Starspots: A Key to the Stellar Dynamo

By S. Berdyugina. 2005

427 citations recorded by the source corpus.

Magnetic activity similar to that of the Sun is observed on a variety of cool stars with external convection envelopes. Stellar rotation coupled with convective motions generate strong magnetic fields in the stellar interior and produce a multitude of magnetic phenomena including starspots in the photosphere, chromospheric plages, coronal loops, UV, X-ray, and radio emission and flares. Here I review the phenomenon of starspots on different types of cool stars, observational tools and diagnostic techniques for studying starspots as well as starspot properties including their temperatures, areas, magnetic field strengths, lifetimes, active latitudes and longitudes, etc. Evolution of starspots on various time scales allows us to investigate stellar differential rotation, activity cycles, and global magnetic fields. Together these constitute the basis for our understanding of stellar and solar dynamos and provide valuable constraints for theoretical models.

Subfields: Astronomy and Astrophysics

View Paper: https://www.semanticscholar.org/paper/4aaccda07d926ece1f40507da9b28b990fac33a2

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In Astronomy and Astrophysics

Citations in the corpus

Estimating the frequency of extremely energetic solar events, based on solar, stellar, lunar, and terrestrial records (2012, background): “…younger and thus magnetically much more active than the present-day Sun, and with generally different patterns in their dynamos as reflected, for example, in the existence of high-latitude or polar activity and in the general lack of simple cycle signatures [e.g., Berdyugina, 2005; Hall , 2008].”
Magnetic activity in the photosphere of CoRoT-Exo-2a. Active longitudes and short-term spot cycle in (2008, background): “Considering stars with photometric variations of a few 0.1 mag, Berdyugina (2005) found a relationship between the temperature of the spots and that of the unperturbed photosphere.”
Observations of Cool-Star Magnetic Fields (2012, background): “For reviews on observations of coronal emission, chromospheric emission, and starspots the reader is referred to the reviews by Güdel (2002, 2004), Berdyugina (2005), and Hall (2008).”
Do Kepler Superflare Stars Really Include Slowly Rotating Sun-like Stars?—Results Using APO 3.5 m Telescope Spectroscopic Observations and Gaia-DR2 Data (2019, methodology): “ΔF/F values taken from McQuillan et al. (2014) were used, and we applied the following relation on the temperature difference between photosphere and spot (Tstar−Tspot) deduced from Berdyugina (2005): T T T T T T3.”
Magnetic Fields of Nondegenerate Stars (2009, background): “Most cool stars exhibit a large number of solar-like activity phenomena; dark spots are present at the their surfaces (e.g., Berdyugina 2005), where they comeand go on timescales ranging from days (as they are carried in and out of the observer’s view by the star’s rotation) to months (as they…”
Rotation periods of 12 000 main-sequence Kepler stars: Dependence on stellar spectral type and comparison with v sin i observations (2013, background): “Brightness variations are also seen in other stars and are commonly attributed to the presence of magnetic activity in the case of main-sequence cool dwarfs (e.g. Berdyugina 2005).”
A multiwavelength study of the M dwarf binary YY Geminorum (2015, background): “Berdyugina (2005) has written a comprehensive review of current techniques for the determination of starspot temperatures.”
Statistical properties of superflares on solar-type stars based on 1-min cadence data (2015, background): “Astar and Tstar for each superflare star were taken from Huber et al. (2014), and we assumed Tspot = 4, 000 K (Berdyugina 2005).”