Have a nice day! In this show we talk to Dr Ronnie Jansson about magnetic fields in space, Professor Dennis Zaritsky tells us about the evolution of galaxies and Professor Andrew MacFadyen talks about the deaths of stars. As always, Dr Tim O'Brien answers your astronomical questions, we report on some odds and ends from the world of (astro)physics and we round up your feedback since the last show.
Interview with Dr Ronnie Jansson
Dr Ronnie Jansson is a researcher in astrophysics at the Center for Cosmology and Particle Physics in the Department of Physics at New York University. His work is focussed on cosmic magnetism, in particular the Galactic Magnetic Field (GMF). While this magnetic field is still poorly understood, it has a strong impact on numerous processes in our Galaxy, and affects how stars form and how the Galaxy evolves. Because it is not possible to travel around the Milky Way with a compass to directly measure the magnetic field, we must resort to very indirect techniques to study the GMF. In this interview he also talks about Ultra-High Energy Cosmic Rays (UHECRs), the search for their astrophysical origin and their connection with the GMF. If the GMF is regular on large scales, it can significantly deflect a charged UHECR, and hence obfuscate the true source direction of the cosmic ray.
Interview with Professor Dennis Zaritsky
Professor Dennis Zaritsky hails from the University of Arizona and has a very wide-ranging set of research interests in astronomy and astrophysics. In this interview he talks about galaxy evolution, considers whether we can describe all galaxies with a single structure and discusses the first direct evidence of dark matter.
Interview with Professor Andrew MacFadyen
Professor Andrew MacFadyen works on models of the explosive deaths of massive stars and on the growth of the black holes that result from stellar collapse, as well as the development of more massive black holes at the centres of galaxies. He uses parallel computers to simulate the flow of gas in astrophysical environments where strong shock waves, ultra-relativistic speeds, and magnetic fields, as well as neutrino emission and nuclear reactions, are important.
Ask an Astronomer
Libby Jones puts your astronomical questions to Dr Tim O'Brien:
- Our first question is from Millie. She emailed in to ask "Hello. We've been studying the theory of relativity in Physics for GCSE and I was just wondering whether you could answer my question? If there were 2 atomic clocks, one on the Earth and one in a space ship traveling near the speed of light. If the people on the Earth could see the people on the spaceship would they have the appearance of moving slower. Or would they be moving the same as the people on Earth only thinking their clock is slow?"
- We had an enquiry from Roupen. He says "Is there a limit to how much matter a black hole can suck up?"
- The next question is from Jerry. He wrote in to say "If the universe originated at a single point with the Big Bang, and it has been expanding ever since, then should it not simply be an expanding spherical shell, rather than an essentially continuous mass?
Also, although there are slight variations in the cosmic microwave background, shouldn't there be a definite thermal gradient across the universe as a result of the expansion?"
- The final question this month is from Marie who says: "Like lots of people, I'm really intrigued by this newly identified planet in the Goldilocks zone of the star Gliese 581. I have a few questions:
I have read that the planet is considered to have enough gravity to hold an atmosphere. Has this been misquoted, or taken out of context, and if not, then how do we know it has gravity and/or an atmosphere? How would they be identified?
How far away from its sun is the planet?
What would it be like on a planet which has a 37 day orbit?
Which general direction in our night sky is this star system? (I know I can't see it, but I just want to know which way!)
Oh, and how old is the planet?
Odds and Ends
Not astronomical, but worthy of reporting: two Manchester physicists have won the 2010 Nobel Prize in Physics. Professors Andre Geim and Konstanstin Novoselov were awarded the prize "for groundbreaking experiments regarding the two-dimensional material graphene". Graphene is a one-atom thick sheet of carbon, we're now wondering if you can find it in space!
In the February 2010 Extra show we reported on the discovery of a strange X-shaped, comet-like object discovered in the asteroid belt. Since its discovery, the Hubble Space Telescope has been monitoring this object and the latest information indicates that it is the remains of an asteroid collision.
|Interview:||Dr Ronnie Jansson and David Ault|
|Interview:||Professor Dennis Zaritsky and David Ault|
|Interview:||Professor Andrew MacFadyen and David Ault|
|Ask An Astronomer:||Dr Tim O'Brien and Libby Jones|
|Presenters:||Jen Gupta and Mark Purver|
|Editors:||Mark Purver, David Ault, Jen Gupta and Tim O'Brien|
|Segment voice:||Lizette Ramirez|
|Website:||Stuart Lowe and Jen Gupta|
|Cover art:||An artist's concept showing a gamma-ray burst close up. Observations suggest that material is shot outwards in a two-component jet (white and green beams) Credit: NASA/Swift/Mary Pat Hrybyk-Keith and John Jones|