The NASA/ESA Hubble Space Telescope has produced an outstanding image of the interacting, spiral-lenticular galaxy pair Arp 140.
The lenticular galaxy NGC 274 is visible on the right side of this Hubble image, and the barred spiral galaxy NGC 275 is at left. Image credit: NASA / ESA / R. Foley, University of California – Santa Cruz / Gladys Kober, NASA & Catholic University of America.
Arp 140 is located approximately 70 million light-years away in the constellation of Cetus.
This galaxy duo is part of the Atlas of Peculiar Galaxies, a catalog of 338 galaxies compiled in 1966 by the American astronomer Halton Arp.
It consists of NGC 274 (also known as LEDA 2980) and NGC 275 (LEDA 2984).
NGC 274 is classified as a lenticular galaxy, while NGC 275 is a barred spiral galaxy.
“Lenticular galaxies and barred spiral galaxies have different structures,” the Hubble astronomers explained.
“In barred spiral galaxies, a bar of stars runs through the central bulge of the galaxy (seen here as a bright-white, vertical haze in NGC 275).”
“Typically, the arms of the galaxy start at the end of the bar.”
“Lenticular galaxies, on the other hand, are classified somewhere between elliptical and spiral galaxies,” the researchers added.
“They get their name from the edge-on appearance that resembles a disk.”
“Lenticular galaxies have large central bulges and flattened disk-like spirals, but no spiral arms.”
“They don’t have much gas and dust and are made up primarily of old stars.”
Previous observations of Arp 140 revealed a tidal tail extending many light-years from NGC 275 beyond the interacting pair.
They also showed that in contrast to the often-assumed picture of interacting galaxies, NGC 275 doesn’t display enhanced star formation.
