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…

Ingredients for Life on Gliese 581g?

Credit: Lynette Cook

Just in case you haven’t heard, astronomers have released news about an “Earth-like” exoplanet orbiting within the “Goldilocks zone” of a star some 20 light-years away. This is awesome, but does it mean Gliese 581g is habitable? Does it mean life is already slithering across its surface?

Judging by an exuberant claim by Steven Vogt, professor of astronomy and astrophysics at University of California Santa Cruz, one would think we now know there’s life on this strangely familiar world.

“Personally, given the ubiquity and propensity of life to flourish wherever it can, I would say that the chances for life on this planet are 100 percent. I have almost no doubt about it,” Vogt told Discovery News when the announcement broke on Wednesday.

100%?

Why did he say that his personal view was that the chances for life on Gliese 581g are 100%? At first glance, it is easy to see where he’s coming from.

Goldilocks Zone

Firstly, the exoplanet orbits close to a small red dwarf star (called Gliese 581), with a fast-paced orbit of 37 days. This is important as the energy output of a red dwarf is tiny when compared to our Sun (which is a yellow dwarf star, in case you were wondering) — to receive an equivalent amount of heating as the Earth, Gliese 581g needs to be much closer to its star.

Also, it isn’t orbiting too close. It is within the habitable zone (or the “Goldilocks zone,” i.e., a zone that’s not too hot or too cold) of the system. Therefore there’s a high probability that if water is present on its surface, it’s likely to be in liquid form. The presence of liquid water would be exciting as Earth Brand™ life likes liquid water.

Secondly, Gliese 581g is small for an exoplanet discovered thus far. Weighing in at a minimum mass of 3x that of the Earth, it could certainly have some Earth-like qualities. This has another implication; the world has enough gravitational oomph to hold onto an atmosphere — another ingredient that life seems to like (assuming it’s not of the bone-crushing, lead-boiling, Venus-type atmosphere).

It’s Complicated

But there’s a few complications. To be within the habitable zone of its parent star, Gliese 581g will be “tidally locked.” This means that one side of the exoplanet will always be facing the star. On the far side (or, indeed, the “dark side”) it will be cold whilst the near side will always be hot. Having one perpetual day doesn’t sound very Earth-like to me. But there is an upside to this strange orbit.

“This planet doesn’t have days and nights. Wherever you are on this planet, the sun is in the same position all the time. You have very stable zones where the ecosystem stays the same temperature… basically forever,” Vogt said. “If life can evolve, it’s going to have billions and billions of years to adapt to the surface.”

So a tidally-locked planet could have a stable atmosphere and perhaps life could evolve as a result. What could be considered to be a negative has just become a positive.

With all this good news, why wouldn’t life be thriving on this world?

Unknowns and Assumptions

There’s still a lot of unknowns and assumptions being made. For a start, the presence of Gliese 581g was detected by measuring the “wobble” of the star as the exoplanet orbits (its gravity tugs on the star as it circles). Therefore its mass and orbital radius can be derived. But we have no information about its atmosphere; the world doesn’t pass in front (or “transit”) the star from our perspective, so we can’t get a peek into its atmosphere.

Therefore we have zero clue as to whether it even has an atmosphere. It might not have an atmosphere, but then again it could have a very thick atmosphere — two extremes that would would put a stop to any Earth Brand™ life evolving. Also, we have zero clue if there’s any water there, it’s just guesswork that suggests there might be. There’s also the huge unknown as to whether life is ubiquitous in the cosmos or not.

Bread in the Oven

It’s a bit like baking a loaf of bread when you have all the necessary ingredients to make bread, but you have no clue about what quantities to use. Gliese 581g appears to have most of the ingredients for life (and with a few assumptions, it has all the ingredients for life), but we only have a general idea as to what quantities these ingredients come in.

If you threw flour, water and yeast straight into the breadmaker in random quantities, would you get a loaf of bread? What if you forgot to add the yeast?

Gliese 581g is that breadmaker. Unfortunately we have no clue if it can make bread.

For more on this incredible discovery, read Irene Klotz’s Discovery News article: “Earth-Like Planet Can Sustain Life

Earth is no Longer ‘One of a Kind’

For this special little planet, today has been a very big day.

Although we’ve speculated that planets the size of Earth must exist elsewhere in the cosmos, it wasn’t until one of the co-investigators working with the Kepler Space Telescope said he had statistical evidence that worlds of the approximate size of Earth appear to dominate our Milky Way.

We now know Earth isn’t unique.

Alas, this historic news didn’t come without controversy. It was unofficially broken at a TED conference in Oxford earlier this month and only after a recording of a presentation given by Dimitar Sasselov was posted online did the news get out. What’s more, the announcement only became clear when Sasselov referred to a presentation slide depicting a bar chart with the different sizes of exoplanets discovered by Kepler:

A slide from Dimitar Sasselov's TED presentation.

This slide shows the number of exoplanets discovered up until this month, binned by size. We have Jupiter-like exoplanets, Saturn-like exoplanets and Neptune-like exoplanets, all compared with Earth’s radius.

The heart-stopping moment comes when looking at the bar that represents Earth-like exoplanets (i.e. worlds with a radius of below 2 Earth radii, or “<2 Re"). According to Sasselov, Kepler has detected a lot of Earth-like worlds, so many in fact that they dominate the picture. From what we have here, it would appear that around 140 exoplanets are considered to be like Earth.

“The statistical result is loud and clear,” said Sasselov. “And the statistical result is that planets like our own Earth are out there. Our Milky Way galaxy is rich in these kinds of planets.”

But why the controversy? Isn’t this good news?

It would appear that the Kepler co-investigator chose not to wait until the official press release from NASA. He publicized these groundbreaking results in the U.K. at an event where you had to buy tickets to attend. This isn’t usually the stage you’d expect this kind of discovery to be announced — a move that will undoubtedly upset many.

“What is really annoying is that the Kepler folks were complaining about releasing information since they wanted more time to analyze it before making any announcements,” Keith Cowing, of NASAWatch.com, wrote in a SpaceRef article today. “And then the project’s Co-I goes off and spills the beans before an exclusive audience – offshore. We only find out about it when the video gets quietly posted weeks later.”

This sentiment is understandable. Only last month there was some frustration vented at the Kepler team for holding back data on 400 exoplanet candidates. While this might be standard practice — the discovering team should be allowed some time to publish work on any discoveries they have uncovered — telling the world’s scientists they will have to wait until February 2011 before they can get their hands on this invaluable data was a bridge too far.

In light of this, for a Kepler scientist to then jump the gun and disclose a groundbreaking discovery at an international conference without the backing of an official NASA release seems a little hypocritical.

But there is another argument to put out there: Why should anyone sit on such a profound discovery? Perhaps NASA and the Kepler team should have issued an earlier press release announcing to the world that 140 candidate Earth-like worlds have been detected and that further work will need to be done to confirm.

Ultimately, this controversy is just background noise when compared to what we have learned today. Official confirmation or not, Dimitar Sasselov’s message is clear. Although these detections need to be confirmed (hence why these worlds are referred to as “candidates”), it would appear there is an overwhelming preponderance of exoplanets measuring 2 Earth radii or less.

For me, that fact alone is astonishing — the first scientific evidence that worlds of Earth dimensions are not rare.

Earth is no longer unique.

For more, read my Discovery News article, “Kepler Scientist: ‘Galaxy is Rich in Earth-Like Planets‘”

Has Kepler Discovered a New Class of Celestial Object?

The strange objects orbiting the two stars could be mangled white dwarfs... but the jury is still out (NASA)

The first results from NASA’s Kepler exoplanet hunter are in and a perplexing early result has been announced. Yes, the space telescope is working fine, and no, it hasn’t spotted an alien homeworld (yet), but the Kepler team have uncovered something pretty cool.

Kepler may have discovered a new class of celestial object (possibly).

But before we start scratching our heads in confusion or popping the champagne corks in celebration, let’s try to work out what Kepler has observed.

Kepler is currently monitoring 100,000 stars in an effort to seek out extra-solar planets (or “exoplanets”) orbiting these stars. Although Kepler was only launched in March 2009 and early doubts about the observatory’s capabilities caused some low-level concern, Kepler appears to be functioning well and mission controllers are already reporting early results.

Five new exoplanet discoveries by Kepler were announced at the American Astronomical Society (AAS) meeting in Washington D.C. on January 4th, and all seem to have very strange characteristics. Fortunately Discovery News blogger Ray Villard was on the scene at the AAS to hear what the Kepler team had to announce:

In sifting through the Kepler data taken so far, postdoctoral student Jason Rowe found a very curious light signature. When an object passed behind its central star, the light from the system dropped significantly. This means the object — called KOI 74b — must be glowing fiercely with its own light that was blocked out when the object was eclipsed.

Hold up, the light dimmed when the exoplanet passed behind its parent star? Something’s not right here. Kepler detects exoplanets when the worlds pass in front of their parent stars, thereby dimming the starlight, not vice versa!

Actually, this is exactly what’s happened. The “exoplanets” orbiting two otherwise ordinary stars appear to be brighter — and hotter — than their host stars. It’s as if the roles of the stars and the exoplanets have been reversed; the stars are dimming the exoplanetary light as the exoplanet passes behind the star.

Needless to say, there is currently no stellar model that predicts this kind of behavior from extra-solar planetary systems.

This means the object — called KOI 74b — must be glowing fiercely with its own light that was blocked out when the object was eclipsed […] It is seething at 70,000 degrees Fahrenheit while the parent star is 17,000 degrees Fahrenheit. The strange object can’t be a star because the transit data show that it is no bigger than Jupiter.Ray Villard, Discovery News.

One theory is that KOI 74b (and the other strange object, KOI 81b) could be a white dwarf star that migrated close to its stellar partner. Through binary interactions, the white dwarf was stripped of some of its mass, causing it to puff up and appear like a gas giant exoplanet. That would certainly go to some way of explaining why these two “exoplanets” are so hot.

Of course, the other option is that Kepler has made a groundbreaking discovery and identified a whole new class of celestial object… but I suspect there are other, more mundane reasons for these observations.

I suppose we’ll just have to wait and see until followup observations are made…

Source: Discovery News

Could Extraterrestrial Genes Be Like Ours?

DNA and amino acids. Not just a terrestrial thing?
DNA and amino acids. Not just a terrestrial thing? (©CG4TV)

This is probably one of the biggest questions that hang over science fiction story lines: Will extraterrestrials have any resemblance to Life As We Know It™? To be honest, to toy with the thought of anything other than carbon-based life is pure conjecture, just because there might be some other form of life (such as silicon-based creatures), doesn’t mean there is (doesn’t mean there isn’t, either). So, here we are with the only form of life we know and understand, carbon-based life that was somehow spawned via a crazy mix of amino acids and some astronomical or terrestrial event that sparked the formation of prokaryotes (a.k.a. the simplest single-celled speck of life) some 4 billion years ago.

So we have an understanding of what formed life on Earth, perhaps if we look for the traces of evidence that evolved into Life As We Know It™ we can gauge whether extraterrestrial life has-formed/is-forming/will-form elsewhere in the observable Universe. From simulations of Earth evolution, scientists have predicted that 10 types of amino acids should form with the planet. These 10 amino acids are found inside the proteins of all living things on Earth. The same 10 amino acids have been found inside meteorites. Therefore, we already have a connection with the amino acids we find here on Earth and amino acids found in chunks of rock from elsewhere in the Solar System.

Now, a group of Canadian researchers have found that the same 10 amino acids are readily available elsewhere in the cosmos. Does this mean the components for life are common, not only on Earth, in the Solar System, but also in the Milky Way (and beyond)? It looks like it
Continue reading “Could Extraterrestrial Genes Be Like Ours?”

Listening Out for the Magnetospheres of Habitable Exoplanets

Searching for Earth-like exoplanets (© Mark Garlick)
Searching for Earth-like exoplanets (© Mark Garlick*)

Is there a new way to hunt for habitable Earth-like exoplanets? According to a US Naval Research Laboratory researcher there is an obvious, yet ingenious, way of listening for these worlds. Like most Earth-like exoplanet searches, we are looking for characteristics of our own planet. So what do we need to survive on Earth? Obviously we need water and the correct mix of oxygen with other atmospheric gases, but what about the magnetic bubble we live in? The Earth’s magnetosphere protects us from the worst the Sun can throw at us, preventing the atmosphere from being eroded into space and deflecting life-hindering radiation.

Although we have yet to develop sensitive enough radio telescopes, it may be possible in the future to detect the radio waves generated as charged particles in stellar winds interact with Earth-like exoplanetary magnetospheres. If there’s a magnetosphere, there may be a protected atmosphere. If there’s an atmosphere, perhaps there’s life being nurtured below

*This image is copyright Mark A. Garlick and has been used with permission. Please do not use this image in any way whatsoever without first contacting the artist.
Continue reading “Listening Out for the Magnetospheres of Habitable Exoplanets”

A Short Message for Kepler, from Astroengine.com…

The Delta II ignition: Kepler begins its mission on Friday at 10:49pm EST (© United Launch Alliance)
The Delta II ignition: Kepler began its mission on Friday at 10:49pm EST (© United Launch Alliance)

In the 17th Century, Johannes Kepler defined the laws of planetary motion around our star. Now the Kepler space telescope will define the motion of alien worlds around distant stars. Go find us some exoplanets!

I saw this image on The Write Stuff blog at the Orlando Sentinel, and I had to share. It is the moment of ignition of the Delta II rocket from Space Launch Complex-17B at Cape Canaveral Air Force Station, just before lift-off of NASA’s Kepler mission.

For more information and the original image (this one was slightly adjusted to remove compression artefacts), check out The Write Stuff »

Replacing Warheads With Telescopes

Left: The first ever rocket launch from Cape Canaveral, Bumper 2 (based on the V-2 weapon design), was in July 1950. Right: The Kepler space telescope launches onboard a Delta II rocket from Cape Canaveral, March 2009 (NASA)
Left: The first ever rocket launch from Cape Canaveral, Bumper 2 (based on the V-2 weapon design), was in July 1950. Right: The Kepler space telescope launches onboard a Delta II rocket from Cape Canaveral, March 2009 (NASA)

Kepler, the exoplanet-hunting space telescope, successfully launched from Cape Canaveral Air Force Station on top of a Delta II rocket at 10:49 pm EST. In a word: awesome. Unfortunately I missed lift off, but it was good to watch NASA TV as the flames from the first stage receded into the black. Obviously today’s event will come as a huge relief to NASA having lost the Orbital Carbon Observatory (OCO) last month when the Taurus XL upper stage fairing failed to separate, locking the satellite in a doomed sub-orbital trajectory, crashing into the Antarctic Ocean.

The highest any rocket had gone before: A 1947 US V-2 rocket, with nose cone camera, captures the limb of the Earth (NASA)
The highest any rocket had gone before: A 1947 US V-2 rocket, with nose cone camera, captures the limb of the Earth (NASA)

On checking out the NASA homepage, the headline news was obviously about Kepler, but underneath was a fascinating image (left). From the NASA Image of the Day, there’s a vintage piece of spaceflight history. Two images, one facing north, the other south, shows the first view from an altitude of over 100 miles (160 km). The pictures were taken by a camera in the nose cone of an experimental V-2 rocket launched by the US on March 7th, 1947. The V-2 technology, as used by Nazi Germany in World War II, had been captured after the war and developed by US scientists. In this case, the V-2 nose cone housed a camera, rather than an explosive warhead, to carry out the first high altitude atmospheric observations.

The camera returned a series of images to the Earth, and these striking panoramas were constructed, covering a million square miles of our planet’s surface. This was the first time a rocket had been used for rudimentary space science; before this time, rockets only had military applications.

62 years later, almost to the day, a Delta II carries one of the most ambitious NASA projects into orbit, to begin another peaceful application, not studying the atmosphere of our own planet, but to search for other Earths orbiting distant stars.

How far we’ve come

For more about Kepler’s launch and exciting mission, check out Anne Minard’s article on the Universe Today, “Success: Kepler Lifts Off to Look for Other Earths

Here’s One We Didn’t Discover Earlier

The 1998 archive Hubble image of HR 8799 after image analysis - one of the star's exoplanets have been resolved (NASA/HST)
The 1998 archive Hubble image of HR 8799 after image analysis - one of the star's exoplanets have been resolved (D. Lafrenière et al., ApJ Letters)

What’s just as exciting as directly imaging an exoplanet in a new observing campaign? To discover an exoplanet in an old observing campaign.

Like so many significant astronomical discoveries, archival images of the cosmos provide a valuable tool to astronomers. On its most basic level, astronomers can compare new images with images taken by the same (or different) observatory months, years or decades ago. This method can lead to the discovery of planets, asteroids and comets (when comparing two pictures of the night sky, a celestial object appears to move relative to the background stars). However, a new technique to analyse archived Hubble data in the search for exoplanets, has just revealed one of three known exoplanets orbiting the star HR 8699. The image in question was captured in 1998, when astronomers thought HR 8799 was an exoplanet-less star
Continue reading “Here’s One We Didn’t Discover Earlier”

Introducing the Exomoon, and Detecting them via Exoplanet Wobble

Can astronomers really detect exomoons?
Can astronomers really detect exomoons?

Exomoon: The natural satellite of an exoplanet.

Before today, I hadn’t heard anything about the possibility of looking for moons orbiting planets in other star systems. Sorry, exomoons orbiting exoplanets in other star systems. But a British astronomer has calculated that it is possible to not only detect exomoons, but it is possible to deduce their distance from the parent exoplanet and their mass.

All this is done by measuring the exoplanet’s “wobble”; a practice more commonly used in the pursuit of the exoplanets themselves. By detecting the wobble of distant stars, the gravitational pull of the exoplanet becomes obvious. The same can be done with exoplanets, possibly revealing the presence of Earth-like exomoons.

Of the 300+ exoplanets discovered, 30 are within the habitable zones of their stars. If these large gas giant exoplanets (usually several times the mass of Jupiter) have an exoplanet system of their own, these exomoons also fall within the habitable zone…

Makes you think, doesn’t it?

For the full article, check out Astronomers Now Looking For Exomoons Around Exoplanets on the Universe Today…