|
|
Hubble Uncovers a Baby Galax
…
| Title |
Hubble Uncovers a Baby Galaxy in a Grown-Up Universe |
|
Hubble Uncovers a Baby Galax
…
| Title |
Hubble Uncovers a Baby Galaxy in a Grown-Up Universe |
|
Hubble Finds 'Dorian Gray' G
…
| Title |
Hubble Finds 'Dorian Gray' Galaxy |
|
Hubble Finds 'Dorian Gray' G
…
| Title |
Hubble Finds 'Dorian Gray' Galaxy |
|
I Zwicky 18: The Case of the
…
| Title |
I Zwicky 18: The Case of the Aging Galaxy |
| Explanation |
How old is this galaxy? The galaxy on the left, I Zwicky 18 [ http://antwrp.gsfc.nasa.gov/apod/ap041203.html ], was once thought to be one of the youngest galaxies on record since its bright stars indicated an age of only 500 million years. The galaxy was also intriguing because it resembled galaxies forming [ http://antwrp.gsfc.nasa.gov/apod/ap070910.html ] in the very early universe, but mysterious since it is so nearby -- only 59 million light years [ http://chandra.harvard.edu/photo/cosmic_distance.html ] away -- and surrounded by galaxies that are significantly older. Recent images [ http://www.spacetelescope.org/images/html/heic0716a.html ] of I Zwicky 18 by the Hubble Space Telescope [ http://antwrp.gsfc.nasa.gov/apod/ap010806.html ] have helped resolve this mystery, discovering a population of old faint stars [ http://antwrp.gsfc.nasa.gov/apod/ap060520.html ] intermixed with the bright star [ http://antwrp.gsfc.nasa.gov/apod/ap060501.html ] population. Therefore I Zwicky 18 [ http://en.wikipedia.org/wiki/I_Zwicky_18 ] is now thought to be just as old as its neighbors, roughly 10 billion years old, but with an intense episode of relative new star formation [ http://antwrp.gsfc.nasa.gov/apod/ap060226.html ]. Possibly the trigger for this recent episode of bright star formation is the changing gravitational influence of I Zwicky 18 [ http://adsabs.harvard.edu/abs/2007ApJ...667L.151A ]'s smaller companion galaxy, visible at the upper right. |
|
I Zwicky 18: Young Galaxy
| Title |
I Zwicky 18: Young Galaxy |
| Explanation |
The Milky Way is an ordinary [ http://antwrp.gsfc.nasa.gov/apod/ap040701.html ] 12 billion year old spiral galaxy, and even our middle-aged Sun is pushing 4.5 billion years. But "all" the stars in dwarf galaxy I Zwicky 18 [ http://hubblesite.org/newscenter/newsdesk/archive/ releases/2004/35/ ] are much younger. In fact, based on Hubble Space Telescope image data, that galaxy's first stars formed only about 500 million years ago, making it the youngest known galaxy. In this view [ http://hubblesite.org/newscenter/newsdesk/archive/ releases/2004/35/image/a ], the bright knots are the two major star forming [ http://antwrp.gsfc.nasa.gov/apod/ap040205.html ] regions of I Zwicky [ http://nedwww.ipac.caltech.edu/level5/Sept02/ Zwicky/frames.html ] 18, embedded in expanding filaments of glowing interstellar gas. Scattered, much older background galaxies are seen as small red blobs, and a companion galaxy lies just beyond the upper right corner of the cropped picture. Astronomers believe that diminutive I Zwicky 18 [ http://arxiv.org/abs/astro-ph/0408391 ] resembles the earliest galaxies formed, but also want to understand how such a young galaxy can be only 45 million light-years away - surrounded by mature galaxies in an aging Universe [ http://antwrp.gsfc.nasa.gov/apod/ap031231.html ]. The tiny galaxy itself is a mere 3,000 light-years across [ http://hubblesite.org/newscenter/newsdesk/archive/ releases/2004/35/fastfacts/ ]. |
|
|
