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Title: STABLE AND UNSTABLE REGIMES OF MASS ACCRETION ONTO RW AUR A

We present monitoring observations of the active T Tauri star RW Aur, from 2010 October to 2015 January, using optical high-resolution (R ≥ 10,000) spectroscopy with Canada–France–Hawaii Telescope/ESPaDOnS. Optical photometry in the literature shows bright, stable fluxes over most of this period, with lower fluxes (by 2–3 mag) in 2010 and 2014. In the bright period our spectra show clear photospheric absorption, complicated variation in the Ca ii λ8542 emission profile shapes, and a large variation in redshifted absorption in the O i λλ7772 and 8446 and He i λ5876 lines, suggesting unstable mass accretion during this period. In contrast, these line profiles are relatively uniform during the faint periods, suggesting stable mass accretion. During the faint periods, the photospheric absorption lines are absent or marginal, and the averaged Li i profile shows redshifted absorption due to an inflow. We discuss (1) occultation by circumstellar material or a companion and (2) changes in the activity of mass accretion to explain the above results, together with near-infrared and X-ray observations from 2011 to 2015. Neither scenario can simply explain all the observed trends, and more theoretical work is needed to further investigate their feasibilities.
Authors:
; ; ; ;  [1] ;  [2] ;  [3] ;  [4] ;  [5] ;  [6] ;  [7] ;  [8] ;  [9] ;  [10]
  1. Institute of Astronomy and Astrophysics, Academia Sinica, 11F of Astronomy-Mathematics Building, AS/NTU, No.1, Sec. 4, Roosevelt Rd., Taipei 10617, Taiwan, R.O.C. (China)
  2. Space Telescope Science Institute, 3700 San Martin Dr., Baltimore, MD 21218 (United States)
  3. Canada–France–Hawaii Telescope, 65-1238 Mamalahoa Hwy., Kamuela, HI 96743 (United States)
  4. Institute of Astronomy, National Central University, Taiwan 320, Taiwan (China)
  5. Max-Planck-Institut für Radioastronomie, Auf dem Hügel 69, D-53121 Bonn (Germany)
  6. National Astronomical Observatory of Japan, 2-21-1 Osawa, Mitaka, Tokyo 181-8588 (Japan)
  7. Research School of Astronomy and Astrophysics, The Australian National University, Cotter Rd., Weston, ACT 2611 (Australia)
  8. Centro de Radioastronomía y Astrofísica, UNAM, Apdo. Postal 3-72 (Xangari), 58089 Morelia, Michoacán, México (Mexico)
  9. Subaru Telescope, 650 North Aohoku Place, Hilo, HI 96720 (United States)
  10. UPS-Toulouse/CNRS-INSU, Institut de Recherche en Astrophysique et Plańetologie (IRAP) UMR 5277, Toulouse F-31400 (France)
Publication Date:
OSTI Identifier:
22518538
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal; Journal Volume: 820; Journal Issue: 2; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; ABSORPTION; ACCRETION DISKS; CALCIUM; ECLIPSE; EMISSION; HELIUM; LITHIUM; MASS; MONITORING; OXYGEN; PHOTOMETRY; RED SHIFT; RESOLUTION; STAR ACCRETION; T TAURI STARS; TELESCOPES; X RADIATION