Shut That Door! In the show this time, Emily Petroff explains how to tell the difference between an extragalactic radio burst and a microwave oven, Dr Joe Zuntz reveals the preliminary results of the Dark Energy Survey, and your astronomical questions are answered by Dr George Bendo in Ask an Astronomer.
JodBite with Dr Joe Zuntz
Dr Joe Zuntz spoke about the Dark Energy Survey (DES) in a previous Jodcast interview, and returns to tell us about its preliminary results. He describes the mystery of dark energy, known only through the apparent acceleration of the Universe's expansion, and explains how the DES is looking for its influence by observing hundreds of millions of distant galaxies. Among other characteristics, the observed shapes of the visible parts of these galaxies are expected to be distorted as the gravity of dark matter bends the light coming from them. Dark energy, in turn, has an effect on the clustering of the dark matter, and it is this effect that the DES is investigating. Dr Zuntz tells us about the map of dark matter that has been made from the first year of DES observations, and explains how future measurements will refine our knowledge of the behaviour of dark energy.
Interview with Emily Petroff
Emily Petroff is a PhD student at Swinburne University of Technology in Melbourne, Australia. She studies Fast Radio Bursts (FRBs), unexplained blasts of radio waves that last for only around 1 millisecond but seem to come from outside our own galaxy. Emily tells us how FRBs can be used to study extreme (though as yet unknown) phenomena, and also how they can be used to measure the density of electrons in the intergalactic medium. She also talks about the recent unmasking of a source of false FRBs, called perytons, which originate from microwave ovens when they are switched off by someone opening the door. As Emily explains, these can be distinguished from true FRBs because their characteristic emission can now be readily reproduced by inquisitive and hungry astronomers.
Ask an Astronomer
Dr George Bendo answers your astronomical questions:
- Steve Smethurst asks: "Is dark matter in thermal equilibrium with the rest of the Universe?"
- John Brooks asks: "How does our Solar System rotate in comparison to the Milky Way?"
- Mike Nash says: "Could man-made radio emission from the Earth really be detectable by aliens at interstellar distances?"
Odds and Ends
NASA's New Horizons spacecraft is now less than 100 million kilometres from Pluto and is bearing down on it at over 1 million kilometres per day. For the first time, its Long Range Reconnaissance Imager (LORRI) has taken photographs showing Pluto's smaller moons: Hydra, Nix, Styx and Kerberos. The images of Pluto and its system of moons will continue to improve over the coming months, and may reignite the debate over Pluto's planetary status.
A bed bug detector and a surgical tool for performing heart surgery are just two examples of the more unusual technology inspired by the Rosetta mission. The spacecraft's probe, Philae, landed on Comet 67P/Churyumov-Gerasimenko last year with scientific equipment to explore the its composition. Philae's compact chromatograph and mass spectrometer, designed to look for organic molecules on the comet's surface, have inspired a hand-held device to detect the chemical signals released by bed bugs. Technology from the probe's device for making 3D maps of dust grains has also been used to create a tool to dampen muscle movements, which could allow coronary artery bypass operations to be performed without needing to stop the heart, potentially making operations safer.
NASA's Nuclear Spectroscopic Telescope Array (NuSTAR) has discovered evidence that core-collapse supernovae explode lopsidedly, not symmetrically. NuSTAR is an X-ray telescope detecting emission spanning 3-79 keV and has observed the supernova remnant 1987A. Some of the X-rays being emitted from 1987A originate from titanium-44, an element formed in the centre of the explosion, which outlines an asymmetrical shape. We can be confident that this tells us directly about the mechanics of the explosion and not about anything else as titanium-44 has a lifetime of only 85 years before it decays into something more stable. This means that the titanium-44 must originate from the collapsed star and not the surrounding interstellar medium. The asymmetry comes from the ejecta of the supernova travelling in one direction, with the core of the star travelling in the other. The original story can be found here, along with links to the images and simulation referred to in the Jodcast.Show Credits
| JodBite: | Dr Joe Zuntz and Mark Purver |
| Interview: | Emily Petroff and Charlie Walker |
| Ask An Astronomer: | Dr George Bendo and Indy Leclercq |
| Presenters: | Josie Peters, Mark Purver and Hannah Stacey |
| Editors: | Ben Shaw, George Bendo, Monique Henson and Charlie Walker |
| Segment Voice: | Kerry Hebden |
| Website: | Mark Purver and Stuart Lowe |
| Producer: | Mark Purver |
| Cover art: | Hubble Space Telescope image of Supernova 1987A. CREDIT: ESA/Hubble |