Query : 2014A&A...562A.107K

2014A&A...562A.107K - Astronomy and Astrophysics, volume 562A, 107-107 (2014/2-1)

Spot activity of the RS Canum Venaticorum star σ Geminorum.


Abstract (from CDS):

We model the photometry of RS CVn star {sigma} Geminorum to obtain new information on the changes of the surface starspot distribution, that is, activity cycles, differential rotation, and active longitudes. We used the previously published continuous period search (CPS) method to analyse V-band differential photometry obtained between the years 1987 and 2010 with the T3 0.4m Automated Telescope at the Fairborn Observatory. The CPS method divides data into short subsets and then models the light-curves with Fourier-models of variable orders and provides estimates of the mean magnitude, amplitude, period, and light-curve minima. These light-curve parameters are then analysed for signs of activity cycles, differential rotation and active longitudes. We confirm the presence of two previously found stable active longitudes, synchronised with the orbital period Porb=19.60d, and found eight events where the active longitudes are disrupted. The epochs of the primary light-curve minima rotate with a shorter period Pmin,1=19.47d than the orbital motion. If the variations in the photometric rotation period were to be caused by differential rotation, this would give a differential rotation coefficient of α≥0.103. The presence of two slightly different periods of active regions may indicate a superposition of two dynamo modes, one stationary in the orbital frame and the other one propagating in the azimuthal direction. Our estimate of the differential rotation is much higher than previous results. However, simulations show that this may be caused by insufficient sampling in our data.

Abstract Copyright:

Journal keyword(s): stars: activity - starspots - stars: individual: sigma Geminorum

VizieR on-line data: <Available at CDS (J/A+A/562/A107): phot.dat res.dat>

Simbad objects: 4

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Number of rows : 4
N Identifier Otype ICRS (J2000)
ICRS (J2000)
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2023
1 HD 60318 ** 07 35 08.8032282360 +30 57 39.304643436   6.366 5.347     K0III 119 1
2 * ups Gem PM* 07 35 55.3500141720 +26 53 44.680194960 7.54 5.60 4.06 2.82 1.91 M0III 202 0
3 * sig Gem RS* 07 43 18.7276907303 +28 53 00.631838445 6.38 5.41 4.29 3.37 2.79 K1IIIe 473 0
4 V* FK Com PM* 13 30 46.7996390256 +24 13 57.781233768   9.04 8.245   7.204 G4III 370 1

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