In the show this time, we talk to Prof. Sir Francis Graham-Smith about the crab pulsar and his long career in astronomy, Dr. Iain McDonald tells us how evolved stars chemically enrich the Galaxy in this month's JodBite, and your astronomy questions are answered by Dr. Joe Zuntz in Ask an Astronomer.
JodBite with Iain McDonald
For this month's Jodbite, we interview one of JBCA's postdoctoral researchers, Dr Iain McDonald. Iain talks about his research into stellar metallicity and globular clusters.
Interview with Prof. Sir Francis Graham-Smith
Professor Graham-Smith has been working in radio astronomy since the 1940s, even though - as he explains - he didn't think of himself as an astronomer when he started. In this interview, he talks about his current work on the enigmatic Crab Pulsar, which has been observed for the last 45 years at Jodrell Bank Observatory. He then traces the path of his career, from radar work during the Second World War to radio investigations of the sky under Professor Martin Ryle in Cambridge (discussed in a previous interview), and on to Jodrell Bank via a detour into optical astronomy on La Palma. Sir Graham recalls the debates over the nature of quasars and, later, pulsars, and cites his accurate measurement of the position of Cygnus A - which enabled it to be associated with an optically visible galaxy - as his favourite piece of research. He discusses his early use of the technique of radio interferometry, developed by British and Australian groups to measure the positions and sizes of radio sources and now used as the basis for almost all new radio telescopes. Sir Graham ends by looking at the lighter side of being Astronomer Royal and Director of Jodrell Bank Observatory, reminiscing about giving Anneka Rice a piggyback during an episode of Treasure Hunt and talking about his new book, Unseen Cosmos.
Ask an Astronomer
Dr. Joe Zuntz answers your astronomical questions:
- Oli Sargent asks us how the age of the Universe is reconciled with stellar populations.
- John Brooks asks: "How do physicists determine the contents of the distant universe?"
- John Brooks asks: "How big would the Sun appear to be from the surface of Mercury?"
Odds and Ends
The standard method for determining the ages of stars has been to use a colour magnitude diagram and measure the age of a cluster as a whole. However, a new technique has been unveiled to deliver a high level of accuracy to age individual stars. Astrophysicists at the Harvard-Smithsonian Center for Astrophysics have been using Kepler data to determine the ages of individual stars based on their spin rate, and confirming their predictions against the known age of a cluster. Sunspots on a stars surface dim starlight, and by measuring the frequency of these dimming effects the spin rate can be determined. As stars age, they slow down and the sunspots become smaller, fainter and more infrequent. This makes the spin of older stars more difficult to measure. Previously, the data had not been sensitive enough to use this technique accurately on stars older than 0.6 billion years, but with the Kepler data their predictions are correct to within 10% on stars at least 2.5 billion years old within open cluster NGC 6819.
This month marks the discovery of Kepler's 1000th exoplanet, and to celebrate the NASA Jet Propulsion Laboratory team have been designing travel posters for some of the potentially habitable planets which they have found. Under the name Exoplanet Travel Bureau they have released a fantastic set of posters in the bright, bold style of 1930s railway posters. There are currently three with more on the way, and you can check them out and print them at the Planet Quest website .
Astronomers have detected diffuse interstellar bands, which appear as fuzzy dark lines in the spectra of stars, for nearly a century, but they still have no idea how the spectral features are created. To trigger ideas from astronomers on what could be the source of these bands, a group at Johns Hopkins University recently created an interactive online map of where these diffuse interstellar bands are seen in the sky. The map is available at this website. More information can be found in the the press release from Johns Hopkins University.
|JodBite:||Dr. Iain McDonald and Hannah Stacey|
|Interview:||Prof. Sir Francis Graham-Smith and Mark Purver|
|Ask An Astronomer:||Dr. Joe Zuntz and Charlie Walker|
|Presenters:||George Bendo, Josie Peters, Charlie Walker|
|Editors:||Adam Avison, Monique Henson, Benjamin Shaw and Prabu Thiagaraj|
|Segment Voice:||Tess Jaffe|
|Website:||George Bendo and Stuart Lowe|
|Producer:||Sally Cooper and Benjamin Shaw|
|Cover art:||Depiction of the view from Kepler 16b of its twin stars, were it a terrestrial planet. CREDIT: NASA/JPL-Caltech|