Tuesday, January 10, 2012

Before They Were Stars: New Image Shows Space Nursery

The stars we see today weren't always as serene as they appear, floating alone in the dark of night. Most stars, likely including our sun, grew up in cosmic turmoil - as illustrated in a new image from NASA's Spitzer Space Telescope.

The image shows one of the most active and turbulent regions of star birth in our galaxy, a region called Cygnus X. The choppy cloud of gas and dust lies 4,500 light-years away in the constellation Cygnus the Swan. Cygnus X was named by radio astronomers, since it is one of the brightest radio regions in the Milky Way. (It should not be confused with the black hole Cygnus X-1.)

The Cygnus-X star-forming region is located 4,600 light-years from Earth and spans more than 600 light-years. It contains 10 times as much gas as the Orion Nebula - enough to make over three million Suns. This infrared photograph from the Spitzer Space Telescope reveals more than a thousand protostars in the earliest stages of forming. Light of 3.6 microns is color-coded blue: 4.5-micron light is blue-green; 8.0-micron light is green; and 24-micron light is red.
A bubbling cauldron of star birth is highlighted in this new image from NASA's Spitzer Space Telescope.
Credit: NASA/JPL-Caltech/J. Hora (CfA)

Cygnus X, which spans an area of the sky larger than 100 full moons, is home to thousands of massive stars, and many more stars around the size of our sun or smaller. Spitzer has captured an infrared view of the entire region, which is bubbling with star formation.

"Spitzer captured the range of activities happening in this violent cloud of stellar birth," said Joe Hora of the Harvard-Smithsonian Center for Astrophysics, who is the principal investigator of the research. "We see bubbles carved out from massive stars, pillars of new stars, dark filaments lined with stellar embryos and more."

The majority of stars are thought to form in huge star-forming regions like Cygnus X. Over time, the stars dissipate and migrate away from each other. It's possible that our sun was once packed tightly together with other, more massive stars in a similarly chaotic, though less extreme, region.

The turbulent star-forming clouds are marked with bubbles, or cavities, which are carved out by radiation and winds from the most massive of stars. Those massive stars tear the cloud material to shreds, terminating the formation of some stars, while triggering the birth of others.

"One of the questions we want to answer is how such a violent process can lead to both the death and birth of new stars," said Sean Carey, a team member from NASA's Spitzer Science Center at the California Institute of Technology. "We still don't know exactly how stars form in such disruptive environments.

A bubbling cauldron of star birth is highlighted in this new image from NASA's Spitzer Space Telescope. Infrared light that we can't see with our eyes has been color-coded, such that the shortest wavelengths are shown in blue and the longest in red. The middle wavelength range is green.

Massive stars have blown bubbles, or cavities, in the dust and gas -- a violent process that triggers both the death and birth of stars. The brightest, yellow-white regions are warm centers of star formation. The green shows tendrils of dust, and red indicates other types of dust that may be cooler, in addition to ionized gas from nearby massive stars. Cygnus X is about 4,500 light-years away in the constellation Cygnus, or the Swan.
 
Credit: NASA/JPL-Caltech/J. Hora (CfA)

Blue represents light at 3.6 microns: 4.5-micron light is blue-green; 8.0-micron light is green; and 24-micron light is red. These data were taken before the Spitzer mission ran out of its coolant in 2009, and began its "warm" mission.

Infrared data from Spitzer is helping to answer questions like these by giving astronomers a window into the dustier parts of the complex. Infrared light travels through dust, whereas visible light is blocked. For example, embryonic stars blanketed by dust pop out in the Spitzer observations. In some cases the young stars are embedded in finger-shaped pillars of dust, which line the hollowed-out cavities and point toward the central, massive stars. In other cases, these stars can be seen lining very dark, snake-like filaments of thick dust.

In this new action-packed view of the Cygnus X star-forming region from NASA's Spitzer Space Telescope, stars can be seen at different stages of development. Infrared light that we can't see with our eyes has been color-coded, such that the shortest wavelengths are shown in blue, the longest in red, and the middle wavelengths in green.

The top left box shows AFGL 2636, which is a bright-rimmed shell of material, carved out by winds and radiation from massive stars. These massive stars are located near the tip of the pillar in the center of the region. The inner region is glowing red due to gas that has been ionized by the massive stars. Spitzer has revealed a cluster of young stars with planet-forming disks in the central region, and embryonic stars embedded in the rim around the cavity. The situation is similar in the top right image, a region called DR22.
 
Credit: NASA/JPL-Caltech/J. Hora (CfA)

The lower left and right images show clouds that are so thick to appear dark even to the dust-piercing, infrared eyes of Spitzer. Young stars, visible as red points, are buried in these dark clouds. They are red because they are heating up surrounding dust, causing it to glow at longer infrared wavelengths.

The red orb in the lower right image surrounds what is thought to be a star called a luminous blue variable, visible as the blue central point. This is a more evolved massive star that, after periods of instability, cast off a shell of material (red) from its outer layers. The bright object below the dark cloud in the lower right image is the tip of a large pillar, called DR 15, which is being eroded by winds and radiation from a large number of massive stars located above it.
Another question scientists hope to answer is how these pillars and filaments are related.

"We have evidence that the massive stars are triggering the birth of new ones in the dark filaments, in addition to the pillars, but we still have more work to do," said Hora. "The biggest results from this survey are yet to come."

Infrared light in this image has been color-coded according to wavelength. Light of 3.6 microns is blue: 4.5-micron light is blue-green; 8.0-micron light is green; and 24-micron light is red. These data were taken before the Spitzer mission ran out of its coolant in 2009, and began its "warm" mission.

This release is being issued jointly with the Jet Propulsion Laboratory.

NASA’s Jet Propulsion Laboratory, Pasadena, Calif., manages the Spitzer Space Telescope mission for NASA’s Science Mission Directorate, Washington. Science operations are conducted at the Spitzer Science Center. Caltech manages JPL for NASA. For more information about Spitzer, visit http://spitzer.caltech.edu/ and http://www.nasa.gov/spitzer.

Headquartered in Cambridge, Mass., the Harvard-Smithsonian Center for Astrophysics (CfA) is a joint collaboration between the Smithsonian Astrophysical Observatory and the Harvard College Observatory. CfA scientists, organized into six research divisions, study the origin, evolution and ultimate fate of the universe.

Contacts and sources:
David A. Aguilar
Director of Public Affairs
Harvard-Smithsonian Center for Astrophysics

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