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Spitzer Captures Fruits of Massive Stars’ Labors

May 30, 2005

Astronomers using NASA’s Spitzer Space Telescope have imaged a giant molecular cloud being shredded by howling stellar winds and searing radiation, exposing a group of towering dust pillars harboring infant stars, according to a University of Colorado at Boulder researcher.

Nathan Smith, a Hubble Fellow and postdoctoral researcher at CU-Boulder’s Center for Astrophysics and Space Astronomy, said the violent panorama is unfolding in the Carina Nebula, located in the southern Milky Way some 10,000 light years from Earth.

The orbiting infrared telescope imaged a new generation of stars in various stages of evolution, several dozen of which now gleam like gems at the heads of huge dust pillars created by the galactic weather conditions.

“Spitzer is providing us with the first snapshot of a molecular cloud being shredded on such a large scale,” said Smith. “Stellar winds and blowtorch-like radiation coming off the massive stars are ripping apart the cloud, exposing a new generation of stars at the ends of these pillars.”

Smith presented the results of the NASA-funded study at the 206th meeting of the American Astronomical Society held May 29 to June 2 in Minneapolis.

“One of the motivations for our observations is that our own sun probably formed in a violent region like the one we are seeing in the Carina Nebula,” said Smith.

Located in the southern Milky Way galaxy, the Carina Nebula is visible to the human eye and contains the variable star Eta Carina, which puts out more energy than 1 million suns and which is expected to explode into a supernova in the coming millennia. Stellar winds whipping from Eta Carina and several dozen other massive stars in the region blow at 2,000 kilometers a second, or more than 4 million miles per hour.

“There is a fierce contest going on,” said Smith. “On one hand we have these massive, first-generation stars trying to remove all of this gaseous material, and the young stars like those embedded in the dust pillars are trying to accrete the material to build themselves up.”

Launched in 2003, the heat-seeking Spitzer Space Telescope is an ideal observatory to study the wild activity in the Carina Nebula, said Smith. The orbiting telescope’s infrared array camera penetrates regions like Carina filled with dense clouds of gas and dust, allowing astronomers to witness star formation processes that are shrouded from the view of other types of telescopes.

The study also included the University of Wisconsin-Madison’s Ed Churchwell, Brian Babler and Marilyn Meade, Barbara Whitney of the Space Science Institute in Boulder, Vanderbilt University’s Keivan Stassun, Arizona State University’s Jon Morse and the University of Minnesota’s Robert Gehrz. The Spitzer Space Telescope is managed for NASA by the Jet Propulsion Laboratory in Pasadena and science operations for the effort are conducted at the Spitzer Science Center at the California Institute of Technology in Pasadena.

Smith and his colleagues combined several hundred images obtained by scanning the South Pillar region of the nebula with Spitzer in spring 2005 to produce the mosaic. Using four different camera filters, the team detected more than 17,000 stars, including those forming at the pillar heads. “We looked only at the most active region, but there are probably many more stars embedded in pillars in the surrounding area,” he said.

The researchers believe Eta Carina was the primary player that shaped the gigantic dust pillars. Before 1840 — when the star shed the equivalent of 10 solar masses of material from its outer layer — it is thought to have been the most luminous UV light source in the nebula. For several years after the 1840 event, Eta Carina was the second brightest star in the sky.

Sculpted from reservoirs of gas and dust by the whipping stellar winds and high-energy radiation, the dust pillars “point back” toward the luminous Eta Carina, said Smith. “All of the different pillars were exposed to the same light bulb.”

The Carina Nebula has a diameter of about 200 light years, and the dust pillars are up to 10 light years, or 50 trillion miles, in length, said Smith. The Carina Nebula is about 100 times more luminous than the much closer Orion Nebula and may contain as many as 100,000 young stars, most of which are faint, low mass stars like the sun.

Videos and Animations

Video 1: Pillars Behind the Dust — The movie begins with a visible-light picture of the southern region of our Milky Way galaxy then slowly zooms into the area imaged by the NASA’s Spitzer Space telescope. The dust pillars are fewer and appear dark in the visible-light view because the dust is soaking up visible light. Spitzer’s infrared detectors cut through this dust, allowing it to see the heat from warm, embedded star embryos, as well as deeper, more-buried pillars.

This false-color image taken by Spitzer shows the “South Pillar” region of the star-forming region called the Carina Nebula. Like cracking open a watermelon and finding its seeds, the infrared telescope “busted open” this murky cloud to reveal star embryos (yellow or white) tucked inside finger-like pillars of thick dust (pink). Hot gases are green and foreground stars are blue. Not all of the newfound star embryos can be easily spotted.

Eta Carinae is a behemoth of a star, with more than 100 times the mass of our Sun. It is so massive that it can barely hold itself together. Over the years, it has brightened and faded as material has shot away from its surface. Some astronomers think Eta Carinae might die in a supernova blast within our lifetime.

Eta Carinae’s home, the Carina Nebula, is located in the southern portion of our Milky Way galaxy, 10,000 light-years from Earth. This colossal cloud of gas and dust stretches across 200 light-years of space. Though it is dominated by Eta Carinae, it also houses the star’s slightly less massive siblings, in addition to the younger generations of stars.

The Spitzer image was taken by the infrared array camera on the telescope. It is a three-color composite of invisible light, showing emissions from wavelengths of 3.6 microns (blue), 4.5 microns (green), 5.8 microns (orange), and 8.0 microns (red).

The visible-light picture is from the National Optical Astronomy Observatory.

Slow Connections (160×120): Windows Media (100 KB) | QuickTime 4.0 (68 KB)
Fast Connections (320×240): Windows Media (604 KB) | QuickTime 4.0 (1 MB) | QuickTime 6.0 (1.1 MB) | MPEG 1 (1.3 MB) | MPEG 4 (804 KB)
Full-Size (640×480): Windows Media (3.4 MB) | QuickTime 6.0 (4.2 MB) | MPEG 4 (3.2 MB)
Broadcast Quality

Video 2: Carina in Context — This animation starts with an image of a larger but lower resolution image of the Carina Nebula from the Midcourse Space Experiment that did an infrared survey of the sky while in operation from 1996-97. The image shows the dying star Eta Carinae as the bright spot near the center of the image. As it rotates and zooms in, the area that Spitzer studied in detail comes into focus.

The “pillars” in the Spitzer image are being sculpted by ultraviolet radiation and stellar winds from the massive star Eta Carinae, a star with more than 100 times the mass of our Sun, and its neighboring stars.

Spitzer’s infrared detectors can see the heat from warm, embedded star embryos, as well as deeper, more buried pillars. The Spitzer image was taken by the infrared array camera on the telescope. It is a three-color composite of invisible light, showing emissions from wavelengths of 3.6 microns (blue), 4.5 microns (green), 5.8 microns (orange), and 8.0 microns (red).

Slow Connections (160×120): Windows Media (104 KB) | QuickTime 4.0 (68 KB)
Fast Connections (320×240): Windows Media (620 KB) | QuickTime 4.0 (1 MB) | QuickTime 6.0 (1 MB) | MPEG 1 (1.3 MB) | MPEG 4 (808 KB)
Full-Size (640×480): Windows Media (3.4 MB) | QuickTime 6.0 (4.5 MB) | MPEG 4 (3.3 MB)
Broadcast Quality

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On the Net:

Spitzer Space Telescope

University of Colorado at Boulder


Spitzer Captures Fruits of Massive Stars8217 Labors Spitzer Captures Fruits of Massive Stars8217 Labors


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