In this show, we talk to Professor Albert Zijlstra about a tasty-looking nebula, Dr Stella Offner tells us about low-mass star formation and we hear from Kirsten Gottschalk about processing astronomical data using your computer's spare time. Dr Tim O'Brien answers your big questions and we discuss a few whimsical odds and ends.
Interview with Prof. Albert Zijlstra
Cracking the Fried Egg nebula: Prof. Albert Zijlstra, director of the Jodrell Bank Centre for Astrophysics (our boss!), talked to Leo and Libby about an egg-citing discovery recently made by astronomers from the University of Manchester and others. New observations of the "Fried Egg" Nebula, made with the Very Large Telescope (VLT) at Paranal in Chile, overturn previous theories about the object, less deliciously known as IRAS 17163-3907, which was thought to be a post-AGB (Asymptotic Giant Branch) star. AGB stars are the progenitors of planetary nebulae and are the late evolutionary stage for stars like our Sun. The recent studies have shown that IRAS 17163-3907 is in fact a much larger and brighter yellow hypergiant, undergoing an unstable phase in which it ejects strong dusty stellar winds. Yellow hypergiants, being many times the mass of the Sun, may go on to become Wolf-Rayet stars and supernovae. The VLT observations reveal a nebula consisting of three dusty shells - the "egg white" - with the yellow star at its 'yolky' centre. This system shows some parallels with that of Eta Carinae, which is known to be a binary system.
Interview with Dr Stella Offner
Jen talked to Dr Stella Offner (Harvard Smithsonian Center for Astrophysics) about her work making computer simulations of how low-mass stars form. In this interview, Stella explains the current theory of low-mass star formation and some of the problems with our present understanding. When we look at stars that are forming near to us, they are a lot dimmer than the models predict. Stella tells us about one of the theories that explains this - "episodic accretion" - where there are bursts of accretion of dust and gas onto the protostar.
Interview with Kirsten Gottschalk
Megan talked to Kirsten Gottschalk of the International Centre for Radio Astronomy Research (ICRAR) about their recently launched distributed computing project: theSkyNet. The project uses the spare computing power donated by volunteers to simulate a single powerful machine which is being used to process real data from radio telescopes in order to help make discoveries about our Universe.
Ask an Astronomer
Dr Tim O'Brien answers your astronomical questions:
- The first question this month is from Roupen, who says: "I've located a star that seems to be flickering several colours in an odd way. The star is called Canopus, but I'd like to know why it flickers and why in different colours. p.s. You guys rock!"Tim talked about ESO's adaptive optics instrumentation.
- The next question is from Matthew Hyman. "In the last Jodcast you talked about our Milky Way Galaxy colliding in the future with the Andromeda Galaxy. We are told that the Universe is expanding ever quicker from the Big Bang, so my question is: if everything goes out from a central point (the Big Bang), how can two galaxies collide? Is one galaxy slower than the other? Thanks and great work!"
- Next up is Philip Jones, who says: "Can you please explain how black holes lose energy by radiation and how this forms a jet of particles? Surely if it's a black hole then nothing can escape? Also, if these particles are formed from vacuum energy, how come they form a jet and are not present all around the event horizon?"
Tim referred to the radio galaxy Cygnus A - the VLA produced this classic picture of the double radio source produced by oppositely directed relativistic jets.
- The final question this month is from Martin Webb, who writes: "I was wondering: is there any evidence that the speed of light in a vacuum (299,792,458 m/s) could be exceeded,or will faster-than-light travel always remain in the realm of science fiction?"
In his answer, Tim mentioned the recent paper on "faster-than-light" neutrinos. He also described how this might relate to observations of Supernova 1987A.
Odds and Ends
Cosmologists Saul Perlmutter, Brian Schmidt and Adam Riess won the 2011 Nobel Prize in Physics for the discovery that the expansion of the Universe appears to be accelerating. This is based on the cosmological redshift of distant supernovae, the results of which were published in 1998.
NASA's new International Space Station Live! website gives real-time information about what's happening aboard the ISS, including instrument data and crew schedules. It is currently under testing, with more interactive features to be available soon.
The German-led ROSAT X-ray satellite brings a sense of déjà vu as it plummets into the Earth's atmosphere this month. Launched in 1990 and unused since 1999, it will finally fall between the 20th and 25th of October. Although much of it will burn up in the atmosphere, some pieces will fall to Earth in as-yet unpredictable locations, and there is an estimated 1-in-2000 chance of a person being hit. This translates into odds of 1 in 10 trillion for an individual.
The Draconid meteor shower peaked at around 300 meteors per hour on the 8th of October, according to radio observations. As the particles producing the shower are not yet fully spread around the 13-year orbit of their parent comet, Giacobini-Zinner, a more intense shower happens every 13 years, and this was one such year. For the same reason, the intensity is also largely unpredictable.
|Interview:||Prof. Albert Zijlstra, Leo Huckvale and Libby Jones|
|Interview:||Dr Stella Offner and Jen Gupta|
|Interview:||Kirsten Gottschalk and Megan Argo|
|Ask An Astronomer:||Dr Tim O'Brien|
|Presenters:||Melanie Gendre, Mark Purver and Joel Radiven|
|Editors:||Mark Purver, Megan Argo, Jen Gupta and Tim O'Brien|
|Segment Voice:||Liz Guzman|
|Website:||Mark Purver and Stuart Lowe|
|Cover art:||False-colour infrared image taken at a wavelength of 10 micrometres with the VISIR instrument on the VLT, showing a yellow hypergiant star surrounded by its cast-off outer layers, which have been dubbed the Fried Egg Nebula. CREDIT: ESO/E. Lagadec|