 |
|
Next-generation adaptive optics produces sharper Jupiter images
October 03, 2008Berkeley -- A two-hour observation of Jupiter using an improved technique to remove atmospheric blur has produced the sharpest whole-planet picture ever taken from the ground, according to astronomers from the University of California, Berkeley, and the European Southern Observatory (ESO).
The series of 265 snapshots taken with the help of a prototype Multi-Conjugate Adaptive Optics (MCAO) instrument mounted on the ESO's Very Large Telescope (VLT) revealed changes over the past three years in Jupiter's smog-like haze, probably a response to a planet-wide upheaval more than a year ago.
The images prove the value of multi-conjugate systems, which use two or more guide stars instead of one as references to sense the atmospheric turbulence in the instrument's field of view, and two or more deformable mirrors to correct for it. The multiple-star technique produces sharp images over a wider area of sky - an area about three times larger than that produced by single-star adaptive optics systems employed on large telescopes such as Keck II and Gemini North in Hawaii.
"This type of adaptive optics has a big advantage for looking at large objects, such as planets, star clusters or nebulae," said lead researcher Franck Marchis, a research astronomer at UC Berkeley and the SETI Institute in Mountain View, Calif. "While regular adaptive optics systems provide excellent correction in a small field of view, MCAO provides good correction over a larger area of sky."
A full MCAO instrument is due to be installed on Gemini North by 2010 and is proposed for the VLT.
With conventional adaptive optics systems like those on Gemini and Keck, the sharpening degrades with distance between the target and a reference object, be it a star or a moon of a planet. Multi-conjugate adaptive optics maintains a steady sharpness over the whole sky area between the reference objects.
This allowed the researchers to observe Jupiter for almost two hours on Aug. 16 and 17, 2008, a record duration, according to the observing team. Conventional adaptive optics systems using a single reference moon cannot monitor Jupiter that long because the moon moves too far from the planet. The Hubble Space Telescope cannot observe Jupiter continuously for more than about 50 minutes, because it is regularly blocked by the Earth during Hubble's 96-minute orbit.
Using the MCAO Demonstrator (MAD) mounted on the Melipal 8.2-meter telescope of the VLT, ESO astronomer Paola Amico, MAD project manager Enrico Marchetti and MAD integration engineer Sebastien Tordo tracked two moons, Europa and Io, one on each side of Jupiter, to provide a good correction across the full disk of the planet.
"It has been the most challenging observation we performed with MAD because we had to track with high accuracy the two moons having different absolute velocities while simultaneously chasing Jupiter, which was moving with respect to them," said Marchetti.
The VLT image had a resolution of 90 milliarcseconds, "twice the resolution of the Hubble Space Telescope," said Marchis. The improved resolution is due not only to MCAO but also the much larger aperture of the 8.2-meter VLT. "Ground-based telescopes are getting comparable to or better than Hubble in the near-infrared, even for extended objects like Jupiter," he said.
"We wanted to check if there is a link between South Equatorial Belt outbreaks and the Great Red Spot's turbulent wake," explained team member Mike Wong, a UC Berkeley research astronomer. The belt is some 18,000 kilometers wide north-to-south, and it encircles Jupiter just above the track of the Great Red Spot.
Instead, the team found a major alteration in the brightness of the equatorial haze, which lies in a 16,000-kilometer wide belt over Jupiter's equator. More sunlight reflecting off upper atmospheric haze means that the amount of haze has increased, or that it has moved up to higher altitudes. The brightest portion had shifted south by more than 6,000 kilometers, Wong said.
This conclusion came from a comparison of images taken in 2005 by Wong and UC Berkeley astronomer Imke de Pater using the Hubble Space Telescope's Near Infrared Camera and Multi-Object Spectrometer (NICMOS) instrument. The Hubble images, taken at infrared wavelengths very close to those used for the VLT study, show more haze in the northern half of the bright Equatorial Zone, while the 2008 VLT images show a clear shift to the south.
The haze, which could be the nitrogen compound hydrazine - used on Earth as a rocket propellant - or possibly frozen crystals of ammonia, water or ammonium hydrosulfide from deeper in the gaseous planet, is very prominent in infrared images. Because visible light can penetrate to deeper levels than infrared light, optical telescopes see light reflected from deeper, thicker clouds lying beneath the haze.
The haze behaves somewhat like particles in the tops of thunderheads (known as cumulonimbus anvils) on Earth or in the ash plumes from large volcanic eruptions, which rise into the upper atmosphere and spread around the world, Wong said. On Jupiter, ammonia injected into the upper atmosphere also interacts with sunlight to form hydrazine, which condenses into a mist of fine ice particles. The hydrazine chemistry in Jupiter's atmosphere is similar to that occurring in the Earth's atmosphere after a volcanic eruption, when sulfur dioxide is converted by solar ultraviolet light into sulfuric acid.
"The change we see in the haze could be related to big changes in cloud patterns associated with last year's upheaval, but we need to look at more data to narrow down precisely when the changes occurred," Wong said.
University of California - Berkeley
"This type of adaptive optics has a big advantage for looking at large objects, such as planets, star clusters or nebulae," said lead researcher Franck Marchis, a research astronomer at UC Berkeley and the SETI Institute in Mountain View, Calif. "While regular adaptive optics systems provide excellent correction in a small field of view, MCAO provides good correction over a larger area of sky."
A full MCAO instrument is due to be installed on Gemini North by 2010 and is proposed for the VLT.
With conventional adaptive optics systems like those on Gemini and Keck, the sharpening degrades with distance between the target and a reference object, be it a star or a moon of a planet. Multi-conjugate adaptive optics maintains a steady sharpness over the whole sky area between the reference objects.
This allowed the researchers to observe Jupiter for almost two hours on Aug. 16 and 17, 2008, a record duration, according to the observing team. Conventional adaptive optics systems using a single reference moon cannot monitor Jupiter that long because the moon moves too far from the planet. The Hubble Space Telescope cannot observe Jupiter continuously for more than about 50 minutes, because it is regularly blocked by the Earth during Hubble's 96-minute orbit.
Using the MCAO Demonstrator (MAD) mounted on the Melipal 8.2-meter telescope of the VLT, ESO astronomer Paola Amico, MAD project manager Enrico Marchetti and MAD integration engineer Sebastien Tordo tracked two moons, Europa and Io, one on each side of Jupiter, to provide a good correction across the full disk of the planet.
"It has been the most challenging observation we performed with MAD because we had to track with high accuracy the two moons having different absolute velocities while simultaneously chasing Jupiter, which was moving with respect to them," said Marchetti.
The VLT image had a resolution of 90 milliarcseconds, "twice the resolution of the Hubble Space Telescope," said Marchis. The improved resolution is due not only to MCAO but also the much larger aperture of the 8.2-meter VLT. "Ground-based telescopes are getting comparable to or better than Hubble in the near-infrared, even for extended objects like Jupiter," he said.
"We wanted to check if there is a link between South Equatorial Belt outbreaks and the Great Red Spot's turbulent wake," explained team member Mike Wong, a UC Berkeley research astronomer. The belt is some 18,000 kilometers wide north-to-south, and it encircles Jupiter just above the track of the Great Red Spot.
Instead, the team found a major alteration in the brightness of the equatorial haze, which lies in a 16,000-kilometer wide belt over Jupiter's equator. More sunlight reflecting off upper atmospheric haze means that the amount of haze has increased, or that it has moved up to higher altitudes. The brightest portion had shifted south by more than 6,000 kilometers, Wong said.
This conclusion came from a comparison of images taken in 2005 by Wong and UC Berkeley astronomer Imke de Pater using the Hubble Space Telescope's Near Infrared Camera and Multi-Object Spectrometer (NICMOS) instrument. The Hubble images, taken at infrared wavelengths very close to those used for the VLT study, show more haze in the northern half of the bright Equatorial Zone, while the 2008 VLT images show a clear shift to the south.
The haze, which could be the nitrogen compound hydrazine - used on Earth as a rocket propellant - or possibly frozen crystals of ammonia, water or ammonium hydrosulfide from deeper in the gaseous planet, is very prominent in infrared images. Because visible light can penetrate to deeper levels than infrared light, optical telescopes see light reflected from deeper, thicker clouds lying beneath the haze.
The haze behaves somewhat like particles in the tops of thunderheads (known as cumulonimbus anvils) on Earth or in the ash plumes from large volcanic eruptions, which rise into the upper atmosphere and spread around the world, Wong said. On Jupiter, ammonia injected into the upper atmosphere also interacts with sunlight to form hydrazine, which condenses into a mist of fine ice particles. The hydrazine chemistry in Jupiter's atmosphere is similar to that occurring in the Earth's atmosphere after a volcanic eruption, when sulfur dioxide is converted by solar ultraviolet light into sulfuric acid.
"The change we see in the haze could be related to big changes in cloud patterns associated with last year's upheaval, but we need to look at more data to narrow down precisely when the changes occurred," Wong said.
University of California - Berkeley
Jupiter Current Events and Jupiter News RSSLooking through Galileo's eyes
In 1609, exactly four centuries ago, Galileo revolutionised humankind's understanding of our position in the Universe when he used a telescope for the first time to study the heavens, which saw him sketching radical new views of the moon and discovering the satellites orbiting Jupiter.
Jupiter-like Planets Could Form Around Twin Suns
Life on a planet ruled by two suns might be a little complicated. Two sunrises, two sunsets. Twice the radiation field.
Wobbly planets could reveal Earth-like moons
Moons outside our Solar System with the potential to support life have just become much easier to detect, thanks to research by an astronomer at University College London (UCL).
Europa does the wave to generate heat
One of the moons in our solar system that scientists think has the potential to harbor life may have a far more dynamic ocean than previously thought.
Astronomers use ultra-sensitive camera to measure size of planet orbiting star
A team of astronomers led by John Johnson of the University of Hawaii's Institute for Astronomy has used a new technique to measure the precise size of a planet around a distant star. They used a camera so sensitive that it could detect the passage of a moth in front of a lit window from a distance of 1,000 miles.
Hubble finds carbon dioxide on an extrasolar planet
The NASA/ESA Hubble Space Telescope has discovered carbon dioxide in the atmosphere of a planet orbiting another star.
Jupiter's rocky core bigger and icier, model predicts
Jupiter has a rocky core that is more than twice as large as previously thought, according to computer calculations by a University of California, Berkeley, geophysicist who simulated conditions inside the planet on the scale of individual hydrogen and helium atoms.
Scripps Research Scientists Shed Light on How DNA Is Unwound So That Its Code Can Be Read
Researchers at The Scripps Research Institute have figured out how a macromolecular machine is able to unwind the long and twisted tangles of DNA within a cell's nucleus so that genetic information can be "read" and used to direct the synthesis of proteins, which have many specific functions in the body.
Beta Pictoris planet finally imaged?
A team of French astronomers using ESO's Very Large Telescope have discovered an object located very close to the star Beta Pictoris, and which apparently lies inside its disc.
UBC researchers develop breakthrough technique to unlock the secret of plasmas
University of British Columbia researchers have developed a technique that brings scientists a big step closer to unlocking the secrets of the most abundant form of matter in the universe.
More Jupiter Current Events and Jupiter News Articles
 | Jupiters Travels: Four Years Around the World on a Triumph by Ted Simon Simon rode a motorcycle around the world in the seventies, when such a thing was unheard of. In four years he covered 78,000 miles through 45 countries, living with peasants and presidents, in prisons and palaces, through wars and revolutions. What distinguishes this book is that Simon was already an accomplished writer. In 25 years this book has changed many lives, and inspired many to travel,... |
 | Max Goes to Jupiter: A Science Adventure with Max the Dog (Science Adventures with Max the Dog series) by Jeffrey Bennett, Nick Schneider, Erica Ellingson Scientifically-accurate illustrations and information-packed sidebars enrich this fascinating tale, the third in this acclaimed series about diversity and space exploration. Set in the future, Max the Dog’s friend Tori is all grown up and is the chief scientist of the Jupiter Mission. In order to reach their spacecraft, Max and his crew must take an amazing ride on a new device called the... |
 | The Enemies of Jupiter (The Roman Mysteries) by Caroline Lawrence The fever that started in Ostia is sweeping through Rome, and Jonathan, Flavia, Nubia, and Lupus are called by the Emperor to investigate. The friends' investigations take them from the Imperial Palace to Tiber Island, but Jonathan is distracted by a secret mission of his own. Suddenly, he finds that everything is terrifyingly out of control. This is the seventh volume in the popular series of... |
 | Exploring Jupiter: The Astrological Key to Progress, Prosperity & Potential by Stephen Arroyo |
 | The Moons of Jupiter by Alice Munro In these piercingly lovely and endlessly surprising stories by one of the most acclaimed current practitioners of the art of fiction, many things happen: there are betrayals and reconciliations, love affairs consummated and mourned. But the true events in The Moons Of Jupiter are the ways in which the characters are transformed over time, coming to view their past selves with an anger, regret,... |
 | Destination: Jupiter by Seymour Simon When the unmanned spacecraft Galileo landed on Jupiter in 1995, what mysteries did it uncover?...Did you know that...Jupiter is so large that more than 1,300 planet Earths could fit inside.The Great Red Spot on the planet is actually an enormous hurricane that changes in size and color over the years.A person weighing 100 pounds on Earth would weigh 264 pounds on Jupiter.Life might exist on... |
 | Dreaming of Jupiter: In Search of the World--Thirty Years On by Ted Simon Back in the seventies, Ted Simon drove a Triumph motorcycle around the world. His book, Jupiter's Travels, became the acknowledged classic of motorcycle adventure. It inspired thousands, Ewan McGregor included, to roam the globe. Now in his own seventies, thirty years after his epic journey began, Ted has retraced that epic journey, still on a bike, to rediscover himself, his world and the... |
 | Dreaming of Jupiter by Ted Simon Ted Simon is the author of the classic travel book JUPITER'S TRAVELS. It documents his four-year journey round the world by motorbike, travelling through Europe, Africa, South and North America, and Asia. A number one bestseller in the late 1970s, it is still regarded as one of the greatest motorcycle books - indeed, one of the greatest travel books - ever written. In 2001, at the age of 69, Ted... |
 | Jupiter: A Novel (The Grand Tour) by Ben Bova Grant Archer only wanted to study astrophysics. But the forces of the "New Morality," the coalition of censorious do-gooders who run 21st-century America, have other plans for him. To his distress, Grant is torn from his young bride and sent to a research station in orbit around Jupiter, to spy on the scientists who work there. Their work may lead to the discovery of higher life forms in the... |
 | Madalyn Aslan's Jupiter Signs by Madalyn Aslan While most people know the importance of their Sun sign, few know about the importance of their Jupiter sign-the only sign governed by a planet great enough to give you the luck you need to transform your life, money, work, and love. Now, in her new book, MADALYN ASLAN'S JUPITER SIGNS: How to Improve Your Luck, Career, Health, Finances, Appearance and Relationships Through the New Astrology,... |
| © 2009 BrightSurf.com |