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A stunning end to the IYA

The year 2009 is almost over, and it has been an amazing one for astronomy. I've done more outreach and talked to more people than I can count, and it's been brilliant. The International Year of Astronomy has resulted in enourmous amounts of outreach around the entire planet and huge numbers of people getting their first look through a telescope. But, for many astronomers in the UK, this has now been overshadowed by the latest in the great STFC saga.

In an announcement posted on the STFC website on Wednesday last week, the outcome of the latest reprioritisation exercise was revealed. On the chopping block are numerous facilities that are currently doing good science, some that are in construction, some which are only in the planning stages, as well as a significant number of studentships and fellowships. This has been coming for some time now, and has involved a long consultation with the community (so, some progress since last time then). Here's the full PPAN list from the announcement:

Projects to be funded:
Astronomy: Advanced LIGO, JCMT (to 2012), Gemini (until end 2012), ING (to 2012), KMOS, VISTA, Dark Energy Survey, E-ELT R&D, SKA R&D, SuperWASP, e-MERLIN, Zeplin III; Total cost of £87m over 5 years.
Particle Physics: ATLAS, CMS, GridPP, nEDM, Cockroft Institute, IPPP, LHCb, MICE, SuperNEMO, T2K, John Adams Institute. Total cost of £155m over 5 years.
Nuclear Physics: NUSTAR. Total cost of £11m over 5 years.
Space: Aurora, GAIA, Herschel, JWST-MIRI, LISA Pathfinder, Rosetta, Planck, ExoMars, Hinode, Cosmic Vision, Solar Orbiter, Stereo, Swift, Bepi-Colombo. Total cost of £114m over 5 years.

Current PPAN projects subject to discussions leading to managed withdrawal:
Astronomy: Auger, Inverse Square Law, ROSA, ALMA regional centre, JIVE, Liverpool Telescope, UKIRT. Additional reduction imposed on ongoing projects of £16m. Total savings of £29m over 5 years.
Particle Physics: Boulby, CDF, D0, eEDM, Low Mass, MINOS, Particle Calorimeter, Spider, UK Neutrino Factory. Additional reduction imposed on ongoing projects of £25m. Total Savings of £32m over 5 years.
Nuclear Physics: AGATA, ALICE at CERN, PANDA. Additional reduction imposed on ongoing projects of £2m. Total Savings of £12m over 5 years.
Space: Cassini, Cluster, SOHO, Venus Express, XMM. Additional reduction imposed on ongoing projects of £28m. Total Savings of £42m over 5 years.

That's a lot of cuts. Why are we losing so much? This goes back a couple of years now, to the merger of the Particle Physics and Astronomy Research Council (PPARC) and the Council for the Central Laboratory of the Research Councils (CCLRC) in 2007. A combination of the move to full economic costing, the loss of protection on exchange rate fluctuations on international subscriptions, inadequate allowance for inflation and GDP fluctuations, cost overruns on existing projects, and the merger process itself, resulted in a large gap between what was being funded and what we could actually afford as a community.

The first indication many of us had that anything was wrong was when, with no warning or consultation, STFC pulled out of the Gemini collaboration back in November 2007. Since then there have been numerous develoments, not many of which have given the astronomical community in the UK much cause for optimism. This hasn't just hit astronomers either, particle and nuclear physics are also facing rather devastating cuts as a result of all this. The whole sorry affair has been documented in extraordinary detail by Paul Crowther, an astronomer in Sheffield.

So what do the politicians have to say about all this? In Gordon Brown's fist (and, to date, only) speech about science on February 27th 2009 he said:

"Some say that now is not the time to invest, but the bottom line is that the downturn is no time to slow down our investment in science but to build more vigorously for the future. And so we will not allow science to become a victim of the recession - but rather focus on developing it as a key element of our path to recovery."

This statement seems at odds with what is currently happening. You've got to wonder if the PM is aware of the magnitude of the current situation with STFC and the very real impact it will have on the research community. How much science are we losing for what is really a small amount by government standards? (How much does a single Eurofighter cost?) Yes, we are in an economic downturn. Yes, there are many demands on a much-tightened budget. But destroying whole fields of research seems like a really good way of hobbling the country even further during a recession which is going to need scientists and engineers to help pull us out of.

The current science minister, Lord Drayson, does seem aware that this is now a serious situation. He put out a statement on the same day as the STFC announcement which contained the following:

"...it has become clear to me that there are real tensions in having international science projects, large scientific facilities and UK grant giving roles within a single Research Council. It leads to grants being squeezed by increases in costs of the large international projects which are not solely within their control. I will work urgently with Professor Sterling, the STFC and the wider research community to find a better solution by the end of February 2010."

I've written about the STFC troubles before, but it is still deteriorating. It looks like it could get even worse before it gets better. The outcome of the recent prioritisation exercise seems to have puzzled many in the community. Some projects which were ranked low are still funded, while all of the highly ranked facilities will still have to deal with cuts. Add to that the significant reduction in PhD scholerships and postdoc positions, and the UK stands to lose a large proportion of its promising talent, both to other careers and overseas.

From my point of view, currently working overseas and shortly to start looking for my next post, the future does not look promising. A part of me was hoping that I might be able to find a position back in the UK - I miss the hills, the snow, and my family - but this now looks like a vanishingly small prospect. What incentive is there to return? Not much that I can see, from a career perspective. If I did go back, chances are that it would not be to academia. Now, we don't train up so many astronomers expecting them all to stay in academia: it benefits industry when students take the skills they learn in research and apply it to real world problems. But, honestly, I have no idea what else I might do since I've never wanted to do anything else. So, as long as I can find work in astronomy, it looks like I will stay overseas for the forseeable future.

Read the RAS response to this in their press release, and more on the whole situation on various blogs around the intertubes, watch the #stfc hashtag on Twitter, and keep an eye on Paul Crowther's website for updates as they happen.

Posted by Megan on Sunday 20th Dec 2009 (12:30 UTC) | Add a comment | Permalink

And finally: latest results from LCROSS

LCROSS imapcted the Moon on October 9th
Artists impression of the impact of the LCROSS spacecraft on the Moon back on October 9th CREDIT: NASA

In a press briefing on November 14th, members of the LCROSS team presented the latest results from the impact of the spacecraft on the Moon back on October 9th. The Lunar CRater Observation and Sensing Satellite was one of two man-made objects to impact the Moon that day. The ejecta cloud produced by the empty Centaur upper stage of the rocket created a plume of material which was imaged by an infra-red camera on board the LCROSS probe which was following four minutes behind

The roughly ten-kilometre sized cloud filled the field of view of some of the sensors on board LCROSS, resulting in good measurements of the composition of the lunar regolith. One infra-red image, taken by LCROSS from a height of just 10 km, shows the floor of the Cabeus crater for the first time, including a fresh crater from the impact of the Centaur upper stage.

The initial results from the spectra obtained by LCROSS show deep absorption features due to water, implying that there was roughly 100 kg of water in the field of view of the instrument, approximately equivalent to a dozen or so 2-gallon buckets. As well as water, the spectra also show absorption due to several other compounds, the identities of which are yet to be confirmed. See all the images from the press conference here.

Posted by Megan on Wednesday 02nd Dec 2009 (14:33 UTC) | Add a comment | Permalink

In the News this month: spectacular outflows in Orion

Artist's conception of the boiling disk surrounding the massive young stellar object known as orion source I
Artist's conception of the "boiling disk" surrounding the massive young stellar object known as Orion Source ICREDIT: Bill Saxton, NRAO/AUI/NSF

The constellation of Orion contains some massive complex regions of star formation, the most obvious of which is the Great Orion Nebula, M42, located in Orion's sword. Through an optical telescope you can see a large glowing cloud of gas illuminated by a cluster of young, hot stars. But behind this cloud, hidden from view, lies another cluster of proto-stars, clumps of gas still collapsing under gravity in the process of forming stars. As ordinary light cannot penetrate through the gas, other parts of the electromagnetic spectrum are needed to see these proto-stars. Luckily, radio waves can penetrate through the thick gas and dust and can provide images of these stars in the process of formation. Using the Very Long Baseline Array, a collection of ten radio telescopes located across the USA, a team of astronomers has peered into this hidden region and imaged it at high resolution.

The team, led by Lynn Matthews at MIT's Haystack Observatory, used the VLBA to study an object known as source I over two years. This source lies at a distance of just 414 parsecs, making it the closest known example of the class known as Young Stellar Objects. The astronomers used the VLBA to make regular monthly images over two years, studying the motion of sources known as masers, naturally occurring objects which act like lasers but at radio wavelengths. The images show thousands of silicon monoxide masers in outflows from the proto-star known as source I, and by stitching together all of the images taken over two years, the team produced a movie showing the outflows of molecular material between 20 and 100 astronomical units from the young star in unprecedented detail.

It is already known how these massive stars die - they explode catastrophically as supernovae - but how they form is more of a mystery since the formation process takes place inside a thick cloud of gas. These observations show signs of a rotating accretion disk around the proto-star, drawing surrounding material in a spiral motion towards the centre where the new star is still growing. They also show material flowing out from the centre, perpendicular to the disk, in two large cones, one above and one below the disk. Outflows like these help the star formation process by carrying angular momentum away from the system, if a protostar spun too quickly it might start losing material and ultimately rip itself apart. The movie also shows the outflows starting to curve as they leave the accretion disk, suggesting that magnetic fields may be influencing the motion of material near to the star. The paper describing this work has been accepted for publication in the Astrophysical Journal in January 2010.

L. D. Matthews, L. J. Greenhill, C. Goddi, C. J. Chandler, E. M. L. Humphreys, & M. Kunz (2009). A Feature Movie of SiO Emission 20-100 AU from the Massive Young Stellar Object Orion Source I Astrophysical Journal arXiv: 0911.2473v1

Posted by Megan on Wednesday 02nd Dec 2009 (14:03 UTC) | Add a comment | Permalink

In the News this month: a new way to search for exoplanets

Artist’s impression of a baby star still surrounded by a protoplanetary disc in which planets are forming
Artist’s impression of a baby star still surrounded by a protoplanetary disc in which planets are forming CREDIT: ESO/L. Calçada

Planet searching techniques are continuously being refined and are detecting ever smaller planets at greater and greater distances from their parent stars. But a team of astronomers have discovered a link between planetary systems and lithium abundance that could provide a new tool in the search for exoplanets. Most methods of searching for planetary systems around other stars are best suited to finding large planets orbiting very close to their host stars. But what if there was a way to determine the likelihood of a particular star hosting planets, without actually detecting the planets at all? A team, led by Garik Israelian of the Instituto de Astrofisica de Canarias in Tenerife, think they have found a link between whether stars host planets and how much lithium is observed.

Lithium is one of the lightest chemical elements and is present in detectable quantities in most stars. The surface abundance of lithium on the Sun is 140 times less than what it was in the protostellar cloud from which the Sun formed. The surface of the Sun consists of a convective layer where material is constantly circulated in large convection cells, but the temperature at the base of this layer is not high enough to burn lithium, so where did it go?

The team studied spectra of 451 stars, some of which host planets while some do not. All the stars in the sample were similar to the Sun with surface temperatures between 4900 and 6500 degrees Kelvin. When they compared the lithium abundances, they found that for stars with surface temperatures in the range 5600 to 5900 Kelvin, the majority of stars known to host planets were severely depleted in lithium, whereas the non-planet hosting stars showed a much lower level of depletion. This indicates a possible link between lithium depletion and planet formation which could be used to pre-screen stars for planet searches.

However, the link is only seen for stars in a particular temperature range: above 5900 Kelvin the convective layer is too shallow to reach a depth where the temperature is high enough to burn helium, while below 5700 Kelvin the convective layers penetrate deeper and all stars show significant lithium depletion. Within this range, the amount of lithium depletion seen in star hosting planets is independent of both the star's surface temperature, metallicity and age, indicating that the presence of a planetary system is related.

While there is currently no model that explains this apparent link, the authors suggest a few ideas. The existence of a planetary system may result in a variation in the rotation rate of the star, increasing the mixing of material within layers; planetary migration may also alter the stellar rotation resulting in a similar effect. Another suggestion is that an interaction of the proto-star with the surrounding accretion disk may lead to a large variation in rotation speeds of different layers within the star, with the outer layers slowed down by the disk compared to the core, again resulting in greater mixing of material and more lithium being dragged down to layers where the temperature is high enough to destroy it.

While more observations and detailed modeling is required to determine the physical process causing lithium depletion in planetary systems, these results suggest that an understanding of the Sun's lack of lithium may be best understood by looking at other planetary systems.

Israelian, G., Mena, E., Santos, N., Sousa, S., Mayor, M., Udry, S., CerdeƱa, C., Rebolo, R., & Randich, S. (2009). Enhanced lithium depletion in Sun-like stars with orbiting planets Nature, 462 (7270), 189-191 DOI: 10.1038/nature08483

Posted by Megan on Wednesday 02nd Dec 2009 (13:41 UTC) | Add a comment | Permalink

In the News this month: mystery at the centre of Cas A

The Cassiopeia A supernova remnant
The Cassiopeia A supernova remnant CREDIT: X-ray: NASA/CXC/SAO; Optical: NASA/STScI; Infrared: NASA/JPL-Caltech/Steward/O.Krause et al

When massive stars explode as supernovae, they leave behind a dense, compact object: either a neutron star or a black hole depending on the mass of the original star. They also produce an expanding shell of debris known as a supernova remnant. Many of these shells are known in the Milky Way, but compact objects are not detected in all of them. One object in particular, the remnant known as Cassiopeia A has been expanding since its progenitor star exploded about 330 years ago, but for a long time no compact object was detected, despite many searches. Then, in 1999, observations from the Chandra X-ray Observatory showed X-ray emission coming from the centre of the remnant. But, the emission characteristics of the object did not match what astronomers expected to see from a neutron star or black hole, so its nature remained uncertain. Now, two researchers think they know why.

In a paper published in the journal Nature on November 5th, the astrophysicists suggest that Cas A does contain a central compact neutron star, but that it may be surrounded by an unusual atmosphere of carbon. The Cassiopeia A remnant is located at a distance of 3.4 kiloparsecs from the Earth and is one of the youngest known in the Milky Way, the explosion of the star which created the remnant may have been witnessed by the Astronomer Royal at the time, John Flamsteed, in 1680. Wynne Ho from the University of Southampton and Craig Heinke of the University of Alberta, created models of the emission that would be expected from various different types of neutron star atmospheres, and compared their models to spectra of Cas A from archive Chandra observations of the central compact object.

What their models showed was that if the neutron star has a normal hydrogen or helium atmosphere, the size of the emission region would be only 4 or 5 kilometres in diameter, much smaller than the size of this type of star predicted by standard models. This would suggest that the emission would be coming not from the entire surface, but from hotspots, however such hotspots would be hard to produce, and difficult to maintain at a constant temperature. If the star had a carbon atmosphere however, the predicted radius of the emission region is 12 to 15 kilometres, closely matching the predictions for the radius of a normal neutron star.

So why is the compact object in Cas A so unusual? The authors suggest that this could be due to its young age. They think that the neutron star could accumulate an atmosphere of hydrogen and helium over time, and develop a detectable spin, making it appear more like other, well-studied, neutron stars. While this is a plausible model for the compact object in Cas A, further observations are still required in order to prove it is the correct explanation.

Ho, W., & Heinke, C. (2009). A neutron star with a carbon atmosphere in the Cassiopeia A supernova remnant Nature, 462 (7269), 71-73 DOI: 10.1038/nature08525

Posted by Megan on Wednesday 02nd Dec 2009 (13:20 UTC) | Add a comment | Permalink

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