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February 22nd: The Science Of Studying The Heliosheath Q&A with George Gloeckler

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Date: February 22, 2012

Title: The Science Of Studying The Heliosheath Q&A with George Gloeckler

Podcasters: Chris Lindsay with George Gloeckler

Organization: Ann Arbor Science & Skeptics

Links: For more information about Dr. George Gloeckler, please see http://aoss.engin.umich.edu/people/gglo

For more information about the Ann Arbor Science & Skeptics, please see http://www.annarborscienceskeptic.com.

For more information about the Critical Wit Podcast, please see http://criticalwitpodcast.com

Description: This episode consists of an interview with George Gloeckler, research professor of physics at the University of Michigan. Dr. Gloeckler was a contributing researcher on the space probe, Ulysses that studied the gasses that came into our solar system from interstellar space. He talks about his work both with the Ulysses and its new successor probe, IBEX (Interstellar Boundary Explorer).

Bios: Dr. George Gloeckler’s research consists of studying the properties of the local interstellar medium, such as its magnetic field, density and composition of its gas, and its interaction with the solar system utilizing a new sensing technique that led to his discovery of interstellar gas deep inside the solar system.

Chris Lindsay is the organizer of the Ann Arbor Science & Skeptics, and host of the Critical Wit podcast, a podcast about science, literature, and the arts.

Sponsor: This episode of the “365 Days of Astronomy” podcast is sponsored by — NO ONE. We still need sponsors for many days in 2012, so please consider sponsoring a day or two. Just click on the “Donate” button on the lower left side of this webpage, or contact us at signup@365daysofastronomy.org.

Transcript:

Hello. Thank you for listening to 365 Days of Astronomy. I’m Chris Lindsay, the organizer of the Ann Arbor Science and Skeptics and host of Critical Wit, a short weekly podcast about science, literature, and the arts.

The two space probes, Ulysses and IBEX have been important tools in understanding the origins and composition of interstellar gas that enters our solar system. I spoke with Dr. George Gloeckler, research professor of physics with the University of Michigan, to talk about why we study the heliosheath of our solar system.

Chris Lindsay: So one of the reasons why I wanted to talk with you was specifically about was how we study and why we study the boundary of our solar system and beyond. So what sorts of observations in general are scientists making, regarding studying the heliosphere and the interstellar dust that comes into our solar system?

George Gloeckler: That’s a good question, of course, as you know, astrophysics and astronomy by observing photons from various stars, and their absorption into interstellar medium, they learn an awful lot, about what is between the source (emitting the photons) and us. Sort of a line integral, and you get average quantities. Now what we can do with particles, and more recently, with neutral particles – I mean they’re both charged particles and neutrals – is to actually probe the immediate surrounding interstellar medium, in which the sun and the solar system finds itself. And we can do it by various means, for example, cosmic rays, which were discovered, so called galactic cosmic rays were discovered a hundred years ago, come from the interstellar medium, and they are able to make their way, all the way to the orbit of Earth. And their spectrum, the essential measurements are several. It’s the spectrum of these particles, that is, how are they distributed in energy, you know it’s almost like the spectrum of a photon, sort of a plot of intensity versus energy of the particle. And the other is that it tells us a lot of the composition, the abundance of the various elements that can be identified. So this is the oldest one, the cosmic rays, and over time, it was important to go down in energy to close the gap, and make observations. Because all the spectra and composition, they carry information from the remote regions in the particles of which they come from. And this way, we can sort of figure out what their history was, in the way they were propagating to us, and also what they looked like at their origin.

Chris: So, when you say cosmic rays come from the interstellar medium, can you provide a little more detail in….

George: Yeah, there are sources of energy, so called free energy, that exists in the interstellar medium. I mean, the Big Bang, of course, was a big event that caused all sorts of processes to happen. But after that, you know, one has explosions of stars, to which produce supernovae, and these supernovae are essentially huge explosions which drive the gas, and they shock the gas, I mean they move the gas so fast, it becomes a shock – like a sonic boom ‘shock.’ And in that process, you can transfer energy from such explosions to particles, like cosmic rays, and that’s the way they get their energy. The other way to transfer energy is through interstellar medium, that gas is in turbulent motions, all the time, and it’s possible to extract energy from the turbulent motions and transfer them to particles. And the interesting thing is you take the energy available, and you take really just a few particles, and you give them these enormously high energies. And one of the quests is to figure how this is really happening, theoretically. My colleague, Len Fisk, at Michigan, who is a theoretician and I have been doing a lot of work in this direction.

Chris: So are there any hypotheses or theories that are trying to be confirmed or falsified with studying the heliosheath, or is this essentially, more or less, fact-finding and data-gathering?

George: Well a lot of it is certainly discovery and fact-finding and data-gathering. But what is important as far as the composition goes, is that it tells us what the present state of the gas in the interstellar medium is because all our other composition, and composition is extremely important because it goes back to how elements are cooked in stars. Most of our composition measurement comes from the sun, our own sun. We know most about the composition of elements from our sun, but know very little about the composition of the interstellar gas. So this adds a lot of important points to this composition story, which tells you the present state of the interstellar medium. In other words, is it the same as things were four billion years ago when the sun was formed, or is it different, and if so, why is it different. What processes have produced, and come about to have changed this composition.

Chris: What do you feel has been the predominant thought, has it been consistent or different in terms of comparisons between what we know come from the sun, and what we know comes from the interstellar medium?

George: Yeah, actually the surprising part is that things are remarkably similar to what the sun is, the composition. And this is sort of surprising. In other words, the composition hasn’t changed all that much. Of course, we don’t have all the elements to check, but we have the ones we do check, there’s no disagreement.

End of podcast:

365 Days of Astronomy
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