While doing my rutine of reading WRH website I stumbled upon this story; thought some of you may find this interesting. Telescope Finds Bigger 'Baby' Galaxies By Associated Press December 23, 2004, 4:08 AM EST PASADENA, Calif. -- An orbiting NASA telescope that scans the heavens has found evidence of massive "baby" galaxies that runs counter to a belief that only small new galaxies are being formed by the aging universe. The findings released Tuesday come from the Galaxy Evolution Explorer, a mission led by the California Institute of Technology that was launched into Earth orbit in 2003 to study 10 billion years of the evolution of galaxies. "We knew there were really massive young galaxies eons ago, but we thought they had all matured into older ones more like our Milky Way," said Chris Martin, principal investigator for Galex at Caltech. "If these galaxies are indeed newly formed, then this implies parts of the universe are still hotbeds of galaxy birth," Martin said in a statement issued by NASA's Jet Propulsion Laboratory. The discoveries include three dozen bright and compact galaxies that look like the young galaxies that existed more than 10 billion years ago, the researchers said. Those galaxies are considered to be relatively close, on the order of 2 billion to 4 billion light years from Earth, and their ages may be 100 million years to 1 billion years. By comparison, Earth's galaxy, the Milky Way, is about 10 billion years old. The researchers said the discoveries will allow scientists to see what the Milky Way might have looked like when it was young. "It's like finding a living fossil in your own backyard," said Tim Heckman of Johns Hopkins University in Baltimore, one of Martin's colleagues. "We thought this type of galaxy had gone extinct, but in fact newborn galaxies are alive and well in the universe." The Galaxy Evolution Explorer made the discoveries because it has sensitive ultraviolet light detectors, and young stars emit mostly ultraviolet wavelengths. The mission was developed under a program at NASA's Explorers Program at Goddard Space Flight Center in Greenbelt, Md. JPL manages the mission. Two other nations, South Korea and France, are partners in it. http://www.newsday.com/news/nationw...94816.story?coll=sns-ap-nationworld-headlines Images: http://www.nasa.gov/centers/jpl/missions/galex.html Godless.
cool but this brings up some questions i have been wondering about.. how are they deciding how a young galaxy is young? by the age of their stars? by how big it "appears" to be? really the milky way could be such a tiny galaxy on the grand scale of the universe and the galaxies it contains. I think its good we are searching for other galaxies, but speculation on whether they are young or old should remain till we have more accurate way of proving that. From my expierence they use planet and star formation to depict a galaxies "age" as according to NASA. How can we see supernova remnants? How do we not know that solar system once blew up and is now repairing itself with new formation of stars and planets? I dont personally understand this maybe due to a lack of education as of yet. if someone would care to elaborate for me that would be awesome, especially if im wrong Please Register or Log in to view the hidden image!
Hum, Good point... Yeah the hydrogen gas has just begun to form stars. We know that the stars are young due to the spectra - that the stars lack the heavy elements and are metal poor, also that they emit mostly ultraviolet wavelengths. The evolution of stars are well understood ... (look up Hertzberg Russell diagrams) The new galaxies are the tail end of the bulk of galaxy production that occurred very early on in the history of the universe, and may be due to the gases thrown off during very early galaxy collisions, and that are just now coalescing together now...
Ah! well It's determined by size. But this web site here can explain it better than I ever could. Godless.
If observers can discerne two distinct stellar populations within a galaxy, with different metallicity, spectra and percentage of high-mass stars, there's another major clue that the galaxy has a long history behind it.
http://www.maddad.org/astronomy/galaxies.htm I discovered a pic of a very young galaxy, I Zwicky 18, that I included in my galaxy photos. It's a bit of a mystery because it isn't where it ought to be, and it isn't when it ought to be. We determine age by the age of the oldest stars in the galaxy that have not yet left the main sequence. Since the galaxy exhibits almost no metalicity, that means that there were no previous generations of stars that enriched the interstellar medium with heavier elements. The gas in I Zwicky 18 is primordial.
