The way Journal Club works around here is by a roster - everyone gets a date and has to pick a paper on whatever the topic is at the time, with topics usually lasting for three weeks. It's my turn again this week, and the topic at the moment is masers. I'm first up in this topic and I've picked a paper from Nature that I read recently anyway as part of researching the News*. Yes, I'm lazy. The advantage of this is that not only is is a short paper, but there is also a handy press release, and my script from the January issue, so the talk was already half written before I started. This turned out to be a very good thing given how much other stuff is going on at the moment. The next two weeks are going to be manic. Here's the story...
Observations made using the 100-m Effelsberg telescope in Germany have detected the presense of water vapour in a galaxy at a record ditancefrom the Earth. The study used an effect known as gravitational lensing to search for radio emission in the quasar MG J0414+0534, located at a redshift of 2.64, a light-travel time of 11.1 billion years. The previous record for the detection of water was at a redshift of 0.66 corresponding to a light-travel time of just 6 billion years. The astronomers were looking for water masers - radiation beamed and amplified in as imilar way to light in a laser, but at microwave wavelengths instead. Masers occur naturally in regions of dense gas in areas of high star formation or around supermassive black holes in active galaxies as highly energetic megamasers. The water maser found in J0414 has a luminosity equivalent to 10,000 times the luminosity of the Sun, making it more powerful than most water masers seen in nearby galaxies, but without the effects of gravitational lensing an observation of 580 days would have been required, rather than the 14 hours that were used. In looking for distant regions of water the group selected a distant quasar where a foreground galaxy was along the same line of sight, acting like a magnifying glass, allowing sensitive observations out to much greater distances than is normally possible. The presence of a water maser in the first gravitationally lensed object observed by the group implies that water may have been mush more abundant in the early universe than first thought, pointed out by John McKean, a co-author of the discovery paper published in Nature during December 2008.
Climate change is a big issue, and one that's the subject of some argument here given the PM's mere 5% emissions reduction target which many, many people think is far too low. At "Who On Earth Cares?" (a project from the ACF) there are more than twenty three thousand Australians who have signed up to say they care and want to do something about it. Some of the comments on there are very well written. Here's what I wrote:
Why do you care about climate change? Because our world is such a beautifully fragile place but as a species we have been slowly destroying its future. Today, we know what damage we are causing and what effects it will have in the long term, both for us and the millions of other species with which we share this fragile biosphere. There is no excuse for doing nothing.
How concerned are you about climate change? Ifclimate change continues at the rate of even the most conservative predictions, this planet will be a very different place in only a few generations. I do not want to be responsible for that. The current state of the world is a legacy left to us by previous generations, but that does not mean that it is not our responsibility to do something about it if we can. We have the means, but as a species we seem to lack the will.
What do you want Australia to be like in the future? Australia is a beautiful country. Although it is not my homeland, I'm lucky enough to live and work here and appreciate the amazing wildlife and the diverse habitats which are their homes. Climate change would irreversibly change that landscape. I would like to see Australia take a lead in reducing our impact on the planet for the better, using renewable energies and living sustainable lives so that those habitats are protected.
Here in our new offices we've been complaining that it's too cold since we moved in a few weeks ago, I usually change out of my cycling kit straight into jeans and a jumper when I arrive. Well, some guys from building services came round just now and discovered why - the air conditioning in our area was set to 17 degrees! Ridiculous! So, they've changed it to around 23/24 degrees which is far more sensible. That should make us feel far more comfortable, and dramatically reduce the power consuption in the building, yey!
Last night I went to see The Cat Empire in Freo. I first came across these guys a few years ago when one of the students at Jodrell introduced the entire MSc room contingent to their music, but this was the first opportunity I've had to see them live, and it was definitely worth it. Their support act was very good, too: Paprika Balkanicus, a group of musicians who play music from the Balkans and eastern Europe and are very entertaining.
The Cat Empire, Fremantle, March 5th 2009. Left: the band on stage. Centre: Felix Riebl. Right: crazy fans. CREDIT: Megan
The Cat Empire, Fremantle, March 5th 2009. Felix having fun! CREDIT: Megan
The Empire do have some mad fans: one couple turned up wearing cat suits! No, not skin-tight leather, but full Sylvester costumes! Everyone seemed to be having a great time and there was a very friendly atmosphere, everyone jumping around like mad to most of the songs (they're all brilliant, and yes, even I was jumping around). Everyone on stage looked to be thoroughly enjoying themselves too, especially when Paprika Balkanicus came back on to do a couple of songs - 13 people on stage at the same time! Brilliant.
So, a while back I posted on the DIUS consultation "A vision for science and society". It seems they noticed as they linked to my post. I wasn't the only one either, they even commented on Angela Saini's post where she complained about all the widgets and other clutter on the campaign's page (I have to admit, I agree with Angela - it was very cluttered, and the widgets didn't even work properly).
So what did they do with all the responses? Well, there's a report of course, along with a list of all the people and organisations who responded (I'm in there, along with several other astronomers), but if that's a bit long for your tastes, then they produced some wordles as well. Here's one of them, see if you can guess which question it's from...
DIUS wordle from the Vision for Science and Society consultation CREDIT: DIUS
It's actually from the answers to question 3: "How can scientists further improve and professionalise engagement with the public?" If you're interested, there's more analysis over at the consultation's pages.
The first article is by Simon Singh and is rather bizarrely about mathematics and football. Specifically, the naming of of two symmetry groups after Spurs players. Singh tells us that the naming of these groups is offered by Oxford professor Marcus Du Sautoy who uses the scheme as a fund-raiser for a charity called Common Hope (unlike some "name a star" schemes I've seen around which tend to be very dishonest about what you're actually getting in return for your cash). It seems that these two particular symmetry groups have been named by Tony Mann, a mathematician at the University of Greenwich in South London. Why? Apparently, because Du Sautoy is an Arsenal fan, and Mann enjoys winding him up. Curiously, if you look down the list of requests, Mann has also requested one be named "For Vanilla Beer - birthday 4 July". Who says mathematicians don't have a sense of humour?!
Entertaining, but a bit lacking in substance to be honest.
At four minutes to five in the morning on February 10th, an active communications satellite operated by Iridium and a retired Russian military satellite collided 800km above Siberia. Moving at a relative speed of 10 km/s, the collision released an estimated 50 kilojoules of energy per gram, according to researchers at the University of Southampton in the UK who simulated the incident. The collision took place in a busy part of Earth orbit and created more than 600 pieces of debris large enough to be tracked from the ground. The space around Earth is already home to many hundreds of satellites, including 66 satellites operated by Iridium, and the amount of debris is increasing every year, raising the risk of further damaging collisions between objects.
Simulation of the collision Credit: Southampton University
While astronauts on the International Space Station use a much lower orbit and so are not likely to be at risk from debris from this particular incident, it has increased the chances of a collision during the planned shuttle mission to fix the Hubble Space Telescope. Even before this particular incident, a previous test of a Chinese anti-satellite weapon in 2007 had increased the chances of a catastrophic collision during a Hubble servicing mission to close to NASA's acceptable level of risk for a manned mission. This incident has further increased that risk and could mean the mission is scrapped.
The problem of space debris is only going to get worse as more satellites are launched into increasingly busy orbits filled with older satellites which are often left in orbit once they reach the end of their operational lifetimes. While both NASA and ESA track many thousands of pieces of space debris, there are many more fragments of space junk orbiting Earth which are far too small to be detected from the ground, but which could cause serious damage to other orbiting spacecraft if another collision were to occur.
In the News this month... surprising star formation from primordial clouds
Orbiting around large galaxies are collections of dwarf galaxies, relatively small groups of stars gravitationally bound to a larger companion. New results from the Galaxy Evolution Explorer, a satellite operating in the ultra-violet part of the spectrum, has found a collection of very unusual dwarf galaxies forming in a way not seen before.
Most galaxies in the nearby universe contain large amounts of dark matter, and their stars formed from gas that had already been processed by a previous generation of stars and so contains a significant proportion of elements heavier than helium. Large galaxies, especially those involved in mergers, are often surrounded by tidal dwarf galaxies, formed from the gas stripped out in the interaction. These tidal dwarfs have very little dark matter but a high proportion of heavy elements since the gas used to form them comes from previous populations of stars in the nearby larger galaxy. But a study of gas in a region known as the Leo Ring, led by David Thilker of Johns Hopkins University in the US, has found a collection of dwarf galaxies forming from gas which lacks both dark matter and heavy elements.
Radio map of the Leo Ring (contours) over the optical view (DSS) CREDIT: Arecibo / DSS / Schneider et al
The Leo Ring is a huge cloud of mainly hydrogen and helium gas surrounding two massive galaxies, M105 and NGC3384, located in the constellation Leo. The cloud contains a mass of hydrogen almost 2 million times the mass of the Sun and is 200 kiloparsecs or more than 650 thousand light years in diameter. It was first discovered 25 years ago but is only visible at radio wavelengths where emission from hydrogen atoms is detectable. No optical emission has been detected from the ring, and no stars have been found to be associated with it. It is thought that the cloud is a primordial object, leftover gas from the early universe which has remained unchanged over billions of years, lacking the heavy elements created by stellar populations. The new observations with the GALEX satellite, however, have discovered evidence that star formation has been happening recently in the ring. Young stars burn bright and hot, emitting large numbers of ultra-violet photons which GALEX is sensitive to.
GALEX view of the Leo Ring CREDIT: NASA/JPL-Caltech/DSS
What the team discovered was ultraviolet signatures of young stars in several clumps of gas within the southern half of the ring, and they suggest that this is due to dwarf galaxies forming from the primordial gas. Normal galaxies are dominated by dark matter, so these star forming regions in the Leo Ring where dark matter is absent are somewhat unusual and possibly demonstrates a new mode of dwarf galaxy formation. The study was published in Nature on the 19th of February, and the authors suggest that clouds similar to the Leo Ring would have been more common in the early universe, and so many more dark-matter deficient dwarf galaxies may be out there waiting to be discovered.