Category Archives: Milky Way Galaxy

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Rattling the Galaxy’s Bones

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Dark Cloud in the Milky Way

The galactic “bone” was identified while studying a dust cloud that in 2010 was nicknamed “Nessie” after the Loch Ness Monster. Nessie turns out to be at least twice, and perhaps as much as eight times, longer than originally claimed. Both the original 2010 “Nessie” and the extended structure are outlined and labeled here on a Spitzer infrared image.
Credit: NASA/JPL/SSC

Once in a while a story really grabs my attention, like yesterday’s census of planets in the Milky Way.  It really opened up a galaxy of possible worlds to explore. Today, I was sitting in a press conference, listening to astronomers talking about using radio astronomy to study a cloud of gas and dust that they described as the one of the Milky Way’s “bones”, meaning an important part of its structure.

The structure is nicknamed “Nessie” because it bears a resemblance to the Loch Ness Monster. That right there was enough to grab my attention because as CEO of Loch Ness Productions, I’m quite used to being called one of the “Nessies” by our colleagues in the field. So, I approve of my monstrous namesake in the sky!

It’s a cool name and a memorable mental visual.

So, what’s Nessie all about?

Think about our galaxy. It’s what’s known as a barred spiral galaxy. That means it is a typical spiral — with two principal spiral arms wrapping around, and a bar cutting across the middle.

The central region of our the Milky Way has tantalized astronomers since forever, but it’s tough to see because it’s hidden by clouds of gas and dust. However, if you look at it in infrared light or using radio telescopes, you can make out structures not only in the core but along the plane of the Milky Way.

Astronomers have done that using a variety of techniques. In the case of Nessie, they used the Spitzer Space Telescope to probe along the plane (a line drawn across the central region from edge to edge) and found this cloud feature that got nicknamed Nessie by James Jackson of Boston University.

Alyssa Goodman at Harvard Center for Astrophysics and her team looked at Nessie and analyzed it using various data set. It’s really a long tendril of dust and gas that they called a “bone.”

Goodman gave a talk at the AAS today about Nessie. “This is the first time we’ve seen such a delicate piece of the galactic skeleton,” she said, and pointed out that other spiral galaxies also display internal bones or endoskeletons. Observations, especially at infrared wavelengths of light, have found long skinny features jutting between galaxies’ spiral arms. These relatively straight structures are much less massive than the curving spiral arms.

Computer simulations of galaxy formation show webs of filaments within spiral disks. It is very likely that the newly discovered Milky Way feature is one of these “bone-like” filaments.

Radio emissions from clouds of molecular gas in the center of the Milky Way region show that Nessie is in the galactic plane, and is more than 300 light-years long but only 1 or 2 light-years wide. The amount of mass is enough to make about  100,000 Suns. It’s possible that this odd feature bone is part of a spiral arm, or maybe is part of a web connecting other spiral features. Goodman and her colleagues hope to find more of these bones, and once they have enough data, it will give them enough information to create a cool 3D version of the galaxy and its skeleton.

 

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More from the Astronomy Fire Hose

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Some Thoughts on a Galaxy of Possibilities

I am always amazed at the depth and breadth of discoveries in astronomy that get announced at these AAS meetings. I mean, we all KNOW it’s a big universe and there are always going to be amazing discoveries – but, what we don’t always know is just WHAT those finds will be.

Earlier today we heard from scientists using data from the Sloan Digital Sky Survey to create the largest multicolor image of the night sky. It’s essentially the Palomar Sky Survey of our time, but in digital format. You can browse through their work here, and eventually you’ll see much of their work in GalaxyZoo, World Wide Telescope, and GoogleSky.

As I sat there and listened to the scientists talk about their work, it struck me just how much astronomers learn each DAY and how LITTLE we see about it in the news media.  To be sure, there’s a LOT of news every day, and science has to struggle for attention among all the other events of our time.

An SDSS stellar map of the northern sky part of the sky as seen from Earth. It shows trails and streams of stars. These are from satellite galaxies of the Milky Way Galaxy that were torn apart as they strayed too far into our galaxy’s gravitational field of influence. The insets show new dwarf companions discovered by the SDSS (credit: V. Belokurov).

Did you know that astronomers are using the Sloan Survey using a technique called “spectroscopy” to look at the light from those stars and figure out their chemical compositions, the velocity (speed) they’re moving through space, and a host of other characteristics?  It’s true.  One of the coolest outcomes of such a study is that they can now tell which stars came from our own galaxy and which ones were or are parts of galaxies that are being sucked into the Milky Way galaxy.  Stars from galaxies being gobbled up have slight differences in their metallicity (the heavier elements they contain), as well as definite variations in their velocities and direction of travel.

These factors, in turn, give astronomers some important clues to how galaxies form – essentially, the Milky Way has gotten bigger by gobbling up stars from smaller galaxies that were once neighbors moving along the cosmic highway with it. Trace the characteristics of those stars spectroscopically and you learn more about the former neighbor satellites that are now mingling their stars with the Milky Way Galaxy.

Well… THAT was just one tiny part of what Sloan Digital Sky Survey scientists discussed this morning–just a small drip from the firehose of astronomy information flowing at this meeting.  There is literally a galaxy of science to be learned here.