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VLBI Idiot

Yesterday was the annual "summer" barbecue at ASTRON; this being the Netherlands though, you can imagine the weather was more reminiscent of, well, anything but summer. This year the crowd were entertained (I hope that's the right word) by MEGASTRON, a band made up of students and employees of both ASTRON and JIVE, including me (but, before you ask, the name was not my idea and I had no say in the matter!). The five of us had been playing together for about two months, working on cover versions of sixteen songs altogether, but there was an issue with one song in particular: we planned to do Green Day's American Idiot, but none of us is American so the lyrics seemed a bit odd. So... out came my pen. By popular demand, and with sincere apologies to Green Day, here is the version we sang:

Don't wanna be a VLBI idiot
Observations stored on old media
And can you hear the sound of a pulsar?
The sub-luminal tick tock phenomena

Chorus: Welcome to a new observation
             All across the European Network
             My fringes seem to be okay
             Publication dreams of tomorrow
             Telescopes, the sources will follow
             With referees we'll argue!

Well maybe I'm an all-round astronomer
I'm not a part of a radio agenda
Now everybody do the funky quasar
And sing along in the age of LOFAR ALMA

Chorus

Don't wanna be a VLBI idiot
Observations stored on old media
Information in the correlator
I'll flag my RFI later

Chorus



And, if you really want a laugh, you can see the video (recorded by our director) on youtube. There was a static camera recording the whole gig, a recording of the sound from the mixing desk, and I don't know how many other cameras in the room, but we haven't looked at any of it yet... part of me doesn't really want to!

Posted by Megan on Friday 22nd Jun 2012 (11:52 UTC) | Add a comment | Permalink

Calling all astronomers: e-MERLIN cycle 0 call for proposals now open!

It's finally here! The call for proposals for cycle 0 of e-MERLIN observations was issued in December and today the proposal submission tool went live. Astronomers have until January 29th to submit their proposals for observations on the upgraded and much-improved facility. Details of the technical capabilities are available on the e-MERLIN website. There are already many approved legacy programmes which will make use of large chunks of the available time over the next couple of years, but that still leaves time available for general observations. I'm putting together a couple of proposals myself, and will probably be involved with one or two others as well.

MERLIN had a bunch of tools for doing both the first-stage data processing, and a pipeline available as both a script which would generate a bespoke AIPS runfile based on user interaction or as an AIPS procedure which could be run as a task inside AIPS. Data output from the new e-MERLIN correlator is different and, although the data volumes are much larger, is simpler to process in that no processing is required before reading the data into AIPS.

I spent the summer of 2011 working at JBCA, helping with commissioning efforts, processing early-science datasets and helping out the odd early e-MERLIN user. While I was there, I started to play with ParselTongue (the Python interface to AIPS, nothing to do with Harry Potter) and by the end of the summer I had working scripts to take care of the initial loading and housekeeping procedures, and a functioning data reduction pipeline for simple datasets.

At the end of the summer I moved to the Netherlands to work for ASTRON. Unfortunately, due to a malicious attack on the Jodrell computer system not long after I left Manchester, the latest versions of the scripts are not situated at Jodrell at all (where they would be most useful!), but here on rigel instead. If you're an astronomer and you play with these scripts, please send me some feedback. Contact details are on the page with the scripts.

Posted by Megan on Wednesday 11th Jan 2012 (16:27 UTC) | Add a comment | Permalink

Advice to speakers

The postdocs here are about to be sent on a communication skills course. The idea is to improve our presentation skills to help both our careers and the outward impression of the institute (if the staff are more articulate when speaking in public, people go away from talks with a better impression of the place and are more likely to remember the cool stuff happening here). It's not a bad idea and I'm actually looking forward to it, but personally I think such training would have been useful at PhD level - not everyone who does a PhD goes on to become a research scientist, but everyone needs to communicate and scientists do have a bad reputation for this particular skill (it's not hard to see why).

I've lost count of how many talks I've given since I started my PhD back in 2003. A great number of those have been public or schools talks rather than scientific presentations (in reality these are a lot closer in form than you might think - a conference talk does not have to be incomprehensibly full of jargon in order to be good), and I've taken part in science debates and radio shows. One reason I started doing outreach was precisely because I hated public speaking: I knew I'd have to overcome this if I was going to stay in research. Today I still get very nervous before standing up to give any kind of talk, but I have become much better at hiding it - to the extent that people no longer believe me when I tell them I get nervous...

So, having given many talks at all levels, recorded some of them so I could listen back and find ways to improve, listened to a great many good (and bad) colloquium and conference speakers, interviewed people, been interviewed myself, been a guest on the odd talk show, and recorded many hours of podcasts, here are a few bits of advice I would give to speakers based on what I've observed:

  • Do not address the screen - you are meant to be talking to the audience; they came to hear what you had to say, not read your slides and admire the back of your head (however impressive it might be).

  • Do not assume your audience has the same knowledge of the subject as you and your collaborators: some of them might, but many wont. This is especially important in a public talk, but it also goes for conferences - do not assume the audience knows everything about your particular bit of the subject (I've seen speakers get this badly wrong and send a room full of physicists to sleep - it's not a pretty sight).

  • Do not assume the audience want to know the subject in the same level of detail as you and your collaborators - this is a one-off talk after all, not an undergraduate lecture series. If someone really does want all the gory details, they can always ask you later.

  • Do not fill your slides with words - trust me, your audience can read faster than you can talk. If I want to read what you did, I can look at the conference proceedings later. On a related note....

  • Use images wherever possible. Make yourself short notes if you need them (there's nothing wrong with that) but make them short enough you can remind yourself of what you wanted to say with a quick glance - don't stare at your notes either!

  • Project your voice - if your audience can't actually hear you, what's the point in talking? This can be a tough skill to master, but it's worth it.

  • Talk at a reasonable pace - too slow and your audience will fall asleep, too fast and some of them will be unable to keep up. (This is one I know I'm often guilty of myself - I often speak quite quickly, especially when I am excited by the subject, and it is something I have consciously been trying to change. May be I should stick to researching boring stuff?)

  • Don't talk with your hand in front of your mouth - as well as making your speech indistinct, if anyone in your audience is hard of hearing (what's the average age of a conference audience?) they may well need to see your mouth in order to understand what you are saying.

  • Make sure you end with a conclusion - remember the old adage: tell them what you're going to tell them, tell them, then tell you what you've told them. A talk without a conclusion is like dinner without dessert, you leave the audience feeling like something is missing (and wondering what the point was).

  • Don't spend 45 minutes of a 50-minute talk introducing the background information, your audience wants to know what you found, not take a lecture course in why you asked the question.

  • Record yourself - it may be painful to watch/listen to yourself give a talk, but at least you will discover what mannerisms you have and can then learn to avoid them in future.

This is just what comes to mind at the moment of course, it is far from a complete list of things to avoid / common mistakes made when giving presentations. The important thing to remember is that you could be doing the most exciting science in the world, but if you are unable to communicate it then you may as well not do the research in the first place.

Oh, and for a highly entertaining read on the subject of scientists and communication, I'd recommend Don't Be Such A Scientist by biologist-turned-filmmaker Randy Olson.

Posted by Megan on Saturday 05th Nov 2011 (17:03 UTC) | Add a comment | Permalink

In the news this month: a primitive star in our own backyard

The spectrum of SDSS J102915+172927
The distribution of the light of different colours coming from the remarkable star SDSS J102915+172927 after it has been split up by the X-Shooter instrument on the ESO VLT. CREDIT: ESO/E. Caffau


Our current model of the early universe says that, as it expanded and cooled after the Big Bang, quarks began to coalesce to form protons and neutrons which, when the temperature dropped far enough, began to form simple nuclei. Eventually this material, mainly hydrogen with some helium and trace amounts of lithium, began to clump together, forming the stars and galaxies that we see today. Heavier elements such as carbon, nitrogen and oxygen, in fact pretty much everything that makes up this planet and all the life on it, were created later by processing of this primitive material in stars and supernova explosions. This processing in nuclear fusion reactions produces all the heavier elements that make up the universe. Since less massive stars last longer before running out of fuel, there should be a population of very low mass stars which have been around since the early days of the universe. Such stars would be small, dim, and have an extremely low proportion of elements heavier than hydrogen and helium and, in a paper published in the journal Nature on September 1st, a team led by Elisabetta Caffau at the University of Heidelberg in Germany have found just such a star in the halo of the Milky Way, but with an unusual chemical make-up.

The star, located in the constellation of Leo and known as SDSS J102915+172927, has been found to have the lowest amount of elements heavier than helium of all stars yet studied, a quantity known as metalicity. While a few other primitive stars with very low metalicities have been found, the others all have carbon, nitrogen and oxygen in far greater quantities than would be expected for stars from the very first population. It is thought that low mass stars such as these could only form after the interstellar gas had been enriched by supernova explosions with elements such as carbon and oxygen, since these elements act as a vital cooling agent, reducing the temperature of the gas cloud to the point where gravity can begin to overcome pressure and cause the clumping which eventually leads to stars. This conclusion means that the low abundance of elements including carbon, nitrogen and oxygen in the newly discovered star does not fit with current models of star formation in the early universe.

A further puzzle with this star is the amount of lithium it contains; it's lithium abundance is at least 50 times smaller than that predicted by big bang nucleosynthesis. The likely explanation is that the stellar material must have experienced temperatures >2 million K, the temperature required to destroy lithium. While the chemical composition of this star is something of a challenge to current models of early star formation, along with other examples that should be unearthed in planned surveys, it should provide clues which will help in our understanding of the very first stellar population.



This blog post is a news story from the Jodcast, aired in the October 2011 edition.

Caffau, E., Bonifacio, P., Fran├žois, P., Sbordone, L., Monaco, L., Spite, M., Spite, F., Ludwig, H., Cayrel, R., Zaggia, S., Hammer, F., Randich, S., Molaro, P., & Hill, V. (2011). An extremely primitive star in the Galactic halo Nature, 477 (7362), 67-69 DOI: 10.1038/nature10377

Posted by Megan on Tuesday 11th Oct 2011 (15:49 UTC) | Add a comment | Permalink

Afraid of the dark

I've never been afraid of the dark.  When it's all you've ever known, it seems a rather silly notion.  But now... well, this seems different somehow.  Now we're all frightened.

It wasn't always like this.  We all grew up with the stories about the old times, when there were colonies every few parsecs, all set on planets (artificial or otherwise) around healthy stars, and supply stations strung along the major trade routes likes beads of water on an invisible web.  The galaxy thrived back then, or so the stories go.  Civilisation reaching ever outwards, colonising, trading, cooperating, and fighting, naturally.  There was rarely ever total peace, not in our nature say the historians.  But it's all long gone now.

Slowly, imperceptibly at first, night began to fall across the universe.  Complete and total darkness, the end of all things.  Our own star (we knew it as Suryan) faded from glory long before I was born.  I've never known real daylight, never felt the warmth of the midday sunlight on my skin.  Growing up, we were all told the stories and legends of the light times, when Suryan made the sky glow from horizon to horizon and stars filled the sky when Suryan herself slipped below the edge of the world.

But all that has faded with the generations.  Long ago our star melted away into the darkness and we were left clinging to this rock, digging ever deeper into its crust just to reach the feeble warmth of the planet's ancient cooling core.  At least we had that, other colonies were not so lucky.  Those who had settled on artificial planets didn't last long when their stars faded, their power systems were never designed to cope with such extreme cold.  The cold metal constructions lost their heat quickly and their inhabitants (those unlucky enough not to make an escape on whatever ships they might have had) froze in a matter of months.  There are those who say that was a better way to go.

Suryan isn't completely dead of course, that takes billions of years.  When she ran out of material to fuse, her outer atmosphere expanded, reaching almost as far as our colony here on the fourth planet.  Protected under the colony's thick-walled domes, the inhabitants watched from safety as the star put on its last and greatest show.  While the core began to shrink, those burnt-orange layers continued to expand, becoming a fading wisp-like shell centred on the dying remains of what had once been a giant nuclear fusion reactor.  That remnant core still sits at the centre of this system like the last dying ember of a fire.  It still produces light and heat of course but not enough to be useful, not by a long way.

It's been some decades now since the last ship left this system.  When Suryan burnt its last, up there in the sky, there was widespread panic.  People were desperate to leave, to go somewhere else with a star that was still viable.  But there wasn't anywhere to go.  Slowly but surely, the stars were dying everywhere and there was no more gas left to create new ones.  These are the last days of the Universe, but people refused to believe it.  Somewhere there's another star, they said, somewhere.  The ships left, heading out towards whatever points of light they could see in the sky, and those who stayed behind attempted to carry on as normal.  We've known what was coming for generations but there was nothing we could do.  You either accept it and get on with life as best you can, or panic and most likely hasten your demise.  While we have no ships any more, nor the capabilities to construct any, we can still communicate with other colonies although that happens rarely these days.  There isn't anything left to communicate, and it uses power we can little afford to waste.

I often wonder what happened to those ships that left.  The records show that they kept in communication with the colony for some time after they set out, promising to return for survivors when they found a new home in the sunlight.  But then the logs stop.  When I was younger I assumed they just stopped transmitting, that they were saving energy or something.  But now, well, I've heard the stories from other colonies of madness and chaos and I wonder if the same fate befell those ships we dispersed into the night like seeds.

That's the problem with space flight of course.  It takes time.  Those ships leaving Suryan would each have headed towards a distant glimmer of light, some far-off star that hadn't yet reached the end of its days.  But in the mean time, the light from those little balls would have been travelling for centuries before it reached our system, if not longer.  What would happen to the crew if, after using all of the fuel they could spare to send them rushing onwards towards some distant star, keeping just enough to slow down again at their intended destination, they suddenly saw that their promised Eden was disappearing, fading away before their very eyes?  By that point there would be nothing they could do, no way of changing course without using up the precious fuel they would need in order to slow down once they reached somewhere habitable.  Game over.  What then?

I ask myself: what would I do in that situation?  It would be tempting to open an airlock, destroy the safety interlocks and just let everything be pulled out into the vacuum.  Not a pleasant way to go, certainly, but quicker than most options available on a tug.  We were never an exploration colony, merely a mining outpost, and those craft had never been designed for long-term use.  Your options were starvation (water was recycled, even on the tugs, so no problem there), carbon dioxide poisoning (the filters worked pretty well, but were usually replaced every couple of years), or some manner of your own choosing.  Most colonists would rather chose their way out rather than go slowly - we'd all seen it happen, read the case studies.  It was part of basic schooling on these outposts.  Harsh, may be, but the sooner you realised the realities of colony life the better.

So, here lies the remains of a once busy and reasonably prosperous colony.  Mirroring the downfall of the empire, it withered with the dying of the light.  There were those who refused to believe it would happen, others who proclaimed it as the ultimate test of faith in whatever deity they served, still others who maintained that we'd find a way out somehow.  But the truth was that we'd known for generations that this was coming.  Ways of restarting stars were proposed, but they all required more energy than the empire could spare, just for a single star.  Society crumbled, the trade routes grew silent, colonies began shutting off their contact with the outside world.  Where colonies were close enough, wars broke out.

The stars didn't all go out at once.  It takes time for a star to use up its fuel, and that depends on many things, but larger stars burn up faster.  Despite the dangers, the empire loved placing colonies around massive stars because they were the most profitable.  You could have several large artificial colonies around a massive star where they could harvest huge amounts of energy, and stellar mechanics was developed enough that the onset of a catastrophic supernova explosion, so characteristic of these massive stars, could be predicted to an accuracy of a few months.  Smaller stars like our Suryan were far more sedate.  Not massive enough to go supernova, they took many billions of years to use up their fuel.  While our colony was never rich, we lasted longer then many others simply because our star was a comparative weakling.

But even by the time this colony was founded, the universe was old.  Really, it was a wonder our species had lasted as long as it had without destroying itself from within.  Galaxies formed new stars at the rate of a few per standard solar year, but they have to come from something, you need gas to create them.  No more gas, no more stars.  We knew, as a species, that this was what would happen someday but, like countless cultures before us had done throughout history, we always assumed it would be far enough in the future that it would be someone else's problem.  For the most part that was right, but now we are that someone else, and we are scared.

Most of the colony, those who didn't leave in the tugs, have chosen to carry on as normal.  Each year we just dig a bit deeper towards the dying heart of the planet to keep the thermal plants supplied with enough energy from our world's cooling interior.  None of us alive now really knew Suryan as anything other than the dying ember that hangs in the sky today, so to us the sight is normal.  I once saw a holograph of an Earthscape - its open spaces and vivid blue sky were nauseating.  There were no stars in that picture either, apart from Sol of course, now long gone.

That's the difference.  Their sky was bright and harsh.  Ours is black and cold, as if oblivion had been given form.  I look out every day at that sky and my eyes wander, searching for the last faint pinpricks of light - something I know I'll never see again, now.  Last night, the last star in our sky faded forever.  We knew it had to happen sometime, but it was still something of a shock when it finally came.  None of us can claim to be astronomers, but we all knew the movements of that last star.  We watched it grow fainter and fainter, occasional bursts of light giving unwarranted hope of a reprieve.  Every one of those upward-gazing eyes knew what those fits meant, but still the soul hopes.... may be.

The last star.  The final vestiges of warmth are gone from the sky.  Those photons will continue on, travelling out into the darkness long after this little colony has gone.  For all we know, we may be the last, interstellar communication is a luxury that we can no longer afford.  But what's left now?  There will be no more stars, no more colonies, just endless darkness and cold like the long-dead surface of this planet.

There's still time for a walk before lights out.  I've never been outside the dome before, may be the air isn't as poisonous as they say.... I'm not afraid of the dark.



This is really going to happen, eventually. Galaxies only form stars from their own gas reservoirs, supplemented by the gas which falls onto them from their own halos, the surrounding intergalactic medium, or from galactic cannibalism where a merging galaxy provides a fresh injection of gas (often triggering a massive burst of star formation). Eventually though, this gas will run out and stars will stop forming, but not for billions of years. Stars will only shine while they have sufficient fuel in their cores for nuclear fusion to proceed; when that fuel runs out, the star dies. The ultimate fate of a star is determined by its mass, but they all stop shining eventually. The story above is based on the following paper by Braun et al. What Braun et al do in this paper is study a sample of particularly luminous galaxies known as ULIRGs, Ultra-Luminous InfraRed Galaxies, investigating their molecular gass mass. Studies of these galaxies can tell us about the evolution of molecular gass mass over time which can help in our understanding of the evolution of star formation rate density, both past and future. This particular sample is interesting because they sample a particular redshift range (0.2<z<0.5) where data is currently sparse. Coincidentally, I spotted the associated this press release from CSIRO a week after I wrote this story. You can find the paper here:

Braun, R., Popping, A., Brooks, K., & Combes, F. (2011). Molecular gas in intermediate-redshift ultraluminous infrared galaxies Monthly Notices of the Royal Astronomical Society, 416 (4), 2600-2606 DOI: 10.1111/j.1365-2966.2011.19212.x

Posted by Megan on Friday 23rd Sep 2011 (07:43 UTC) | Add a comment | Permalink

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