Publications (25)
Magnetic field topology of the RS CVn star II Pegasi
O. Kochukhov, M. J. Mantere, T. Hackman +1
The dynamo processes in cool active stars generate complex magnetic fields responsible for prominent surface stellar activity and variability at different time scales. For a small…
Spot activity of the RS CVn star Ï Geminorum
P. Kajatkari, T. Hackman, L. Jetsu +2
We model the photometry of RS CVn star Geminorum to obtain new information on the changes of the surface starspot distribution, i.e., activity cycles, differential rotation an…
First measurement of the magnetic field on FK Com and its relation to the contemporaneous starspot locations
H. Korhonen, S. Hubrig, S. V. Berdyugina +5
In this study we present simultaneous low-resolution longitudinal magnetic field measurements and high-resolution spectroscopic observations of the cool single giant FK Com. The va…
Study of FK Comae Berenices: VII. Correlating photospheric and chromospheric activity
K. Vida, H. Korhonen, I. V. Ilyin +3
We study the connection between the chromospheric and photospheric behaviour of the active late-type star FK Comae. We use spot temperature modelling, light curve inversion based o…
Shapes of stellar activity cycles
T. Willamo, T. Hackman, J. J. Lehtinen +4
Magnetic activity cycles are an important phenomenon in both the Sun and other stars. The shape of the solar cycle is commonly characterised by a fast rise and a slower decline, bu…
Study of FK Comae Berenices. II. Spot evolution from 1994 to 1997
H. Korhonen, S. V. Berdyugina, T. Hackman +2
We present new surface (Doppler) images of the late-type single giant FK Com for June-July 1996, July-August 1996, April 1997 and June 1997. These images are compared with the prev…