December 10, 2013
NGC 454, interacting galaxies in Phoenix
Image Credit: NASA, ESA, the Hubble Heritage (STScI/AURA)-ESA/Hubble Collaboration, and M. Stiavelli (STScI)
NGC 454 is an interacting pair of galaxies which is located about 154 million light-years away from Earth in the southern constellation of Phoenix, while it is speeding away from us at approximately 3,645 kilometers per second.
The pair consists of NGC 454W(est) or PGC 4461, an irregular gas-rich blue galaxy of some 50 thousand light-years across, which may have been a disk galaxy, and NGC 454E(ast) or PGC 4468, a large red elliptical galaxy of about 85 thousand light-years across.
The system is in the early stages of an interaction that has already severely distorted both components. Other evidence for the interaction between the galaxies comes from the fact that both objects are embedded in a common, low surface brightness halo, and from the young stellar populations in the system.
A population of young, bright blue star clusters has formed around the irregular blue galaxy less than 5–10 million years ago and is probably also part of it. The three very blue knots to the right of the two main components are possible young globular clusters.
Although the dust lanes that stretch all the way to the center of the elliptical galaxy suggest that gas has penetrated that far, no signs of significant star formation or nuclear activity are visible, even though there probably are recently formed stars in its nucleus.
This image is taken on March 6, 1997 with the Wide Field Planetary Camera 2 onboard the Hubble Space Telescope using three different color filters. It is part of a large collection of 59 images of merging galaxies taken by the Hubble Space Telescope and released on the occasion of its 18th anniversary on 24th April 2008.