Deep inside the famous Orion Nebula, a colony of very young stars have been imaged by NASA’s Spitzer Space Telescope.
Although the observatory ran out of liquid helium coolant in May 2009, two modules inside its Infrared Array Camera (IRAC) remain fully operational, capturing wonderfully detailed pictures of Orion’s star-forming region currently exploding with stellar life.
The best thing about Spitzer’s new “Warm Mission” is that it can observe the same location for very long periods of time. The space telescope is carrying out the “Young Stellar Object Variability” program and has been watching the same region for 40 days, sending back 80 images. Another long observing campaign is planned for the end of 2010.
The advantage of keeping a watchful eye on this star-forming region is that the brightness of Orion’s baby stars change rapidly, so the longer you watch, the more variability you see.
Many of these stars are only a million years old, a tiny amount of time in cosmological timescales (compare that with our middle-age sun at a geriatric 4.6 billion years old). And as these stars are so young, there’s lots of changing features on (or near) the newborn stars, holding a wealth of information about how stars are born, grow and mature.
“This is an exploratory project. Nobody has done this before at a wavelength sensitive to the heat from dust circling around so many stars,” said John Stauffer, the principal investigator of the research at NASA’s Spitzer Science Center, at Caltech in Pasadena. “We are seeing a lot of variation, which may be a result of clumps or warped structures in the planet-forming disks.”
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Artist impression of a young star plus surrounding proto-planetary disk. Spitzer is very sensitive to the infrared radiation emitted by the heated dust in these planet-forming systems (NASA)
Young stars have temper tantrums, spinning faster than their older cousins, displaying rapid changes. Often these changes in brightness are caused by “cold spots” that cover huge areas on the stars’ surfaces, causing them to dim. As the stars spin, they “twinkle” from an observer’s point of view as the light and dark regions rotate into view. Other times, the brightness variability is caused by huge clouds of dust blanketing the stars, blocking starlight from view.
But Spitzer doesn’t stop at studying stellar formation, it can also see clues of how planetary systems form.
Surrounding many of these young stars are disks of dust and gas that may eventually clump together, coalesce and form planets. Fortunately, Spitzer is very well suited to look out for these dusty disks.
As stars heat up surrounding dust, it glows with infrared light; wavelengths that the space telescope can easily spot.
So although Spitzer has depleted its coolant, it hasn’t quit making ground-breaking discoveries. The telescope continues to reveal more science behind the development of stars, but it may also give us a clue as to how planetary systems, like our solar system, evolved.