Family portrait of the stars
Posted: Friday, August 22, 2008 6:22 PM by Alan Boyle
The team behind NASA's Spitzer Space Telescope is celebrating the orbiting observatory's fifth birthday with a glittering, multigenerational picture of a star-forming region.
CfA / NASA / JPL-Caltech |
Stars young and old glitter in the Spitzer Space Telescope's latest infrared view of the W5 star-forming region. Click on the image for a larger version.
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The new infrared view of the W5 region in the constellation Cassiopeia was unveiled today at Los Angeles' Griffith Observatory as part of a celebration marking five years since Spitzer's launch in 2003. The view takes in an area of the sky equivalent to four full moons, 6,500 light-years from Earth, in one of our Milky Way's most picturesque stellar nurseries.
Three years ago, an earlier Spitzer picture of WB was hailed as showing the "Mountains of Creation," a vista of dust, gas and stars on a par with Hubble's "Pillars of Creation." The latest picture offers a wider view - and shows how one generation of massive stars gives rise to the next. That's something astronomers have been trying to pin down for years.
"Triggered star formation continues to be very hard to prove. But our preliminary analysis shows that the phenomenon can explain the multiple generations of stars seen in the W5 region," Xavier Koenig of the Harvard Smithsonian Center for Astrophysics said in a news release issued jointly by the center, NASA and the Spitzer Science Center at Caltech.
Koenig is the lead author of a paper about the findings that has been accepted for publication in The Astrophysical Journal. The idea is that when a star-forming region of gas and dust kicks into high gear, the most massive stars are formed first in the region's core. Such stars range from 15 to 60 times the mass of our sun, scientists say.
Some of that stellar material flies off in radiation-driven gusts of cosmic wind, carving out cavities around the stars and compressing the gas and dust along the rims of those cavities. That squeezes out the next generation of stars - and the process continues, moving out from the star-forming core.
The result should be a radial "family tree," with the oldest stars in the center, and progressively younger stars farther out, astronomers say.
Two hollow cavities are on display in today's wide-angle photo. The blue dots are older, more massive stars, and the pink and white dots represent younger stars shrouded in the "Mountains of Creation."
Spitzer takes its pictures in infrared wavelengths, which makes the space telescope a better choice than Hubble for peering through the dust surrounding the stars. Koenig and his colleagues made age estimates for the stars in the cavities as well as the stars on the edges - and found that the pattern matched what would be expected for a radial family tree.
"Our first look at this region suggests we are looking at one or two generations of stars that were triggered by the massive stars," Lori Allen of the Center for Astrophysics said in the news release. "We plan to follow up with even more detailed measurements of the stars' ages to see if there is a distinct time gap between the stars just inside and outside the rim."
The march of the stellar generations is expected to continue for millions of years. But when the central massive stars blow apart, they're likely to kill some of their children as well - a violent turn in a family drama that's more star-studded than "The Sopranos."
For more stunners from Spitzer, feast your eyes on the space telescope's first science images, as well as this colorful view of our galaxy's dusty core and a look at the faraway Fireworks Galaxy.
In addition to Koenig and Allen, authors of the upcoming Astrophysical Journal paper include Smith College's Robert Gutermuth, the University of Exeter's Chris Brunt, the University of Arizona's James Muzerolle and the Center for Astrophysics' Joseph Hora.
