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Astron. Astrophys. Suppl. Ser. 147, 151-168
Doppler imaging from artificial data
Testing the temperature inversion from spectral-line
profiles
J.B. Rice1 - K.G. Strassmeier2
Send offprint request: K.G. Strassmeier
1 - Department of Physics, Brandon University, Brandon,
Manitoba R7A 6A9, Canada
e-mail: rice@BrandonU.ca
2 -
Institut für Astronomie, Universität Wien,
Türkenschanzstraße 17, A-1180 Wien, Austria
e-mail: strassmeier@astro.univie.ac.at
Received April 6; accepted August 31, 2000
Abstract:
We present extensive numerical tests of our temperature-based image
reconstruction code T
EMPM
AP. Two test cases that represent a
rapidly-rotating low-inclination star and a moderately-rotating
high-inclination star are used for the forward problem. Tests are
then made to recover the original input map and include data
errors and input-parameter errors. The former include variations
of photon noise, continuum displacement, continuum slopes,
scattered light in the spectrograph, and phase gaps with and
without continuum information. The input-parameter tests include
the confusion in the recovery of hot versus cool spots,
uncertainties of atmospheric parameters such as radial-tangential
macroturbulence and gravity, and the influence of line strength
and line damping. In general, we find that the geometric
information is less dependent on photon noise and on input errors
than the temperature information. Our test inversions also show
that, at the
of these test cases, no significant
gain in image quality is achieved once
S/
N of 300:1 is surpassed.
Key words: stars: imaging -- stars: activity -- line: profiles --
techniques: spectroscopic
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