2008/09/19 by Hao Yang, Christopher M. Johns-Krull, Jeff A. Valenti
Physics and Astronomy · #Astrophysics and Star Formation Studies #Solar and Space Plasma Dynamics #Stellar, planetary, and galactic studies #astro-ph
paper · pdf · doi:10.1088/0004-6256/136/6/2286
34 pages, 7 figures. Accepted by the Astronomical Journal on Sept. 11, 2008
arxiv created 2008/09/19 · openalex publication_date 2008/11/04 · arxiv updated 2009/12/01 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/01
We present an analysis of infrared echelle spectra of five stars in the TW Hydrae Association (TWA). We model the Zeeman broadening in four magnetic-sensitive Ti i lines near 2.2 μm and measure the value of the photospheric magnetic field averaged over the surface of each star. To ensure that other broadening mechanisms are properly taken into account, we also inspect several magnetically insensitive CO lines near 2.3 μm and find no excess broadening above that produced by stellar rotation and instrumental broadening, providing confidence in the magnetic interpretation of the width of the Ti i lines. We then utilize our results to test the relationship between stellar magnetic flux and X-ray properties and compare the measured fields with equipartition field values. Finally, we use our results and recent results on a large sample of stars in Taurus to discuss the potential evolution of magnetic field properties between the age of Taurus (∼2 Myr) and the age of TWA (∼10 Myr). We find that the average stellar field strength increases with age; however, the total unsigned magnetic flux decreases as the stars contract onto the main sequence.