There's an undeniably lovely elliptical theme about the universe. Moons orbit planets, planets orbit stars, stars orbit larger stars... and entire galaxies orbit supermassive black holes. As any astronomer (and probably quite a few school kids) will probably tell you, if you want to find a supermassive black hole, look in the centre of any sizeable galaxy. Well... Almost any sizeable galaxy. A colleague of mine was doing some reading around and found something quite interesting about one of the Milky Way's neighbours, the Triangulum Galaxy. Seemingly, it has no central black hole!

The hulking behemoths at a galaxy's heart have a huge influence over the rest of the galaxy, seemingly causing the formation of massive stars, occasionally ripping them to pieces as supernovae and enriching the galaxy's interstellar medium with heavy elements and metals. They've also been seen to power huge jets of matter as they greedily devour anything which may stray too close.

It may be a surprise then, to find a galaxy with no supermassive black hole at all. Specifically, the Triangulum Galaxy here, also known as M33. One of three members of our local group of galaxies, it lies around 2.3 million light years away, making it the most distant object visible to the naked eye.

Triangulum is a galaxy without a heart. Most spiral galaxies have a fairly obvious bulge at their centre where their black hole resides. In fact, the size of that bulge is a good indicator of how massive the central black hole is (as I learned at a quite excellent talk I went to the other day). Triangulum however, scarcely even has a bulge at its center. Some researchers have reached the conclusion that M33 has no supermassive black hole at all!* If M33 even contains a central black hole, it's a relatively tiny one with a mere 3000 solar masses (compared to Sagittarius A* at the Milky Way's core with 4 million solar masses). The reason is still unclear.

An interesting (albeit highly unlikely) consideration is that it may have been stolen somehow. Perhaps by the Andromeda galaxy. It seems like a wild assertion (and I'll admit, I have nothing to back up this unusual idea), but Andromeda and Triangulum have certainly interracted in the past. There's a bridge of neutral gas between them, suggesting some kind of tidal interraction. What's more, Andromeda has been seen to have a double nucleus, meaning that it could contain not one but two black holes in it's core. It's far more likely, however, that the second nucleus is the remains of a smaller galaxy which was devoured in its entirety by Andromeda. There's no known mechanism by which one galaxy could simply steal a black hole from another. Seemingly, the question of what happened to Triangulum's black hole is still an open one. Perhaps for one reason or another, it simply didn't form a supermassive black hole to begin with.**

It's interesting to think that perhaps the Milky Way is the only large spiral galaxy in our local group which has a "normal" core. But then, in some ways, maybe we don't yet know enough about the way galaxies work to be able to define what "normal" is.

* Incidentally, I have a suspicion that not everyone agrees with this conclusion. Some things are difficult to say with certainty in astronomy. I'm no expert on galaxies, so if you know of any, please do link me to any publications with other viewpoints!

** It's worth noting that some smaller galaxies have no supermassive black hole. However, with triangulum being only about 100 times less massive than Andromeda or the Milky Way, it seems rather surprising.

Planets are resilient things. They can survive a lot of punishment from their host stars, with some planets having survived being broiled and others even having survived being engulfed as their parent star swells into a red giant. Amazingly, the means by which planets form is no less hardy, for instance being formed in the debris left after a supernova as pulsar planets. So if the method for planet formation is so rugged, what would happen if you started out with an extremely massive star? Could the largest stars in the Universe form smaller stars as if they were planets?

It may at first seem strange to think of stars forming the way planets do. Generally, it's believed that the star forms first and planets start to slowly assemble from the stellar leftovers afterwards. This disparity has caused problems in the past for theorists, many of whom are still a little uncertain as to whether brown dwarfs prefer to form like stars or like planets. Seemingly, the answer could be both.

Planets can actually form in one two two ways. The more traditional picture is of planets accreting from a dusty disk around a young star, slowly building up from a jumble of ice. This simply takes too long. The stellar wind would blow away the dust before any planets could start to condense. In the other picture, the star has a much thicker disk of dust around it. Tiny instabilities in the disk start do destabilise it and clumps start to form*, inexorably collapsing in on themselves, condensing into planets. Most planets formed this way would be gas giants, but some would be large enough to ignite as stars. In fact, this paper uses some rather elegant maths to find that if you consider a star 100 times as massive as the Sun, objects could form in orbit with as much as 0.3 solar masses. That's heavy enough to be a red dwarf star. In fact, it's three times as massive as Proxima. Even for those not attaining such a high mass, it seems quite likely that a few brown dwarfs would form.

All that said, this isn't likely to happen too often. Stars with 100 solar masses are the rarest of the rare. Exceedingly hot O-stars which burn through all of their fuel rapidly in just a few million years. They only form in the densest interstellar clouds where they can find enough mass to collapse from. This does lend strength to the idea that these massive stars may have planets and orbiting stars forming though. Forming a star around a star would require an extremely dense, massive disk of material. Massive enough to fragment into collapsing starlets and dense enough to shield those starlets from the intense radiation from the central star. Any stars or even planets which form around such a star would form with huge orbital radii. But then, we've already found planets orbiting very far from their parent star, such as Fomalhaut b. Such monstrous disks of dust have also been found around some extremely massive stars.

One final thing to note is that low mass stars live for much much longer than the most massive ones. A few thousand times longer, in fact. Which means that while it's a lovely image to imagine a hulking hypergiant with a system of stars in tow, just like Jupiter and its moons, a system like this wouldn't last long. Quite rapidly, the hypergiant would evolve into a luminous blue variable and then a Wolf-Rayet star and start to puff off its outer layers, losing mass. Any orbiting stars would find their orbits steadily less circular and more eccentric until-- BOOM! Finally, their giant parent would explode as a supernova and they'd be scattered long before they'd even finished forming. They might even start forming planets of their own.

It's interesting to wonder how many red dwarfs and brown dwarfs might have formed this way, before being kicked out into the dark. Or even planets. Interstellar planets, too small for us to ever even know they exist, rich in heavy elements from supernova condensates.

* This always happens in my saucepan when I make bechamel sauce...


Image: The Carina Nebula. ESO/IDA/Danish 1.5 m - R.Gendler, J-E. Ovaldsen, C. Thöne, and C. Feron.

Amit Kashi, & Noam Soker (2010). Forming Low Mass Stars and Brown Dwarfs in Protoplanetary Disks of Very Massive Stars preprint arXiv: 1002.4693v1

Wow. Just wow. I just found out that Supernova Condensate has been shortlisted for the Research Blogging Awards 2010. In two categories: Research Blog of the Year and Funniest Blog. I'm... a little speechless to be honest. And quite amazed. So I just want to say a massive massive thank you to anyone and everyone who may have nominated me or voted for me in this.

Quite frankly, I'm honoured to appear on the list next to names like Not Exactly Rocket Science, Skulls in the Stars, Uncertain Principles and Rigel. Anyone with a moment to spare should click the link below and have a read through any of the blogs shortlisted. They're all of the highest calibre and written by some of the brightest and wittiest bloggers you'll ever read.

The ramifications of all of this are still sinking in. This blog started as little more than a few brief summaries of interesting things I was reading about. In the couple of years since I've been writing, it's grown exponentially. Sincerely, thank you to all of my readers for being wonderful. And if you happen to be a research blogger who likes what I write... maybe consider throwing a vote my way? I don't really expect to win, especially given the competition. To have made it this far at all is pretty incredible to me.

I love imagination. I particularly love the kind of imagination that goes into delightful ideas like this one! This little dude, known as Le Petit Prince (in a cutesy reference to Antoine de Saint-Exupéry), is an ingenious solution to what may someday be a genuine problem.

Earth is getting crowded, with a population of over 6 billion. Science fiction authors have been writing about the possibility of colonising other worlds for a long time now, but in perfect honesty, it's a logical conclusion to make if the human population on our planet is going to keep growing. And Mars, being relatively hospitable, is probably one of the most obvious places to move to. But the thing about Mars is that it recieves less insolation. Sunlight is that much weaker out by our butterscotch coloured neighbour world that some plants may have difficulty getting enough sunlight to survive. Wouldn't it be helpful if plants could walk to sunnier locations?

Well, with little gadgets like this guy, maybe they will. Le Petit Prince is intended to wander the martian surface, looking for both sunlight and nutrients to keep the growing conditions optimal for it's leafy passenger. A swarm of these robots could then keep in touch wirelessly to map out the best places to grow. And frankly, the idea of a herd of robots roaming across the plains of Mars is just such a lovely idea.

The intention is that, as well as acting like a life support system for a plant, these little mobile greenhouses are also intended to act as a kind of robotic pet for early martian colonists. Actually, I'd love one as a pet myself. They're really cute!



Source: Tuvie

Oh frosty, frosty Pluto, how you tantalise us. So small that even the most powerful telescopes can only discern you as a handful of pixels, yet immutably fascinating every time we learn something new about you!

I've written before about the insane seasonal variations experienced by the little world, and the Bad Astronomer wrote a good summary of why Pluto's atmosphere is actually upside down. Most recently though, last week NASA released the most detailed images of Pluto ever recorded. And very pretty they are too! Granted, they still don't have enough detail to pick out individual surface features like craters or mountains, but they're pretty impressive all the same. Incidentally, these images were taken quite some time ago. It's taken 4 years of computer processing to boost the image quality even this high!

Even with all of that image processing, we can still only resolve features a few hundred miles across, but this is still enough to see that this tiny little planet is full of fascinating variations. A molasses coloured world mottled with dark splotches and occasional light patches. From the picture, it's certainly easy to imagine you're looking at northern highlands and tarry southern seas of nitrogen and tholin. Alas, it's still speculation for now. Just a few more years for New Horizons to arrive and we'll suddenly get a much better view of the place!

One thing is for certain though. Pluto is an incredibly dynamic place. Some used to believe that being so far away, Pluto would be frozen solid. Unchanging and alone in the darkness. Evidently, this couldn't be further from the truth. These two black and white images show maps of Pluto's surface recorded in 1994 and 2002/03 respectively. The changes are actually quite astonishing. In fact, without knowing better, it would be easy to believe that these are maps of two different planets. Just imagine any part of Earth transforming that much in just a decade.

The reason is almost certainly the huge variations in temperature caused by Pluto's eccentric orbit. Between 1988 and 2002, Pluto's atmosphere nearly doubled in mass as it drew closer to the Sun and ices sublimed into gas. Now it's starting to retreat further out again, and obviously those gasses are starting to freeze out again.

One thing which has everyone puzzled is that brigh spot towards the right of these maps. It's an area rich in carbon monoxide ice, and no one knows quite why it's there or what's caused it. Personally, I think it would be fascinating if it's some kind of cryogenic geological (cryological?) feature. Perhaps a cryovolcano which somehow erupted due to the additional recent insolation. On Earth, carbon monoxide has a melting point of 68K, some 25 degrees higher than the average surface temperature on Pluto. But then, Pluto has a much lower pressure, and it varies greatly. Maybe such volcanoes could erupt seasonally. Or alternatively, perhaps the cause is more likely to be a geyser, similar to those seen on Triton and Enceladus. Whatever the cause, it certainly makes this a dramatic feature next to that patch of black material. The nature of that black material is also, incidentally, still a mystery.

I have a feeling that Pluto's going to continue to tantalise us all for many years to come, even long after New Horizons has been and gone...

Source (images and information): NASA press release

One of the things I really love about astronomy is the fact that there's so much in the Universe which nobody understands. I love a good mystery, and Epsilon Aurigae is a very good mystery!

In the constellation of Auriga, it's a bright white A-type supergiant star. With a magnitude of around +3, it's easily visible in the night sky if you know where to look for it. But all isn't quite as it seems with Epsilon Aurigae. Roughly every 27 years, it suddenly drops in brightness by one magnitude. It then stays dim for about 2 years (around 640-720 days) before rapidly returning to brightness. The reason why is still an open question.

The curious variable nature of Epsilon Aur was first noted in 1821 by Johann Fritsch, but wasn't studied properly till around 20 years later, by Eduard Heis and Friedrich Wilhelm Argelander. They were fascinated, not only by the dramatic dimming of the star, but also by its short term variability. Since then, a number of possible explanations for the 27 year fadings have been put forward. The currently favoured explanation is that Epsilon Aur has an unseen orbiting companion. A companion surrounded by a big dusty disk 4AU in diameter and 0.5 AU thick. If this companion was to pass between us and Epsilon Aur in its orbit, it would eclipse the central star, causing the dimming. It's believed, in fact, to be a big B5 star enveloped in dust.

While the details are still under debate, Epsilon Aurigae has been under a lot of scrutiny lately, after it was publicised during the end of IYA2009. Being observed under the collaborative Citizen Sky project, it's going to be dim for the rest of 2010. I wonder what might be waiting in this star system, to be discovered...

Image Credit: Alson Wong and Citizen Sky.

What do you do if you happen to be piloting an alien spaceship near to an average looking G5V class star somewhere near the Orion Arm of the Milky Way galaxy? Try not to be spotted by any local space telescopes, that's what!



Well, ok, it isn't an alien spaceship. Though you must admit, it does a very good impression of this Centauri Vorchan Cruiser from Babylon 5. Hubble recently imaged this curious looking object. Travelling at around eleven thousand miles per hour, it currently goes by the catalog number of P/2010-A2. But what exactly is it? In all seriousness, nothing quite like this has been spotted before, which implies it's either something new, or some rare event. Either way, it's cause for scientists to be excited.

It isn't a comet. It's a bit like one because of that tail, caused by tiny dust particles being blown away by radiation pressure.* But beyond that, it doesn't look like a comet. The dusty gas clouds around comets are a lot smoother-looking, without any of those apparent filaments, which seem to have been thrown out from the nucleus of this object. Perhaps stranger still, is the fact that its apparent nucleus is actually not in the centre of that cloud of dust where you'd expect it to be, but sitting just outside it (the white spot towards the left of the image above).

When all's considered, the most likely explanation is that Hubble managed to spot an asteroid collision. Two previously unknown small asteroids smashing into each other and creating a huge cloud of dusty debris which is now streaming out behind them. Interestingly, though you can't be certain by looking at the image, only one large object seems to be there. Maybe the less resilient of these two space rocks disintegrated completely in the collision. Or maybe it's just lost in the middle of that dust cloud somewhere...

Statistically, it's to be expected that asteroids must collide from time to time. After all, the Solar System's full of them.** But to catch them in the process of actually colliding? That's just cool.



*Radiation pressure is the pressure caused by light. Photons of sunlight hit molecules and tiny dust grains and transfer their momentum, causing force. The effect causes the spectacular tails seen streaming from regular comets, as well as oddballs like this.
**In fact, asteroids too small to be anything more dangerous than a pretty shooting star pass closer to us than the Moon roughly once a week on average.

Now, I've heard all manner of stories about mysogynies in the academic world, from school level right the way up to senior academics. Frankly, I fail to understand how, in a supposedly enlightened age, such things can endure. Some of the stories I've read on blogs like Female Science Professor make me want to apologise on behalf of my entire gender sometimes. And then I see things like this news article, posted on a friend's Facebook page...

The title alone, "Self-doubt plagues female astronomers" leaves little uncertainty as to what the rest of the article is about. Essentially, a study was done to investigate how many astronomers are fearful that they might be exposed as having a lack of knowledge. At least in the groups surveyed (in US institutions), women are more fearful than men in regards to being "exposed".

I have to say, I'm not entirely sure what to make of this. As with a lot of sociological studies, the sample size is fairly small. Scientifically, I'd have to say that further study is warranted. It would be interesting to see if this graph changes geographically. Are people less concerned in Europe than in America? What about China, India or South America? It's also noteworthy that in both genders, the majority vote was for "agree". Feelings of inadequacy are a fear for both men and women. On the other hand, more women "strongly agree", which does hint at a greater lack of confidence. Could it be that women are more fearful than men? Alternatively, could it be that men are simply less likely to consider a lack of knowledge in some areas to be a problem? These are open questions which it's difficult to speculate on. It's also notable that female professors are quite rare in physical sciences. Lecturers less so, but professors certainly. One has to wonder if it would be helpful to have more female role models like good old Jocelyn Bell Burnell.

If I'm perfectly honest, my gender notwithstanding, showing a lack of knowledge is always a concern of mine. I'll admit that it's probably irrational. No one can be expected to know everything about everything, and in research it seems remarkably common for people to become so engrossed in their own specialty that they start to lose track of other fields. That's a big part of why I keep this blog. To write about things, I need to read about them. If I read it helps me understand. Maybe it's true what they say, that knowledge is power. Or mayhap it's just academic currency. All the same, from an inside perspective it's easy to see how a lack of knowledge can feel like weakness. It feels almost darwinian at times. Survival of the smartest, perhaps. Rational or otherwise, thoughts like these running through my mind are usually enough to make me think twice about raising my hand to ask a question at the end of a seminar.

The so-called "impostor syndrome" has apparently been documented in all parts of the academic world (and indeed, elsewhere too). It's characterised by paranoia and unfounded feelings of inadequacy. The impression that one doesn't belong where they are and is at constant risk of being discovered and cast out -- even inspite of overwhelming evidence to the contrary. Feelings like this can really add to stress levels, as well as sapping motivation. In the most extreme cases, it's easy to see how impostor syndrome could cause someone to actually change professions. In fact, it's lamentable how many brilliant minds may already have been lost in this way.

So what can be done? Well, irrespective of gender, not chastising others for a lack of knowledge would certainly be beneficial. Likewise, teaching people to realise that sometimes you need to feel a little bit ignorant. Sometmes, that's precisely what should give you the motivation to improve yourself. It isn't always immediately apparent that, if ever you're worried that you don't know enough -- everyone, from undergrads to vice chancellors have felt the same way in the past. And probably still do. The bottom line here is: several of my most respected colleagues (and very good friends) are women. Should any of them ever consider leaving astronomy due to the feeling that they aren't good enough, I'd be dismayed.

Image credit: AIP/AAS
Source article: NatureJobs.com

So I've had a rather frenetic few weeks. Seriously, I've been busy with all sorts (and I really do mean all sorts). As a result, I guess I've been a little poor as bloggers go. But such is the life one lives when pursuing a PhD.

What is cool though is that coming up, I have two whole weeks of observing time in South Africa! Yeah! Those lovely people at the SAAO decided to approve our application. Stars shall be looked at. And spectra shall be taken. Oh yes. I'm really rather excited about the whole thing!

Anyway, no time to write much now. After working all week only to find out that my deadline got extended quite generously*, it is now my intention to go and drink beer.



*By which I mean so generously that it's less of an extended deadline and more of a distended deadline.