A New Look at the Helix Nebula — a Giant “Eye” in Space

This comparison shows a new view of the Helix Nebula acquired with the VISTA telescope in infrared light (left) and the more familiar view in visible light from the MPG/ESO 2.2-metre telescope (right). The infrared vision of VISTA reveals strands of cold nebular gas that are mostly obscured in visible light images of the Helix. Credit: ESO/VISTA/J. Emerson. Acknowledgment: Cambridge Astronomical Survey Unit

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Who is looking at who here? A brand new image of the Helix Nebula (breathlessly called the “Eye of God” in viral email messages) was taken by ESO’s VISTA telescope, at the Paranal Observatory in Chile. In infrared light — compared previous images of the Helix Nebula taken in visible light — the “eye” appears to have put on a colored contact lens, changing the color from blue to brown. What infrared really reveals are strands of cold gases within the nebula, as well as highlighting a rich background of stars and galaxies.

The Helix Nebula is a planetary nebula, and is located in the constellation Aquarius, about 700 light-years away from Earth. This strange object formed when a star like the Sun was in the final stages of its life. In fact, our own Sun might look like this one day, several billion years from now.

ESO’s VISTA telescope, at the Paranal Observatory in Chile, has captured a striking new image of the Helix Nebula. Credit: ESO/VISTA/J. Emerson.

The Helix Nebula is a huge cavern of glowing gases. The main ring of the Helix is about two light-years across, roughly half the distance between the Sun and the nearest star. However, material from the nebula spreads out from the star to at least four light-years. This is particularly clear in this infrared view since red molecular gas can be seen across much of the image.

At its center is a dying star which has ejected masses of dust and gas to form tentacle-like filaments stretching toward an outer rim composed of the same material. Unable to hold onto its outer layers, the hot central star is slowly shedding shells of gas that became the nebula. It is evolving to become a white dwarf star and appears as the tiny blue dot seen at the center of the image.

The VISTA telescope also reveals fine structure in the nebula’s rings. The infrared light picks out how the cooler, molecular gas is arranged. The material clumps into filaments that radiate out from the center and the whole view resembles a celestial firework display – or a giant eye.

Source: ESO

Microlensing Study Says Every Star in the Milky Way has Planets

This artists’s cartoon view gives an impression of how common planets are around the stars in the Milky Way. The planets, their orbits and their host stars are all vastly magnified compared to their real separations. A six-year search that surveyed millions of stars using the microlensing technique concluded that planets around stars are the rule rather than the exception. The average number of planets per star is greater than one. Credit: ESO/M. Kornmesser

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How common are planets in the Milky Way? A new study using gravitational microlensing suggests that every star in our night sky has at least one planet circling it. “We used to think that the Earth might be unique in our galaxy,” said Daniel Kubas, a co-lead author of a paper that appears this week in the journal Nature. “But now it seems that there are literally billions of planets with masses similar to Earth orbiting stars in the Milky Way.”

Over the past 16 years, astronomers have detected more than 3,035 exoplanets – 2,326 candidates and 709 confirmed planets orbiting other stars. Most of these extrasolar planets have been discovered using the radial velocity method (detecting the effect of the gravitational pull of the planet on its host star) or the transit method (catching the planet as it passes in front of its star, slightly dimming it.) Those two methods usually tend to find large planets that are relatively close to their parent star.

But another method, gravitational microlensing — where the light from the background star is amplified by the gravity of the foreground star, which then acts as a magnifying glass — is able to find planets over a wide range of mass that are further away from their stars.

Gravitational microlensing method requires that you have two stars that lie on a straight line in relation to us here on Earth. Then the light from the background star is amplified by the gravity of the foreground star, which thus acts as a magnifying glass.

An international team of astronomers used the technique of gravitational microlensing in six-year search that surveyed millions of stars. “We conclude that stars are orbited by planets as a rule, rather than the exception,” the team wrote in their paper.

“We have searched for evidence for exoplanets in six years of microlensing observations,” said lead author Arnaud Cassan from the Institut de Astrophysique in Paris. “Remarkably, these data show that planets are more common than stars in our galaxy. We also found that lighter planets, such as super-Earths or cool Neptunes, must be more common than heavier ones.”

The Milky Way above the dome of the Danish 1.54-metre telescope at ESO's La Silla Observatory in Chile. The central part of the Milky Way is visible behind the dome of the ESO 3.6-metre telescope in the distance. On the right the Magellanic Clouds can be seen. This telescope was a major contributor to the PLANET project to search for exoplanets using microlensing. The picture was taken using a normal digital camera with a total exposure time of 15 minutes. Credit: ESO/Z. Bardon

The astronomers surveyed millions of stars looking for microlensing events, and 3,247 such events in 2002-2007 were spotted in data from the European Southern Observatory’s PLANET and OGLE searches. The precise alignment needed for microlensing is very unlikely, and statistical results were inferred from detections and non-detections on a representative subset of 440 light curves.

Three exoplanets were actually detected: a super-Earth and planets with masses comparable to Neptune and Jupiter. The team said that by microlensing standards, this is an impressive haul, and that in detecting three planets, they were either incredibly lucky despite huge odds against them, or planets are so abundant in the Milky Way that it was almost inevitable.

The astronomers then combined information about the three positive exoplanet detections with seven additional detections from earlier work, as well as the huge numbers of non-detections in the six years’ worth of data (non-detections are just as important for the statistical analysis and are much more numerous, the team said.) The conclusion was that one in six of the stars studied hosts a planet of similar mass to Jupiter, half have Neptune-mass planets and two thirds have super-Earths.

This works out to about 100 billion exoplanets in our galaxy.

The survey was sensitive to planets between 75 million kilometers and 1.5 billion kilometers from their stars (in the Solar System this range would include all the planets from Venus to Saturn) and with masses ranging from five times the Earth up to ten times Jupiter.

This also shows that microlensing is a viable way to find exoplanets. Astronomers hope to use other methods in the future to find even more planets.

“I have a list of 17 different ways to find exoplanets and only five have been used so far,” said Virginia Trimble from the University of California, Irvine and the Las Cumbres Observatory, providing commentary at the American Astronomical Scoeity meeting this week, “I expect we’ll be finding many more planets in the future.”

Sources: Nature, ESO, AAS briefing

Nebula of Many Names Revealed in Beautiful New Image

This image of the Omega Nebula (Messier 17), captured by ESO's Very Large Telescope (VLT), is one of the sharpest of this object ever taken from the ground. It shows the dusty, rosy central parts of the famous star-forming region in fine detail. Credit: ESO

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The Omega Nebula goes by many names, depending on who observed it when and what they thought they saw. So, what do you see in this new image from the Very Large Telescope? This is one of the sharpest images of this nebula ever taken from the ground, and it reveals incredible detail in the smoky-pink gas clouds and dark dust, highlighted with brilliant newborn stars.

Astronomers from the European Southern Observatory said the “seeing” — a term astronomers use to measure the distorting effects of Earth’s atmosphere — on the night of the observations this image was taken was very good, thus this incredibly vivid image.

A common measure for seeing is the apparent diameter of a star when seen through a telescope. In this case, the measure of seeing was an extremely favorable 0.45 arcseconds, meaning little blurring and twinkling occurred while the VLT stared at this nebula.

The other names given to the Omega Nebula include the Swan Nebula, the Horseshoe Nebula and the Lobster Nebula. It also has the official catalog names of Messier 17 (M17) and NGC 6618. The nebula is located about 6,500 light-years away in the constellation of Sagittarius. It is a popular target of astronomers, and is one of the youngest and most active stellar nurseries for massive stars in the Milky Way.

The gas and dust visible in the Omega Nebula provides the raw materials for creating the next generation of stars. The newborn stars shine brightly in blue-white light, illuminating the entire nebula. , The gas appears in pink hues, as the hydrogen gas glows from the intense ultraviolet rays from the hot young stars.

The image was taken with the FORS (FOcal Reducer and Spectrograph) instrument on Antu, one of the four Unit Telescopes of the VLT.

Source: ESO

Staking Out A Vampire Star

These super-sharp images of the unusual vampire double star system SS Leporis were created from observations made with the VLT Interferometer at ESO’s Paranal Observatory using the PIONIER instrument. The system consists of a red giant star orbiting a hotter companion. Note that the stars have been artificially coloured to match their known temperatures. Credit: ESO/PIONIER/IPAG

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How do you peer into the dark heart of a vampire star? Try combining four telescopes! At ESO’s Paranal Observatory they created a virtual telescope 130 metres across with vision 50 times sharper than the NASA/ESA Hubble Space Telescope and observed a very unusual event… the transfer of mass from one star to another. While you might assume this to be a violent action, it turns out that it’s a gradual drain. Apparently SS Leporis stands for “super slow”.

“We can now combine light from four VLT telescopes and create super-sharp images much more quickly than before,” says Nicolas Blind (IPAG, Grenoble, France), who is the lead author on the paper presenting the results, “The images are so sharp that we can not only watch the stars orbiting around each other, but also measure the size of the larger of the two stars.”

This stellar duo, cataloged as SS Leporis, are only separated by slightly more than one AU and have an orbital period of 260 days. Of the two, the more massive and cooler member expands to a size of about Mercury’s orbit. It’s this very action of being pushed closer that draws the hot companion to feed on its host – consuming almost half of its mass. Weird? You bet.

“We knew that this double star was unusual, and that material was flowing from one star to the other,” says co-author Henri Boffin, from ESO. “What we found, however, is that the way in which the mass transfer most likely took place is completely different from previous models of the process. The ‘bite’ of the vampire star is very gentle but highly effective.”

The technique of combining telescopes gives us an incredibly candid image – one which shows us the larger star isn’t quite as large as surmised. Rather than clarifying the picture, it complicates. Just how did a red giant lose matter to its companion? Researchers are guessing that rather than streaming material from one star to another, that stellar winds may have released mass – only to be collected by the companion vampire star.

“These observations have demonstrated the new snapshot imaging capability of the Very Large Telescope Interferometer. They pave the way for many further fascinating studies of interacting double stars,” concludes co-author Jean-Philippe Berger.

Where’s van Helsing when you need him?

Original Story Source: ESO Press Release For Further Reading: An Incisive Look At The Symbiotic Star SS Leoporis.

Incredible Spinning Star Rotates At A Million Miles Per Hour!

This is an artist's concept of the fastest rotating star found to date. The massive, bright young star, called VFTS 102, rotates at a million miles per hour, or 100 times faster than our Sun does. Centrifugal forces from this dizzying spin rate have flattened the star into an oblate shape and spun off a disk of hot plasma, seen edge on in this view from a hypothetical planet. The star may have "spun up" by accreting material from a binary companion star. The rapidly evolving companion later exploded as a supernova. The whirling star lies 160,000 light-years away in the Large Magellanic Cloud, a satellite galaxy of our Milky Way. Credit: NASA, ESA, and G. Bacon (STScI)

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Located in the Large Magellanic Cloud, a star named VFTS 102 is spinning its heart out… Literally. Rotating at a mind-numbing speed of a million miles per hour (1.6 million kph), this hot blue giant has reached the edge where centrifugal forces could tear it apart. It’s the fastest ever recorded – 300 times faster than our Sun – and may have been split off from a double star system during a violent explosion.

Thanks to ESO’s Very Large Telescope at the Paranal Observatory in Chile, an international team of astronomers studying the heaviest and brightest stars in the Tarantula Nebula made quite a discovery – a huge blue star 25 times the mass of the Sun and about one hundred thousand times brighter was cruising through space at a speed which drew their attention.

“The remarkable rotation speed and the unusual motion compared to the surrounding stars led us to wonder if this star had an unusual early life. We were suspicious.” explains Philip Dufton (Queen’s University Belfast, Northern Ireland, UK), lead author of the paper presenting the results.

ESO's Very Large Telescope has picked up the fastest rotating star found so far. This massive bright young star lies in our neighbouring galaxy, the Large Magellanic Cloud, about 160 000 light-years from Earth. Astronomers think that it may have had a violent past and has been ejected from a double star system by its exploding companion. Credit: ESO

What they’ve discovered could possibly be a “runaway star” – one that began life as a binary, but may have been ejected during a supernova event. Further evidence which supports their theory also exists: the presence of a pulsar and a supernova remnant nearby. But what made this crazy star spin so fast? It’s possible that if the two stars were very close that streaming gases could have started the incredible rotation. Then the more massive of the pair blew its stack – expelling the star into space. So what would be left? It’s elementary, Watson… A supernova remnant, a pulsar and a runaway!

Even though this is a rather tidy conclusion, there’s always room for doubt. As Dufton concludes, “This is a compelling story because it explains each of the unusual features that we’ve seen. This star is certainly showing us unexpected sides of the short but dramatic lives of the heaviest stars.”

Original Story Source: HubbleSite News Release and ESO News Release. For Further Reading: he VLT-FLAMES Tarantula Survey I. Introduction and observational overview.

The Way Cool Clouds Of The Carina Nebula

The APEX observations, made with its LABOCA camera, are shown here in orange tones, combined with a visible light image from the Curtis Schmidt telescope at the Cerro Tololo Interamerican Observatory. The result is a dramatic, wide-field picture that provides a spectacular view of Carina’s star formation sites. The nebula contains stars equivalent to over 25 000 Suns, and the total mass of gas and dust clouds is that of about 140 000 Suns.

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It’s beautiful…. But it’s cold. By utilizing the submillimetre-wavelength of light, the 12 meter APEX telescope has imaged the frigid, dusty clouds of star formation in the Carina Nebula. Here, some 7500 light-years away, unrestrained stellar creation produces some of the most massive stars known to our galaxy… a picturesque petri dish in which we can monitor the interaction between the neophyte suns and their spawning molecular clouds.

By examining the region in submillimetre light through the eyes of the LABOCA camera on the Atacama Pathfinder Experiment (APEX) telescope on the plateau of Chajnantor in the Chilean Andes, a team of astronomers led by Thomas Preibisch (Universitäts–Sternwarte München, Ludwig-Maximilians-Universität, Germany), in close cooperation with Karl Menten and Frederic Schuller (Max-Planck-Institut für Radioastronomie, Bonn, Germany), have been able to pick apart the faint heat signature of cosmic dust grains. These tiny particles are cold – about minus 250 degrees C – and can only be detected at these extreme, long wavelengths. The APEX LABOCA observations are shown here in orange tones, combined with a visible light image from the Curtis Schmidt telescope at the Cerro Tololo Interamerican Observatory.

This amalgamate image reveals the Carina nebula in all its glory. Here we see stars with mass exceeding 25,000 sun-like stars embedded in dust clouds with six times more mass. The yellow star in the upper left of the image – Eta Carinae – is 100 times the mass of the Sun and the most luminous star known. It is estimated that within the next million years or so, it will go supernova, taking its neighbors with it. But for all the tension in this region, only a small part of the gas in the Carina Nebula is dense enough to trigger more star formation. What’s the cause? The reason may be the massive stars themselves…

With an average life expectancy of just a few million years, high-mass stars have a huge impact on their environment. While initially forming, their intense stellar winds and radiation sculpt the gaseous regions surrounding them and may sufficiently compress the gas enough to trigger star birth. As their time closes, they become unstable – shedding off material until the time of supernova. When this intense release of energy impacts the molecular gas clouds, it will tear them apart at short range, but may trigger star-formation at the periphery – where the shock wave has a lesser impact. The supernovae could also spawn short-lived radioactive atoms which could become incorporated into the collapsing clouds that could eventually produce a planet-forming solar nebula.

Then things will really heat up!

Original Story Source: ESO News Release.

Antique Stars Could Help Solve Mysteries Of Early Milky Way

The Milky Way is like NGC 4594 (pictured), a disc shaped spiral galaxy with around 200 billion stars. The three main features are the central bulge, the disk, and the halo. Credit: ESO
The Milky Way is like NGC 4594 (pictured), a disc shaped spiral galaxy with around 200 billion stars. The three main features are the central bulge, the disk, and the halo. Credit: ESO

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Utilizing ESO’s giant telescopes located in Chile, researchers at the Niels Bohr Institute have been examining “antique” stars. Located at the outer reaches of the Milky Way, these superannuated stellar specimens are unusual in the fact that they contain an over-abundance of gold, platinum and uranium. How they became heavy metal stars has always been a puzzle, but now astronomers are tracing their origins back to our galaxy’s beginning.

It is theorized that soon after the Big Bang event, the Universe was filled with hydrogen, helium and… dark matter. When the trio began compressing upon themselves, the very first stars were born. At the core of these neophyte suns, heavy elements such as carbon, nitrogen and oxygen were then created. A few hundred million years later? Hey! All of the elements are now accounted for. It’s a tidy solution, but there’s just one problem. It would appear the very first stars only had about 1/1000th of the heavy-elements found in sun-like stars of the present.

How does it happen? Each time a massive star reaches the end of its lifetime, it will either create a planetary nebula – where layers of elements gradually peel away from the core – or it will go supernova – and blast the freshly created elements out in a violent explosion. In this scenario, the clouds of material once again coalesce… collapse again and form more new stars. It’s just this pattern which gives birth to stars that become more and more “elementally” concentrated. It’s an accepted conjecture – and that’s what makes discovering heavy metal stars in the early Universe a surprise. And even more surprising…

Right here in the Milky Way.

“In the outer parts of the Milky Way there are old ‘stellar fossils’ from our own galaxy’s childhood. These old stars lie in a halo above and below the galaxy’s flat disc. In a small percentage – approximately one to two percent of these primitive stars, you find abnormal quantities of the heaviest elements relative to iron and other ‘normal’ heavy elements”, explains Terese Hansen, who is an astrophysicist in the research group Astrophysics and Planetary Science at the Niels Bohr Institute at the University of Copenhagen.

The 17 observed stars are all located in the northern sky and could therefore be observed with the Nordic Optical Telescope, NOT on La Palma. NOT is 2.5 meter telescope that is well suited for just this kind of observations, where continuous precise observations of stellar motions over several years can reveal what stars belong to binary star systems.
But the study of these antique stars just didn’t happen overnight. By employing ESO’s large telescopes based in Chile, the team took several years to come to their conclusions. It was based on the findings of 17 “abnormal” stars which appeared to have elemental concentrations – and then another four years of study using the Nordic Optical Telescope on La Palma. Terese Hansen used her master’s thesis to analyse the observations.

“After slaving away on these very difficult observations for a few years I suddenly realised that three of the stars had clear orbital motions that we could define, while the rest didn’t budge out of place and this was an important clue to explaining what kind of mechanism must have created the elements in the stars”, explains Terese Hansen, who calculated the velocities along with researchers from the Niels Bohr Institute and Michigan State University, USA.

What exactly accounts for these types of concentrations? Hansen explains their are two popular theories. The first places the origin as a close binary star system where one goes supernova, inundating its companion with layers of heavier elements. The second is a massive star also goes supernova, but spews the elements out in dispersing streams, impregnating gas clouds which then formed into the halo stars.

The research group has analysed 17 stellar fossils from the Milky Way’s childhood. The stars are small light stars and they live longer than large massive stars. They do not burn hydrogen longer, but swell up into red giants that will later cool and become white dwarves. The image shows the most famous of the stars CS31082-001, which was the first star that uranium was found in.
“My observations of the motions of the stars showed that the great majority of the 17 heavy-element rich stars are in fact single. Only three (20 percent) belong to binary star systems – this is completely normal, 20 percent of all stars belong to binary star systems. So the theory of the gold-plated neighbouring star cannot be the general explanation. The reason why some of the old stars became abnormally rich in heavy elements must therefore be that exploding supernovae sent jets out into space. In the supernova explosion the heavy elements like gold, platinum and uranium are formed and when the jets hit the surrounding gas clouds, they will be enriched with the elements and form stars that are incredibly rich in heavy elements”, says Terese Hansen, who immediately after her groundbreaking results was offered a PhD grant by one of the leading European research groups in astrophysics at the University of Heidelberg.

May all heavy metal stars go gold!

Original Story Source: Niels Bohr Institute News Release. For Further Reading: The Binary Frequency of r-Process-element-enhanced Metal-poor Stars and Its Implications: Chemical Tagging in the Primitive Halo of the Milky Way.

Asteroid Lutetia… A Piece Of Earth?

This image of the unusual asteroid Lutetia was taken by ESA’s Rosetta probe during its closest approach in July 2010. Lutetia, which is about 100 kilometres across, seems to be a leftover fragment of the same original material that formed the Earth, Venus and Mercury. It is now part of the main asteroid belt, between the orbits of Mars and Jupiter, but its composition suggests that it was originally much closer to the Sun. Credit: ESA 2010 MPS for OSIRIS Team MPS/UPD/LAM/IAA/RSSD/INTA/UPM/DASP/IDA

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According to data received from ESA’s Rosetta spacecraft, ESO’s New Technology Telescope, and NASA telescopes, strange asteroid Lutetia could be a real piece of the rock… the original material that formed the Earth, Venus and Mercury! By examining precious meteors which may have formed at the time of the inner Solar System, scientists have found matching properties which indicate a relationship. Independent Lutetia must have just moved its way out to join in the main asteroid belt…

A team of astronomers from French and North American universities have been hard at work studying asteroid Lutetia spectroscopically. Data sets from the OSIRIS camera on ESA’s Rosetta spacecraft, ESO’s New Technology Telescope (NTT) at the La Silla Observatory in Chile, and NASA’s Infrared Telescope Facility in Hawaii and Spitzer Space Telescope have been combined to give us a multi-wavelength look at this very different space rock. What they found was a very specific type of meteorite called an enstatite chondrite displayed similar content which matched Lutetia… and what is theorized as the material which dates back to the early Solar System. Chances are very good that enstatite chondrites are the same “stuff” which formed the rocky planets – Earth, Mars and Venus.

“But how did Lutetia escape from the inner Solar System and reach the main asteroid belt?” asks Pierre Vernazza (ESO), the lead author of the paper.

It’s a very good question considering that an estimated less than 2% of the material which formed in the same region of Earth migrated to the main asteroid belt. Within a few million years of formation, this type of “debris” had either been incorporated into the gelling planets or else larger pieces had escaped to a safer, more distant orbit from the Sun. At about 100 kilometers across, Lutetia may have been gravitationally influenced by a close pass to the rocky planets and then further affected by a young Jupiter.

“We think that such an ejection must have happened to Lutetia. It ended up as an interloper in the main asteroid belt and it has been preserved there for four billion years,” continues Pierre Vernazza.

Asteroid Lutetia is a “real looker” and has long been a source of speculation due to its unusual color and surface properties. Only 1% of the asteroids located in the main belt share its rare characteristics.

“Lutetia seems to be the largest, and one of the very few, remnants of such material in the main asteroid belt. For this reason, asteroids like Lutetia represent ideal targets for future sample return missions. We could then study in detail the origin of the rocky planets, including our Earth,” concludes Pierre Vernazza.

Original Story Source: ESO News Release.

Are Pluto and Eris Twins?

Artist's rendering of the distant dwarf planet Eris. New suggests that Eris is almost exactly the same diameter as Pluto. Eris is very reflective - possibly due to the frozen remains of its atmosphere. Image Credit: ESO/L. Calçada

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Back a couple of weeks ago, I wrote an article highlighting the debate between scientists on which dwarf planet is bigger, Pluto or Eris. During a planetary science conference earlier this month in France, word “leaked” out that Eris was still more massive, but likely smaller in diameter.

Today, the latest findings were published in Nature, and as such are now “official”. There’s also some additional information, so I’d like to revisit this topic and include some new details which may help answer the question:

Could Eris and Pluto actually be twins?

Before we answer the pressing question, let’s revisit my prior post at: http://www.universetoday.com/89901/pluto-or-eris-which-is-bigger/.

Bruno Sicardy of the Paris Observatory and his team calculated the diameter of Eris in 2010. The technique they used took advantage of an occultation between Eris and a faint background star. Sicardy’s results provided a diameter of 2,326 kilometers for Eris, slightly less than his 2009 estimate of Pluto’s diameter at 2,338 kilometers.

Combining the diameter estimate with mass estimates yielded a density estimate for Eris which suggests, and is supported by its extra mass, that its composition is far more rocky than Pluto, with Eris being only 10-15% ice by mass.

In this week’s announcement by the European Southern Observatory, additional information was presented which sheds new light on cold, distant Eris.

Regarding the new density estimates, Emmanuel Jehin, one of Sicardy’s team members mentions, “This density means that Eris is probably a large rocky body covered in a relatively thin mantle of ice”.

Further supporting Jehin’s assertion, The surface of Eris was found to be extremely reflective, (96% of the light that falls on Eris is reflected, making it nearly as reflective as a backyard telescope mirror). Based on the current estimate, Eris is more reflective than freshly fallen snow on Earth. Based on spectral analysis of Eris, its surface reflectivity is most likely due to a surface of nitrogen-rich ice and frozen methane. Some estimates place the thickness of this layer at less than one millimeter.

Jehin also added, “This layer of ice could result from the dwarf planet’s nitrogen or methane atmosphere condensing as frost onto its surface as it moves away from the Sun in its elongated orbit and into an increasingly cold environment. The ice could then turn back to gas as Eris approaches its closest point to the Sun, at a distance of about 5.7 billion kilometers.”

Based on the new information on surface composition and surface reflectivity, Sicardy and his team were able to make temperature estimates for Eris. The team estimates daytime temperatures on Eris of -238 C, and that temperatures on the night side of Eris would be much lower.

Sicardy concluded with, “It is extraordinary how much we can find out about a small and distant object such as Eris by watching it pass in front of a faint star, using relatively small telescopes. Five years after the creation of the new class of dwarf planets, we are finally really getting to know one of its founding members.”

Source(s): ESO Press Release , Universe Today