Credit: The Hubble Heritage Team (AURA/STScI/NASA/ESA)

Space Telescope Science Institute astronomers are giving the public chances to decide where to aim NASA's Hubble Space Telescope. Guided by 8,000 Internet voters, Hubble has already been used to take a close-up, multi-color picture of the most popular object from a list of candidates, the extraordinary "polar-ring" galaxy NGC 4650A. Located about 130 million light-years away, NGC 4650A is one of only 100 known polar-ring galaxies. Their unusual disk-ring structure is not yet understood fully. One possibility is that polar rings are the remnants of colossal collisions between two galaxies sometime in the distant past, probably at least 1 billion years ago. What is left of one galaxy has become the rotating inner disk of old red stars in the center. Meanwhile, another smaller galaxy which ventured too close was probably severely damaged or destroyed. During the collision the gas from the smaller galaxy would have been stripped off and captured by the larger galaxy, forming a new ring of dust, gas, and stars, which orbit around the inner galaxy almost at right angles to the old disk. This is the polar ring which we see almost edge-on in Hubble's Wide Field Planetary Camera 2 image of NGC 4560A, created using 3 different color filters (which transmit blue, green, and near-infrared light). This HST image clearly distinguishes structures in this extraordinary galaxy that only recently were discovered in images made using large ground-based telescopes. It also displays features that were previously unknown. The image confirms that the bright central concentration of light, which appears to be slightly orange in this image, has a completely smooth, regular appearance, indicating that it is a dense system composed of older stars and containing little gas or dust. We believe this was once a typical medium-sized galaxy that has been altered, probably by the process that made the complex polar ring. The central dark lanes are due to blockage of light by clouds of gas and dust i

Provider: Space Telescope Science Institute

Image Source: https://hubblesite.org/contents/news-releases/1999/news-1999-16

Curator: STScI, Baltimore, MD, USA

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