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FR Cnc revisited: photometry, polarimetry and spectroscopy

Authors

  • A. Golovin,

    Corresponding author
    1. Main Astronomical Observatory of National Academy of Sciences of Ukraine, Zabolotnogo str., 27, Kiev 03680, Ukraine
      E-mail: golovin.alex@gmail.com
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  • M. C. Gálvez-Ortiz,

    1. Centro de Astrobiología (CSIC-INTA), Ctra de Ajalvir, km 4, E-28850 Torrejón de Ardoz, Madrid, Spain
    2. Centre for Astrophysics Research, University of Hertfordshire, College Lane, Hatfield, Hertfordshire AL10 9AB
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  • M. Hernán-Obispo,

    1. Astrophysics Department, Physic Faculty, Universidad Complutense de Madrid, E-28040 Madrid, Spain
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  • M. Andreev,

    1. Main Astronomical Observatory of National Academy of Sciences of Ukraine, Zabolotnogo str., 27, Kiev 03680, Ukraine
    2. Terskol Branch of the Astronomy Institute of RAS, Kabardino-Balkaria Republic, 361605 Terskol, Russia
    3. International Center for Astronomical, Medical and Ecological Research of National Academy of Sciences of Ukraine (ICAMER of NASU), Zabolotnogo str., 27, Kiev 03680, Ukraine
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  • J. R. Barnes,

    1. Centre for Astrophysics Research, University of Hertfordshire, College Lane, Hatfield, Hertfordshire AL10 9AB
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  • D. Montes,

    1. Astrophysics Department, Physic Faculty, Universidad Complutense de Madrid, E-28040 Madrid, Spain
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  • E. Pavlenko,

    1. Crimean Astrophysical Observatory (CrAO), Nauchny, 98409 Crimea, Ukraine
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  • J. C. Pandey,

    1. Aryabhatta Research Institute of Observational Sciences (ARIES), Manora Peak, Nainital 263129, India
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  • R. Martínez-Arnáiz,

    1. Astrophysics Department, Physic Faculty, Universidad Complutense de Madrid, E-28040 Madrid, Spain
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  • B. J. Medhi,

    1. Aryabhatta Research Institute of Observational Sciences (ARIES), Manora Peak, Nainital 263129, India
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  • P. S. Parihar,

    1. Indian Institute of Astrophysics, Block II, Koramangala, Bangalore 560 034, India
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  • A. Henden,

    1. AAVSO, Clinton B. Ford Astronomical Data and Research Center, 49 Bay State Road, Cambridge, MA 02138, USA
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  • A. Sergeev,

    1. Terskol Branch of the Astronomy Institute of RAS, Kabardino-Balkaria Republic, 361605 Terskol, Russia
    2. International Center for Astronomical, Medical and Ecological Research of National Academy of Sciences of Ukraine (ICAMER of NASU), Zabolotnogo str., 27, Kiev 03680, Ukraine
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  • S. V. Zaitsev,

    1. Main Astronomical Observatory of National Academy of Sciences of Ukraine, Zabolotnogo str., 27, Kiev 03680, Ukraine
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  • N. Karpov

    1. Terskol Branch of the Astronomy Institute of RAS, Kabardino-Balkaria Republic, 361605 Terskol, Russia
    2. International Center for Astronomical, Medical and Ecological Research of National Academy of Sciences of Ukraine (ICAMER of NASU), Zabolotnogo str., 27, Kiev 03680, Ukraine
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Based on the observations made: with the 2.2-m telescope of the German–Spanish Astronomical Centre, Calar Alto (Almería, Spain), operated by Max-Planck-Institute for Astronomy, Heidelberg, in cooperation with the Spanish National Commission for Astronomy; with the Nordic Optical Telescope (NOT), 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 Astrofísica de Canarias; with the Isaac Newton Telescope (INT) operated on the island of La Palma by the Isaac Newton Group in the Spanish Observatorio del Roque de Los Muchachos of the Instituto de Astrofísica de Canarias; with the Italian Telescopio Nazionale Galileo (TNG) operated on the island of La Palma by the Centro Galileo Galilei of the Istituto Nazionale di Astrofisica (INAF) at the Spanish Observatorio del Roque de Los Muchachos of the Instituto de Astrofísica de Canarias; with ASAS-3 survey; with robotic 0.35-m telescope at the Sonoita Research Observatory (Arizona, USA); with 29-cm telescope, operated by Terskol Branch of the Astronomy Institute, Russia; with 104-cm Sampurnanand Telescope of ARIES, Nainital, India; with 2.0-m Himalayan Chandra Telescope, operated at the Indian Astronomical Observatory (Mt Saraswati, Hanle, India).

E-mail: golovin.alex@gmail.com

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 iλ6707.8 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 km s−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.

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