What Do You See When SETI’s Allen Telescope Array Is Aimed At The Sun?

A comparison between an observation of the sun using the ATA's 2.75 GHz band (left) and SOHO's 195A filter. Both are near-simultaneous observations on Oct. 1, 2009 (Saint-Hilaire et al., 2011)

A comparison between an observation of the sun using the ATA's 2.75 GHz band (left) and SOHO's 195A filter. Both are near-simultaneous observations on Oct. 1, 2009 (Saint-Hilaire et al., 2011).

And no, “aliens” isn’t the answer.

The Allen Telescope Array (ATA), located near Hat Creek, California, isn’t only used by the SETI Institute to seek out signals from extraterrestrial civilizations. The 42 6.1-meter antennae form an interferometer that can be used for a variety of astronomical studies — in reality, this is the main focus of the project. SETI studies “piggyback” the active astronomical research, passively collecting data.

Due to the radio interferometer’s wide field of view, one surprising use of the ATA is solar astronomy — at radio frequencies. The ATA can be used to simultaneously observe the whole of the solar disk at a range of frequencies rarely studied. As outlined in a recent arXiv publication, a University of California, Berkeley, team of astronomers headed by Pascal Saint-Hilaire have carried out the first ATA solar study, producing images of the sun in a light we rarely see it in (shown above).

According to the paper, active regions were observed at radio and microwave frequencies, spotting the emissions associated with bremsstrahlung — electromagnetic radiation generated by accelerated charged particles caught in intense magnetic fields, a feature typical inside solar active regions. Also, coronal interactions, or gyroresonance, between solar plasma and plasma waves (propagating along magnetic field lines) was detected.

Combining the ATA’s wide field of view, range of frequencies and high resolution, it looks like the ATA is the only solar radiotelescope on the planet.

For more on this fascinating study, read “Allen Telescope Array Multi-Frequency Observations of the Sun,” Saint-Hilaire et al., 2011. arXiv:1111.4242v1 [astro-ph.SR]

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Exoplanet Count Tops 700

An artist's impression of a lone exoplanet transiting its parent star. There are now 700 confirmed alien worlds orbiting other stars (ESO)

An artist's impression of a lone exoplanet transiting its parent star. There are now 700 confirmed alien worlds orbiting other stars (ESO)

On Friday, the Extrasolar Planets Encyclopedia registered more than 700 confirmed exoplanets. Although this is an amazing milestone, it won’t be long until the “first thousand” are confirmed.

There are now more than 700 confirmed exoplanets in the database. The latest addition is the planet HD 100655 b.
— announced via the Exoplanet iPhone app

Only two months ago, the encyclopedia — administered by astrobiologist Jean Schneider of the Paris-Meudon Observatory — registered 600 confirmed alien worlds. Since then, there has been a slew of announcements including the addition of a batch of 50 exoplanets by the European Southern Observatory’s (ESO) High Accuracy Radial velocity Planet Searcher (or HARPS) in September.

The first exoplanet was discovered orbiting a Main Sequence star in 1995, and the rate of exoplanet detections has been accelerating ever since.

It is worth noting that hundreds more candidate exoplanet detections have been made, many of which have been spotted by NASA’s Kepler space telescope. Kepler is staring at the same patch of sky, waiting for alien worlds to cross the line of sight between their parent star and Earth, registering a slight dip in starlight brightness. The 1,235 candidates will be confirmed (or denied) as Kepler awaits future transits.

Detecting the slight dimming of starlight isn’t the only tool exoplanet hunters have to spot these alien worlds. The “radial velocity” method — as employed by systems such as the ESO’s HARPS — can detect the slight “wobble” of stars as orbiting worlds gravitationally “tug” on their parent stars. Both methods have their advantages and both are notching up an impressive exoplanet count. “Microlensing” has also been employed to spot a handful of exoplanets, as has direct imaging.

Exoplanetary studies are amongst the most exciting astronomical projects out there. Not only are we realizing there is a veritable zoo of worlds — some Earth-sized, others many times the mass of Jupiter — we are also pondering the most profound question: could extraterrestrial life inhabit these worlds?

For now, we have no clue, but life as we know it has a habit of springing up where we least expect it, it’s only a matter of time before we start to have some clue as to the existence of life as we don’t know it.

Some Galaxies Die Young… Others Recycle

Some galaxies undergo a rapid star formation phase, losing stellar gases to intergalactic space, others choose to recycle, thereby extending their star forming lifespans.

Some galaxies undergo a rapid star formation phase, losing stellar gases to intergalactic space, others choose to recycle, thereby extending their star forming lifespans (NASA, ESA, and A. Feild (STScI))

It sounds like an over-hyped public service announcement: If you don’t recycle, you’ll die a premature death.

But in the case of galaxies, according to three new Science papers based on Hubble Space Telescope data, this is a reality. Should a galaxy “go green,” reusing waste stellar gas contained within huge halos situated outside their visible disks, they will fuel future star-birth cycles, prolonging their lifespans.

Sadly for “starburst” galaxies — galaxies that undergo rapid star generation over very short time periods — they care little for recycling, resulting in an untimely death.

Using data from Hubble’s Cosmic Origins Spectrograph (COS), three teams studied 40 galaxies (including the Milky Way) and discovered vast halos of waste stellar gases. Contained within these spherical reservoirs — extending up to 450,000 light-years from their bright disks of stars — light elements such as hydrogen and helium were found to be laced with heavier elements like carbon, oxygen, nitrogen and neon. There’s only one place these heavy elements could have come from: fusion processes in the cores of stars and supernovae.

Interestingly, the quantity of heavy elements contained within the newly-discovered halos is similar to what is contained in the interstellar gases within the galaxies themselves.

“There’s as much heavy elements out in the halos of the galaxies as there is in their interstellar medium, that is what shocked us.” said Jason Tumlinson, an astronomer for the Space Telescope Science Institute in Baltimore, Md., in an interview for my Discovery News article “Galaxies That Don’t Recycle Live Hard, Die Young.”

But these heavy elements are stored in halos outside the galaxies; how the heck did it get there?

According to the researchers, powerful stellar winds jetting into intergalactic space have been observed, transporting the heavy elements with them. But there’s a catch. If the outflow is too strong, waste stellar gases are ejected from the galaxies completely. Unfortunately for one sub-set of galaxies, powerful stellar outflows come naturally.

Starburst galaxies rapidly generate stars, ejecting speedy streams of stellar waste gas. Some of these streams have been clocked traveling at 2 million miles per hour, escaping from the galaxy forever. In the case of a starbust galaxy, a “recycling halo” cannot be re-supplied — future star birth is therefore killed off.

“We found the James Dean or Amy Winehouse of that population, you know, the galaxies that lived fast and died young,” Tumlinson pointed out. “(Todd) Tripp’s team studied that in their paper.”

“That paper used a galaxy that is known as a ‘post-star burst galaxy’ and its spectrum showed that it had a very robust star burst (phase),” he continued. “It was one of those live fast, die young galaxies.”

Although fascinating, one idea struck me the hardest. On asking Tumlinson to speculate on how galactic recycling of stellar material may impact us, he said:

“Your body is 70 percent water and every water molecule has an oxygen atom in it. The theorists say the recycling time (in the Milky Way’s halo) is approximately a billion years, so that means — potentially — that some of the material (oxygen) inside your body has cycled in and out of the galaxy ten times in the history of the galaxy. At least once, maybe up to ten times.”

As Carl Sagan famously said: “We’re made of star stuff;” perhaps this should be rephrased to: “We’re made of recycled star stuff.”

Publications:

Could Kepler Detect Borg Cubes? Why Not.

That's no sunspot.

"That's no sunspot."

Assuming Star Trek‘s Borg Collective went into overdrive and decided to build a huge cube a few thousand miles wide, then yes, the exoplanet-hunting Kepler space telescope should be able to spot it. But how could Kepler distinguish a cube from a nice spherical exoplanet?

With the help of Ray Villard over at Discovery News, he did some digging and found a paper dating back to 2005 — long before Kepler was launched. However, researcher Luc Arnold, of the Observatoire de Haute-Provence in Paris, did have the space telescope in mind when he studied what it would take to distinguish different hypothetical shapes as they passed in front of his theoretical stars.

The big assumption when looking for exoplanets that drift between distant stars and the Earth — events known as “transits” — is that the only shape these detectable exoplanets come in are spheres. Obvious really.

As a world passes in front of its parent star, a circular shadow will form. However, from Earth, we’d detect a slight dimming of the star’s “light curve” during the transit, allowing astronomers to deduce the exoplanet’s orbital period and size.

The transit method has been used to confirm the presence of hundreds of exoplanets so far, and Kepler has found over 1,200 additional exoplanet candidates. But say if astronomers paid closer attention to the shape of the received light curve; spherical objects have a distinct signature, but say if something looked different in the transiting “planet’s” light curve? Well, it could mean that something non-spherical has passed in front of a star. And what does that mean? Well, that would be a pretty convincing argument for the presence of a huge planet-sized artificial structure orbiting another star. Artifical structure = super-advanced alien civilization.

Arnold tested his theory that all manner of shapes could be detected by Kepler, assuming the transiting structure was on the scale of a few thousand miles wide. In this case, Arnold was testing his hypothesis to see whether we could detect an advanced civilization’s “shadow play.” Perhaps, rather than beaming messages by radio waves, an advanced civilization might want to signal their presence — SETI style — by blocking their sun’s light with vast sheets of lightweight material. As the shape passes in front of the star, the slight dimming of starlight would reveal an artificial presence in orbit.

By putting a series of these shapes into orbit, the aliens could create a kind of interstellar Morse code.

Of course, this is a rather “out there” idea, but I find it fascinating that Kepler could detect an alien artifact orbiting a star tens or hundreds of light-years away. Although this research is only considering orbital “billboards,” I quite like the idea that Kepler might also be able to detect a large structure like… I don’t know… a big Borg mothership. Having advanced warning of the presence of an aggressive alien race sitting on our cosmic doorstep — especially ones of the variety that like to assimilate — would be pretty handy.

Publication: Transit Lightcurve Signatures of Artificial Objects, L. Arnold, 2005. arXiv:astro-ph/0503580v1

Want to Feel Good? Watch the Aurora Borealis in HD

The Aurora from Terje Sorgjerd on Vimeo.

I actually posted this jaw-dropping video on Discovery News last month, but today it got picked up on Digg, so I was reminded why I had to feature it.

The video is actually composed of 22,000 high-definition photographs, stitched together is a finely crafted time lapse video. The photographer in question is Terje Sorgjerd who braved -22C temperatures in the Arctic Circle to bring us this stunning perspective of the Aurora Borealis, or the Northern Lights. Throw in the Hans Zimmer “Gladiator” theme tune “Now We Are Free” and we get a timeless classic video that can be watched over and over again and never get bored.

So, sit back and enjoy the Sun-Earth interaction at its most spectacular.

For more of Sorgjerd’s work, check out his Facebook page.

Special thanks to my good friend Geir Barstein, science journalist at the Norwegian newspaper Dagbladet for originally writing about Sorgjerd’s work.

Screaming Exoplanets: Detecting Alien Magnetospheres

Exoplanets may reveal their location through radio emissions (NASA)

Exoplanets may reveal their location through radio emissions (NASA)

In 2009, I wrote about a fascinating idea: in the hunt for “Earth-like” exoplanets, perhaps we could detect the radio emissions from a distant world possessing a magnetosphere. This basically builds on the premise that planets in the solar system, including Earth, generate electromagnetic waves as space plasma interacts with their magnetospheres. In short, with the right equipment, could we “hear” the aurorae on extra-solar planets?

In the research I reviewed, the US Naval Research Laboratory scientist concluded that he believed it was possible, but the radio telescopes we have in operation aren’t sensitive enough to detect the crackle of distant aurorae. According to a new study presented at the RAS National Astronomy Meeting in Llandudno, Wales, on Monday, this feat may soon become a reality, not for “Earth-like” worlds but for “Jupiter-like” worlds.

“This is the first study to predict the radio emissions by exoplanetary systems similar to those we find at Jupiter or Saturn,” said Jonathan Nichols of the University of Leicester. “At both planets, we see radio waves associated with auroras generated by interactions with ionised gas escaping from the volcanic moons, Io and Enceladus. Our study shows that we could detect emissions from radio auroras from Jupiter-like systems orbiting at distances as far out as Pluto.”

Rather than looking for the magnetospheres of Earth-like worlds — thereby finding exoplanets that have a protective magnetosphere that could nurture alien life — Nichols is focusing on larger, Jupiter-like worlds that orbit their host stars from a distance. This is basically another tool in the exoplanet-hunters’ toolbox.

Over 500 exoplanets have been confirmed to exist around other stars, and another 1,200 plus exoplanetary candidates have been cataloged by the Kepler Space Telescope. The majority of the confirmed exoplanets were spotted using the “transit method” (when the exoplanet passes in front of its host star, thereby dimming its light for astronomers to detect) and the “wobble method” (when the exoplanet gravitationally tugs on its parent star, creating a very slight shift in the star’s position for astronomers to detect), but only exoplanets with short orbital periods have been spotted so far.

The more distant the exoplanet from its host star, the longer its orbital period. To get a positive detection, it’s easy to spot an exoplanet with an orbital period of days, weeks, months, or a couple of years, but what of the exoplanets with orbits similar to Jupiter (12 years), Saturn (30 years) or even Pluto (248 years!)? If we are looking for exoplanets with extreme orbits like Pluto’s, it would be several generations-worth of observations before we’d even get a hint that a world lives there.

“Jupiter and Saturn take 12 and 30 years respectively to orbit the Sun, so you would have to be incredibly lucky or look for a very long time to spot them by a transit or a wobble,” said Nichols.

By assessing how the radio emissions for a Jupiter-like exoplanet respond to its rotation rate, the quantity of material falling into the gas giant from an orbiting moon (akin Enceladus’ plumes of water ice and dust being channeled onto the gas giant) and the exoplanet’s orbital distance, Nichols has been able to identify the characteristics of a possible target star. The hypothetical, “aurora-active” exoplanet would be located between 1 to 50 AU from an ultraviolet-bright star and it would need to have a fast spin for the resulting magnetospheric activity to be detectable at a distance of 150 light-years from Earth.

What’s more, the brand new LOw Frequency ARray (LOFAR) radio telescope should be sensitive enough to detect aurorae on Jupiter-like exoplanets, even though the exoplanets themselves are invisible to other detection methods. Nice.

As we’re talking about exoplanets, magnetospheres and listening for radio signals, let’s throw in some alien-hunting for good measure: “In our Solar System, we have a stable system with outer gas giants and inner terrestrial planets, like Earth, where life has been able to evolve. Being able to detect Jupiter-like planets may help us find planetary systems like our own, with other planets that are capable of supporting life,” Nichols added.

Although Nichols isn’t talking about directly detecting habitable alien worlds (just that the detection of Jupiter-like exoplanets could reveal Solar System-like star systems), I think back to the 2009 research that discusses the direct detection of habitable worlds using this method: Aliens, if you’re out there, you can be as quiet as you like (to avoid predators), but the screaming radio emissions from your habitable planet’s magnetosphere will give away your location…

Sometimes, You Just Have To Make Chocolate Mars Rover Cake

It's a chocolate Mars rover! Photo credit and cake-making skills: Will Gater

It's a chocolate Mars rover! Photo credit and cake-making skills: Will Gater

OK, so Astroengine has been a little quiet of late due to some uber-cool space news writing over at Discovery News, but to kick off an era of increased productivity (and not just Photoshop fun), I just had to share this superb chocolate-covered tribute to Mars Exploration Rover Spirit.

Created by my mate Will Gater, science writer and editor of Sky at Night Magazine, this is Mars rover Spirit, complete with silica-churned (white chocolate) Mars regolith in its tire tracks. I’ll be back in the UK next week Will, I hope you saved me a slice!

Latest news on Spirit: Mars Rover Down? Spirit Stays Silent

Speaking of Mars rovers, in case you missed it, I had the awesome fortune to visit the next Mars rover to be launched to the Red Planet later this year. Seeing the nuclear-powered, laser-toting, car-sized rover up close is something I’ll never forget. For more, take a look at the Discovery News slide show I created with pictures from my NASA Jet Propulsion Laboratory adventures.

This is me, in the NASA JPL clean room housing Mars rover Curiosity. As you can see, I'm very happy to be there.

This is me, in the NASA JPL clean room housing Mars rover Curiosity. As you can see, I'm very happy to be there.