Sunday, 12 April 2015
Our star is five billion years younger than most in the Milky Way
Our sun is nearly 4.5 billion years — which means it missed the charming initial years of the Milky Way galaxy. If you were standing on a planet nearly about 10 billion years ago, when the Milky Way was pretty young, the night sky would have appeared very different. The image below is an artist's impression of the night sky on a planet in a relatively young Milky Way-type galaxy, the way our galaxy was 10 billion years ago. You can see "the sky are ablaze with star birth. Pink clouds of gas harbor newborn stars, and bluish-white, young star clusters litter the landscape," as NASA explains.
Image Credit: NASA/ESA/Z. Levay (STScI)
A recent study of young galaxies like our own demonstrates that as these galaxies slow down creating stars, they also stop developing as quickly in general. Which is quite logical. NASA explains:
“Astronomers don’t have baby pictures of our Milky Way’s formative years to trace the history of stellar growth so they studied galaxies similar in mass to our Milky Way, found in deep surveys of the universe. The farther into the universe astronomers look, the further back in time they are seeing, because starlight from long ago is just arriving at Earth now. From those surveys, stretching back in time more than 10 billion years, researchers assembled an album of images containing nearly 2,000 snapshots of Milky Way-like galaxies. The new census provides the most complete picture yet of how galaxies like the Milky Way grew over the past 10 billion years into today’s majestic spiral galaxies. The multi-wavelength study spans ultraviolet to far-infrared light, combining observations from NASA’s Hubble and Spitzer space telescopes, the European Space Agency’s Herschel Space Observatory, and ground-based telescopes, including the Magellan Baade Telescope at the Las Campanas Observatory in Chile.”
Above is a selection of Hubble Space Telescope photos, displaying how galaxies similar to our own developed over time.
Source : Physics-astronomy