stars toward the Taurus-Auriga star-forming region (Tau-Aur SFR) has been investigated. Based on accurate data on their basic physical parameters obtained from original photometric observations and published data, we have refined the evolutionary status of these objects. We show that 50 objects are young stars with ages of 1-40 Myr and belong to the Tau-Aur SFR. Other 20 objects have a controversial evolutionary status and can belong to both Tau-Aur SFR and the Gould Belt. We have analyzed the relationship between the rotation period, mass, and age for 50 magnetically active stars. The change in the angular momentum of the sample stars within the first 40 Myr of their evolution has been investigated. An active star-protoplanetary disk interaction is shown to occur on a time scale from 0.7 to 10Myr. The positions of the sample stars on the Rossby diagram have been analyzed. All stars are shown to be in the regime of a saturated dynamo, where the X-ray luminosity reaches its maximum and does not depend on the Rossby number. A correlation has been found between the lithium line equivalent width and the age of a solar-mass (from 0.7 to 1.2 Msun) pre-main-sequence star. The older the age, the smaller the Li line equivalent width. Analysis of the long-term photometric variability of these stars has shown that the photometric activity of the youngest stars is appreciably higher than that of the older objects from the sample. This result can be an indirect confirmation of the evolution of the magnetic field in premain-sequence stars from redominantly dipole and axisymmetric to multipole and nonaxisymmetric.
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