Bibcode
Gondoin, P.; Gandolfi, D.; Fridlund, M.; Frasca, A.; Guenther, E. W.; Hatzes, A.; Deeg, H. J.; Parviainen, H.; Eigmüller, P.; Deleuil, M.
Bibliographical reference
Astronomy and Astrophysics, Volume 548, id.A15, 11 pp.
Advertised on:
12
2012
Journal
Citations
12
Refereed citations
10
Description
Aims: The present study reports measurements of the rotation
period of a young solar analogue, estimates of its surface coverage by
photospheric starspots and of its chromospheric activity level, and
derivations of its evolutionary status. Detailed observations of many
young solar-type stars, such as the one reported in the present paper,
provide insight into rotation and magnetic properties that may have
prevailed on the Sun in its early evolution. Methods: Using a
model based on the rotational modulation of the visibility of active
regions, we analysed the high-accuracy CoRoT lightcurve of the active
star CoRoT 102899501. Spectroscopic follow-up observations were used to
derive its fundamental parameters. We compared the chromospheric
activity level of Corot 102899501 with the R'HK index
distribution vs age established on a large sample of solar-type dwarfs
in open clusters. We also compared the chromospheric activity level of
this young star with a model of chromospheric activity evolution
established by combining relationships between the R'HK index
and the Rossby number with a recent model of stellar rotation evolution
on the main sequence. Results: We measure the spot coverage of
the stellar surface as a function of time and find evidence for a
tentative increase from 5 - 14% at the beginning of the observing run to
13-29% 35 days later. A high level of magnetic activity on Corot
102899501 is corroborated by a strong emission in the Balmer and Ca ii H
and K lines (R'HK ~ -4). The starspots used as tracers of the
star rotation constrain the rotation period to 1.625 ± 0.002 days
and do not show evidence for differential rotation. The effective
temperature (Teff = 5180 ± 80 K), surface gravity (log
g = 4.35 ± 0.1), and metallicity ([M/H] = 0.05 ± 0.07 dex)
indicate that the object is located near the evolutionary track of a
1.09 ± 0.12 M&sun; pre-main sequence star at an age of
23 ± 10 Myr. This value is consistent with the "gyro-age" of
about 8-25 Myr, inferred using a parameterization of the stellar
rotation period as a function of colour index and time established for
the I-sequence of stars in stellar clusters. Conclusions: We
conclude that the high magnetic activity level and fast rotation of
CoRoT 102899501 are manifestations of its stellar youth consistent with
its estimated evolutionary status and with the detection of a strong Li
i λ6707.8 Å absorption line in its spectrum. We argue that
a magnetic activity level comparable to that observed on CoRot 102899501
could have been present on the Sun at the time of planet formation.
Based on observations obtained with CoRoT, a space project operated by
the French Space Agency, CNES, with participation of the Science
Programme of ESA, ESTEC/RSSD, Austria, Belgium, Brazil, Germany and
Spain.Based on observations made with the Anglo-Australian Telescope;
the 2.1-m Otto Struve telescope at McDonald Observatory, Texas, USA; the
Nordic Optical Telescope, operated on the island of La Palma jointly by
Denmark, Finland, Iceland, Norway, and Sweden, in the Spanish
Observatorio del Roque de los Muchachos of the Instituto de Astrofisica
de Canarias, in time allocated by the NOT "Fast-Track" Service
Programme, OPTICON, and the Spanish Time Allocation Committee (CAT).The
research leading to these results has received funding from the European
Community's Seventh Framework Programme (FP7/2007-2013) under grant
agreement number RG226604 (OPTICON).
Related projects
Helio and Astero-Seismology and Exoplanets Search
The principal objectives of this project are: 1) to study the structure and dynamics of the solar interior, 2) to extend this study to other stars, 3) to search for extrasolar planets using photometric methods (primarily by transits of their host stars) and their characterization (using radial velocity information) and 4) the study of the planetary
Savita
Mathur