As part of my Ph.D. thesis, I am working with my advisor Holland Ford , as well as with collaborators Ken Freeman and Rick White, on the nearby elliptical galaxy NGC 5128 (Centaurus A). We looked for faint, anomolously blue features that could be the signatures of small galaxies that have fallen in and merged with Cen A. The picture at left shows a blue arc (identified by arrows) that traces a partial ellipse around the galaxy center. (There is also an image without arrows ). Using our imaging and spectroscopic data, we show that this stream of young stars is likely to have originated in an event 200-400 million years ago when a small dwarf galaxy fell in and was torn apart by the gravitational tidal forces of the larger elliptical. The disruption caused the dwarf galaxy's hydrogen gas to destabilize and collapse, causing a burst of star formation that produced the blue stars and star clusters we see in the arc today. This discovery nicely illustrates how galactic halos can be built up over an extended period of time from the infall and destruction of small galaxies and gas fragments.
Click on the picture for a higher resolution image.
News and Information on Centaurus A Stellar Stream
Johns Hopkins Magazine (February, 2003)
NOAO Newsletter #72 (December, 2002) [We made the cover!]
Astronomy Picture of the Day : "The Outer Shells of Centaurus A", (November 11, 2002)
NOAO Image Gallery: Full-frame and BlueArc (November, 2002)
CNN.com (October 25, 2002)
Aftenposten, [Norwegian paper] (October 22, 2002)
United Press International [UPI] (October 18, 2002)
Science Daily (October 18, 2002)
Astronomy Picture of the Day : "Centaurus A: Young Blue Star Stream", (October 17, 2002)
Astronomy (October 17, 2002)
Space.com (October 17, 2002)
Cosmiverse (October 16, 2002)
Spaceflight Now (October 16, 2002)
SpaceRef.com (October 15, 2002)
National Optical Astronomy Observatory (NOAO) News Release (October 15, 2002)
Johns Hopkins University News Release (October 15, 2002)
Preprint of our paper on arXiv.org
Final published article in the December issue (on the cover!) of Astronomical Journal
Related Links
| Cerro Tololo Inter-american Observatory
(CTIO) |
The observatory near La Serena,
Chile that we used to gather our data. |
|
National Optical Astronomy Observatory (NOAO) |
Funded by the National Science Foundation, they run American
public observatories. |
Page created by Eric Peng
Eric.Peng at nrc-cnrc . gc . ca