Volcanic Shenanigans

I should be getting the last of my things sorted out right now, before getting on a train to Heathrow and then catching a flight to Cape Town for a 2 week observing run to study interstellar clouds with the SAAO. Unfortunately, it doesn't currently look like this is going to be happening quite as planned, courtesy of a large cloud of volcanic ash which is inconveniently sitting right above the UK. So while I'm waiting for 11:00 when I'm supposed to call South African Airways back, I figured I might as well write a bit about just what the hell is going on...

The volcano Eyjafjallajökull (pronounced EYE-ah-FYAT-la-JO-kootl) erupted on Wednesday, spewing a huge plume of ash 8km into the atmosphere. Winds have since blown this ash into a huge cloud which is currently covering Northern Europe, almost in its entirety. Seemingly, while volcanoes normall tend to produce some amount of ash, it's been exacerbated in this case by Eyjafjallajökull being under a glacier. Hot magma meeting cold ice causes an immense burst of steam as the water is vapourised instantly. Unfortunately, so it would seem, that burst of steam has also served to aerosolise additional volcanic ash, meaning that Eyjafjallajökull is one messy beast. The ash itself, is essentially finely powdered volcanic rock. Silicates, mostly.

The volcanic ash is stopping planes from flying because of the way jet engines work. Because jet engines suck in air, they'd also suck in ash, with the end result being a fine coating of volcanic glass on the inside of the jet turbines. Needless to say, this isn't good. Volcanic ash has been seen to cause aircraft engines to fail before, and while it's inconvenient to be stuck on the ground, it's far preferable to falling out of the sky!


Airports closed due to the ash cloud are shown in red.

So the end result is a huge closure of airports across Europe. Bloody typical. What happens when I'm due to go on my first observing run? "One of the largest disruptions in commercial aviation history" happens. That's what.

Perhaps the most interesting thing going on though, is that the skies have been eerily empty for days now. No jet trails at all. In fact, nothing. No clouds either, and a light haze near the horizon. I'd initially thought there might be lots of clouds, because of the sulfur compounds released by the volcano. Sulfurous aerosols (particularly sulfate and methyl sulfonate) have been shown to nucleate cloud particles, seeding clouds and causing rainfall. But there are no clouds at all. Perhaps all the water has already fallen from the air by the time it reaches this far inland.
EDIT-- Actually, there are indeed clouds now, so I may be wrong on some of this.

Despite all the furore that's normally associated with the matter, you have to wonder precisely what the environmental effect of all of this might be. European air traffic, it has to be said, contributes a large amount of carbon dioxide to the atmosphere. Much more on a daily basis than a volcanic eruption. What's more, sulfur compounds in the atmosphere will likely serve to increase Earth's albedo (albeit only fractionally). The albedo of a planet means how much light its atmosphere reflects. All of the sulfur in Venus's atmosphere gives it one of the highest albedos in the Solar system and is the reason why it reflects so much sunlight and shines so brightly in the evening sky. There's even the possibility that this volcano might help to cool the Earth's northern hemisphere slightly*. Volcanic eruptions in the past have managed to cool the average temperature at the Earth's surface by up to half a degree in the past century -- which may not sound like a lot, but on a global scale, that's rather significant!

Anyway, I'd better call the airline and find out what my travel plans are. I suspect the next few days are going to be no less worrisome than the last few.


*Specifically, sulfur compounds tend to sit in the stratosphere. This cools the lower atmosphere by reflecting away sunlight, but those sulfur compounds also absorb heat from Earth's surface causing the stratosphere to warm slightly. While this may be beneficial for glaciers and ice caps, the effect on the weather would remain to be seen...

Image credits:
"Cracks of Doom" - Skarpi's photostream
The Ash Cloud and Airport Shutdowns - Flowing Data

Earth Day

Happy Earth Day!

If you're not sure what Earth Day is supposed to be all about,
try this. Step outside. Take a deep breath. Taste the air. Whatever
the weather may be, feel the sun on your face, the wind in your
hair or the rain on your skin. Marvel at this planet and all
the myriad ways in which it keeps us alive, and cradles the only
life we know of in this entire Universe.
This tiny crucible.
Our pale blue dot.

Views from the Top

The road up to the telescope domes.


Radcliffe Telescope dome, flanked by the 20 inch and 40 inch telscope domes in the background.


Radcliffe entranceway, with SALT in the background.

Naos

O-type stars are rare. In fact they're very rare. Less than one in every hundred thousand stars formed will be an O-star. The reason they're so rare is that they're incredibly massive. Stars with such immense mass will burn through all of their fuel rapidly, so fast that they can only live for a few million years. An O-star which formed when the dinosaurs became extinct would be long dead by now.

Naos here, is an O-star. With an estimated age of about 4 million years, it's quite old for its type. In fact, it's one of the few O-stars in the galaxy which are visible to the naked eye. Being an extreme blue supergiant with 59 solar masses and a surface temperature of over 42000 kelvins, Naos is actually one of the brightest stars in the Milky Way. It's almost 800 000 times as bright as the Sun, although most of that light is ultraviolet. So much so that in the visible, it's only around 21000 times as bright visually.

Nonetheless, an O-star is a powerful object. If Naos was as close to us as Sirius, it would have an apparent magnitude of -9. That's bright enough to cast shadows on Earth's surface, and easily bright enough to read a book by at midnight! The full moon, for comparison, has a magnitude around -12. Even where Naos is, at around 1090 light years away, when it starts to die in somewhere between a few thousand to a million years, it'll become one of the brightest stars in the sky for a time. Eventually it will explode as a supernova much brighter than the full moon.



It's interesting what you discover sometimes when you're looking for standard stars to calibrate your data with...

Radcliffe

Ladies and gentlemen, this is the Radcliffe Telescope, and it's what I've been eagerly awaiting the use of for quite some time now. Unfortunately, while I'd love to be recording some spectra of the various stars on our target list right now, the weather is refusing to cooperate. With the mountaintop covered in fog, observing is currently off the menu. Sadly. So while I'm waiting for things to clear up, I might as well write a little about the 'scope...

Radcliffe is a lovely blend of early 20th century engineering and late 20th century electronics. Five metric tonnes worth of wrought iron telescope, equatorially mounted with another five metric tonnes worth of counterweight. With a 1.9 metre mirror, Radcliffe is essentially an oversized Newtonian telescope, not unlike the one I've had since I was a little kid. It's simply been scaled up. While it works as a cassegrain now, it even still has a Newtonian mounting on it. As you may be starting to guess, Radcliffe is an old telescope.

It wasn't even originally at this site. Named after an English physician, John Radcliffe, it was originally the telescope of the Radcliffe Observatory in Pretoria where it was operated between 1948 and 1972. In 1972, it was moved to its current site at the South African Astronomical Observatory here in Sutherland. Until the mirrors were installed in SALT in 2004, Radcliffe remained the largest telescope in Africa. Indeed, for quite a few years after its construction it was actually the largest telescope in the southern hemisphere, and joint fourth largest telescope in the world. Those days, however, are past and 2 metre class telescopes like Radcliffe are now considered "small telescopes" by professional astronomers. Compared to the shiny new 10 metre class telescopes now dotted around the world, Radcliffe is quite a downbeat piece of equipment with its fully manual operation and its old fashioned mechanisms. And frankly, therein lies its charm.

The most beautiful thing about using an old school telescope like this one is how hands on everything is. A series of buttons on a metal panel move the telescope, the mirror cover has to be opened using a metal crank with a wooden handle, and the sensors need to be cooled by manually refilling the liquid nitrogen tank periodically. It even has a finderscope attached to it, though this hasn't been used for some time. The finder alone is still significantly bigger than many amateur telescopes, mind you. The reason this gorgeous piece of engineering is so hands on is, simply, because it's old. Newer telescopes don't allow you quite so much freedom. I've been told that some telescopes don't really allow you to do anything yourself, being more a matter of clicking the odd button on occasion, or simply telling a telescope operator what to do. Purely for the thrill of being able to manually operate the telescope, it's been a lot of fun working with it so far, as I have no doubt it will continue to be. Provided the weather stops thwarting us!

Low Flying Rocks!

The internet is quite a marvellous thing really. I mean, supposing an asteroid 530-1200m in diamater and travelling at 29 kilometres every second were to pass a mere 28 600 000 km from our planet, you'd want to know about it, right? Yeah, so would I. And conveniently, you can.

Low Flying Rocks is one of the most brilliant uses of twitter I've ever seen. Whenever anything large and rocky passes within 0.2 AU of our planet, an update is automatically posted, like the one above. Though it may be enough to make you paranoid that updates are posted to this twitter feed frequently. Sometimes several times daily. The one above is one of the largest objects I've seen in quite a while, though mercifully twenty eight million kilometres isn't actually all that close. Every once in a while though, you do find one that passes closer to Earth than the Moon.*

Don't panic. Really, don't. The thing is, you see, while all of this might appear to be somewhat apocalyptic, the real reminder here is that random chunks of space rock passing close to Earth aren't particularly unusual. In fact, most of those asteroids have likely been in orbit around the Sun as long as Earth has. Some of them, perhaps longer. While it's always possible that our planet may be struck by a rogue asteroid, the chances are fairly slim. Space, after all, is rather big.

That's not to say, however, that we should simply close our eyes to space rocks. It's certainly a good idea to keep an eye on them. As some have said in the past, if nearly as much money and effort was spent on actually looking for "killer asteroids" as has been on films about them, we'd have a much better idea of how safe we are. This, for example, is Toutatis. 4179 Toutatis to be precise. While it might appear innocent enough, minding its own business in its orbit around the Sun, it's one of many nearby space rocks earmarked as a potentially dangerous object!

Still... "Potentially dangerous" isn't a lot to worry about. These asteroids are as potentially dangerous to the Earth as cars are potentially dangerous to people crossing the street. Just because their paths cross, doesn't mean that there's going to be a collision. For now, it's probably best to trust asteroid surveys like pan-STARRS to spot anything genuinely dangerous in time for us to do something about it. I think it's safe to say that there won't be any death from the skies anytime soon...

In the meantime, if your mind's a little more at ease now, why not have a glance at Low Flying Rocks on twitter? Don't be scared. They're only asteroids.

An Odd Couple

The cool thing about science is that it isn't the normal everyday things that you learn new things from. It's the things that seem a little unusual. Unusual like a tiny star which goes by the name of 2M044144, a mere 450 light years away in the Taurus molecular cloud. Well... I say "star". Really, 2M044144 is barely a star at all. It's a brown dwarf. A stellar runt, too small to burn hydrogen. The interesting thing is that this tiny star has a planet in tow. Not just any planet, but a giant planet!

In fact, with an estimated mass of between 5 and 10 jupiter masses, this is a sizeable planet. Much larger and it would be capable of being a brown dwarf itself. It's also estimated as being only around 1 million years old, which is about the same age estimated for the star itself. In short, there was no way that this planet (which is in a close orbit at only around 24 AU away) could have formed the way a "regular" planet does. It simply hasn't had the time.

Remarkably, that means that this planet must have condensed directly from the same cloud of gas and dust that the star did. Had it accumulated more mass, the whole system would have been a binary star. Astronomers found fairly recently that stars can form the way planets do. Apparently, planets can form the way stars do too!

Which makes you wonder how many interstellar planets might be drifting around in interstellar space, having formed directly. Born the way stars are, but forever dark and silent. Perhaps there may be many more planets in our galaxy than we realise.



The paper about the 2M044144 system is available from the Astrophysical Journal.