In the show this time, Prof. Joss Bland-Hawthorn talks to us about the interplay between baryonic and dark matter in galaxy formation, Eddie Blackhurst about low noise amplifiers and microwave recievers in this month's JodBite and your astronomical questions are answered by Dr Tim O'Brien in Ask an Astronomer.
JodBite with Eddie Blackhurst
Eddie Blackhurst is a radio engineer and technician at Jodrell Bank Observatory. He designs and produces low-noise amplifiers for radio and microwave receivers. In this JodBite, Eddie demonstrates the cryostat used for cooling and testing the amplifiers that operate on the Planck spacecraft and the e-MERLIN array. He tells us how he makes components that help astronomers to investigate the history and composition of the Universe, and how to make sure those components are reliable before they are sent into space.
Interview with Prof. Joss Bland-Hawthorn
Prof. Joss Bland-Hawthorn studies the large-scale environments of galaxies at the University of Sydney and gave a plenary talk on the subject at the National Astronomy Meeting. He is particularly interested in the behaviour of 'normal' baryonic gas within the dark matter haloes that surround galaxies and galaxy clusters. While numerical simulations of dark matter show how it formed structure, it is much harder to model the complex interactions of the gas that followed the dark matter and ultimately formed the galaxies, stars and planets we see in our Universe. Prof. Bland-Hawthorn explains what we know about early star formation, and what we still don't know about the subsequent history of matter. He describes how galaxies reside either in clusters or in 'the field', where they exist in filaments or sheets of matter. In particular, he talks about the 'missing baryons' that we can't easily detect and that constitute the majority of normal matter. These probably exist as very hot, diffuse intergalactic gas that can be inferred from their absorption of light from quasars or detected in X-rays.
Prof. Bland-Hawthorn discusses how future instruments may find the missing baryons more easily and tell us why it does not seem to be streaming into galaxies as simulations suggest. He is planning balloon and satellite experiments using the technology of photonics to locate ultraviolet emission from the gas. He describes the novel field of astrophotonics and how it can reduce the size and cost of components, such as spectrographs, which are used on professional telescopes.
Ask an Astronomer
Dr Tim O'Brien answers your astronomical questions:
- First question is Nick Sanders who asks 'I am interested in matter falling in to black holes. It has long been a problem for me to understand how matter ever crosses the event horizon. To an external observer, matter will never cross the event horizon, but just get closer and closer to it. To an observer falling in to the black hole (assuming they survived spaghettification), wouldn't the black hole evaporate before they crossed the horizon?'
- Next question is from Peter Ellinger who says 'Since obtaining a new telescope it's hardly stopped raining here in Sheffield. I've almost forgotten what the Moon and stars look like. I got to wondering what other observational techniques could I employ to do some observing while waiting for the clear skies to return? I came up with 2 options which I'd like advice on please. Option 1 - Radio astronomy, Option 2 - Radar imaging. Would either of these work when it's raining? What could I expect to get out of the kit by way of images?'
- Final question for this month is from Phil Thomas who asks 'How do potential exoplanet researchers discriminate between a sunspot on the local star and an orbiting exoplanet?'
Odds and Ends
There was an apparent impact on Jupiter on the 10th of September. The impact was first observed by amateur astronomers Dan Peterson and George Hall, the latter of whom had video footage of the impact which is now available online.
A lunar space elevator is a proposed cable running from the surface of the moon into space. Its centre of gravity would be in a geostationary position above the surface of the moon. The key sticking point is the cable, this cable would have to be stronger than any material that is manufactured today. But a Japanese company has pledged to build it by 2050.
250,000 newly observed galaxies are now awaiting classification on the Galaxy Zoo website. Anyone can log on and identify galaxies that have never been seen by human eyes before, helping with astronomical research. You can also
JodBite: Eddie Blackhurst and Mark Purver Interview: Prof. Joss Bland-Hawthorn and Mark Purver Ask An Astronomer: Dr Tim O'Brien Presenters: Liz Guzman, Mark Purver and Christina Smith Editors: Christina Smith, Leo Huckvale Tim O'Brien and Mark Purver Producer: Christina Smith Segment Voice: Cormac Purcell Website: Christina Smith and Stuart Lowe Cover art: A true color mosaic of Jupiter taken by NASA's Cassini spacecraft on December 29, 2000. CREDIT: NASA/JPL/Space Science Institute