July 12, 2000
On the day you were born, the universe was already ancient beyond measure — and yet, in all those billions of years, it had never once...
A Giant Starspot on HD 12545
Birthday · July 12, 2000
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APOD published July 12, 2000. Credit: K. Strassmeier (U. Wien), Coude Feed Telescope, AURA, NOAO, NSF. A publication-date match, not a photo taken on your date. Independent of NASA.
What could cause a star to have such a large spot? Our Sun itself frequently has sunspots, relatively cool dark magnetic depressions that move across its surface. HD 12545, however, exhibits the largest starspots yet observed. Doppler imaging - the use of slight changes in color caused by the rotation of the star - was used to create this false-color image. The vertical bar on the right gives a temperature scale in kelvins. This giant, binary, RS CVn star, also known as XX Trianguli, is visible with binoculars in the constellation of Triangulum. The starspot is thought to be caused by large magnetic fields that inhibit hot matter from flowing to the surface.
Image credit: K. Strassmeier (U. Wien), Coude Feed Telescope, AURA, NOAO, NSF