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Title: CSI 2264: characterizing accretion-burst dominated light curves for young stars in NGC 2264

Based on more than four weeks of continuous high-cadence photometric monitoring of several hundred members of the young cluster NGC 2264 with two space telescopes, NASA's Spitzer and the CNES CoRoT (Convection, Rotation, and planetary Transits), we provide high-quality, multi-wavelength light curves for young stellar objects whose optical variability is dominated by short-duration flux bursts, which we infer are due to enhanced mass accretion rates. These light curves show many brief—several hours to one day—brightenings at optical and near-infrared wavelengths with amplitudes generally in the range of 5%-50% of the quiescent value. Typically, a dozen or more of these bursts occur in a 30 day period. We demonstrate that stars exhibiting this type of variability have large ultraviolet (UV) excesses and dominate the portion of the u – g versus g – r color-color diagram with the largest UV excesses. These stars also have large Hα equivalent widths, and either centrally peaked, lumpy Hα emission profiles or profiles with blueshifted absorption dips associated with disk or stellar winds. Light curves of this type have been predicted for stars whose accretion is dominated by Rayleigh-Taylor instabilities at the boundary between their magnetosphere and inner circumstellar disk, or where magneto-rotational instabilities modulatemore » the accretion rate from the inner disk. Among the stars with the largest UV excesses or largest Hα equivalent widths, light curves with this type of variability greatly outnumber light curves with relatively smooth sinusoidal variations associated with long-lived hot spots. We provide quantitative statistics for the average duration and strength of the accretion bursts and for the fraction of the accretion luminosity associated with these bursts.« less
Authors:
; ; ;  [1] ;  [2] ;  [3] ; ; ;  [4] ; ;  [5] ;  [6] ;  [7] ;  [8] ;  [9] ; ;  [10] ;  [11] ;  [12] ;  [13] more »; « less
  1. Spitzer Science Center, California Institute of Technology, Pasadena, CA 91125 (United States)
  2. LESIA, Observatoire de Paris-Meudon, 5 place Jules Janssen, F-92195, Meudon (France)
  3. Departamento de Física-ICEx-UFMG, Av. Antônio Carlos, 6627, 30270-901, Belo Horizonte, MG (Brazil)
  4. Astronomy Department, California Institute of Technology, Pasadena, CA 91125 (United States)
  5. UJF-Grenoble 1/CNRS-INSU, Institut de Planétologie et d'Astrophysique de Grenoble (IPAG) UMR 5274, Grenoble, F-38041 (France)
  6. Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109 (United States)
  7. Infrared Processing and Analysis Center, California Institute of Technology, Pasadena, CA 91125 (United States)
  8. Department of Physics and Astronomy, 5151 State University Drive, California State University at Los Angeles, Los Angeles, CA 90032 (United States)
  9. Centro de Astrobiología, Dpto. de Astrofísica, INTA-CSIC, P.O. Box 78, E-28691, ESAC Campus, Villanueva de la Cañada, Madrid (Spain)
  10. INAF - Osservatorio Astronomico di Palermo, Piazza del Parlamento 1, I-90134, Palermo (Italy)
  11. Department of Physics and Astronomy, The University of Georgia, Athens, GA 30602-2451 (United States)
  12. Five College Astronomy Department, Smith College, Northampton, MA 01063 (United States)
  13. Department of Astronomy, University of Michigan, 500 Church Street, Ann Arbor, MI 48105 (United States)
Publication Date:
OSTI Identifier:
22340306
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astronomical Journal (New York, N.Y. Online); Journal Volume: 147; Journal Issue: 4; 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; AMPLITUDES; CARBON NITRIDES; COLOR; CONVECTION; EMISSION; LUMINOSITY; MONITORING; RAYLEIGH-TAYLOR INSTABILITY; ROTATION; SPACE; STARS; STELLAR WINDS; TELESCOPES; ULTRAVIOLET RADIATION; VARIATIONS; VISIBLE RADIATION; WAVELENGTHS