Free access article
| Issue |
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A&A
Volume 414,
Number 3,
February II 2004
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Page(s)
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1139 - 1152 |
| Section |
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Planets and planetary systems |
| DOI |
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10.1051/0004-6361:20034039 |
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A&A 414, 1139-1152 (2004)
DOI: 10.1051/0004-6361:20034039
Characterising stellar micro-variability for planetary transit
searches
S. Aigrain1, F. Favata2 and G. Gilmore1
1
Institute of Astronomy (IoA), University of Cambridge,
Madingley Road, Cambridge CB3 0HA, UK
e-mail: suz@ast.cam.ac.uk,gil@ast.cam.ac.uk
2
Astrophysics Division, Research & Scientific Support Department,
European Space Agency, PO Box 299, 2200 AG Noordwijk, The Netherlands
e-mail: Fabio.Favata@rssd.esa.int
(Received 2 July 2003 / Accepted 8 October 2003)
Abstract
A method for simulating light curves containing stellar
micro-variability for a range of spectral types and ages is
presented. It is based on parameter-by-parameter scaling of a
multi-component fit to the solar irradiance power spectrum (based on
VIRGO/PMO6 data), and scaling laws derived from ground based
observations of various stellar samples.
A correlation is observed in the Sun between the amplitude of the
power spectrum on long (weeks) timescales and the BBSO Ca
II
K-line index of chromospheric activity. On the basis of this
evidence, the chromospheric activity level, predicted from rotation
period and
B-
V colour estimates according to the relationship
first introduced by Noyes (1983) and Noyes et al. (1984), is used to predict the
variability power on weeks time scales. The rotation period is
estimated on the basis of a fit to the distribution of rotation
period versus
B-
V observed in the Hyades and the Skumanich (1972)
spin-down law. The characteristic timescale of the variability is
also scaled according to the rotation period.
This model is used to estimate the impact of the target star
spectral type and age on the detection capability of space based
transit searches such as
Eddington and
Kepler. K stars
are found to be the most promising targets, while the performance
drops significantly for stars earlier than G and younger than 2.0 Gyr. Simulations also show that
Eddington should detect
terrestrial planets orbiting solar-age stars in most of the
habitable zone for G2 types and all of it for K0 and K5 types.
Key words: Sun: activity
-- stars: activity
-- stars: planetary systems
--
techniques: photometric
Offprint request: S. Aigrain,
suz@ast.cam.ac.ukSIMBAD Objects
© ESO 2004
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