sunspot

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sunspot

Dermatology
(1) Actinic keratosis, see there.
(2) Actinic lentigo, see there.
 
Meteorology
A region of intense magnetic activity on the sun’s surface resulting in a local reduction in convection and temperature, which appears are dark spots.
References in periodicals archive ?
2007 was also the year of lowest starspot activity so far recorded.
However, while our star experiences a 11-year sunspot activity cycle - with the Sun being nearly spot-free during solar minimum, and having over 100 spots covering less than 1 percent of its surface at solar maximum - on Proxima Centauri, there would be occasions when roughly 20 percent of the surface would be covered in starspots.
In addition we modelled two starspots to enhance the curve fit.
Chromospherically active stars with starspots appear to vary as they rotate;
Steven Vogt, Don Penrod and Artie Hatzes of the University of California at Santa Cruz have developed a method for finding starspots, cool spots on a star's surface that are similar to sunspots (SN: 7/17/82, p.
But analyses of stellar activity turned up no big starspots that could masquerade as a planet, and d stayed in the catalogs --and on the list of potentially habitable planets, because much of its predicted orbit fell in GJ 581's habitable zone.
The stars seem to become dimmer when their starspots are on their visible sides.
To measure a star's spin, astronomers look for changes in its brightness caused by dark spots known as starspots crossing the star's surface.
Observing as many stars as they can, and continuing to do so, they started to see rotation periods from the periodic brightening and dimming of the stars, as starspots come in and go out of view.
Because of the way they form, starspots similar to the ones observed on the Sun require that the star have a convective zone near its surface, where boiling motions carry out energy produced within the star.
As a star's spinning slows, so does the generation of starspots and solar storms associated with starspots.
The team found that Proxima Cen indeed has a 7-year cycle, with its X-ray and ultraviolet emission (which comes from flares) going up when the star's optical brightness goes down (that is, when starspots plaster the surface).