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Astronomers have used a planet-hunting satellite to see a white dwarf abruptly switching on and off for the first time. The researchers led by Durham University, UK, used NASA's Transiting Exoplanet Survey Satellite (TESS) to observe the unique phenomenon. White dwarfs are what most stars become after they have burned off the hydrogen that fuels them. They are approximately the size of the Earth, but have a mass closer to that of the Sun. The white dwarf observed by the team is known to be accreting, or feeding, from an orbiting companion star. With the new observations astronomers saw it...

Black holes often are thought of as just endless pits in space and time that destroy everything they pull toward them. But new findings confirm the reverse is true, too: Black holes can drive extraordinarily powerful winds that push out and force star formation and shape the fate of a galaxy. Supermassive black holes are suspected to lurk in the hearts of many—if not all—large galaxies. These holes drag gas inward, which accrues in rapidly spinning, glowing disks. Astronomers have long thought that such "accretion disks" give off mighty winds that shape the host galaxies, profoundly influencing how they grow....

Astronomy Picture of the Day Discover the cosmos! Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer. 2002 August 25 Nebula Nova Cygni Turns On Credit: Peter Garnavich (Notre Dame), 1.2-m Telescope, Whipple Observatory Explanation: Old photographs show no evidence of the above nebula. In 1992, a white dwarf star toward the constellation of Cygnus blew off its outer layers in a classical nova explosion: an event called Nova Cygni 1992. Light flooded the local interstellar neighborhood, illuminated this existing gas cloud, excited the existing...