Astronomers using the NASA/ESA/CSA James Webb Space Telescope have captured a new infrared image of a pair of interacting galaxies known as Arp 142.
This Webb image shows two interacting galaxies known as Arp 142: at left is NGC 2937, nicknamed the Egg for its appearance; at right is NGC 2936, nicknamed the Penguin for its appearance. Image credit: NASA / ESA / CSA / Webb / STScI.
The interacting pair Arp 142 is located about 326 million light-years away in the southern constellation of Hydra.
The system is a member of the Arp catalog of peculiar galaxies observed by astronomer Halton C. Arp in the 1960s.
It contains the star-forming spiral galaxy NGC 2936 along with its elliptical companion NGC 2937 at lower left, and bears a striking resemblance to a penguin guarding its egg.
The ‘Penguin’ part of the pair, NGC 2936, was probably once a relatively normal-looking spiral galaxy, flattened like a pancake with smoothly symmetric spiral arms.
Rich with newly-formed hot stars, its shape has now been twisted and distorted as it responds to the gravitational tugs of its neighbor.
The ‘Egg’ of the pair, NGC 2937, hosts a population of much older stars and, by contrast, is nearly featureless.
The absence of glowing red dust features informs us that it has long since lost its reservoir of gas and dust from which new stars can form.
“The pair made their first pass between 25 and 75 million years ago — causing ‘fireworks,’ or new star formation, in the Penguin,” the Webb astronomers said in a statement.
“In the most extreme cases, mergers can cause galaxies to form thousands of new stars per year for a few million years.”
“For the Penguin, research has shown that about 100 to 200 stars have formed per year. By comparison, our Milky Way Galaxy (which is not interacting with a galaxy of the same size) forms roughly six to seven new stars per year.”
“This gravitational shimmy also remade the Penguin’s appearance,” they noted.
“Its coiled spiral arms unwound, and gas and dust were pulled in an array of directions, like it was releasing confetti.”
“It is rare for individual stars to collide when galaxies interact (space is vast), but the galaxies’ mingling disrupts their stars’ orbits.”
“Today, the Penguin’s galactic center looks like an eye set within a head, and the galaxy has prominent star trails that take the shape of a beak, backbone, and fanned-out tail. A faint, but prominent dust lane extends from its beak down to its tail.”
“Despite the Penguin appearing far larger than the Egg, these galaxies have approximately the same mass,” the astronomers said.
“This is one reason why the smaller-looking Egg hasn’t yet merged with the Penguin.”
“The oval Egg is filled with old stars, and little gas and dust, which is why it isn’t sending out ‘streamers’ or tidal tails of its own and instead has maintained a compact oval shape.”
“If you look closely, the Egg has four prominent diffraction spikes — the galaxy’s stars are so concentrated that it gleams.”
“Now, find the bright, edge-on galaxy at top right. It may look like a party crasher, but it’s not nearby.”
Cataloged LEDA 1237172, it lies 100 million light-years closer to Earth. It is relatively young and isn’t overflowing with dust, which is why it practically disappears in Webb’s mid-infrared view.”
Source : Breaking Science News