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Lars Occhionero
Astrophysicsist in training and geek
Astrophysicsist in training and geek

Lars's posts

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Attention all international friends!
My friend +Christian Elleby Andersen is looking for an industrial placement this autumn 2015 somewhere abroad!

The topic he would like to work with is how to manage Research and development or innovation activities, and the learning and knowledge gained through these activities
The industry placement would be centered around a project in this topic, but can also include other internships duties alongside with it.

Go network ;) 

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Understanding pain

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49 Photos - View album

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Rumor Weed

Yesterday there was a flurry of news about a gamma ray burst (GRB) appearing in the Andromeda galaxy.  This would make it the closest observed gamma ray burst, which would be a boon for astronomers.  News of this discovery travelled fast, particularly on Twitter and other social networks.  Pretty soon a few news sites had picked up the story. But it turns out it wasn’t a gamma ray burst.  

It all started with a space telescope known as Swift.  Swift is designed to study gamma ray bursts, and one of its detectors is a wide field telescope known as the Burst Array Telescope (BAT).  The BAT is designed to look for bursts of high energy radiation from unknown sources.  If it detects one, it “triggers” and sends an alert so that other telescopes can be position to observe the event.  Gamma ray bursts can be short lived, so time is of the essence.

Normally the level needed for the BAT to trigger is pretty high (6.5 sigma for you statisticians) so that it doesn’t cry wolf all the time (what are known as spurious events).  But the bar is set a bit lower if the energy burst seems to be from a nearby galaxy.  So Tuesday night (EDT) BAT detected a burst, and Swift’s x-ray telescope also observed a burst of x-rays.  The burst also happened to be in the direction of the Andromeda galaxy.  So it triggered and the alert went out.

Naturally, some of the astronomers working in this area of research use Twitter, and started tweeting about a possible GRB in Andromeda.  This was picked up by their fans and other astronomers, and the whole thing cascaded.  It turns out it was a known x-ray source, probably an x-ray binary.  So while it initially looked promising, it turned out to be a spurious event.  Sometimes this happens, and it is better to have the occasional false alarm rather than miss an important event.

Of course all of this played out in the social media circles, and its seems rather chaotic at the time. It also means sometimes things get reported as far more certain than they actually are.  If you actually look at what is being said, however, you’ll see something rather interesting.  If you go back and look at the comments, such as those tagged with #GRBM31 on Twitter, you’ll notice that the astronomers are pretty careful about saying things like “possible” GRB.  They spread the tentative news, and start looking for evidence to confirm or deny the event.  As they learn things from a clear source, they start tweeting that as well.  You’ll also note there is a great deal of excitement.

This is part of what makes science interesting.  Cool things happen, even if we later find out it isn’t as cool as we thought.

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Battle of the Bands

When light passes through gas and dust in the interstellar medium, some of the light is absorbed. Since the gas and dust only absorb certain wavelengths or colors of light, by by looking at these absorption bands we can determine the type of material that makes up the interstellar media.  Well, most of the time. It turns out there are a range of absorption bands that we haven’t been able to identify. They are known as diffuse interstellar bands.

One of the difficulties with these diffuse interstellar bands is that they don’t seem to match any known atoms or molecules. We know there are molecules that could form within the interstellar medium, but many of them haven’t been analyzed in the labs. Analyzing the line spectra of different compounds in a range of conditions such as vacuum and low temperatures is time consuming. Since it isn’t very glamorous, it doesn’t tend to get much funding, and that limits our ability to analyze the bands.

Another challenge is that different bands can be stronger or weaker relative to each other. This means they are likely due to a range of processes.  There is some evidence that the strength of the bands correlates with the amount of dust in the region, so they are likely related to some kind of dust feature.  Right now one of the favored ideas is that they are due to some kind of larger hydrocarbon molecule. But as for the details, we just don’t know.

Image: NASA/P. Jenniskens and F.-X. Desert
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