Abstract:
This paper is part of a multiwavelength study aimed at using complementary photometric,
polarimetric and spectroscopic data to achieve an understanding of the activity process in
late-type stars. Here, we present the study of FR Cnc, a young, active and spotted star.
We performed analysis of All Sky Automated Survey 3 (ASAS-3) data for the years 2002–08
and amended the value of the rotational period to be 0.826518 d. The amplitude of photometric
variations decreased abruptly in the year 2005, while the mean brightness remained the same,
which was interpreted as a quick redistribution of spots. BVRC and IC broad-band photometric
calibration was performed for 166 stars in FR Cnc vicinity.
The photometry at Terskol Observatory shows two brightening episodes, one of which
occurred at the same phase as the flare of 2006 November 23. Polarimetric BVR observations
indicate the probable presence of a supplementary source of polarization. We monitored FR
Cnc spectroscopically during the years 2004–08.We concluded that the radial velocity changes
cannot be explained by the binary nature of FR Cnc. We determined the spectral type of FR
Cnc as K7V. Calculated galactic space-velocity components (U,V ,W) indicate that FR Cnc
belongs to the young disc population and might also belong to the IC 2391 moving group.
Based on Li I λ6707.8 measurement, we estimated the age of FR Cnc to be between 10 and
120 Myr. Doppler tomography was applied to create a starspot image of FR Cnc.We optimized
the goodness of fit to the deconvolved profiles for axial inclination, equivalent width and v sin i,
finding v sin i = 46.2 kms−1 and i = 55◦. We also generated a synthetic V -band light curve
based on Doppler imaging that makes simultaneous use of spectroscopic and photometric data.
This synthetic light curve displays the same morphology and amplitude as the observed one.
The starspot distribution of FR Cnc is also of interest since it is one of the latest spectral
types to have been imaged. No polar spot was detected on FR Cnc.
