OK so yet again I’m blogging on a topic I don’t know terribly much about but that I found interesting. A month ago this paper by Paolo Molaro and Pierluigi Selvelli from Trieste Observatory appeared outlining the interesting case of early telescopes in paintings.
The paper focusses on the work of Jan Brueghel the Elder and in particular two works made between 1608 and 1617. My knowledge of Flemish painters is limited to Jan van Eyck and Hieronymus Bosch (and most if the latter comes from watching In Bruge) so forgive me if I can’t discuss the finer technical points of the art, there does appear however that there could be be a fascinating story behind the paintings.
In the early 17th century the Eighty Years’ War had reached stalemate. Most of what is now The Netherlands was held by the new Dutch Republic while their Spanish opponents and former overlords remained in control of Flanders to the south. It was in this environment that the telescope was first invented. Who invented it is not certain, but we do know that the first public demonstration was in Den Haag in 1608.
Around this time Jan Brueghel the Elder was working as the court painter for Archduke Albert VII (the sovereign of the Spanish/Austrian portion of the Low Countries). At some time in-between 1608 and 1611 he painted “Extensive Landscape with View of the Castle of Mariemon” (I can’t find a picture online, see the original paper). In this the archduke is seen viewing the scenery through a telescope. Given the date it is likely this is one of the earliest such device. The authors then go on to speculate that this device could have been made by the inventor of the telescope. One letter from a Papal envoy to a nephew of Pope Paul V claims that, having seen the telescope being demonstrated in Den Haag while he was there negotiating a peace deal with Dutch Stadthouder Maurice of Nassau, Ambrosio Spinola (the Genoese commander of the Spanish Army in the Low Countries) was impressed and managed to obtain one of these “spyglasses”. Another letter written by a Udine nobleman (to Galileo of all people) claims this came from the inventor himself.
Brueghel also worked on a series of paintings in collaboration with Ruebens. In The Allegory of Sight (1617, see below),
he paints a long, silver telescope. The authors deduce from its style and dimensions that this instrument could be one of the first Keplerian Telescopes (one where the eyepiece as well as the objective lens is convex). These were first described in principle by Kepler in 1611 and could have been manufactured shortly after. They suggest that Christoph Scheiner, one of the first people to observe sunspots, had presented Keplerian telescopes to Archduke Albert’s brother in Innsbruck. A Keplerian Telescope produces an image which is upside down, Scheiner added a third lense to flip the image to the correct orientation. So again it is quite possible that this is one of the first ever device of its type ever made.
I hope I’ve given a reasonable run-down of a subject, if you want to know the full story from a much better source then I urge you to read the original paper. And if you understand what the title of this post is a nod to, don’t complete it in the comments thread (please).
Paolo Molaro, & Pierluigi Selvelli (2009). The mystery of the telescopes in Jan Brueghel the Elder’s paintings Memorie della Società Astronomica Italiana arXiv: 0908.2696v1
Earlier this year, on the 14th of May, the rocket Ariane V launched from the French Guiana with an astonishing precious cargo on board: the Hershel and the Planck satellites, two very ambitious European astronomy experiments, each with its own mission.
So you may remember that a while ago, Emma announced the release of the first images from Hershel, and last Thursday it was the turn of its sister mission’s first light to be set free to the public. Planck is out there to capture radiation which was created when the Universe was incredibly young, just a mere 340,000 years old or so – we call it the Cosmic Microwave Background radiation. If that sounds like a lot, remember that the Universe is around 13,500,000,000 years old today (give or take a few hundreds of thousands of years)! In human terms, it’s the equivalent of looking at a picture of myself 6 hours after my birth – prior to my first bath, even.
The difference between me and the Universe – or one of – is the fact that we can tell an awful lot about the content, geometry and evolution of the Universe from such an early on picture. Our understanding of Cosmology has in fact been shaped by a previous experiment that has been mapping the Cosmic Microwave Background since 2004 – NASA’s Wilkinson Microwave Anisotropy Probe. WMAP has answered many questions and raised tons more, both being the mark of a successful science experiment. Planck is like WMAP in its primary goal – which is to map the Cosmic Microwave Background with unprecedented detail and precision – but differs in just how well it can do it, which in turn broadens the scope of scientific questions it can answer. And of the ones it can raise!
So here you have it – a true, honest to heart picture of the Universe when it was less than 400,000 years old:
What you see is actually a combination of two pictures, so let me explain. The colourful strip that twists around the picture is the data that has come from Planck. The background, is an image of the full night sky, projected into two dimensions (like you would for a world map, pretty much) and with our own Milk Way going along the centre. The background is just there to give you a frame of reference – eventually Planck will map the whole sky, as that colourful strip extends to cover more and more of the sky. The reason why they look so different is because Planck is designed to pick up radiation in the microwave region of the electromagnetic spectrum, whereas the background picture is in visible light.
Planck will also look at each region of the sky multiple times, and each time it does it will improve the scientific value of the data. This is simply a preliminary picture, in the way of an example – but the data quality is excellent and all seems to be in place for a highly successful and smooth mission. We have to wait a while yet for the first science results to come out, but rest assured that we will cover them here on weareallinthegutter as they arrive.
These are good times, exciting times for science and cosmology – exciting times indeed!
Would you let the general public do your work for you? How about just the bits that are fundamentally important but would take you months of repetitive effort to get through on your own? In 2007, the GalaxyZoo team did exactly that and its been a massive success. They had images of a million galaxies from the Sloan Digital Sky Survey which they needed to classify multiple times (to ensure accuracy) and by eye (because people are much better at this than computers). They decided to see if they could use the power of the internet to harness a team of volunteers – the ‘Zooites’ – to help them. The site they set up, www.galaxyzoo.org, received nearly 1.5 million classifications from more than 35000 volunteers in the first 24 hours alone and continues to be very popular to this day. Go and help them if you’ve got a bit of spare time…
But what was motivating these citizen scientists to put in all this effort? To find out the GalaxyZoo team have been carrying out a series of interviews alongside forum discussion threads. They collated the results and narrowed the responses down to 12 motivation categories including “looking at galaxies that few people have seen before”, “enjoying the beautiful galaxy images” and simply “fun”. The three most popular were interestingly “interested in Astronomy”, “excited to contribute to original scientific research” and “amazed by the vast scale of the Universe”. I think if you asked most professional astronomers they’d say exactly the same thing!
This was just a pilot study, involving a small number of people (and may be biased towards the more proactive volunteers). However, armed with these 12 categories the team are now repeating the study with a much larger sample to get a better insight, which in turn will help the research teams of the future design new and exciting projects for the citizen scientists to get involved in.
M. Jordan Raddick, Georgia Bracey, Pamela L. Gay, Chris J. Lintott, Phil Murray, Kevin Schawinski, Alexander S. Szalay, & Jan Vandenberg (2009). Galaxy Zoo: Exploring the Motivations of Citizen Science Volunteers to be published in Astronomy Education Review arXiv: 0909.2925v1
In my last post I spent a lot of time explaining what a quasar is. Which is handy as Goto et al. have just detected the host galaxy of the most distant quasar currently known (its a vast 12.8 billion light years away from us which means we’re seeing back to a time when the Universe was 16 times younger than it is today).
Quick recap – remember that a quasar is an AGN orientated such that its light completely outshines the light from the galaxy hosting it. “Well”, you’re probably thinking, “if that’s true, how is it possible to see the host at all then?” The answer’s simple – it can’t be seen, not directly. Its (very faint) light makes up a tiny part of the total received by us though. If the quasar’s (massive) contribution could be completely removed, then the galaxy would appear.
This tricky measurement is exactly what Goto et al. did using a newly upgraded camera on the Subaru telescope in Hawaii. The image below is from their paper (copyright Tomotsugu Goto, University of Hawaii). On the left is the original image of the most-distant-quasar CFHQSJ2329-0301 (yes, that really is its name); the blob in the middle is their model of the quasar light coming from the central black hole region. The final image on the right is what’s left after subtracting the model – i.e. the host galaxy. Incidentally, 4 arcseconds (“) are equivalent to 22 kpc or 72,000 light years at the distance of this object.
The detected host turns out to be as large as our own Milky Way which is interesting as it means that it, and its associated supermassive, quasar creating, black hole must have formed rapidly to be the size they are at this early epoch of the Universe. Studying this system, and others like it, will help to understand the complicated mechanisms of galaxy formation.
Tomotsugu Goto, Yousuke Utsumi, Hisanori Furusawa, Satoshi Miyazaki, & Yutaka Komiyama (2009). A QSO host galaxy and its Lyalpha emission at z=6.43 Accepted for publication in MNRAS arXiv: 0908.4079v1
Right, it’s about time this blog went extragalactic again. As Douglas Adams wrote, “Space…is big. Really big. You just won’t believe how vastly, hugely, mind- bogglingly big it is. I mean, you may think it’s a long way down the road to the chemist’s, but that’s just peanuts to space”. With all that Universe available we shouldn’t spend all our time talking about things in our own back garden! Today, therefore, I want to talk about some new results concerning the behaviour of quasars and radio galaxies – two types of radio loud, active galactic nuclei or AGN.
Before I start though I think I need a paragraph or two to explain what exactly an AGN is, to save those of you who don’t know from having to follow my links to Wikipedia above! Everybody else, I’ll try and be brief but please skip ahead if it gets boring…
So, the first thing to note is that it looks like most, if not all, galaxies have a massive black hole at their centre. Mostly they sit there, minding their own business, not drawing attention to themselves (the one in the Milky Way, the galaxy we live in, is like this – we know it’s there because people have tracked the stars that orbit it). Occasionally though the black hole is surrounded by a rapidly rotating disk of gas and dust, in the process of accreting onto it (I always think of this as being analogous to water swirling round a plughole). Collisions in the disk heat the material and result in the emission of massive amounts of radiation from this small region – so much that the galaxy’s nucleus outshines the combined light of all its stars! Hence the term ‘active nucleus’ or AGN. A further twist to this picture is that about a tenth of these objects also produce twin giant, radio emitting, jets, which emerge perpendicular to the accretion disk, and extend far beyond the extent of the host galaxy, before depositing their energy in huge puffed up lobes. It’s not clear what starts these jets as there’s no telescope good enough to see into this region.
Imagine now viewing one of these AGN from lots of different angles – it would look completely different depending on how it was oriented towards you. When these things were first discovered they were classed as many different types of object because of this, and it took a long time before people realised they could all be linked together. The picture below (ref. here) is a good illustration of this for a radio loud AGN (though bear in mind that not all AGN have all of these features). Looking edge on, the bright central nucleus is obscured by a large, dust torus so the light from the host galaxy isn’t drowned out, and only the jets are seen – a radio galaxy. Increase the angle and the nucleus is no longer obscured so it overshadows everything (including, sometimes, the jets) – a quasar. See here for a more detailed explanation of this!
Ok, now everybody hopefully has some idea what a radio galaxy and a quasar are, and how they’re related we can get back to the point, assuming anyone’s still interested (please still be interested). AGN lifetimes are pretty short compared to the age of the galaxy hosting them – they only last for as long as they have fuel. However, they could presumably reignite if they were refueled, maybe through a merger. When the AGN switches off, the jets would also disappear, but the lobes would linger, slowly depleting the reservoir of energy that’s been deposited in them. This means that the remnants of a previous cycle of activity could still be present at the beginning of the next one. This is exactly what was seen in four radio galaxies by Schoenmakers et al. in a paper published in 2000. They called them Double Double Radio Galaxies as they have two pairs of lobes – one new and one old. Since then, about ten more of these have been identified (including one with three lobe pairs), but none in other radio loud AGN as their orientation makes their jet/lobe structure harder to disentangle.
This all changed last month when Jamrozy et al. presented the first clear detection of a double double structure in a quasar. This is good news for the unification model – different types of radio loud AGN should behave in the same way if the only difference between them is orientation. It’s also more evidence for episodic activity. All that’s left to do now is figure out exactly why this happens… Finding and investigating more of these Double Double sources should hopefully help.
Schoenmakers, A., de Bruyn, A., Rottgering, H., van der Laan, H., & Kaiser, C. (2000). Radio galaxies with a ‘double-double morphology’ – I. Analysis of the radio properties and evidence for interrupted activity in active galactic nuclei Monthly Notices of the Royal Astronomical Society, 315 (2), 371-380 DOI: 10.1046/j.1365-8711.2000.03430.x
M. Jamrozy, D. J. Saikia, & C. Konar (2009). 4C02.27: a quasar with episodic activity? Accepted for publication in MNRAS arXiv: 0908.1508v1