Category Archives: spitzer space telescope

astronomy, spitzer space telescope, starbirth, UKIRT

A Seething Hotbed of Star Birth

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Another Peek at the Orion Nebula

It’s getting to be the time of year when the Orion Nebula isn’t readily available in the night sky because — well, it’s just not a sky sight for the next few months.  So, those of us who love to explore the nebula have to “make do” with the latest in professional studies of this busy, busy star birth region.

The Orion Molecular Cloud as seen by UKIRT and Spitzer Space Telescope. (Click to emiggen -- and you WANT to!)
The Orion Molecular Cloud as seen by UKIRT and Spitzer Space Telescope. (Click to embiggen -- and you WANT to!)

The kind folks at the United Kingdom Infrared Telescope (UKIRT), the IRAM Millimeter-wave Telescope in Spain,  and the orbiting Spitzer Space Telescope did a set of observations and combined them to create this stunning infrared image of the Orion Molecular Cloud. There’s a lot going on here —  star birth is NOT a serene event (just as human births aren’t exactly quiet, respectful events).

Let’s deconstruct this image. (You might want to right-click on it and open it in a new browser window to see all the details.)  First, the glowing green areas are clouds of gas and dust that are the seed material for stars. They’re usually made up of hydrogen gas and dust particles.  There are newborn stars in here — they glow in a sort of golden orange color and they’re heating up the cloud with their ultraviolet radiation. This causes the cloud to glow in a variety of wavelengths — some of them invisible to us — like infrared, which is what UKIRT, IRAM, and Spitzer are sensitive to.

So, it stands to reason that if you want to study the intricacies of star birth, you want to study the infrared light streaming from stellar nurseries.  It can cut right through most of the gas and dust in the region and give us a peek behind the clouds that often hide starbirth from us.

Newborn stars give off more than light and heat. They also emit jets during part of their infancy and childhood. Those jets shove their way out through the clouds and help sculpt the nebula.  In this image, the jets show up as tiny pink–purple arcs and dots.

A close-up of jets in the Orion Molecular Cloud (UKIRT WFCAM). (Click to embiggen.)
A close-up of jets in the Orion Molecular Cloud (UKIRT WFCAM). (Click to embiggen.)

To see the real action in this region, the astronomers took a close-up view of a jet streaming from a newborn star in one of the busier areas of star formation in this nebula.  The image was created from data acquired by the Wide Field Camera (WFCAM) at the United Kingdom Infrared Telescope.

The jet is in red, and you can see other objects — wisps, knots and filaments — that are also jets from other young stars. .

What I find cool about studying regions like the OMC is that at the same time they give us a look at star formation in the current age of the universe, they also give us a look back at the birth pangs of our own Sun and solar system some 4.5 billion years ago.  Some of the baby stars you see popping out here will someday BE like the Sun — and maybe even have their own planets.

alien asteroids, astronomy, spitzer space telescope

Tales from the Stellar Crypt

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Dead Stars Tell No Tales… Or Could They?

The galaxy is full of stars that are dead or dying. You’d think that their stories would be over and we could move on to the next star, right?

Silicates in the dust from alien asteroids circling the white dwarf GD 40; data from Spitzer Space Telescope shows the silicates as seen in recent studies (yellow dots) and older data (orange triangles).

Au contraire… as it turns out, some dead stars are surrounded by the dust of asteroids they chewed up and spat out. And, astronomers are getting a chance to “bite” that dust again by studying the infrared emissions from that material with the spectroscopic “eye” of Spitzer Space Telescope.

The data are intriguing, even if you’re not used to looking at it in X-Y plots like this one.  It shows that the asteroid dust surrounding a dead “white dwarf” star contains silicates. That’s a very common mineral here on Earth — many of our rocks are made of silicates. So are rocks on the Moon and the other rocky planets such as Mars and Venus. And, as it turns out, silicates are found in clouds of debris around other kinds of stars and in the the ghostly shrouds of planetary nebulae.  So, how do asteroids get chewed up and and ground to dust around a white dwarf star?

We all know the story of planetary formation around young stars. Dusty material left over from star birth swirls around the star in a kind of shroud. The dust and particles stick to each other over time, forming larger and large protoplanetary lumps. Eventually, if you stick enough of this stuff together and wait a while (say a few million or so years), you get planets. What’s left over circulates around as chunks of rocks. We call those chunks “asteroids.”

What would shredded asteroids around a white dwarf look like? If you could be close by in a space ship, this artist's conception might be what you'd see. Courtesy CalTech.

Now, fast-forward through the life of the star and its associated planetary system — say, one similar to our Sun. When such a star gets old and cranky, it puffs itself up into a red giant. That action eats up the inner planets and jostles whatever asteroids and outer planets that survive the angry red giant phase. As the star continues to die, it does a most amazing thing:  it blows off its outer layers and then shrinks down into a skeleton of its former self. The end result is a white dwarf, an  object with an intense gravitational field. If anything wanders too close — say an asteroid — it gets shredded to pieces by the gravitational pull of the white dwarf. That scatters around a lot of dust.  The chemical fingerprints of the elements in that dust can be picked out by the infrared spectrograph on Spitzer Space Telescope (for example).

Spitzer looked at eight white dwarf systems and found the dust to be very rich in a glassy silicate material like olivine (which is commonly found here on Earth). The scientists who did the looking, led by Mike Jura at University of California at Los Angeles, plan to search out more of these “dust-bitten” regions around white dwarfs. What they find from the tales these dead stars tell will give us some pretty unique insights into how other star systems treat their planets and asteroids as they form, grow, evolve, and then die.

Note: this story was first released during the AAS meeting a couple of weeks ago. I headlined it at the time, but have been wanting to give it more detailed treatment. For more information, check out the Spitzer press release.