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Co-rotating spots at different latitudes on the stellar surface generate periodic photometric variability and can be useful proxies to detect Differential Rotation (DR). DR is a major ingredient of the solar dynamo but observations of…

Solar and Stellar Astrophysics · Physics 2015-06-16 Timo Reinhold , Ansgar Reiners

We present rotation periods for thousands of active stars in the Kepler field derived from Q3 data. In most cases a second period close to the rotation period was detected, which we interpreted as surface differential rotation (DR). Active…

Solar and Stellar Astrophysics · Physics 2015-06-16 Timo Reinhold , Ansgar Reiners , Gibor Basri

Quasi-periodic modulations of the stellar light curve may result from dark spots crossing the visible stellar disc. Due to differential rotation, spots at different latitudes generally have different rotation periods. Hence, by studying…

Solar and Stellar Astrophysics · Physics 2017-02-22 A. R. G. Santos , M. S. Cunha , P. P. Avelino , R. A. García , S. Mathur

Starspots are cooler and darker than the stellar surface. Therefore, the emitted flux of a star changes when spots are visible on its surface. The presence of spots together with the stellar rotation leads to a periodic modulation on the…

Solar and Stellar Astrophysics · Physics 2017-11-08 A. R. G. Santos , M. S. Cunha , P. P. Avelino , R. A. García , S. Mathur

The characterization of solar surface differential rotation (SDR) from disk-integrated chromospheric measurements has important implications for the study of differential rotation and dynamo processes in other stars. Some chromospheric…

Solar and Stellar Astrophysics · Physics 2015-06-11 Luca Bertello , Alexei A. Pevtsov , A. Pietarila

According to most stellar dynamo theories, differential rotation (DR) plays a crucial role for the generation of toroidal magnetic fields. Numerical models predict surface differential rotation to be anti-solar for rapidly-rotating giant…

Solar and Stellar Astrophysics · Physics 2016-11-30 Zs. Kővári , A. Künstler , K. G. Strassmeier , T. A. Carroll , M. Weber , L. Kriskovics , K. Oláh , K. Vida , T. Granzer

Simulations of magnetohydrodynamics convection in slowly rotating stars predict anti-solar differential rotation (DR) in which the equator rotates slower than poles. This anti-solar DR in the usual $\alpha \Omega$ dynamo model does not…

Solar and Stellar Astrophysics · Physics 2020-01-01 Bidya Binay Karak , Aparna Tomar , Vindya Vashishth

Differential rotation is a key driver of magnetic activity and dynamo processes in the Sun and other stars, especially as the rate differs across the solar layers, but also in active regions. We aim to accurately quantify the velocity at…

In previous work we identified six Sun-like stars observed by Kepler with exceptionally clear asteroseismic signatures of rotation. Here, we show that five of these stars exhibit surface variability suitable for measuring rotation. In order…

Solar and Stellar Astrophysics · Physics 2015-10-07 M. B. Nielsen , H. Schunker , L. Gizon , W. H. Ball

Understanding differential rotation of Sun-like stars is of great importance for insight into the angular momentum transport in these stars. One means of gaining such information is that of asteroseismology. By a forward modeling approach…

Solar and Stellar Astrophysics · Physics 2016-02-22 Mikkel N. Lund , Mark S. Miesch , Jørgen Christensen-Dalsgaard

The present study reports the discovery of Sun-like stars, namely main-sequence stars with $T_{\rm eff}$, $\log g$ and rotation periods $P_{rot}$ similar to solar values, presenting evidence of surface differential rotation. An…

We introduce a method of measuring a lower limit to the amplitude of surface differential rotation from high-precision, evenly sampled photometric time series. It is applied to main-sequence late-type stars whose optical flux modulation is…

Solar and Stellar Astrophysics · Physics 2014-02-28 A. F. Lanza , M. L. Das Chagas , J. R. De Medeiros

Cross-correlation of consecutive Doppler images is one of the most common techniques used to detect surface differential rotation (hereafter DR) on spotted stars. The disadvantage of a single cross-correlation is, however, that the expected…

Solar and Stellar Astrophysics · Physics 2015-06-17 Zsolt Kővári , János Bartus , Levente Kriskovics , Krisztián Vida , Katalin Oláh

Young and active stars generally have regular, almost sinusoidal, patterns of variability attributed to their rotation, while the majority of older and less active stars, including the Sun, have more complex and non-regular light-curves…

Solar and Stellar Astrophysics · Physics 2020-04-22 E. M. Amazo-Gómez , A. I. Shapiro , S. K. Solanki , N. A. Krivova , G. Kopp , T. Reinhold , M. Oshagh , A. Reiners

We report the discovery of a new relationship between a simple morphological characteristic of light curves produced by starspots and stellar rotation periods. The characteristic we examine is whether the light curve exhibits one dip or two…

Solar and Stellar Astrophysics · Physics 2018-08-29 Gibor Basri , Hieu T. Nguyen

The main aim of this work is to determine the solar differential rotation by tracing sunspot groups during the period 1964-2016, using the Kanzelh\"ohe Observatory for Solar and Environmental Research (KSO) sunspot drawings and white light…

Light curves of solar-like stars are known to show highly irregular variability. As a consequence, standard frequency analysis methods often fail to detect the correct rotation period. Recently, Shapiro et al. (2020) showed that the periods…

Solar and Stellar Astrophysics · Physics 2022-10-26 Timo Reinhold , Alexander I. Shapiro , Sami K. Solanki , Gibor Basri

Stellar rotation periods can be determined by observing brightness variations caused by active magnetic regions transiting visible stellar disk as the star rotates. The successful stellar photometric surveys stemming from the Kepler and…

Solar and Stellar Astrophysics · Physics 2020-10-28 E. M. Amazo-Gomez , A. I. Shapiro , S. K. Solanki , G. Kopp , M. Oshagh , T. Reinhold , A. Reiners

Measuring surface differential rotation (DR) on different types of stars is important when characterizing the underlying stellar dynamo. It has been suggested that anti-solar DR laws can occur when strong meridional flows exist. We aim to…

Solar and Stellar Astrophysics · Physics 2016-08-10 G. Harutyunyan , K. G. Strassmeier , A. Künstler , T. A. Carroll , M. Weber

On the Sun, the rotation periods of individual sunspots not only trace the latitude dependence of the surface rotation rate, but also provide clues as to the amount of subsurface fluid shear. In this paper we present the first measurements…

Astrophysics · Physics 2009-11-07 A. Collier Cameron , J. -F. Donati , M. Semel
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