A study of the magnetic field in FK Com

Puzin, V. B.; Саванов, И. С.; Romanyuk, I. I.; Семенко, Е. А.; Дмитриенко, Е. С.

doi:10.1134/s1990341314030079

Cited by 8 publications

(10 citation statements)

References 9 publications

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“…This change might be connected to the results of Korhonen et al (2009) and Puzin et al (2014), who studied longitudinal magnetic field on FK Com using low-resolution spectropolarimetry. According to Korhonen et al (2009), the average longitudinal magnetic field strength of FK Com was in the order of 200 G in 2008 April, but Puzin et al (2014) find that in 2012 May, there was no detectable magnetic field on the star. The measurements from 2011 April-May show significant detections of the longitudinal magnetic field, but with much reduced field strength compared to 2008 April (Korhonen et al, in prep.).…”

Section: General Level Of Activitymentioning

confidence: 73%

“…The measurements from 2011 April-May show significant detections of the longitudinal magnetic field, but with much reduced field strength compared to 2008 April (Korhonen et al, in prep.). The observations of Puzin et al (2014) are of lower accuracy than the ones used by Korhonen et al (2009), and therefore, the non-detection could be due to the field being too weak for them to detect, as the authors also hypothesise in their paper. All this supports the idea that the activity of FK Com has significantly decreased during recent years: decreasing spot contrast of the Doppler maps, weak Hα levels in the last epochs, and decreasing longitudinal magnetic field strength.…”

Section: General Level Of Activitymentioning

confidence: 84%

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Study of FK Comae Berenices

Vida

Korhonen

Ilyin

et al. 2015

A&A

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Aims. We study the connection between the chromospheric and photospheric behaviour of the active late-type star FK Comae. Methods. We use spot temperature modelling, light curve inversion based on narrow-and wide-band photometric measurements, Hα observations from 1997−2010, and Doppler maps from 2004−2010 to compare the behaviour of chromospheric and photospheric features. Results. Investigating low-resolution Hα spectra, we find that the changes in the chromosphere seem to happen mainly on a time scale longer than a few hours, but shorter variations are also observed. According to the Hα measurements, prominences are often found in the chromosphere that reach to more than a stellar radius and are stable for weeks, and they seem to be often, but not always connected to dark photospheric spots. The rotational modulation of the Hα emission typically seems to be anticorrelated with the light curve, but we did not find convincing evidence of a clear connection in the long-term trends of the Hα emission and the brightness of the star. In addition, FK Com seems to be in an unusually quiet state in 2009−2010 with very little chromospheric activity and low spot contrast, which might indicate the long-term decrease in activity.

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Section: General Level Of Activitymentioning

confidence: 73%

Section: General Level Of Activitymentioning

confidence: 84%

Study of FK Comae Berenices

Vida

Korhonen

Ilyin

et al. 2015

A&A

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“…As earlier (see [18]), the observational data for determining the value of the longitudinal magnetic field of the star has been obtained at the Main Stellar Spectrograph of the 6-m telescope of the SAO RAS. The times of observations are given in Table 2.…”

Section: Magnetic Fieldmentioning

confidence: 96%

“…We have previously given the description of the reduction and the analysis technique in [18,21,22]. Here we only briefly mention them.…”

Section: Magnetic Fieldmentioning

confidence: 99%

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Spots and activity cycles of the star FKCom—2013–2015 data analysis

et al. 2016

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We present an analysis of new photometric and spectropolarimetric observations of a chromospherically active star FK Com. Based on this observational data and the data from the literature sources, applying a common technique, we performed an analysis of a complete set of the available photometric data, which were divided into 218 individual light curves. For each of them a reverse problem of restoring largescale temperature irregularities on the surface of the star from its light curve was solved. We analyzed the time series for the brightness of the star in the U -, B-, and V -bands, the brightness variability amplitudes, the total area of the spots on the surface of the star, and the average brightness of each set considered. The analysis of determination results of the positions of active longitudes leads to the conclusion about the existence of two systems of active regions on the FK Com surface. It was determined that the positions of each of these systems undergo cyclic changes. This confirms the conclusion on the likely absence of a strongly pronounced regularity of the flip-flops in FK Com, earlier suggested by other researchers. The results of the new polarimetric observations FK Com in 2014-2015 are presented. These measurements evidence the legitimacy of the proposed interpretation the behavior of the longitudinal magnetic field strength B z , indicating the settling-in of a more symmetric distribution of magnetic region on the FK Com surface. An increasing activity of the star over the recent years, registered from the photometric observations is also consistent with the probable onset of growth in the B z parameter starting from 2014.

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The Program Magreg for Determining the Longitudinal Component of Stellar Magnetic Fields from Spectropolarimetric Observations

Саванов

2020

Astrophysics

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A study of the magnetic field in FK Com

Cited by 8 publications

References 9 publications

Study of FK Comae Berenices

Study of FK Comae Berenices

Spots and activity cycles of the star FKCom—2013–2015 data analysis

The Program Magreg for Determining the Longitudinal Component of Stellar Magnetic Fields from Spectropolarimetric Observations

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