... Its remarkable features include prominent dust lanes, a bright, point-like nucleus, and a bright, bluish ring dominated by the light of young, massive stars. The massive stars in the ring are all likely less than 10 million years old, indicating the galaxy experienced a well-defined era of rapid star formation. ... Publications with keywords: spiral galaxy - star formation . Publications with words: spiral galaxy - star formation . ... NGC 4911: Spiral Diving into a Dense Cluster . ...

... Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer. 2009 July 17 . Starburst Galaxy M94 . ... As a result, while the small, bright nucleus is typical of the Seyfert class of active galaxies, M94 is also known as a starburst galaxy . Because M94 is relatively nearby, astronomers can explore in detail reasons for the galaxy's burst of star formation. ... About APOD | ...

In this gallery are many images of Low Surface Brightness Galaxies which have recently been discovered and analyzed. ... The central surface brightness of this galaxy is 24.28 . Malin 2 This galaxy is another huge disk galaxy with a scale length of 15 kpc and a redshift of 15000 km/a. The high surface brightness knot in one of its spiral arms actually has the same color, luminosity and H-alpha equivalent width as the entire Large Magellanic Cloud . ... Truly it is a Low Surface Brightness Galaxy. ...

An Ancient Universe: How Astronomers Know the Vast Scale of Cosmic Time . THE ANCIENT UNIVERSE . c) The Age of Light from the Most Distant Galaxies: The "Time Machine" Effect . ... Thus we are actually seeing these galaxies not as they are today, but as they were billions of years ago. ... The Universe: An Overview | ... The Ancient Universe - The Age of the Expanding Universe - The Age of the Oldest Stars - The Age of Light From Distant Galaxies - The Age of the Chemical Elements | ...

... For more distant stars we must use other techniques. ... Hence if we see a distant galaxy and can pick out any cepheids lying within it, we can calculate its distance. ... Here then is another method to gauge the size of the Universe and there are yet more. volume at high enough temperature a nuclear fusion reaction sweeps across the white dwarf's surface and eventually we will see a spectacularly bright new star (hence nova) in our skies. ... Why is this relevant to the size of the Universe? ...

... Our Sun is part of a huge wheel-shaped collection of stars. ... Astronomers have long suspected it was a very massive black hole, and that every galaxy had such a central mass, created early in the history of the universe. ... However, unless that object happens to be headed directly at the black hole (a relatively small target) it will just swing around and fly away again, like a comet making a pass at the Sun. The velocity acquired in falling towards the black hole also helps it escape. ...