Dramatically backlit dust in giant galaxy

Apr 07, 2009
The NASA/ESA Hubble Space Telescope captured this image of NGC 7049 in the constellation of Indus, in the southern sky. A family of globular clusters appears as glittering spots dusted around the galaxy halo. Astronomers study the globular clusters in NGC 7049 to learn more about its formation and evolution. The dust lanes, which appear as a lacy web, are dramatically backlit by the millions of stars in the halo of NGC 7049. Credit: NASA, ESA and W. Harris (McMaster University, Ontario, Canada)

A new Hubble image highlights striking swirling dust lanes and glittering globular clusters in oddball galaxy NGC 7049.

The NASA/ESA's has captured this image of NGC 7049, a mysterious looking galaxy on the border between spiral and elliptical . NGC 7049 is found in the constellation of Indus, and is the brightest of a cluster of galaxies, a so-called Brightest Cluster Galaxy (BCG). Typical BCGs are some of the oldest and most . They provide excellent opportunities for astronomers to study the elusive globular clusters lurking within.

The globular clusters in NGC 7049 are seen as the sprinkling of small faint points of light in the galaxy's halo. The halo - the ghostly region of diffuse light surrounding the galaxy - is composed of myriads of individual stars and provides a luminous background to the remarkable swirling ring of dust lanes surrounding NGC 7049's core. Globular clusters are very dense and compact groupings of a few hundreds of thousands of stars bound together by gravity. They contain some of the first stars to be produced in a galaxy. NGC 7049 has far fewer such clusters than other similar giant galaxies in very big, rich groups. This indicates to astronomers how the surrounding environment influenced the formation of galaxy halos in the early Universe.

The image was taken by the Advanced Camera for Surveys on Hubble, which is optimised to hunt for galaxies and in the remote and ancient Universe, at a time when our cosmos was very young.

The constellation of Indus, or the Indian, is one of the least conspicuous in the southern sky. It was named in the 16th century by Dutch astronomer Petrus Plancius from observations made by Dutch navigator Pieter Dirkszoon Keyser and Dutch explorer Frederick de Houtman.

Source: European Space Agency (news : web)

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1 / 5 (3) Apr 07, 2009
I notice that the red shifts of the parent galaxy and it's offspring was conspicuously left out... I wonder if the establishment won't try and convince us that the globular clusters aren't billions of light years away behind the main galaxy and that the above pic isn't an "optical illusion caused by gravity lensing" or some such... ;)
1 / 5 (2) Apr 07, 2009
It would be kind of nice if, somewhere anywhere, on the internet we would be informed how big is big. 200 thousand light years across? 1 million light years? Anything?
4.5 / 5 (2) Apr 08, 2009
small or big should always be linked to the frame of reference in which we are talking. If you take our galaxy, then 100.000 light years is rather large, about 2 times the radius (if i'm not mistaken). If you are talking about multiple galaxies, then 1 million light years isn't really a large distance. Talking about the universe, then 1 million light years is very small and 1 billion is rather large.
So you need to see things in perspective ;-)
5 / 5 (1) Apr 08, 2009
NGC 7049 is an interesting object in the southern sky that is not targeted very often. In size it is about 4.3×3.1 arcmin, whose magnitude is fairly bright 11.7B and has high surface brightness. A moderate amateur telescope also sees mostly the small stellar-like core with a even haze that fades out to the galaxy%u2019s edges.
A mean radial velocity is about 2300km.s^-1, making the distance 29 Mpc. (megaparsecs). The real scale is about 8.3 kpc per arcmin.
Position RA : 21h 19.0m Dec. -48 deg 34 (2000). According to Machetto, F. %u201CA Survey of the ISM in early-type galaxies%u201D; A&A Sup.Ser., 120, 463 (1996) http://adsabs.har...bs/1996A&AS..120..463M , the total mass is about 2.3×10^11 Solar Masses (230 billion solar masses.) Compared to our own Milky Way galaxy, whose mass is 5.8×10^11 Solar Masses - so NGC 7049 must be about half the mass of our own galaxy.
Future investigations may find NGC 7049 might be a little larger than this. Again a nice image from Hubble! Thanks for posting it.
4 / 5 (2) Apr 08, 2009
Thanks WZ - we now can see that this giant galaxy is half the mass of our own average sized galaxy.

One thing is correct though. The picture looks amazing.

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