Astronomers here in Belfast have just announced that they have discovered what they believe to be the youngest ever planet observed. So young that it may have not completely formed yet. They used radio telescopes in the UK (the MERLIN network) and in the US (the VLA) to study the star system of HL Tau, a star in Taurus about 520 light years from Earth

They were looking at the system’s large and unusually bright proto-planetary disc. What they found initially was that the disc contained fairly large lumps of dust and some rocky sized objects, roughly the size of pebbles. On closer inspection the team also noticed a much larger clumping of dust and gas with a mass of about 14 Jupiter masses; orbiting at the same distance from HL Tau as Neptune does from our Sun.

A few years ago another team of astronomers reported seeing nebulosity in the same region that this proto-planet has been seen; leading these astronomers to conclude that what they are seeing really is a newly forming planet still nestled in the dusty disc out of which it emerged. The young planet (now dubbed HL Tau b) could have potentially formed very recently, meaning that even at its oldest possible age (a 100,000 years) it would still be just one percent as old as the previous youngest planet found.

In the RAS press release Dr Jane Greaves who has just presented a talk here on the exoplanet remarks, “we see a distinct orbiting ball of gas and dust, which is exactly how a very young proto-planet should look.” What’s perhaps even more interesting is the result of a computer simulation run to see how a planet forming disc like this might evolve. What it shows is a planet forming that is very similar to the observed HL Tau b.

This is incredible news and a discovery which is yet another step in tying together the evolution of planetary systems from a dusty proto-planetary disc full of dust and gas to a proper system of planets like our own Solar System. Greaves believes that the planet will eventually form a massive gas giant planet like “a massive version of Jupiter”.

Top image: The real data showing the disc around HL Tau with HL Tau b marked ‘b’
Credit: VLA + Pie Town antenna

Bottom image: A computer simulation showing how a dusty disc like HL Tau’s might evolve.
Credit: Greaves, Richards, Rice & Muxlow 2008

You might think that with all the wonderful work astronomers have been doing in the last few decades, we’d know our local neighbourhood pretty well. However, Dan Zucker of the Institute of Astronomy took twenty minutes during one of the morning sessions today to introduce us to a few new neighbours. In 2003 we only knew of nine dwarf spheroidal galaxies, and even fewer around the Andromeda galaxy, far fewer than predicted by models of galaxy formation. In 2003 and 2004 several new galaxies were found in Sloan Digital Sky Survey data, alongside several streams of stars linking systems, but the level of complexity was still much less than that seen in computer simulations.

Astronomers turned to a more systematic technique, plotting the density of stars across the whole quarter (or so) of the sky that the SDSS data covers. As well as the streams of stars that were already known, a few small patches of the sky leapt out; lots of these were perfectly normal globular clusters, but others turned out to be new Milky Way satellites.

These are really faint systems, spread between 30 to 420 kpc away. Intriguingly, their stars are moving rapidly; the stars are moving so fast, in fact, that unless the galaxies are embedded in large haloes of dark matter they would quickly evaporate. The visible light we see would then be just the tip of the iceberg. Yet these galaxies are irregular in shape; normally, we’d attribute these irregularities to tidal interactions, but the gravitational pull of a massive halo should protect a system from this kind of disruption. These newly discovered next door neighbours have plenty more to teach us, it seems.

The second plenary talk of the day is on the topic of the Sun, and has the most distracting powerpoint backgrounds I have ever seen - beautiful movies from Hinode showing active regions on the solar surface. Our view of our parent star is being radically changed by a new generation of missions, including not just Hinode but also STEREO.

A particularly dramatic event is illustrated below in an image being unveiled today by David Long of Trinity College Dublin.

It shows a large wave - a tsunami, perhaps - moving across the Sun’s surface. Traveling at up to a million kilometers per hour, this shock wave was kick started by a coronal mass ejection. These dramatic events involve the ejection of material from the solar surface, although the details are - as whenever magnetic fields get involved in astronomy - complicated almost beyond belief. The close up view provided by STEREO in each of four wavelengths has proved equally confusing; each wavelength of light corresponds to different layers of the Sun’s atmosphere. The wave should pass more slowly in lower and denser atmospheric layers, but instead appears to move with the same speed wherever it’s observed. More mysteries - and more beautiful images - for solar physicists.

Everyone wants a Eureka moment in their scientific career, whether it’s jumping out of a bath or seeing the first light from a supernova. The truth, though, is that they’re very very rare, but in today’s first plenary talk we got a glimpse of the moment when one of the most important discoveries of the last decade or so took place. Brian Schmidt, from the Australian National University, was part of one of the two teams that independently discovered that the Universe was accelerating, rather than slowing down under the influence of gravity as (almost) everyone expected. He showed the audience the page from the lab notebook belonging to Adam Reiss, who was the first to realise what their observations showed; the underlined conclusion was that without acceleration, the results produced a negative mass for the Universe. Thus the assumption was wrong, and thus acceleration. So that’s it - Adam at least had his Eureka moment (and was at least excited enough to underline it!). Except that for the rest of the team, despite being involved in such a remarkable discovery, there was no Eureka. Brian reported his instantaneous reaction was that the result must be wrong…for them this great discovery was not an eureka, but a slow dawning that their result might just be correct… Dual post : Both Will and I are obviously in the same lecture. Here’s his take

Good morning from Belfast! I’m sitting inside the main lecture theatre here at Queen’s University listening to the two early morning plenary session talks. Dr Brian Schmidt from the Australian National University is first up and is giving a great talk on ‘Measuring cosmic acceleration’. It’s a fascinating story which begins, in some sense at least, in the mid to late nineties when astronomers found evidence that the rate at which the Universe was expanding is accelerating.

They had been studying cosmic events called Type Ia supernovae. These are violent thermonuclear events which can appear up to 100 times brighter than Type II supernovae in the night sky and “5 billion times brighter than our Sun”. Astronomers use this particular brand of supernovae as what they call a ‘standard candle’; essentially a cosmic distance marker*. That’s because the mechanisms and processes that form them (currently thought to be the dumping of matter (accretion) onto a white dwarf by a companion star) are fairly well understood. Since they are understood and are extremely bright, for a given distance, astronomers know how bright they should be; thus making them good standard candles.

Today much of what we know about dark energy and the expansion of the Universe has come from observations of distant Type Ia supernovae and the Cosmic Microwave Background. According to Dr Schmidt the whole discussion around the accelerating Universe has developed tremendously in the last ten years. That is primarily because of the discovery of the presence (or really the inference) of dark energy - a component of matter, in the Universe, which appears to be causing the rate of expansion to speed up.

Dr Schmidt has a website here and a great web-presentation on ‘The Accelerating Universe - an explanation for the interested non-scientist’ here.

*It’s worth noting, says Dr Schmidt, that not all Type Ia supernovae are the identical. It’s thanks to work done by several astronomers investigating the nature of different Type Ia events (and their light curves) that we can still use them as good standard candles.

Above: The result of a Type Ia supernova? - Tycho’s Supernova
Credit: NASA/ESA, CXO and P. Ruiz-Lapuente (University of Barcelona)

The result from the all-important 5-a-side football competition was a victory for Edinburgh, beating local favourites QUB 2-1 thanks to a late penalty. Full match reports to follow if and when we can find an unbiased reporter…

There were two plenary talks on the first day of NAM and both were pretty interesting. The first was by Richard Ellis and was about galaxy evolution. He described how our understanding of galaxy formation has suffered a bit of a set-back in recent years as heirarchical growth - growing big galaxies from small ones - has been challenged. Apparently massive galaxies can happily form at high redshift (big distances/early time) and smaller mass galaxies are continuing to grow at low redshifts (relatively nearby/late time).

He also told us about another problem in our understanding. We have measurements of the mass assembly history and the star formation history of galaxies but these don’t really seem to agree. Either there is too much star formation (not likely because we usually over-estimate) or we under-estimate the stellar mass. He suggested that there may have been a problem with the calibration of the data (likely) or there may be something about the universe we don’t yet know (unlikely, but would be interesting).

My favourite quote of the talk was that “a large fraction of massive galaxies are already red and dead by redshift 2 or 3.”

Richard posed the questions: Why do massive galaxies that form early on in the universe not really grow with time whereas smaller mass galaxies are still forming? What cuts off the star formation in massive galaxies? One answer may be that the radio jets from the central black hole stop cooling flow.

He mentioned that gravitational lensing surveys are being used to look for very faint and distant objects that have been greatly magnified. That means that we can look back to earlier times. Also, with adaptive optics on telescopes we can now observe galaxies with a resolution of 100 pc - that is around 326 light years - at a redshift of 3. That is a fairly impressive resolution.

The second plenary talk was by Don Pollacco on the search for exoplanets. As Don said, we live at a tremendous time in astronomy and although the UK was quite slow to join in the area of exoplanet discovery we are now fully involved. The talk started by giving a potted history of exoplanet discovery. The first exoplanet was found around a pulsar in 1991 and is still the only earth sized planet(s) known. The first exoplanet around a Sun-like star was found four years later in 1995. We are now up to around 270 known exoplanets.

Many of the early planets were found to be very close to their stars and that was a shock to astronomers who expected things to look much like our own solar system. It is thought that the planets have to form further out from the stars than we observe them so they must migrate inwards. Interestingly, a lot of the exoplanets have elliptical orbits and there are not many low metallicity stars with planets.  A plot was shown that compared simulations of planet formation (colour-coded by gas giant, icy planet or rocky planet) with the currently observed planets and it seems to show that we are mainly detecting the gas giant planets. Techniques such as gravitational microlensing will probably help find the smaller planets though.

Part of the talk was about the SuperWASP project, which Don works on, and which today announced the discovery of 10 new transiting planets. That is pretty impressive especially considering that only 35 had previously been discovered by the transit method.

Nick (The Jodcast) managed to record audio interviews with both speakers and we’ll try to post them on the NAM Blog tomorrow.

Starting a conference on April 1st could lead to hundreds of practical jokes but I only managed to spot one in a talk by Paul Roche of Cardiff University. He included a slide listing his some of his collaborators as J. Harkness, G. Cooper, I. Jones, O. Harper and T. Sato of the Torchwood Institute.

At the Virtual Observatory session - more on that later - Ryan Scranton of Google Inc had been due to give a talk titled “Using Google Sky as a Science Tool” but it had been cancelled due to “a major release coming up”. The subject of the major release wasn’t explained but I assume it wasn’t related to the April 1st announcement that Google and Virgin were creating Virgle to establish a human base on Mars.

It must only be UK astronomers who associate NAM with meeting old friends and catching up on science rather than old war movies and Apocalypse Now, but at least this year’s National Astronomy Meeting is starting with a bang. An new image released by a team from our hosts, Queen’s University Belfast, shows a supernova in the galaxy NGC 2397.

The picture includes an image of supernova 2006bc, an explosion that marked the death of a massive star. Unusually, the image includes the supernova while it is still on the rapid climb to maximum brightness; capturing supernovae early is crucial to improving our understanding of these dramatic events. The work of the team at QUB focuses on combing through images taken before the explosion in order to determine the nature of the stars which will end their lives so dramatically. Their hard work seems to show that a stellar mass of just seven times that of the Sun is sufficient to produce such an explosion, but no very massive stars have been identified as supernova precursors. That suggests that these massive stars might be directly collapsing to black holes - an intriguing possibility.

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