The Spot Activity of FK Comae Berenices

Jetsu, L.; Pelt, J.; Tuominen, I.; Nations, H. L.

doi:10.1017/s0252921100079963

Cited by 12 publications

(1 citation statement)

References 3 publications

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“…As mentioned in Section 3.2, we have detected the flip-flop phenomena on LO Peg. The flip-flop has also been noticed by several authors such as Jetsu et al (1991), Korhonen et al (2002). This phenomenon is well explained by the dynamo based solution where a non-axisymmetric dynamo component with two permanent active longitudes (180 • apart) is needed along with an oscillating axisymmetric magnetic field.…”

Section: Discussionmentioning

confidence: 57%

Magnetic activities on active solar-type stars

Karmakar¹,

Pandey²,

Naik³

et al. 2019

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Indian Institute of Astrophysics, II Block Koramangala, Bangalore 560034, India We present results obtained from the studies of magnetic activities on four solar-type stars (F-type star KIC 6791060, K-type star LO Peg, and two M-type planet-hosting stars K2–33 and EPIC 211901114) by using optical observations from several ground- and space-based telescopes. In this study, we investigate magnetic activities such as spot-topographic evolution and flaring events in these stars. We compare the results obtained from this study with that of the Sun. In the surface temperature maps, one active longitude has been detected in KIC 6791060, whereas in each of the other three cases two active longitudes are seen. The spottedness was found to vary in the range of 0.07–0.44%, 9–26%, 3.6–4.2%, and 4.5–5.3% for KIC 6791060, LO Peg, K2–33, and EPIC 211901114, respectively. Several flaring events have been identified in each star. An increasing trend in flaring frequency per stellar rotation has been found in the stars with change in spectral type from F to M. These findings indicate the increase in magnetic activities with the spectral type of stars. This can be explained due to increasing the ratio of the thickness of the convection zone to the radiation zone from F-type star to the M-type stars.

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Section: Discussionmentioning

confidence: 57%

Magnetic activities on active solar-type stars

Karmakar¹,

Pandey²,

Naik³

et al. 2019

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Spots on FK Com: active longitudes and “flip‐flops”

Korhonen¹,

Berdyugina²,

Tuominen³

2004

Astron Nachr

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Abstract.We have earlier investigated the surface structures of a late-type, single, giant FK Com for the years 1994-1998 using Doppler imaging. These surface temperature maps revealed long-lived active regions at high latitudes. Long-term photometric observations also show that these active regions tend to occur at two permanent active longitudes which are 180 degrees apart from each other, and that the activity switches the longitude with an average period of about 3 years (the

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Flip‐flop phenomenon: observations and theory

Elstner

Korhonen

2005

Astron Nachr

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Abstract. In many active stars the spots concentrate on two permanent active longitudes which are 180• apart. In some of these stars the dominant part of the spot activity changes the longitude every few years. This so-called flip-flop phenomenon has up to now been reported in 11 stars, both single and binary alike, and including also the Sun. To explain this phenomenon, a non-axisymmetric dynamo mode, giving rise to two permanent active longitudes at opposite stellar hemispheres, is needed together with an oscillating axisymmetric magnetic field. Here we discuss the observed characteristics of the flip-flop phenomenon and present a dynamo solution to explain them.

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The Spot Activity of FK Comae Berenices

Cited by 12 publications

References 3 publications

Magnetic activities on active solar-type stars

Magnetic activities on active solar-type stars

Spots on FK Com: active longitudes and “flip‐flops”

Flip‐flop phenomenon: observations and theory

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