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          Institute: MPI für Astronomie     Collection: Publikationen_mpia     Display Documents

ID: 198397.0, MPI für Astronomie / Publikationen_mpia
Natural coronagraphic observations of the
eclipsing T Tauri system KH 15D: Evidence of
accretion and bipolar outflow in a weak-line T
Tauri star
Authors:Hamilton, Catrina M.; Herbst, William; Mundt, Reinhard; Bailer-Jones, Coryn A. L.; Johns-Krull, Christopher M.
Date of Publication (YYYY-MM-DD):2003
Title of Journal:The Astrophysical Journal
Journal Abbrev.:The Astrophysical Journal
Start Page:L45
End Page:L48
Review Status:not specified
Audience:Not Specified
Abstract / Description:We present high-resolution (R~44,000)
UV-Visual Echelle Spectrograph spectra of the
eclipsing pre-main-sequence star KH 15D covering
the wavelength range 4780-6810 Å obtained at
three phases: out of eclipse, near minimum light,
and during egress. The system evidently acts as a
natural coronagraph, enhancing the contrast
relative to the continuum of hydrogen and
forbidden emission lines during eclipse. At
maximum light, the H**alpha; equivalent width was
~2 Å and the profile showed broad wings and a
deep central absorption. During egress, the
equivalent width was much higher (~70 Å) and the
broad wings, which extend to +/-300 km
s-1, were prominent. During eclipse
totality, the equivalent width was less than
during egress (~40 Å) and the high-velocity wings
were much weaker. H**beta; showed a somewhat
different behavior, revealing only the
blueshifted portion of the high-velocity
component during eclipse and egress. [O I]
**lambda;**lambda;6300, 6363 lines are easily
seen both out of eclipse and when the photosphere
is obscured and exhibit little or no flux
variation with the eclipse phase. Our
interpretation is that KH 15D, although clearly a
weak-line T Tauri star by the usual criteria, is
still accreting matter from a circumstellar disk
and has a well-collimated bipolar jet. As the
knife-edge of the occulting matter passes across
the close stellar environment, it is evidently
revealing structure in the magnetosphere of this
pre-main-sequence star with unprecedented spatial
resolution. We also show that there is only a
small, perhaps marginally significant change in
the velocity of the K7 star between the maximum
light and egress phases probed here. Based on
UV-Visual Echelle Spectrograph observations
collected at the European Southern Observatory's
Very Large Telescope via Director's Discretionary
Time, within the observing program P267.C-5736.
Free Keywords:Accretion; Accretion Disks; Line: Profiles;
; Stars: Individual: Alphanumeric: KH 15D
External Publication Status:published
Document Type:Article
Communicated by:N. N.
Affiliations:MPI für Astronomie
External Affiliations:University, Middletown, CT 06459;
Department of Physics, Wesleyan University,
Middletown, CT 06459.), AB(Department of
Astronomy, Wesleyan University, Middletown, CT
AC(Max-Planck-Institut für Astronomie,
Königstuhl 17, D-69117 Heidelberg, Germany;
AD(Max-Planck-Institut für Astronomie, Königstuhl
17, D-69117 Heidelberg, Germany;
AE(Department of Physics and Astronomy, Rice
University, 6100 Main Street, Houston, TX 77005;
Identifiers:URL:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?bi... [ID No:1]
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