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Recently in AAS Meeting May 2010 Category

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By Hamish Johnston

Greetings from Seattle, where I will be for the next few days reporting from the 217th Meeting of the American Astronomical Society.

Today was mostly one of leisure as my colleagues and I recovered from our 9.5 hour flight and prepared ourselves for the coming feast of astronomy and astrophysics.

Highlights of the day included a ferry ride across Puget Sound to Bainbridge Island. I took the above photo from the ferry and you can see that the skies were particularly leaden – but what you can’t see is the biting wind and chilly temperatures. That’s the futuristic Space Needle at the far left.

But now it’s down to business…or at least a bit of schmoozing at the pre-meeting reception.

Next stop: Seattle

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By Michael Banks in Miami, Florida

So that was this summer’s American Astronomical Society (AAS) meeting. We had some nice talks about NASA’s Solar Dynamics Observatory (SDO), the CoRoT exoplanet hunter and the Herschel satellite as well as how to destroy asteroids and unexpected results from research into supermassive black holes.

I would say it was SDO that stirred the most interest, and talks about the mission were usually given to a packed auditorium. Indeed, SDO’s booth in the exhibition centre was always busy with people staring in awe at the new images of the Sun the satellite has recently produced.

One thing you always probably take away with you when attending talks on astronomy is the sheer scale of the universe. For example, in a talk on Herschel today (see previous entry) even when zooming into an average image taken by the satellite three or four times there are still more than 6000 galaxies in the picture possibly containing millions of stars and thousands of planets.

And that brings in another aspect of astronomy – handling the huge amounts of data that missions are now producing second by second. The Wide-field Infrared Survey Explorer (WISE), for example, is taking an image every few seconds transmitting terabytes of data every day. Astronomers think it will take at least 20 years before they have analysed all of WISE’s data.

Hopefully astronomers working on missions such as SDO, WISE and Herschel will be able to tell us even more about our Sun and the universe when the next AAS meeting is held in Seattle starting on 9 January. See you there!

Mapping the cosmos

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Inspecting the 3.5 wide mirror of the Herschel telescope

By Michael Banks in Miami, Florida

It seems I have something (rather tenuously, I admit) in common with the European Space Agency’s Herschel mission: we were both “born” in 1982. (Although I am not sure what else I could have in common with a space satellite.)

Goran Pilbratt from the European Space Agency (ESA) told delegates today at the 216th American Astronomical Society meeting in Miami, Florida, all about the Herschel mission that was first proposed way back in May 1982 at an ESA workshop.

Herschel features two cameras (named PACS and SPIRE) and a spectrometer (HIFI) to study star formation in our galaxy and galaxy formation across the universe.

Herschel also has a dewar of liquid helium that cools its detectors down to 2 K so that it can better measure objects in the sky in infrared via its 3.5 m wide mirror.

With 30 years invested in the instrument, you could perhaps forgive astronomers for being nervous when Herschel launched on 14 May 2009. “Herschel has no moving parts, so if there is something wrong after it launches we can’t do anything about it,” says Pilbratt.

Herschel in the end made a “perfect launch” and it even started taking data only 30 hours after launching.

But not everything has been plain sailing since then. In August 2009 HIFI stopped working and its software had to be rebooted taking around five months in total to fix.

Once back online in January, astronomers are now really reaping the rewards of HIFI. Pilbratt showed some spectroscopy data taken from the Orion constellation that contained more than 100,000 spectral lines originating from signatures of specific elements or compounds. That’s likely to take some time to trawl through.

Indeed, although the Herschel mission has only been going for around a year, astronomers have already written more than 120 research papers, which will be published in an upcoming special issue of Astronomy and Astrophysics. With another three years to run, that is likely to only be the start.

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Impact zone That’s a lot of dots

By Michael Banks in Miami, Florida

We all know the plot for the film Armageddon starring Bruce Willis. An asteroid the size of Texas is on a collision course with Earth, and the US government sends a bunch of astronauts to plant a nuclear device underneath the asteroid to blow it to pieces, thus saving humanity.

Well that is how it goes in Hollywood. But what would we do if we suddenly found a large asteroid that would hit the Earth within the next 50 years?

Last night David Dearborn, a physicist at Lawrence Livermore National Laboratory in California, gave a talk here at the 216th American Astronomical Society meeting in Miami, Florida, about the best technologies to avoid an asteroid extinction event.

In 1998 NASA started a project named Spaceguard with the aim of cataloguing 90% of all asteroids in the solar system larger than a kilometre before 1998. Currently the project has detected around 80%, mainly because, rather unsettlingly, astronomers are finding more and more of them.

Then, in 2005, Congress asked astronomers to catalogue 90% of asteroids greater than 140 m by 2020 using a number of telescopes including the Large Synoptic Survey Telescope, which is currently being built in Chile and is expected to come online in 2015.

If an asteroid is on a collision course, Dearborn says that it is important to know its composition, whether it is made up of rubble, has a solid core, or even if it is a collection of solid rocks held together by rubble.

One point Dearborn reiterated is to deflect an asteroid only when we are 100% confident that it will hit the Earth. “You have to leave it alone until you know if it is going to be a problem,” says Dearborn.

So how do you blow up an asteroid or at the very least deflect it out of harms way? One option is painting the asteroid white, which would change its albedo and slowly start to change its orbit. Given that Dearborn says it would take decades to carry out this paintball exercise on a celestial scale it is perhaps not the best option.

Another is firing a high-powered laser pulse at the asteroid, but this again would take around 6000 years to change its speed by around 1 metre per second. “The National Ignition Facility is not really designed for shooting asteroids,” says Dearborn.

So the best technique for deflecting them is via a nuclear explosion. Two options are to activate a nuclear device just before impact or attempting to strike the object with a nuclear weapon. Dearborn presented a variety of models showing how an impact would break up an asteroid depending on its composition. “Current nuclear technology could handle most possible threats,” concludes Dearborn.

I guess Bruce Willis had it right all along.

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It’s out there

By Michael Banks in Miami, Florida

We need to better understand how other stars behave before we start looking for planets orbiting around them. That was the message from astronomers speaking in a session on searching for exoplanets at the 216th American Astronomical Society meeting in Miami, Florida.

Annie Baglin from the Observatoire de Paris, France, spoke about the $160m Convection Rotation and Planetary Transits (CoRoT) mission, built by the French Space Agency, which launched in 2006.

CoRoT has two objectives: to study the solar variation in other stars as well as searching for exoplanets via a technique known as “transiting”, where a planet passing in front of the star causes its solar output as seen by the satellite to dim slightly.

Indeed, CoRoT has already had breakthroughs in studying solar variations in other stars including hot stars and red giants. Yet the science that gets the most attention is CoRoT’s search for exoplanets.

Although CoRoT lost the use of two of its detectors last year, the craft is still going strong and has managed to detect a range of exoplanets.

Most of the exoplanets spotted by CoRoT are big, hot planets such as CoRoT-3b, which has a mass 21 times that of Jupiter.

On 17 March CoRoT discovered CoRoT-9b, which has a radius similar to Jupiter and a temperature of 350 K. “If it has moons, then they would be habitable,” says Baglin. But getting to the planet is another matter as it is lies 1500 light-years away.

The biggest find to date is possibly CoRoT-7b, discovered in February 2009, which has a similar diameter and mass to Earth.

Baglin outlined in her talk how difficult it is to spot such small planets saying that constant changes in the star’s activity makes it very difficult to detect planets orbiting them. “Once we have a better understanding of a star’s cycle then we will be better placed to start to look for exoplanets,” says Baglin.

CoRoT still has another three years to run, but it has already been superseded somewhat by NASA’s Kepler mission, which launched in March 2009 to look for Earth-like planets. “Kepler will do more than what we have,” says Baglin.

By Michael Banks in Miami, Florida

The common view of black holes residing at the centre of their host galaxies might not be completely true, according to astronomer Daniel Bacheldof, from the Florida Institute of Technology.

Speaking today at the 216th American Astronomical Meeting in Miami, Florida, Bacheldof and colleagues used old data taken from the Hubble Space Telescope to show that the supermassive black hole at the centre of the M87 galaxy is slightly displaced from its centre.

The fact that a supermassive black hole – black holes that are millions or billions time the mass of the Sun – can be displaced from the centre of a galaxy is not new, but the fact that astronomers have spotted such a small displacement means that small off-sets could be more common than previously thought.

The explanation for the displacement comes from the fact that the supermassive black hole in M87 was a merger between two smaller black holes. When they merged, the emission of gravitational waves “kicked” the newly created black hole, knocking it slightly off-centre. “What we are seeing in M87 is in effect indirect evidence for gravitational waves,” notes Bacheldof.

The fact that many other supermassive black holes show similar properties to M87 could indicate that such off-sets are common in the universe. “No longer can it be assumed that all supermassive black holes reside at the centres of their host galaxies,” says Bacheldof, who is looking at other such systems to spot similar effects. Time to re-write those astronomy textbooks?

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Exhibitors at the 216th American Astronomical Meeting

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Out now: the Solar Dynamics Observatory movie

By Michael Banks in Miami, Florida

Walking into the exhibition hall at the 216th American Astronomical Meeting in Miami, Florida, it seems like this year’s must-have is a TV screen.

That is, of course, to show all the awe-inspiring images and movies that their missions are just releasing, be it from the Herschel mission, the Wide-field Infra-red Survey Explorer or the Solar Dynamics Observatory (SDO).

My favourite is the SDO booth and not just because of the free 3D glasses, but because of the quality of the images that the mission has just started to release (though they did give me a nice coaster).

The SDO booth also has two TV screens, obviously one is not enough.

With the enticement of tortilla chips, I also caught some of the poster session, which did not seem overly subscribed. Maybe people were instead enjoying the Miami sun outside.

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Does what it says on the mouse mat

By Michael Banks in Miami, Florida

I was wondering how long it would be before I heard Will Smith’s 1998 hit song “Miami”, but I didn’t expect it while walking into a session at the 216th American Astronomical Society meeting.

This evening I attended a special symposium on the status of the Atacama Large Millimeter/submilliter Array (ALMA), which is currently being constructed in the Atacama desert in Chile.

Built by the European Southern Observatory and the US National Radio Astronomy Observatory (NRAO), when fully complete in 2013, ALMA will contain 66 antennas in total and be 100 times more sensitive than other millimetre telescopes.

ALMA will allow astronomers to study a range of phenomena including planetary and star formation.

There are currently four antennas up and working, with another 12 planned before ALMA begins science operations, which is expected to happen in early 2011.

Al Wootten, from the NRAO, who has been involved with planning ALMA for the last 20 years, says that the sensitivity together with the large bandwidth will make it a unique facility.

Speakers at the symposium were encouraging astronomers to submit ideas for using time on the telescope. “What ALMA will excel at is exploring the unexpected,” says astronomer Kelsey Johnson from the University of Virginia.

Oh, and if you are an engineer or scientist really interested in working at the ALMA telescope then they are currently recruiting and apparently want to hear from you.

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The heart and soul of the universe (credit: NASA/JPL-Caltech/UCLA)

By Michael Banks in Miami, Florida

It’s a hard task to walk into a session here at the 216th American Astronomical Society meeting in Miami, Florida, and not see amazing images of the universe.

But probably one of the best was issued today by researchers working on NASA’s Wide-field Infrared Survey Explorer (WISE).

Wise is an infrared telescope that was launched in December to probe the coolest stars in the universe and the structure of galaxies at four wavelengths between 3 and 25 µm.

Costing $320m, WISE circles the Earth’s poles at an altitude of 525 km scanning the entire sky one-and-a-half times in nine months.

Ned Wright, WISE’s principal investigator, said that the satellite has already taken over a million images and surveyed about three-quarters of the sky. By the beginning of November its objectives should be complete as the solid-hydrogen coolant is exhausted.

The image shows the so-called heart and soul nebula, which lies 6000 light-years away from Earth. WISE allows us to probe this star-making factory in unprecedented detail, letting us see the gas and dust that are just about to form stars.

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Look this way: Dennis Matson telling us all about Titan

By Michael Banks in Miami, Florida

I was up bright and early this morning to attend the opening symposium at the 216th American Astronomical Meeting in Miami, Florida.

The talk was about Titan, the largest moon of Saturn, and was given by Dennis Matson from NASA’s Jet Propulsion Laboratory, a project scientist for the Cassini-Huygens mission that launched in 1997.

Huygens, a European Space Agency mission, was launched together with NASA’s Cassini satellite for a seven-year trip to Saturn. While Cassini travelled off to orbit Saturn, Huygens separated to head to Titan where it landed in 2004.

You might think Titan is a lifeless body orbiting Saturn, but Matson showed it to be anything but. With lakes of Methane on the north pole of the moon – some as large as Lake Superior – as well as evidence for plate tectonics, volcanoes and sand dunes forming on the surface, the moon is very much alive.

That is not all, as Matson flashed images of methane clouds and possible deposits of lava. There is even a claim that an ocean of liquid water exists underneath the rocky surface.

Even with our knowledge of Titan, there is still a lot to find out, including whether the moon has a magnetic field.

After five years on Titan, Huygens has now delivered most of its objectives so astronomers are planning what the next mission could be to Saturn’s sixth moon.

Matson outlined two possible missions astronomers are looking into. One is using a probe attached to a balloon that would circumnavigate the moon at an altitude of 10 km. This would allow scientists to get a global picture of the moon closer to its surface.

The other possible mission is an 85 kg probe that would float on one of Titan’s lakes, which could, for example, probe its depth.

Astronomers probably have other ideas up their sleeves, but in the end they may be constrained by technology. “We even had some people who thought about sending some sort of submarine to Titan to explore the lake,” says Matson.

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