Luminous Blue Variables (sometimes known as LBV stars) are probably one of my favourite types of star. Simply, they're awe inspiring. As with all the most interesting things in the night sky, they're also very rare, with only a handful having been discovered.

A luminous blue is a type of hypergiant. A furious stellar giant, with up to 150 times the Sun's mass. They hold a place amongst the most luminous stars known, easily shining with millions of times the brightness of the Sun. Their huge mass drives nuclear reactions within them to produce prodigous amounts of energy. So much in fact, that most luminous blues are in danger of tearing themselves apart.

The immense stellar wind generated by the rage of these stars, combined with their violently energetic nature causes them to steadily lose mass. Stellar material is constantly thrown off into surrounding space at thousands of kilometres per second, causing these stars to reside in nebular cocoons of their own material.

Needless to say, such a star can't survive for very long. To use the cliché, luminous blues live fast and die young, only surviving for a few million years. Exactly what happens in the life of a luminous blue isn't entirely certain. Simply, we haven't seen enough of them to know for sure. That said, many believe they will evolve into similarly enraged Wolf-Rayet stars, before exploding as supernovae.

A few well known luminous blues include Eta Carinae, S Doradus, P Cygni and the Pistol Star. All are among the most massive and the most luminous stars known (although the debate over which star is actually most luminous, and whether it is indeed an LBV is still open). The Pistol Star, in fact, is so luminous that it emits roughly the same amount of energy in 20 seconds as the Sun does in a year!


Image Credit: "Angry Star" - Brad Moore, Southern Astro

And this isn't even me on a good day!


Seen and yoinked from dr_nebula

I discovered this a little while ago and have been meaning to post about it for a while. Another reason why us astrochemists are a bit atypical by the standards of virtually all other chemists...



The astronomer's periodic table. Effectively, this is what people like me have to work with. How abundant any one element is is shown by the size of its white square. All other elements combined would probably fit inside a single pixel in this image -- possibly with room to spare.

Pretty amazing, huh? Several of those wonderful elements which are essential components of us living creatures (like phosphorus, calcium and sodium) are really quite rare on the grand scale of things. So rare, in fact, that it takes a huge ball of iron and silicates (like Earth) to gravitationally scoop up enough of them for us to exist at all.

This is also why we don't do any astrochemical searches for funkier chemicals in interstellar space. Things like phosphines, boranes and uranium oxides probably all exist in the interstellar medium. There's no good reason why they shouldn't. The thing is, there would be so little of them out there that we could never ever detect them!

So instead, we limit ourselves to elements we actually have a chance of finding. Incidentally, looking at that image, you can also see pretty easily why the most common molecules in the Universe are H₂, CO and H₂O!


Image half-inched from the McCall Research Group website.

So in addition to Supernova Condensate, I'm now also an author on on the collaborative Space Tweep Society blog. A collection of space enthusiasts from Twitter (from all manner of backgrounds). Because, as the tagline says, sometimes 140 characters just isn't enough.

To be honest, it feels a little weird posting to a blog that isn't my own. Plus, this all necessitated finding my way around Wordpress (which is one blogging platform I haven't used before). So I have my first post there now. Please do feel free to stop by and have a read.

And don't worry. I'm certainly not going to be posting here any less. Unless I have to do academic stuff like... you know, write papers and design posters... Stuff.

The twin questions of how and where life could begin from prebiotic chemistry are pretty big ones. Indeed, despite the now famous Miller-Urey experiment creating amino acids by zapping simple chemicals with lightning bolts, we're not much closer to a proper answer for that question. A good place to look for answers though, is Titan. Out on Titan, methane acts like water does on Earth, and the mountains are made from ice and not silicates. Despite these outlandish differences, many believe that the two planets were very similar when they first formed. The only difference essentially is that Earth was simmered on a moderate heat for 4 billion years, while Titan was left in the deep freeze. Even so, some interesting things might have been forming in its atmosphere since then. Things like nucleobases.

Instead of using electrical discharges like Miller and Urey, this latest study concerns photochemistry (a subject rather close to my heart). With it's thick atmosphere of hydrocarbon broth, Titan is like a photochemical laboratory for planetary scientists. We know within reasonable doubt that it's distinctive orange haze is coloured by hydrocarbons, not entirely unlike the photochemical smogs that hang over cities like Los Angeles.

So then, you have the basic premise of an investigation so simple, it's a wonder no one's already done it. As Titan has spent it's entire 4.5 billion year* life being bathed in ultraviolet and soft x-rays from the Sun, could anything prebiotic have formed there? Titan's atmosphere is composed mostly of N₂ and CH₄, both of which can be easily torn apart by certain frequencies of ultraviolet and x-ray radiation. The resulting molecular fragments are free to recombine into whichever form is most stable. Forms such as adenine.

As has been noted in other papers I've read previously, adenine is thermodynamically stable. In fact, it's the thermodynamic sink for anything with the empirical formula of C₅H₅N₅. With an atmosphere full of carbon, nitrogen and hydrogen, you'd expect, logically, that if Titan's atmospheric chemistry is driven by sunlight, at least some adenine should form.

Well, so did Pilling et al in this paper. Subsequently, they recreated an analog of Titan's atmosphere in the lab to try and see what would happen if you hit it with energetic radiation. Their results were very interesting. The experiment yielded a complex mixture of organic molecules, including both aromatic and aliphatic nitriles. This formed a thick tholin** (the reddish tarry stuff that litters many icy moons in the outer solar system). The authors note that the layers of Titan tholin are expected to be over ten metres deep in places. This tholin has been slowly falling onto Titan's surface for billions of years. Evidently, it could be rich in all sorts of prebiotic chemicals too!

So what about adenine? Well interestingly, they didn't find much using infrared spectroscopy (a standard tool in chemistry, and one of the few we have when looking through telescopes. The only spectral lines they found were weak, making the identification tenuous at best. They didn't detect any adenine until they took the sample and put it into some slightly more hardcore analytical chemistry devices. Mass Spectra and NMR showed the fingerprints of adenine... Although there's always a chance that they were just picking up adenine precursors. Perhaps the molecule itself would take longer to form in any significant quantities. Also, they note that no amino acids were created. Which is interesting, but by no means implies that Titan is free of amino acids...

So it seems, an environment like Titan's could readily form adenine -- one of the nucleobases of DNA and a molecule widely found in biology. Usually in things with lovely 3 letter abbreviations, like ATP, DPN, FAD and suchlike.

You have to wonder what other interesting things Titan's haze might be hiding. Furthermore, with all of the complex chemistry there, you have to wonder about a point the authors make in their discussion. In a few billion years, when the Sun exhausts it's hydrogen and swells into a red giant, Titan might have a chance to host Earth-like life. Who knows...?



*Actually, while the author's state the figure of 4.5 gigayears, it's probably closer to 4 gigayears (closer to the estimate of Earth's age). The Sun is roughly 4.5 gigayears old, and it's quite likely that Titan would have formed later.

**It's also worth noting that while the authors refer to tholin as a "polymer", this isn't accurate. "Oligomer" would be a better term to use.

Pilling, S., Andrade, D., Neto, A., Rittner, R., & Naves de Brito, A. (2009). DNA Nucleobase Synthesis at Titan Atmosphere Analog by Soft X-rays The Journal of Physical Chemistry A DOI: 10.1021/jp902824v

I fear that finding this even remotely cool or amusing means that my level of geekiness has reached new depths. Seriously though. Science Scout badges? How could I resist? Well, ok, I could probably resist quite easily, but they amused me too much to not post!

Actually, I'm probably elligible for a couple more, but these entertained me the most. All badge names and descriptions are taken from the originating site. Feel free to point and laugh afterwards...

( Caution: Contains Geekery )

This moment of pure unadulterated geekery was brought to you, courtesy of ravenofdreams who posted them first!

Wormholes are bizarre things. Bizarre things which may not actually exist (although in theory, there's no good reason why they shouldn't). Predicted by General Relativity, the concept is actually quite simple. If you imagine a Universe in just two dimensions, then it could conceivably fold over itself, or it may even be lying on top of another 2D Universe. It it were possible to tunnel between the two (via the third dimension in this case), you could quite easily traverse impossible distances in a relatively short space of time, using a Lorentzian Wormhole (also known as an Einstein-Rosen bridge). Theoretically, anyway. You wouldn't violate Relativity either, because locally, you wouldn't be exceeding the speed of light.

(By the way, if you like to stretch your brain, try visualising that in 4 dimensions. It can be kinda fun to think about!)

The trouble with the theories is that, as you might know, trying to make Quantum Mechanics and General Relativity work together is a bit like trying to use a UK plug in a US socket to power your laptop. Both work perfectly well, but they don't work together. One of the biggest problems is that Relativity predicts spacetime to be curved. No one really seems to know a lot about how Quantum Mechanics will work in curved spacetimes, which is bizarre, because it might open up a whole world of knowledge about weird things like wormholes.

It's true that there's no direct evidence for wormholes, although they can actually be valid if modelled in General Relativity. What's more, looking at a wormhole from the outside, it would appear almost indistinguishable from a black hole. Or it would if it remained stable. It's also been suggested that if a wormhole were to form, it would be highly unstable and would probably close before even photons could make it to the other side. If that's true, then we needn't worry about accidentally falling into one...



Fascinatingly, a recent paper bu Rossen Dandoloff suggests that wormholes might contain some very strange effects, at least for quantum particles like photons and electrons. Specifically, a new type of force hitherto unknown to Physics.

He starts with Heisenberg's Uncertainty Principle, which states that it's impossible to know both the momentum and the position of any given particle -- the act of observing either one will alter the other. This, as you might imagine, can be very annoying for quantum physicists. Although inside a wormhole, this works in a slightly unusual way. Essentially, space is stretched, which causes more uncertainty than normal in a particle's position. This means that the uncertainty in momentum has to be less, and the particle's energy must be lower too.

Particles are a bit like undergrads on a Sunday afternoon. They tend to head towards the lowest energy state they can find, so if they see somewhere with lower energy (such as a potential well in the case of particles, or a comfy sofa in the case of the undergrads) they'll always head towards it. In other words, this new "force" will cause particles to move towards the region of curved space. Essentially, they find it a preferable place to be. Dandolo calls this a "quantum anticentrifugal force". Personally, I'd argue that it isn't really a force so much as an effect... But that's just me being finickity.

I'll admit the accuracy of my knowledge in these things isn't exactly comprehensive (feel free to pick up on any flaws in my Physics), but this all sounds quite interesting to me. We might not actually be any closer to using wormholes for our own purposes, but perhaps we might be a small step closer to understanding how exactly they work...

I've heard people say in the past, how certain things in astronomy (like planet hunting) can be like looking for a needle in a haystack, but this is taking that metaphor quite literally. In my random meanderings on the internet I found this scale replica of Jodrell Bank's Lovell Telescope made from hay bales. And rather impressive it is too!



The creator of this fantastic little sculpture is Park Farm in Cheshire. Makers of the mouthwatering Snugbury's Ice Cream and accomplished straw sculptors.

Original image from Leslie Platt's Photostream

I was about to type the phrase "ice is cool", but then I realised what I was saying and decided that even I can't get away with a pun that bad. At least not at the start of a blog post...

As well as being able to keep your drinks cool on a hot day, ice is actually pretty amazing stuff. Even more amazing as it's now been shown that there are 20 different types of ice -- 15 crystalline forms alongside 5 amorphous (non-crystalline) forms. Actually, this is yet another reason why water is pretty special. Very few substances can exist in this many different solid phases.

Different types of ice crystal form according to how water molecules stack together when they solidify. This varies according to the temperature and pressure. For instance, the ice that you'd throw into a glass of iced mocha is known scientifically as ice I_h. It has a hexagonal crystal structure which makes it very low in density. Hence, it floats in your drink because it's actually less dense than liquid water. If you were to take that same ice though, and put it in a pressure chamber, the molecules would start to become unstable in their hexagonal shape. At a certain critical pressure, the molecules would rearrange themselves and the ice would recrystallise into a different structure.

Actually, ice is capable of forming almost every type of crystal structure if you give it the right environment. Monoclinic, orthorhombic, tetragonal, cubic, hexagonal... You name it.

The newest addition to this little crystalline family though, is ice XV, first reported just last week. Thermodynamically stable at temperatures below around 130K (-143°C) and pressures of 0.8-1.5 gigapascals, it's unlikely to be too prolific in nature. There is, however, always a chance that exotic forms of ice like this might be able to exist inside the kind of icy moons and dwarf planets that litter the outer solar system.

It was also previously predicted that ice XV would be ferroelectric -- the kind of conductive material with potential uses in electronics and suchlike. As it happens, the predictions were wrong. Very wrong in fact. Ice XV is actually antiferroelectric!

It's quite surprising when you think about it, that we're still discovering things about something as fundamental on planet Earth as ice!

Source: arXiv Blog, arXiv.

Nope. Not a word. Even though, in a sense, I've already talked about it, albeit briefly. Instead, I'm going to talk about the bafflement that's apparent over press embargoes and what constitutes "public domain". Am I grabbing the wrong end of the stick here? Or are half the science bloggers in the world missing something? Logically, I'd have to believe I'm the one who's mistaken, but... after looking at this in detail I'm at a loss to see the how or why.

The matter of press embargoes seems to be a sticky one, at best. Seeing as I've thus far not had much cause to communicate with the press (at least in a research capacity), it seems wise to understand the situation with embargos. The basic idea is simple. Send out a press release with an embargo until a set date. The media may then have time to prepare a story, but may not publicise it until the given date (and are professionally obliged not to). Simple, right? Well...

This afternoon, the first utterance I heard about this was on Scienceblogs.com's Dynamics of Cats. He wasn't talking about it either. In keeping with the cat-based theme, this piqued my curiosity somewhat, so I followed his link to a post by Cosmic Variance's Julianne. Nor was she talking about it. But she (and a number of commenters) were bemoaning the embargoing system employed by journals like Nature. This eventually led back to Uncertain Principles not talking about it, but rather questioning the whole affair. Sometimes, the science blogosphere is like a big detective story waiting to happen...

(Note, incidentally, that I'm not even referencing specific blog posts here. Not talking about it.)

Personally, the snippets of information I draw from all of this are thus:

...our cardinal rule has always been to promote scientific communication. We have therefore never sought to prevent scientists from presenting their work at conferences, or from depositing first drafts of submitted papers on preprint servers. So if Nature journalists or those from any other publication should hear results presented at a meeting, or find them on a preprint server, the findings are fair game for coverage — even if that coverage is ahead of the paper's publication. This is not considered a breaking of Nature's embargo. Nor is it a violation if scientists respond to journalists' queries in ensuring that the facts are correct — so long as they don't actively promote media coverage.

-- A Nature editorial on science blogging regarding Nature's embargo policy

So Nature themselves are saying that picking something up from a preprint server and discussing it isn't breaking an embargo at all. In fact, seemingly, the only people able to break the embargo are the authors. And even they may speak freely if questioned. The embargo is only considered broken if they actively incite media coverage. That's interesting.

"Anyone who posts to arxiv with a note “under embargo” is mis-informed. It is *not* under embargo any longer — it is legally published and in the public domain. Please inform me (astronomy editor, Nature) immediately if an author posts with a note “under embargo” and I will tell them that it most definitely is not under embargo.

Authors can post to arxiv at any time, at their convenience. I know our “Guide to Authors” is horribly written and confusing — sorry, but I’ve been unable to get it changed. Again, contact me for clarification."

-- Comment from Leslie Sage, Astronomy Editor at Nature (Left on a post on one of the blogs I've linked to above)

In essence, by posting their preprint to arXiv, the authors have actually broken their own embargo. This tends to make me agree with Uncertain Principles. Is it really sensible for scientists to race to arXiv to be the first to post their preprint? It seems a little silly really. Effectively, a preprint is publishing it to the world, after all. Disconcertingly, so is a blog when you actually think about it.

So in other words, I am, in fact, allowed to talk about it. I would be breaking no rules by doing so, even inspite of what the rest of the science blogosphere seems to believe. But now I don't want to. It's not even my sub-field, and I'd rather not accidentally break any embargoes despite the fact that, apparently, I wouldn't be doing so. Would I...?

I'm so confused...