Oferte Emag

Stars forced to relocate near the Southern Fish

stars-forced-to-relocate-near-the-southern-fish

Copyright ESA

A new Hubble image shows three galaxies locked in a gravitational tug-of-war that may result in the eventual demise of one of them.

About 100 million light-years away, in the constellation of Piscis Austrinus (the Southern Fish), three galaxies are playing a game of gravitational give-and-take that might ultimately lead to their merger into one enormous entity.

A new image from the Advanced Camera for Surveys on the NASA/ESA Hubble Space Telescope allows astronomers to view the movement of gases from galaxy to galaxy, revealing the intricate interplay among them.

The three pictured galaxies — NGC 7173 (middle left), NCG 7174 (middle right) and NGC 7176 (lower right) — are part of the Hickson Compact Group 90, named after astronomer Paul Hickson, who first catalogued these small clusters of galaxies in the 1980s. NGC 7173 and NGC 7176 appear to be smooth, normal elliptical galaxies without much gas and dust.

In stark contrast, NGC 7174 is a mangled spiral galaxy, barely clinging to independent existence as it is ripped apart by its close neighbours. The strong tidal interaction surging through the galaxies has dragged a significant number of stars away from their home galaxies. These stars are now [...]

Mystery spiral arms explained

mystery-spiral-arms-explained

Copyright ESA

Using a trio of space observatories, astronomers may have cracked a 45-year old mystery surrounding two ghostly spiral arms in the galaxy M106 (NGC 4258).

The results, obtained by a team from the University of Maryland (USA), took advantage of the unique capabilities of the ESA’s XMM-Newton X-ray observatory, NASA’s Chandra X-ray Observatory, and NASA’s Spitzer Space Telescope.

M106 (also known as NGC 4258) is a spiral galaxy 23.5 million light-years away, in the constellation Canes Venatici. In visible-light images, two prominent arms emanate from the bright nucleus and spiral outward. These arms are dominated by young, bright stars, which light up the gas within the arms.

“But in radio and X-ray images, two additional spiral arms dominate the picture, appearing as ghostly apparitions between the main arms,” says team member Andrew Wilson of the University of Maryland. These so-called “anomalous arms” consist mostly of gas.

“The nature of these anomalous arms is a long-standing puzzle in astronomy,” says Yuxuan Yang, lead author of the team. “They have been a mystery since they were first discovered in the early 1960s.”

By analyzing data from XMM-Newton, Spitzer, and Chandra, the team have confirmed earlier suspicions that the ghostly arms [...]