Super Star Clusters
In The Antennae Galaxies
(17 October 2006) This new NASA Hubble
Space Telescope image of the Antennae galaxies is the sharpest yet of this
merging pair of galaxies.
During the course of the collision,
billions of stars will be formed. The brightest and most compact of these star
birth regions are called super star clusters.
(courtesy: NASA, ESA, and the Hubble Heritage Team (STScI/AURA)-ESA/Hubble Collaboration)
The two spiral galaxies started to interact
a few hundred million years ago, making the Antennae galaxies one of the
nearest and youngest examples of a pair of colliding galaxies. Nearly half of
the faint objects in the Antennae image are young clusters containing tens of
thousands of stars. The orange blobs to the left and right of image centre are
the two cores of the original galaxies and consist mainly of old stars
criss-crossed by filaments of dust, which appears brown in the image. The two
galaxies are dotted with brilliant blue star-forming regions surrounded by
glowing hydrogen gas, appearing in the image in pink.
The new image
allows astronomers to better distinguish between the stars and super star
clusters created in the collision of two spiral galaxies. By age dating the
clusters in the image, astronomers find that only about 10 percent of the newly
formed super star clusters in the Antennae will survive beyond the first 10
million years. The vast majority of the super star clusters formed during this
interaction will disperse, with the individual stars becoming part of the
smooth background of the galaxy. It is however believed that about a hundred of
the most massive clusters will survive to form regular globular clusters,
similar to the globular clusters found in our own Milky Way galaxy.
The
Antennae galaxies take their name from the long antenna-like "arms" extending
far out from the nuclei of the two galaxies, best seen by ground-based
telescopes. These "tidal tails" were formed during the initial encounter of the
galaxies some 200 to 300 million years ago. They give us a preview of what may
happen when our Milky Way galaxy will collide with the neighbouring Andromeda
galaxy in several billion years.
Acknowledgement: B. Whitmore (Space
Telescope Science Institute)
(source: Space Telescope Science
Institute)