Image of the Day –‘Cosmic Raindrops’ in the Hydra Galaxy Cluster






This is a composite image of the Hydra Galaxy Cluster, including a look at the hot atmosphere of plasma that pervades the cluster, an ultraviolet image of young stars swirling, an optical image of the elliptical galaxy at the heart of the cluster, and a radio image of jets of relativistic plasma.

Using data collected by space telescopes, including the Hubble, and from observatories on the ground, Yale University researchers detect a self-regulating cycle of star births within elliptical galaxies. The jets shooting out of a galaxy's center control the rate at which surrounding gas cools and falls into the galaxy, almost like raindrops.

"The 'raindrops' eventually cool enough to become star-forming clouds of cold molecular gas, and the unique, far ultraviolet capabilities of Hubble allowed us to directly observe these 'showers' of star formation," said Tremblay, who is a NASA Einstein Fellow at Yale. "We know that these showers are linked to the jets because they're found in filaments and tendrils that wrap around the jets or hug the edges of giant bubbles that the jets have inflated, and they end up making a swirling 'puddle' of star-forming gas around the central black hole." Tremblay's work focused on elliptical galaxies in the nearby universe, while Donahue's team looked at galaxies in the more distant universe. Their results indicate that galactic collisions and other extreme cosmic events are not always necessary for the creation of showers of new stars.

Image credit: Courtesy of NASA, the Hubble Space Telescope, Chandra X-ray Observatory, and the Jansky Very Large Array






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