Spaceflight Now Home



Spaceflight Now +



Subscribe to Spaceflight Now Plus for access to our extensive video collections!
How do I sign up?
Video archive

Discovery moves to VAB

Shuttle Discovery is transported from its hangar to the Vehicle Assembly Building for attachment to the external tank and boosters.

 Play

STS-120: The programs

In advance of shuttle Discovery's STS-120 mission to the station, managers from both programs discuss the flight.

 Play

STS-120: The mission

Discovery's trip to the station will install the Harmony module and move the P6 solar wing truss. The flight directors present a detailed overview of STS-120.

 Part 1 | Part 2

STS-120: Spacewalks

Five spacewalks are planned during Discovery's STS-120 assembly mission to the station. Lead spacewalk officer Dina Contella previews the EVAs.

 Full briefing
 EVA 1 summary
 EVA 2 summary
 EVA 3 summary
 EVA 4 summary
 EVA 5 summary

The Discovery crew

The Discovery astronauts, led by commander Pam Melroy, meet the press in the traditional pre-flight news conference.

 Play

STS-69: The Dog Crew

Astronauts flying aboard shuttle Endeavour in September 1995 called themselves the Dog Crew, a lighthearted twist to their complicated mission to launch and then retrieve a pair of satellites.

 Play

Riding on Endeavour

Now you can take a virtual trip aboard shuttle Endeavour's recent launch thanks to video cameras mounted inside the ship's cockpit as well as outside on the twin solid rocket boosters and external tank.

 Full Coverage

"The Time of Apollo"

This stirring 1970s documentary narrated by Burgess Meredith pays tribute to the grand accomplishments of Apollo as men left Earth to explore the Moon and fulfill President Kennedy's challenge to the nation.

 Play

Become a subscriber
More video



Orphan stars discovered in long galaxy tail
CHANDRA X-RAY CENTER NEWS RELEASE
Posted: September 24, 2007

Astronomers have found evidence that stars have been forming in a long tail of gas that extends well outside its parent galaxy. This discovery suggests that such "orphan" stars may be much more prevalent than previously thought.


This composite image of X-ray and optical light shows a tail that has been created as a galaxy plunges into a cluster, shedding material and forming stars behind it. Credit: X-ray: NASA/CXC/MSU/M.Sun et al; H-alpha/Optical: SOAR (MSU/NOAO/UNC/CNPq-Brazil)/M.Sun et al.
 
The comet-like tail was observed in X-ray light with NASA's Chandra X-ray Observatory and in optical light with the Southern Astrophysical Research (SOAR) telescope in Chile. The feature extends for more than 200,000 light years and was created as gas was stripped from a galaxy called ESO 137-001 that is plunging toward the center of Abell 3627, a giant cluster of galaxies.

"This is one of the longest tails like this we have ever seen," said Ming Sun of Michigan State University, who led the study. "And, it turns out that this is a giant wake of creation, not of destruction."

The observations indicate that the gas in the tail has formed millions of stars. Because the large amounts of gas and dust needed to form stars are typically found only within galaxies, astronomers have previously thought it unlikely that large numbers of stars would form outside a galaxy.

"This isn't the first time that stars have been seen to form between galaxies," said team member Megan Donahue, also of MSU. "But the number of stars forming here is unprecedented."

The evidence for star formation in this tail includes 29 regions of ionized hydrogen glowing in optical light, thought to be from newly formed stars. These regions are all downstream of the galaxy, located in or near the tail. Two Chandra X-ray sources are near these regions, another indication of star formation activity. The researchers believe the orphan stars formed within the last 10 million years or so.

The stars in the tail of this fast-moving galaxy, which is some 220 million light years away, would be much more isolated than the vast majority of stars in galaxies.

"By our galactic standards, these are extremely lonely stars," said Mark Voit, another team member from MSU. "If life was to form out there on a planet a few billion years from now, they would have very dark skies."

The gas that formed the orphan stars was stripped out of its parent galaxy by the pressure induced by the motion of the galaxy through the multimillion degree gas that pervades the intergalactic space of the galaxy cluster. Eventually most of the gas will be scoured from the galaxy, depleting the raw material for new stars, and effectively stopping further star formation in the galaxy.

This process may represent an important but short-lived stage in the transformation of a galaxy. Although apparently rare in the present-day universe, galactic tails of gas and orphan stars may have been more common billions of years ago when galaxies were younger and richer in star-forming gas.

These results will appear in the December 10th issue of The Astrophysical Journal. NASA's Marshall Space Flight Center, Huntsville, Ala., manages the Chandra program for the agency's Science Mission Directorate. The Smithsonian Astrophysical Observatory controls science and flight operations from the Chandra X-ray Center in Cambridge, Mass. The SOAR (Southern Astrophysical Research Telescope) is a joint project of Michigan State University, Conselho Nacional de Pesquisas Científicas e Tecnologicas (CNPq-Brazil), The University of North Carolina at Chapel Hill, and the National Optical Astronomy Observatory.