February 14, 2013
Arp 274, a triplet of galaxies in Virgo
Image Credit: NASA, ESA, M. Livio and the Hubble Heritage Team (STScI/AURA)
Especially for Valentine’s Day: Two Lovers and their Little Baby
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Arp 274 (also known as the NGC 5679 group) is a triplet of galaxies that span about 200,000 light-years, and that appear to be partially overlapping in the image. They are located around 400 million light-years away in the constellation of Virgo.
The galaxies are designated: NGC 5679A (right, aka MCG 1-37-34), a spiral galaxy; the largest in the center is NGC 5679B, a barred spiral galaxy (aka NGC 5679 and MCG 1-37-35) and NGC 5679C (left, aka MCG+1-37-36), a small compact galaxy. The name “Arp 274” derives from being included in Arp’s Atlas of Peculiar Galaxies, a catalog of 338 peculiar galaxies, drawn up by Halton Arp in the years from 1962 through 1967.
Although the galaxies of Arp 274 were previously thought to be interacting gravitationally, there seems to be little evidence for this. The spiral shapes of the two larger galaxies appear mostly intact, without the distortions typical of interacting galaxies. The third galaxy (to the far left) shows evidence of star formation.
They may in fact be three galaxies located in the same area of the sky but probably at somewhat different distances. The redshifts of the three components of this system are: left 7483 kilometers per second, central 8654 kilometers per second, and right 7618 kilometers per second. By conventional interpretation left and right are of the same order of distance, while the center galaxy should be a background object.
Two of the three galaxies are forming new stars at a high rate. This is evident in the bright blue knots of star formation that are strung along the arms of the galaxy on the right and along the small galaxy on the left. All three galaxies are laced with dark dust lanes, visible in silhouette against the bright backgrounds.
The central bulges house older, yellowish stars and a bright central cluster of stars. A bright central cluster of stars pinpoint each nucleus. Younger blue stars trace the spiral arms, along with pinkish nebulae that are illuminated by new star formation. The two bright stars immediately above the galaxy on the right are actually located much closer, in fact they are in our own galaxy.
This image was produced by Hubble’s Wide Field and Planetary Camera 2, and is a blend of blue, visible, infrared and hydrogen emissions.