Posted on by Nancy Atkinson

Ground-Based Telescopes Observe Atmospheres of Exoplanets

TrES-3b is a gas giant like Jupiter, but with an orbit much closer to its star than Mercury is to our Sun.Credit: Leiden Observatory.

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For the first time, astronomers have measured light emitted from extrasolar planets around sun-like stars using ground-based telescopes. The observations were obtained simultaneously and independently by two separate teams for two different planets. Incredibly, they were also able to determine properties of the exoplanets’ atmospheres as well. Measuring the light emitted from a planet at different wavelengths reveals the planet’s spectrum, which can be used to determine the planet’s day-side temperature. In addition, this spectrum can reveal many physical processes in the planet’s atmosphere, such as the presence of molecules like water, carbon monoxide and methane, and the redistribution of heat around the planet. “This first direct detection of light emitted by another planet, using existing telescopes on the ground, is a major milestone in the study of planets beyond our own Solar System,” said Professor Gary Davis, Director of the United Kingdom Infrared Telescope (UKIRT). “This is a very exciting scientific discovery.”

The measurements of the first planet, TrES-3b, were conducted by a team of Astronomers from the University of Leiden, using the William Herschel Telescope (WHT) on La Palma (Canary Islands, Spain) and the United Kingdom Infrared Telescope on Mauna Kea in Hawai`i. TrES-3b is in a very tight orbit around its host star, TrES-3, transiting the stellar disk once per 31 hours. For comparison, Mercury orbits the sun once every 88 days. TrES-3b is just a little larger than Jupiter, yet orbits around its parent star much closer than Mercury does, making it a “hot jupiter.”

UKIRT observations caught the planet transiting in front of the star, from which the size of the planet has been worked out extremely precisely. The WHT observations also show the moment the planet moves behind the star, and allow the strength of the planet light to be measured. Astronomers have been trying to observe this effect from the ground for many years, and this is the first success.

Ernst de Mooij, leader of the research team, said, “While a few such observations have been conducted previously from space, they involved measurements at long wavelengths, where the contrast in brightness between the planet and the star is much higher. These are not only the first ground-based observations of this kind, they are also the first to be conducted in the near-infrared, at wavelengths of 2 micron for this planet, where it emits most of its radiation.”

This image shows a comparison between the sizes of the orbits of TrES-3b and Mercury around the primary star. Note that while the orbits are to scale, the sizes of the planets and the star are not.
This image shows a comparison between the sizes of the orbits of TrES-3b and Mercury around the primary star. Note that while the orbits are to scale, the sizes of the planets and the star are not.

The researchers determined the temperature of TrES-3b to be a slightly over 2000 Kelvin. “Since we know how much energy it should receive by the type of its host star, this gives us insights into the thermal structure of the planet’s atmosphere,” added Dr. Ignas Snellen, “which is consistent with the prediction that this planet should have a so-called ‘inversion layer.’ It is absolutely amazing that we can now really probe the properties of such a distant world”.

An atmospheric inversion layer is a layer of air where the normal change of temperature with altitude reverses. Current theory says that there are two types of “hot jupiters,” one with an inversion layer, and one without. One theory is that the presence of an inversion layer would depend on the amount of light the planet receives from its star. If the inversion layer could be confirmed, for example by measurements at other wavelengths, these observations would fit in perfectly with this theory.

A second team has made a ground-based detection of a different extrasolar planet, OGLE-TR-56b,using the Southern Observatory’s Very Large Telescope. This planet is about 5,000 light-years away, located towards the center of the galaxy. The planet is quite hot; its atmosphere is more than 4,400 degrees Fahrenheit (2,400 degrees Celsius). This is one of the hottest extrasolar planets detected.

The researchers say both landmark observations will open up a new window for studying exoplanets and their atmospheres using ground-based telescopes, and show great promise for using future extremely large telescopes which will have much higher sensitivity than the telescopes used today.

Paper for TrES-3b.
Paper for OGLE-TR-56b

Source: Joint Astronomy Center

Posted on by Nancy Atkinson

Viewing Earth as an Extra-Solar Planet

Earth scenes and corresponding spectra reconstructed for two observer’s positions. Credit: Arnold, et al.

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What if another civilization had telescopes and spacecraft better than ours? Would Earth be detectable from another planet a few light-years away? Likewise, what will it take for us to detect life on an Earth-like planet within a similar distance? It’s interesting to consider those questions, and now, there is data to help answer them. In December 1990, when the Galileo spacecraft flew by Earth in its circuitous journey to Jupiter, scientists pointed some of the instruments at Earth just to see how the old home planet looked from space. Since we knew life could definitely be found on Earth, this exercise helped create some criteria that if found elsewhere, would point to the existence of life there as well. But what if Earth’s climate was different from what it is now? Would that signature still be detectable? And could potential biomarkers from extra solar planets holding climates much colder or warmer than ours be obvious? A group of researchers in France input some various criteria garnered from different epochs in Earth’s history to test out this hypothesis. What did they find?

One of the most telling of the criteria from the Galileo flyby revealing life on Earth was what is called the vegetation red edge –a sharp increase in the reflectance of light at a wavelength of around 700 nanometers. This is the result of chlorophyll absorbing visible light but reflecting near infrared strongly. The Galileo probe found strong for this evidence on Earth in 1990.

Luc Arnold and his team at the Saint-Michel-l’Observatoire in France wanted to determine some different parameters where plant life similar to Earth’s would still be detectable via the vegetative red edge on an Earth-like planet orbiting a star several light years away.

Earth from space.
Earth from space.

At that distance the planet would be a non-resolvable (in visible light) point-like dot, so the first question to consider is whether the red edge would be visible at different angles. The planet is likely to be rotating, and for example, on Earth, the continents that have the most vegetation are mainly in the northern hemisphere. If that hemisphere wasn’t leading the view, would a bio-signature still be detectable? They also wanted to allow for the different seasons, where a hemisphere in winter would be less likely to have vegetative biomarkers than one in summer, and potential heavy cloud cover.

They also input different climate criteria from the last Quaternary climate extremes, using climate simulations have been made by general circulation models. They used data from the present time and compared that to an ice age, The Last Glacial Maximum (LGM) which occurred about 21,000 years ago. Temperatures globally were on the order of 4 degrees C colder than today, and ice sheets covered most of the northern hemisphere. Then, they used a warmer time, during the Holocene epoch 6,000 years ago, when the Earth’s northern hemisphere was about 0.5 degrees C warmer than today. The sea level was rising and the Sahara Desert contained more vegetation.

Surprisingly, the researchers found even during winter in an ice age, the vegetation red signal would not be significantly reduced, compared to today’s climate and even the warmer climate.

So if another Earth is out there, the vegetaion red edge should allow us to find that Earth-like planet. But we need better telescopes and spacecraft to find it.

The best hope on the horizon is the Terrestrial Planet Finder. ESA has a similar instrument in the works called Darwin.
The teams behind these instruments say they could spot Earth-like planets orbiting stars at distances of up to 30 light years with an exposure measured in a couple of hours.

Arnold’s team says that spotting the signs of life on such a planet would be much harder. The vegetation red edge might only be seen with an exposure of 18 weeks with a telescope like the Terrestrial Planet Finder’s. An 18 week exposure of a planet orbiting another star would be an almost impossible task.

So when might we eventually see vegetation on another planet? The Terrestrial Planet Finder (TPF) looks unlikely to be launched before 2025 and even then might not have the power to do the job.

More ambitious telescopes later in the century, such as a formation of 150 3-meter mirrors would collect enough photons in 30 minutes to freeze the rotation of the planet and produce an image with at least 300 pixels of resolution, and up to thousands depending on array geometry. “At this level of spatial resolution, it will be possible to identify clouds, oceans and continents, either barren or perhaps (hopefully) conquered by vegetation,” the researchers write.

Sources: arXiv, arXiv blog

Posted on by Ian O'Neill

Hunt is on for “Killer” Third Star in BD+20 307 Binary System

Exoplanet collision in BD+20 301. Possibly an Earth-like rocky exoplanet was involved? (Lynette Cook)

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In September, it was announced the Chandra X-ray Observatory had spotted something very odd about BD+20 307. The binary system appeared to have a dusty disk surrounding it, indicative of a young, planet-forming system a fraction of the age of the Solar System. However, it was well known that the binary was actually several billion years old. It turns out that this disk was created by a rare planetary event; a cataclysmic planetary collision.

On Wednesday, at the AAS conference in Long Beach, I attended the “Extrasolar Planets” session to listen in on more results from Hubble about the exciting exoplanet discoveries in November… however, for me, the most captivating talk was about the strange, dusty old binary and the future detective work to be carried out to track down a planet killer…

The talks by astrophysicists working with the optical Hubble data were superb, showing off some of the science behind last years spate of direct observations of exoplanets, particularly the massive planet orbiting the star Fomalhaut, shaping a scattered disk of dust. However, there was no further news to report, apart from some cool numerical models the scientists will be using to characterize Fomalhaut b and a very interesting talk about the predicted lifetimes of exoplanets undergoing tidal stresses (which, unfortunately, I missed the first five minutes of as I got lost in the Long Beach Convention Center).

The one presentation that did pique my interest was Ben Zuckerman’s review of the progress being made in the study of BD+20 307. A few months ago, this piece of research caused a huge amount of interest as it provided the first piece of evidence of a huge, rocky planetary collision in the star system 300 light years away. Naturally, many news sources ran with article titles like: Is this what the Solar System would look like after Earth was hit by another planetary body? As Zuckerman pointed out, the fact that the group used an artist impression of a colliding Earth-like body (plus land masses and oceans, as pictured top) was no accident. BD+20 307 is certainly at an age when oceans might have formed and life–as Zuckerman morbidly conjectured–may have thrived. Not for any longer…

Usually when we observe dust around a star, we can assume that it is a planet-forming star system that is fairly young. Conversely, as I found out to great depth in the conference, very old white dwarf systems can reveal a lot about their past planetary population when their dusty contaminants are studied. However, the dust contained in the BD+20 307 system is a puzzle. Astronomers had discovered a system, of comparable age to ours with a large amount of warm dust (T~500K). A system of that age will have long since expelled (via stellar wind pressure) or accreted any left-over dust from the planet-forming stages. Therefore, the only remaining explanation is that a rocky body collided with another, ejecting a huge amount of micron-sized warm dust particles.

So is this what the Solar System would look like after Earth is shattered by another planet? Possibly.

Zuckerman then pushed into some work being done to understand how the planetary collision could have happened in the first place. After all, the planets in our Solar System have settled into long-term stable orbits, any planet in BD+20 307 will have the same qualities. There were some questions as to whether the binary stars may have contributed to destabilizing the system, but Zuckerman quickly argued against this idea as the binary has such a tight orbit (with an orbital period of only 3.5 days), the destroyed planet will have found a stable orbit far from any gravitational variations.

So what could have caused the carnage in BD+20 307? We know that massive planetary bodies exert a huge gravitational pull on their host star and other planets in a system (i.e. Jupiter in the case of our Solar System), occasionally bullying (and sometimes capturing) them along the way. A small nudge in the wrong direction and planets could be knocked from their orbits, set on a collision course. So, much effort is now being put into a search for a third, faint star in BD+20 307. Perhaps it could be orbiting far away from the dancing binary, occasionally swinging past the planetary bodies, setting up the huge collision event.

This certainly seems reasonable, as 70% of binary star systems are found to have a third star. However, Zuckerman’s team have yet to find the “killer” third star and he appears confident that after careful analysis that there is no other stellar body within a 20 AU radius of the binary pair. Next, he intends to study the “wobble” of the centre of mass of the BD+20 307 binary to see if there is any gravitational anomaly as the mysterious “third star” tugs at the pair.

Posted on by Fraser Cain

Atmospheres of Super Earths

Artist illustration of a super Earth around Gliese 581

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We stand on the edge of the next phase of planetary discovery. Hundreds of massive, Jupiter-like planets have been discovered, but now astronomers are turning up smaller, more familiar planets. Planets the mass of Earth are out of reach today, but a new class of super Earth planets are now being discovered, and more will be turned up with the next generation of ground and space-based telescopes. Perhaps the most interesting research will be in the atmospheres of these planets.

Super Earths can have up to 10 times the mass of the Earth, but with a solid surface and liquid water they could very well be habitable. A recent presentation by Eliza Miller-Ricci from Harvard University at the 213th meeting of the American Astronomical Society discussed the kinds of atmospheres astronomers might see as these super Earths start turning up. Although interesting scientifically – geologic outgassing, evidence of plate tectonics, and the thickness or thinness of the atmosphere, the most interesting question will be: can super Earth planets support life?

To have life as we understand it, super Earth planets (like regular Earth planets) will need to have liquid water on their surface, and the requires a certain temperature range – the parent star’s habitable zone. As we see in our own Solar System, the atmosphere of a planet helps regulate its temperature; Venus has a thick atmosphere and it’s hot enough to melt lead, while Earth has a nice temperature to allow liquid water to form on its surface. Mars has a thin atmosphere and it’s really cold. It’s not just the thickness of the atmosphere that matters, it’s also what’s in it: carbon dioxide, water, etc.

High mass planets like Jupiter are mostly formed from hydrogen. Low mass terrestrial planets like Earth can’t hold onto their hydrogen and it escapes into space during the planet’s early history. But these super Earths might be able to hold onto their hydrogen. Instead of a low-hydrogen atmosphere like Earth, they might have an atmosphere with large quantities of water. And water is a powerful greenhouse gas – trace amounts of water vapor in Earth’s atmosphere account for 60% of our greenhouse effect, keeping the planet warm and habitable.

I asked Miller-Ricci about what impact large quantities of hydrogen will have on the atmosphere of a super Earth planet. We have water here on Earth, but very little in the atmosphere. Water vapor is a powerful greenhouse gas and would help define the temperature of the planet. “The amount of hydrogen in the atmosphere of a super Earth planet would significantly affect its habitable zone. This is a really important question, it’s what we’re looking at next.”

Current missions can detect super Earths using the transit method, where the planet dims light from its parent star as it passes in front. By subtracting the chemical signature when the planet passes behind the star, astronomers can determine its atmosphere.

Finding super Earths is at the limit of current telescopes, but more powerful instruments are launching soon. NASA’s Kepler mission, launching in April 2009, will turn up even more super Earths than have already been found. But the next generation of space telescopes, like NASA’s James Webb Space Telescope will allow astronomers to image these planet’s atmospheres directly.

Posted on by Nancy Atkinson

The Case of the Disappearing Planetary Disks

photograph from NASA's Spitzer Space Telescope shows the young star cluster NGC 2362. Credit: NASA/JPL-Caltech/T. Currie (CfA)

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After examining the 5-million-year old star cluster NGC 2362, astronomers say that planets like Jupiter must form quickly because the material that form giant gas planets disappears in just few million years in young protoplanetary (planet forming) systems. Using NASA’s Spitzer Space Telescope, astronomers from the Smithsonian Center for Astrophysics found that all stars in this cluster with the mass of the Sun or greater have lost their protoplanetary disks, and only a few stars less massive than the Sun retain their protoplanetary disks. These disks provide the raw material for forming gas giants like Jupiter. Therefore, gas giant planets have to form in less than 5 million years or they probably won’t form at all. However, the material to form rocky terrestrial planets like Earth appears to stick around much longer.

“Even though astronomers have detected hundreds of Jupiter-mass planets around other stars, our results suggest that such planets must form extremely fast. Whatever process is responsible for forming Jupiters has to be incredibly efficient,” said lead researcher Thayne Currie of the Harvard-Smithsonian Center for Astrophysics. Currie presented the team’s findings at a meeting of the American Astronomical Society in Long Beach, California.

Even though nearly all gas giant-forming disks in NGC 2362 have disappeared, several stars in the cluster have “debris disks,” which indicates that smaller rocky or icy bodies such as Earth, Mars, or Pluto may still be forming.

“The Earth got going sooner, but Jupiter finished first, thanks to a big growth spurt,” explained co-author Scott Kenyon.

Kenyon added that while Earth took about 20 to 30 million years to reach its final mass, Jupiter was fully grown in only 2 to 3 million years.

Previous studies indicated that protoplanetary disks disappear within 10 million years. The new findings put even tighter constraints on the time available to create gas giant planets around stars of various masses.

Source: Harvard Smithsonian Center for Astrophysics

Posted on by Ian O'Neill

Astronomers Now Looking For Exomoons Around Exoplanets

An artist impression of an exomoon orbiting an exoplanet, could the exoplanet's wobble help astronomers? (Andy McLatchie)

[/caption]It looks like astronomers have already grown tired of taking direct observations of exoplanets, been there, done that. So they are now pushing for the next great discovery: the detection of exomoons orbiting exoplanets. In a new study, a British astronomer wants to use a technique more commonly associated with the indirect observation of exoplanets. This technique watches a candidate star to see if it wobbles. The wobble is caused by the gravitational pull of the orbiting exoplanet, revealing its presence.

Now, according to David Kipping, the presence of exomoons can also be detected via the “wobble method”. Track an exoplanet during its orbit around a star to see its own wobble due to the gravitational interaction between the exoplanet/exomoon system. As if we needed any more convincing that this is not already an ‘all kinds of awesome’ project, Kipping has another motivation behind watching exoplanets wobble. He wants to find Earth-like exomoons with the potential for extraterrestrial life…

If you sat me in a room and asked me for ten years over and over again: “If you were an astronomer, and you had infinite funds, what would you want to discover?“, I don’t think I would ever arrive at the answer: the natural satellites orbiting exoplanets.” However, now I have read an article about it and studied the abstracts of a few papers, it doesn’t seem like such a strange proposition.

David Kipping, an astronomer working at the University College London (UCL), has acquired funding to investigate his method of measuring the wobble of exoplanets to reveal the presence of exomoons, and to measure their mass and distance from the exoplanet.

“Until now astronomers have only looked at the changes in the position of a planet as it orbits its star. This has made it difficult to confirm the presence of a moon as these changes can be caused by other phenomena, such as a smaller planet,” said Kipping. “By adopting this new method and looking at variations in a planet’s position and velocity each time it passes in front of its star, we gain far more reliable information and have the ability to detect an Earth-mass moon around a Neptune-mass gas planet.”

Kipping’s work appeared in the December 11th Monthly Notices of the Royal Astronomical Society and could help the search for exomoons that lie within the habitable zone. Of the 300+ exoplanets observed so far, 30 are within the habitable zones of their host stars, but the planets themselves are large gas giants, several times the size of Jupiter. These gas giants are therefore assumed to be hostile for the formation for life (life as we know it in any case) and so have been discounted as habitable exoplanets.

But what if these exoplanets in the habitable zone have Earth-like exomoons orbiting them? Could they be detected? It would appear so.

Prof. Keith Mason, Chief Executive of the Science and Technology Facilities Council (STFC), added, “It’s very exciting that we can now gather so much information about distant moons as well as distant planets. If some of these gas giants found outside our Solar System have moons, like Jupiter and Saturn, there’s a real possibility that some of them could be Earth-like.”

Watch this space for an announcement of the first Earth-like exomoon to be discovered, at the rate of current technological advancement in astronomy, we could be looking at our first Earth-like exoplanet exomoon sooner than we anticipated…

Source: New Scientist, STFC

Posted on by Ian O'Neill

Time Magazine Top 10 Scientific Discoveries of 2008: Space and Physics Dominate

Direct observation of an exoplanet orbiting the star Fomalhaut - Number 6 in the top 10 (NASA/HST)

[/caption]2008 has been an astounding year of scientific discovery. To celebrate this fact, Time Magazine has listed the “Top 10 Scientific Discoveries” where space exploration and physics dominate. Other disciplines are also listed; including zoology, microbiology, technology and biochemistry, but the number 1 slot goes to the most ambitious physics experiment of our time. Can you guess what it is? Also, of all our endeavours in space, can you pick out three that Time Magazine has singled out as being the most important?

As we approach the end of the year, ready to welcome in 2009, it is good to take stock and celebrate the mind-blowing achievements mankind has accomplished. Read on for the top 10 scientific discoveries of 2008…

The best thing about writing for a leading space news blog is that you gain wonderful overview to all our endeavours in astronomy, space flight, physics, politics (yes, space exploration has everything to do with politics), space commercialization and science in general. 2008 has been such a rich year for space exploration; we’ve landed probes on other worlds, studied other worlds orbiting distant stars, peered deep into the quantum world, learnt profound things about our own planet, developed cutting-edge instrumentation and redefined the human existence in the cosmos. We might not have all the answers (in fact, I think we are only just beginning to scratch the surface of our understanding of the Universe), but we have embarked on an enlightening journey on which we hope to build strong foundations for the next year of scientific discovery.

In an effort to assemble some of the most profound scientific endeavours of this year, Time Magazine has somehow narrowed the focus down to just 10 discoveries. Out of the ten, four are space and physics related, so here they are:

6. Brave New Worlds: First direct observations of exoplanets

Infrared observations of a multi-exoplanet star system HR 8799 (Keck Observatory)
Infrared observations of a multi-exoplanet star system HR 8799 (Keck Observatory)
In November, we saw a flood of images of alien worlds orbiting distant stars. On the same day, Hubble publicised strikingly sharp images of an exoplanet orbiting a star called Fomalhaut (pictured top) and then a ground-based Keck-Gemini campaign made the first direct observations of a multi-exoplanet system around a star called HR8799 (pictured left). A few days later, yet another image came in from another research group at the European Southern Observatory, spotting the very compact orbit of an exoplanet around the star Beta Pictorus.

Considering there have never been any direct observations of exoplanets before November 2008–although we have known about the presence of worlds orbiting other stars for many years via indirect methods–this has been a revolutionary year for exoplanet hunters.

4. China Soars into Space: First taikonaut carries out successful spacewalk

Zhai Zhigang exits the Shenzhou-7 capsule with Earth overhead (Xinhua/BBC)
Zhai Zhigang exits the Shenzhou-7 capsule with Earth overhead (Xinhua/BBC)
Following hot on the heels of one of the biggest Olympic Games in Beijing, China launched a three-man crew into space to make history. The taikonauts inside Shenzhou-7 were blasted into space by a Long March II-F rocket on September 25th.

Despite early controversy surrounding recorded spaceship transmissions before the rocket had even launched, and then the sustained efforts by conspiracy theorists to convince the world that the whole thing was staged, mission commander Zhai Zhigang did indeed become the first ever Chinese citizen to carry out a spacewalk. Zhai spent 16 minutes outside of the capsule, attached by an umbilical cable, to triumphantly wave the Chinese flag and retrieve a test sample of solid lubricant attached to the outside of the module. His crew mate Liu Boming was also able to do some spacewalking.

Probably the most incredible thing about the first Chinese spacewalk wasn’t necessarily the spacewalk itself, it was the speed at which China managed to achieve this goal in such a short space of time. The first one-man mission into space was in 2003, the second in 2005, and the third was this year. Getting man into space is no easy task, to build an entire manned program in such a short space of time, from the ground-up, is an outstanding achievement.

2. The North Pole – of Mars: The Phoenix Mars Lander

Phoenix (NASA/UA)
Capturing the world's attention: Phoenix (NASA/UA)
Phoenix studied the surface of the Red Planet for five months. It was intended to only last for three. In that time, this robotic explorer captured the hearts and minds of the world; everybody seemed to be talking about the daily trials and tribulations of this highly successful mission. Perhaps it was because of the constant news updates via the University of Arizona website, or the rapid micro-blogging via Twitter; whatever the reason, Phoenix was a short-lived space celebrity.

During the few weeks on Mars, Phoenix discovered water, studied atmospheric phenomena, plus it characterized the regolith to find it is more “soil-like” than we gave it credit for. However, Phoenix also discovered a chemical called perchlorate that could be hazardous to life on the Martian surface, but there is a flip-side to that coin; the chemical may provide energy for basic forms of life.

Like all good adventures there were twists and turns in Phoenix’s progress, with the odd conspiracy thrown in for good measure. Even during Phoenix’s sad, slow death, the lander had some surprises in store before it slowly slipped into a Sun-deprived, low energy coma.

To give the highly communicative lander the last word, MarsPhoenix on Twitter has recently announced: “Look who made Time Mag’s Top 10 list for Scientific Discoveries in 2008: http://tinyurl.com/5mwt2l”

1. Large Hadron Collider

The complexity of the Large Hadron Collider (CERN/LHC/GridPP)
The complexity of the Large Hadron Collider (CERN/LHC/GridPP)

Speaking of “capturing the hearts and minds” of the world, the Large Hadron Collider (LHC) has done just that, but not always in a positive way (although common sense seems to be winning). So, in the #1 spot of Time Magazine’s Top 10 Scientific Discoveries of 2008, the LHC is a clear winner.

In the run-up to the switch-on of the LHC in September, the world’s media focused its attention on the grandest physics experiment ever constructed. The LHC will ultimately probe deep into the world of subatomic particles to help to explain some of the fundamental questions of our Universe. Primarily, the LHC has been designed to hunt for the elusive Higgs boson, but the quest will influence many facets of science. From designing an ultra-fast method of data transmission to unfolding the theoretical microscopic dimensions curled up in space-time, the LHC is a diverse science, with applications we won’t fully appreciate for many years.

Unfortunately, as you may be wondering, the LHC hasn’t actually discovered anything yet, but the high-energy collisions of protons and other, larger subatomic particles, will revolutionize physics. I’d argue that the simple fact the multi-billion euro machine has been built is a discovery of how advanced our technological ability is becoming.

Although the first particles were circulated on that historic day on September 10th, we’ll have to wait for the first particle collisions to occur some time in the summer of 2009. Engineers are currently working hard to repair the estimated £14 million (~$20 million) damage caused by the “quench” that knocked out a number of superconducting electromagnets on September 19th.

For more, check out the Top 10 Scientific Discoveries in Time Magazine, there’s another six that aren’t related to space or physics

Posted on by Ian O'Neill

Carbon Dioxide Detected on Exoplanet HD 189733b

Artist's impression of a transiting exoplanet (ESA - C.Carreau)

[/caption]The Hubble Space Telescope has detected carbon dioxide on a planet orbiting another star. The star in question is HD 189733 (also known as V452 Vulpeculae, a variable star designation), a binary system over 60 light years away, and the planet is approximately the size of Jupiter (called HD 189733b). The exoplanet is already known to contain water and methane molecules from previous Hubble and Spitzer campaigns, but this is the first time CO2 has been discovered.

But why all the fuss? CO2 is another chemical marker for the existance of life. But HD 189733b isn’t a candidate planet for the search for life. After all, this “hot Jupiter” will not be hospitable to the development of even the most basic lifeforms (life as we know it in any case). This discovery is ground-breaking in that CO2 can be sensed on a planet many light years from Earth…

“The carbon dioxide is kind of the main focus of the excitement, because that is a molecule that under the right circumstances could have a connection to biological activity as it does on Earth,” said Mark Swain of NASA’s Jet Propulsion Laboratory. “The very fact that we’re able to detect it, and estimate its abundance, is significant for the long-term effort of characterizing planets both to find out what they’re made of and to find out if they could be a possible host for life.”

Indeed, it wasn’t only carbon dioxide that was found; carbon monoxide was also detected in the exoplanet’s atmosphere. But the fact that CO2 is a “tracer” for life and it has been detected on a planet other than a planet known to contain life (Earth) is incredibly significant. As time goes on, observation techniques advance, it is hoped small rocky bodies will be observed. If this can be done, an Earth-like planetary survey can be carried out.

Earth atmospheric molecules detected by Venus Express (ESA)
Earth atmospheric molecules detected by Venus Express (ESA)
In fact, ESA’s Venus Express was recently used to characterize what Earth looks like from a distant vantage point, providing astronomers and future extraterrestrial hunters with a model that can be used when observing distant star systems. If a planet, with a similar chemical composition to that of the Earth is discovered, it would become a prime candidate for harbouring alien life.

So how did Hubble detect CO2 on HD 189733b? Through a spectroscopic analysis of the infrared radiation being emitted by the hot planet, Hubble’s Near Infrared Camera and Multi-Object Spectrometer (NICMOS) spotted an abundance of CO and CO2. Certain molecules in the exoplanet’s atmosphere absorb certain wavelengths of infrared light, leaving a spectroscopic “fingerprint” in the light detected by Hubble.

This kind of campaign is best carried out on star systems with their ecliptic plane seen edge-on to the Earth. This means the orbit of the exoplanet carries it behind the parent star and then infront of it. HD 189733b transits (or eclipses) its parent star every 2.2 days and then orbits behind the star. This is an ideal situation as astronomers are able to measure the emission from the star (when the line of sight to the exoplanet is blocked by the star) and use those measurements to subtract from spectroscopic analysis of the exoplanet. This technique isolates the exoplanet emission making it possible to analyse the chemical composition of its “day-side” atmosphere.

“We’re starting to find the molecules and to figure out how many of them there are to see the changes between the day side and the night side,” Swain said.

All these developments by Hubble will aid the future of exoplanet studies. In 2013, NASA’s James Webb Space Telescope will be launched to look out for “super-Earth” exoplanets (i.e. rocky planets larger than Earth), observing in near-infrared wavelengths. Therefore, the carbon dioxide discovery in the atmosphere of HD 189733b helps astronomers refine techniques to detect yet another tracer for life…

Source: HubbleSite

Posted on by Nancy Atkinson

Students Find Exoplanet

Francis Vuijsje, Meta de Hoon, and Remco van der Burg (left to right), discovered an extrasolar planet that is larger than and about five times as massive as Jupiter and orbiting a fast-rotating hot star. Credit: Leiden Observatory

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Three undergraduate students doing a research project discovered an extrasolar planet. The planet is about five times as massive as Jupiter, not all that big as far as previously detected exoplanets go. This is also the first planet discovered orbiting a fast-rotating hot star. The students, Meta de Hoon, Remco van der Burg, and Francis Vuijsje from Leiden University in the Netherlands, were testing a method of investigating the light fluctuations of thousands of stars in the OGLE database in an automated way. The brightness of one of the stars was found to decrease for two hours every 2.5 days by about one percent. Follow-up observations, taken with ESO’s Very Large Telescope in Chile, confirmed that this phenomenon is caused by a planet passing in front of the star, blocking part of the starlight at regular intervals. “It is exciting not just to find a planet, but to find one as unusual as this one; it turns out to be the first planet discovered around a fast rotating star, and it’s also the hottest star found with a planet,” says Meta. “The computer needed more than a thousand hours to do all the calculations,” continues Remco.

According to Ignas Snellen, supervisor of the research project, the discovery was a complete surprise. “The project was actually meant to teach the students how to develop search algorithms. But they did so well that there was time to test their algorithm on a so far unexplored database. At some point they came into my office and showed me this light curve. I was completely taken aback!”

The planet is given the prosaic name OGLE2-TR-L9b. “But amongst ourselves we call it ReMeFra-1, after Remco, Meta, and myself,” says Francis.

Artist's impression of the planet OGLE-TR-L9b. Credit: ESO/H. Zodet
Artist's impression of the planet OGLE-TR-L9b. Credit: ESO/H. Zodet

The planet was discovered by looking at the brightness variations of about 15,700 stars, which had been observed by the OGLE survey once or twice per night for about four years between 1997 and 2000. Because the data had been made public, they were a good test case for the students’ algorithm, who showed that for one of stars observed, OGLE-TR-L9, the variations could be due to a transit — the passage of a planet in front of its star. The team then used the GROND instrument on the 2.2 m telescope at ESO’s La Silla Observatory to follow up the observations and find out more about the star and the planet.

“But to make sure it was a planet and not a brown dwarf or a small star that was causing the brightness variations, we needed to resort to spectroscopy, and for this, we were glad we could use ESO’s Very Large Telescope,” says Snellen.

The planet, which is about five times as massive as Jupiter, circles its host star in about 2.5 days. It lies at only three percent of the Earth-Sun distance from its star, making it very hot and much larger than normal planets.

The spectroscopy also showed that the star is pretty hot — almost 7000 degrees, or 1200 degrees hotter than the Sun. It is the hottest star with a planet ever discovered, and it is rotating very fast. The radial velocity method — that was used to discover most extrasolar planets known — is less efficient on stars with these characteristics. “This makes this discovery even more interesting,” concludes Snellen.

Source: ESO

Posted on by Nancy Atkinson

Another Direct Image of an Exoplanet?

Beta Pictorus. Credit: ESO

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Have the floodgates opened for imaging exoplanets?! A team of French astronomers using ESO’s Very Large Telescope have discovered an object located very close to the star Beta Pictoris. This object lies only 8 times the Earth-Sun distance, and it’s likely a giant planet that astronomers suspected was there from the peculiar shape of the disc that surrounds the star. If the object is actually a planet, this would then be the first image of a planet that is as close to its host star as Saturn is to the Sun. This comes on the heels of the news of two of the first direct images ever of exoplanets just last week (see here and here).

Only 12 million years old, the ‘baby star’ Beta Pictoris is located about 70 light-years away towards the constellation Pictor (the Painter). The above image is an infrared image, and visible is the dusty debris disk surrounding the star Beta Pictoris. Debris discs are composed of dust resulting from collisions among larger bodies like planetary embryos or asteroids, and they are a bigger version of the zodiacal dust in our Solar System. Its disc was the first to be imaged — as early as 1984 — and remains the best-studied system. Earlier observations showed a warp of the disc, a secondary inclined disc and infalling comets onto the star. “These are indirect, but tell-tale signs that strongly suggest the presence of a massive planet lying between 5 and 10 times the mean Earth-Sun distance from its host star,” says team leader Anne-Marie Lagrange. “However, probing the very inner region of the disc, so close to the glowing star, is a most challenging task.”

Using an adaptive optics system in infrared wavelengths attached to the VLT, the astronomers were able to discern a feeble, point-like glow well inside the star’s halo. To eliminate the possibility that this was an artifact and not a real object, a battery of tests was conducted and several members of the team, using three different methods, did the analysis independently, always with the same success. Moreover, the companion was also discovered in other data sets, further strengthening the team’s conclusion: the companion is real.

“Our observations point to the presence of a giant planet, about 8 times as massive as Jupiter and with a projected distance from its star of about 8 times the Earth-Sun distance, which is about the distance of Saturn in our Solar System,” says Lagrange.

“We cannot yet rule out definitively, however, that the candidate companion could be a foreground or background object,” cautions co-worker Gael Chauvin. “To eliminate this very small possibility, we will need to make new observations that confirm the nature of the discovery.”

The fact that the candidate companion lies in the plane of the disc also strongly implies that it is bound to the star and its proto-planetary disc.

“Moreover, the candidate companion has exactly the mass and distance from its host star needed to explain all the disc’s properties. This is clearly another nail in the coffin of the false alarm hypothesis,” adds Lagrange.

Candidate planetary systems imaged. Credit: ESO
Candidate planetary systems imaged. Credit: ESO

When confirmed, this candidate companion will be the closest planet from its star ever imaged. In particular, it will be located well inside the orbits of the outer planets of the Solar System. Several other planetary candidates have indeed been imaged, but they are all located further away from their host star: if located in the Solar System, they would lie close or beyond the orbit of the farthest planet, Neptune. The formation processes of these distant planets are likely to be quite different from those in our Solar System and in Beta Pictoris.

“Direct imaging of extrasolar planets is necessary to test the various models of formation and evolution of planetary systems. But such observations are only beginning. Limited today to giant planets around young stars, they will in the future extend to the detection of cooler and older planets, with the forthcoming instruments on the VLT and on the next generation of optical telescopes,” concludes team member Daniel Rouan.

For a list of candidate exoplanets directly imaged, see this link.

Source: ESO