As 2010 begins, the Hubble Space Telescope continues to deliver more stunning photos of our universe. Scientists made public a new series of panaromaic photos yesterday that show a view of some of the youngest galaxies in the universe.
Galaxies are the islands of stars filling the cosmos. Large ones such as our own Milky Way galaxy span more than 100,000 light-years (nearly 600,000 trillion miles) and contain hundreds of billions of stars.
The few faint earliest galaxies that emerge from the survey of about 7,500 galaxies are much smaller and filled with young, massive stars. They shine from only 600 million to 800 million years after the Big Bang, which took place about 13.7 billion years ago.
“These are the seeds of later large galaxies like our own,” says astronomer Garth Illingworth of the University of California-Santa Cruz, speaking at the American Astronomical Society meeting. Filled with blue-tinted stars, these early galaxies are only one-twentieth the diameter and have just 1% of the mass of our own galaxy and later ones seen in the Great Observatories Origins Deep Survey panorama.
“We’re literally seeing galaxies of all shapes, ages and sizes,” says astronomer Rogier Windhorst of Arizona State University in Tempe. The image from the new camera installed aboard Hubble makes clear an epoch of “merging” between galaxies 9 billion to 7 billion years ago, Windhorst says.
Combining the chemistry observation from NASA’s Spitzer infrared telescope and Chandra X-ray telescope, astronomers are gaining a complete picture of how galaxies formed, merged and grew, Windhorst adds.
The big mystery is the era when ultraviolet light from the youngest stars electrically charged early clouds of interstellar gas, triggering magnetic effects that played a role in later galaxy formation, says astrophysicist Mario Livio of the Space Telescope Science Institute, which manages Hubble. This “re-ionization” era probably played out just before or during the time when the lives of the early galaxies turned up in the new Hubble images.
Just how it took place and whether early galaxies or perhaps the first black holes were the triggers to re-ionization should be answered by NASA’s James Webb Space Telescope, which launches in 2014.
“We’re just at the beginning of this story,” says former astronaut John Grunsfeld, who led the team that repaired the space telescope last year and now is the deputy chief of Livio’s institute. “It’s incredibly thrilling to see these new instruments working and delivering results.”
Leave a Reply