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 that we see almost edge-on in this Hubble telescope view.
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 was already used to take a close-up, multi-color picture of the most popular object from a list of candidates, the extraordinary ring galaxy NGC 4650A. The Hubble Heritage Project's picture of NGC 4650A is being released today.
Those people who missed the chance to vote for a Hubble space target will have another opportunity beginning today. The Hubble Heritage Project will launch another voting session, extending until June 4th. This time the public will be invited to vote for their favorite target out of three different groups of interacting galaxies. The winning group will be observed with the Hubble Space Telescope in the summer of 1999, and the pictures will be posted on the World Wide Web shortly thereafter. The website address for voting is: http://heritage.stsci.edu