It is a galaxy like ours but seen edge-on
By BBC News Online science editor Dr
David Whitehouse
This is the "edge-on" galaxy, NGC 4013, as seen by the Hubble Space Telescope (HST). It is edge on in the sense that this is how we view the galaxy's main disc of material.
NGC 4013 is actually a spiral galaxy, similar to our own Milky Way, and lies about 55 million light-years away in the constellation of Ursa Major, the Great Bear. If it was viewed from above, or pole-on, it would probably appear circular in shape.
But this angle of view allows the HST to scrutinise aspects of the galaxy's structure that would otherwise be difficult to get at.
Dark clouds of interstellar dust stand out because they absorb light from background stars. Most of the dust clouds lie in the plane of the galaxy, forming the dark band which is about 500 light-years thick. A light year is 9.6 million, million km (six million, million miles).
By studying the colour and the quantity of light absorbed by the dust clouds, astronomers can estimate the amount of matter in them. Such clouds can contain as much as one million times the amount of mass in our Sun.
Such dark interstellar clouds are believed to be the sites where new stars are born. Later, when the dust disperses, the young stars become visible as clusters of hot and bright blue objects.
Several examples of these stellar nurseries can
be seen in front of the dark band along the
galaxy's equator.
-- Anonymous, March 01, 2001