Posted on by R. Jay Gabany

Astrophoto: The Whirlpool Galaxy by Robert Gendler

The Whirlpool Nebula by Robert Gendler
Looking up into the midnight sky, with a faint cool breeze at your neck and the stars scattered like shards of glass caught in a spotlight, you can gain a sense of serenity. From gazing on the face of forever, your contemplations move from this bright star to that planet overhead. Yet, the universe is filled with routine violence on a scale that is unimaginably powerful and vast.

For example, untold numbers of objects fall to earth and are vaporized in a flash; mammoth tongues of flame leap from the Sun that would instantly incinerate our world we were any closer; and stars in the process of ending their useful lives suddenly implode and rip themselves into pieces during titanic blasts that briefly outshine the combined luminance of their home galaxy. These and many other events just as spectacular are common throughout the Universe. Safely tucked in our docile corner of the Milky Way galaxy, sequestered by a protective sea of air it’s easy to consider these events as abstractions that are curious but irrelevant to everyday life.

Perhaps our perspective would be quite different if our home planet was nestled within a galaxy that ventured too close to its neighbor, such as The Whirlpool Nebula (M51) or its yellow companion, NGC5195, pictured here. Our viewpoint about the nature of the Universe would most likely be quite different and we might quickly learn the consequences of trees falling in a forest even when no one was listening .

Placed within the northern constellation of Canes Venatici, this pair of entwined galaxies, 60 million light years distant, is one of nighttime’s most mesmerizing icons and a favorite target for sky gazers with binoculars or small telescopes. It’s a showpiece but light polluted skies wash away the view and render it unremarkable. But under dark skies hints of spiral structuring can be glimpsed with telescopes as small as 4 inches diameter.

The intense spiral arms of the larger galaxy are the result of its proximity to the smaller, more distant associate. When the two grew closer, the gravity of NGC 5195 induced ripples within the larger member. As these waves moved throughout the big spiral, the edge of each arm was squeezed and their original enormity was further accentuated. This energy formed storm clouds of gas and dark dust that eventually collapsed under their own gravity into dense areas of new star formation that are notably red. The stars these areas produced included massive short-lived members that terminated as supernovas. The winds blown from their massive explosions dissipated the clouds to reveal other new, bright clusters of stars that gave the arms a characteristic blue glow.

Meanwhile, the smaller galaxy became disrupted as its material was both thrown into intergalactic space and pulled into the larger spiral. Over time, these two will further distort and eventually merge through an ongoing spectacle of events that would capture the attention of any civilization possibly existing within either.

This exceptional picture of The Whirlpool Nebula was the result of an epic 42-hour exposure by Robert Gendler. Earlier this year, 21 hours was devoted to capturing black and white luminance data and the same amount of time was used gathering color information. Rob images from his Nighthawk Observatory located in the south central Sacramento Mountains of New Mexico using a 12 and 20 inch Ritchey-Chretien telescope equipped with an 11 mega-pixel camera.

Do you have photos you’d like to share? Post them to the Universe Today astrophotography forum or email them, and we might feature one in Universe Today.

Written by R. Jay GaBany

Posted on by Tammy Plotner

What’s Up This Week – May 22 – May 28, 2006

The Leo Triplet. Image credit: REU Program/NOAO/AURA/NSF. Click to enlarge
Greeting fellow SkyWatchers! This week will be a great time to go galaxy hunting and seeking out all the bright a beautiful deep space objects that signal the end of Spring and the beginning of Summer. So get out your binoculars and telescopes and get ready to rock, because…

Here’s what’s up!

Monday, May 22, 2006 – Tonight would be a great opportunity to do some binocular hunting. Starting at Regulus, see how many faint galaxies you can spot about a fist width due east. Among the brightest will be M105, M95 and M96. Another fist width east will take you just below Theta Leonis for the must easier M65 and M66.

Now return to Regulus. About a thumb’s length to the west-southwest you will spot dim R Leonis – a Mira-type variable. Discovered in 1782 by J.A. Koch, this awesome star moves from magnitude 4.4 to 11.0 magnitude is less than a year. As one of the earliest discovered, you will find it a ruby red color that goes to deep purple during its cycle. A true gem!

Tuesday, May 23 – Tonight we move on to small telescope studies as we begin at Beta Leonis (Denebola) and look about a hand span west-southwest for Epsilon Virginis (Vindemiatrix). Almost directly between them is the most heavily galaxy populated portion of the sky for a small scope!

About three finger-widths west of Epsilon, you will find M59 and M60 with M58 just a breath further west. At low power, shifting northwest one field of view will bring you to M89 and then go northeast another field for M90. Return to M89 and go less than two fields away for M87. Two fields north will bring you to M88, while one east will help you find M91.

If you get lost, don’t worry. One of the most beautiful experiences in Virgo is to simply enjoy all you can see!

Wednesday, May 24 – Be sure to check the sky this morning as brilliant Venus and the Moon have a scenic encounter.

Tonight we’ll head into larger scope territory as we explore the area around the galactic pole and star 31 Comae.

As a known member of Melotte 111, 31 Comae is an eclipsing variable star with a faint companion. Begin by centering on 31, and move south a little more than two degrees for a large, 9.2 magnitude spiral galaxy – NGC 4725. Encircled by a halo, this study contains a luminous oval nucleus. A little more than 3 degrees west-northwest will bring you to the spectacular NGC 4565. This large, slender, edge-on presentation is an easy 9.6 magnitude which shows a dark dust lane.

Now shift NGC 4565 a little more than a degree east to view the small, 9.9 magnitude elliptical galaxy – NGC 4494. Return to NGC 4565 and move two degrees north for NGC 4559. This large, 9.9 magnitude, tilted spiral will show a multi-armed structure and some patchiness to its detail. To complete the tour, four degrees east again and you’ll find yourself back at 31 Comae!

Thursday, May 25 – Has Gemini gained another twin? No. It’s just Mars south of Pollux.

Tonight, let’s try a series of challenges designed to intrigue all SkyWatchers. For visual observers, your goal is just east of Saturn. Allow your eyes plenty of time to dark adapt and seek out a large hazy patch of barely visible stars. Congratulations! You’ve just spotted M44 and seen the light – light that left the cluster in the year 1480!

For binoculars, look a fist width west of bright Spica and you’ll pick up M104. Its light came from 400 million years ago.

For the large telescope, your challenge lies five and a half degrees south of Beta Virginis and one half degree west. Classified as Arp 248, and more commonly known as “Wild’s Triplet,” these three very small interacting galaxies are a real treat! Best observed using higher magnifications, use wide aversion and try to keep the star just north of the trio at the edge of the field to cut glare.

Best of luck!

Friday, May 26 – This evening we’re going to have a look at two of the finest globular clusters for the northern hemisphere. Entering the middle third of the sky to the northeast is everyone’s favorite and champion of the overhead sky – the Great Hercules Cluster – M13. Just grazing the sky’s middle third to the south-southeast is the equally spectacular M5 in Serpens.

At magnitude 5.8, M5 is only slightly brighter cumulatively than M13 and is also just slightly larger. With good reason…It’s 600 light-years closer.

Now let’s go locate each of them. M13 is easily found just one-third the way between Eta and Zeta Herculis along the western flank of the Keystone. To locate M5, you’ll find it slightly northeast of 5 Serpens.

Which gives the better view? Well leave the decision to you!

Saturday, May 27 – Tonight is New Moon Saturday and many observers will be packing their scopes up and heading for dark skies. Many will enjoy the camaraderie of other amateurs – plus opportunities to look through different equipment and discover entirely new night sky favorites. If you’re on your own, keep this in mind: the best locations for observing will be far from city lights, at higher altitudes, and hampered by little foliage – especially to the south where studies sometimes only barely manage to clear the trees before they’re gone again. Since most star parties are held at well-selected locations, a lot of the work has already been done for you!

For observers below 40 degrees north latitude, one study will be on everyone’s list tonight – the incomparable Omega Centauri! To see it, you simply must have a clear view of the horizon to the south and begin looking for it well south of Spica as soon as it starts to get reasonably dark out. Don’t expect much of a view from the northern hemisphere. Omega may look no better than a large unresolved misty glow. But you just have to look anyway!

Even before that peek at Omega, Jupiter will dominate the sky to the south – so arrive early and set up just after sunset. Within a half hour you will see the planet culminating south. Once you’ve had that first look at Jupiter, you might want to look west toward Gemini and say goodbye to Mars and Saturn. If the seeing is really good, you will probably want to spend some quality time with Jupiter throughout the evening. One thing to watch for, the strikingly high contrast and well-defined shadow of a Galilean as it transits Jupiter’s atmosphere.

After Omega Centauri and the planets, the sky’s the limit!

Sunday, May 28 – On this day in 1959, the first primates made it to space. Abel (a rhesus monkey) and Baker (a squirrel monkey) lifted off in the nose cone of an Army Jupiter missile and were carried aloft into sub-orbital flight. Recovered unharmed, Abel died just three days later from anesthesia during an electrode removal, but Baker lived on to the ripe old age of 27.

Tonight let’s monkey around with the stars as we climb into the canopy of the heavens towards 7.7 magnitude M101!

The sprawling nature of this face-on spiral means that the light of an 8th magnitude star has to be spread very thin to cover all that celestial terrain. Its 10th magnitude core region allowed Pierre M?chain to view it on March 27, 1781. This inclusion was the last published entry in Charles Messier’s catalog. Meanwhile William Parsons (Lord Rosse), described M101 as “Large, spiral, faintish; several arms and knots. 14′ diameter at least.” – a description comparable to what is seen through the largest backyard telescopes used today.

At a distance of 27 million light-years, the true size of M101 is extraordinary – some 170,000 light-years in diameter. Its total luminosity is equivalent to over 30 billion suns. Even as large as this galaxy is, it merely approaches the size of the Milky Way!

May all your journeys be at light speed… ~Tammy Plotner with Jeff Barbour.

Posted on by Fraser Cain

Three Storms on Saturn

Three big vortices swirling through Saturn’s southern latitudes. Image credit: NASA/JPL/SSI. Click to enlarge
Three giant storms swirl across the atmosphere of Saturn in this photograph taken by Cassini – the two in the upper part of the photo appear to be interacting. This image was taken by Cassini on April 15 when the spacecraft was approximately 3.9 million kilometers (2.4 million miles) from Saturn.

Three large and impressive vortices, including two that appear to be interacting, are captured here as they swirl through Saturn’s active southern latitudes.

This view shows latitudes slightly to the north of those seen in Round and Round They Go and was taken a few minutes prior to the left side image in that release.

The image was taken with the Cassini spacecraft narrow-angle camera using a spectral filter sensitive to wavelengths of infrared light centered at 750 nanometers. The image was acquired on April 15, 2006, at a distance of approximately 3.9 million kilometers (2.4 million miles) from Saturn. The image scale is 23 kilometers (14 miles) per pixel.

The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. The Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the mission for NASA’s Science Mission Directorate, Washington, D.C. The Cassini orbiter and its two onboard cameras were designed, developed and assembled at JPL. The imaging operations center is based at the Space Science Institute in Boulder, Colo.

For more information about the Cassini-Huygens mission visit http://saturn.jpl.nasa.gov . The Cassini imaging team homepage is at http://ciclops.org .

Original Source: NASA/JPL/SSI News Release

Posted on by Fraser Cain

Exposed Bedrock on Mars

Cobbles appearing on trough floors between wind-blown ripples. Image credit: NASA/JPL. Click to enlarge
NASA’s Opportunity rover captured this photograph of the surface of Mars during its trek from Erebus Crater to Victoria Crater. The image shows exposed bedrock between large windblown sand ripples. Opportunity took the photo on April 27, 2006 during its 802nd Martian day of exploration.

As NASA’s Mars Exploration Rover Opportunity continues to traverse from “Erebus Crater” toward “Victoria Crater,” the rover navigates along exposures of bedrock between large, wind-blown ripples. Along the way, scientists have been studying fields of cobbles that sometimes appear on trough floors between ripples. They have also been studying the banding patterns seen in large ripples.

This view, obtained by Opportunity’s panoramic camera on the rover’s 802nd Martian day (sol) of exploration (April 27, 2006), is a mosaic spanning about 30 degrees. It shows a field of cobbles nestled among wind-driven ripples that are about 20 centimeters (8 inches) high.

The origin of cobble fields like this one is unknown. The cobbles may be a lag of coarser material left behind from one or more soil deposits whose finer particles have blown away. The cobbles may be eroded fragments of meteoritic material, secondary ejecta of Mars rock thrown here from craters elsewhere on the surface, weathering remnants of locally-derived bedrock, or a mixture of these. Scientists will use the panoramic camera’s multiple filters to study the rock types, variability and origins of the cobbles. This is an approximately true-color rendering that combines separate images taken through the panoramic camera’s 753-nanometer, 535-nanometer and 432-nanometer filters.

Original Source: NASA News Release

Posted on by Fraser Cain

“Lucky” Cluster Spacecraft Buffeted by the Solar Wind

Sketch of the different regions in of Earth’s magnetosphere. Image credit: ESA. Click to enlarge
ESA’s Cluster spacecraft were in the right place at the right time when they flew through a region of the Earth’s magnetic field that accelerates electrons to approximately 1/100th the speed of light. The region is called the electron diffusion region; a boundary just a few kilometres thick between the Earth’s magnetic field and the Sun’s. Over the course of an hour, the spacecraft were engulfed in an electron diffusion region, as the solar wind was causing this layer to move back and forth.

ESA’s Cluster satellites have flown through regions of the Earth’s magnetic field that accelerate electrons to approximately one hundredth the speed of light. The observations present Cluster scientists with their first detection of these events and give them a look at the details of a universal process known as magnetic reconnection.

On 25 January 2005, the four Cluster spacecraft found themselves in the right place at the right time: a region of space known as an electron diffusion region. It is a boundary just a few kilometres thick that occurs at an altitude of approximately 60 000 kilometres above the Earth’s surface. It marks the frontier between the Earth’s magnetic field and that of the Sun. The Sun’s magnetic field is carried to the Earth by a wind of electrically charged particles, known as the solar wind.

An electron diffusion region is like an electrical switch. When it is flipped, it uses energy stored in the Sun’s and Earth’s magnetic fields to heat the electrically charged particles in its vicinity to large speeds. In this way, it initiates a process that can result in the creation of the aurora on Earth, where fast-moving charged particles collide with atmospheric atoms and make them glow.

There is also a more sinister side to the electron diffusion regions. The accelerated particles can damage satellites by colliding with them and causing electrical charges to build up. These short circuit and destroy sensitive equipment.

Nineteen times in one hour, the Cluster quartet found themselves engulfed in an electron diffusion region. This was because the solar wind was buffeting the boundary layer, causing it to move back and forth. Each crossing of the electron diffusion region lasted just 10-20 milliseconds for each spacecraft and yet a unique instrument, known as the Electron Drift Instrument (EDI), was fast enough to measure the accelerated electrons.

The observation is important because it provides the most complete measurements yet of an electron diffusion region. “Not even the best computers in the world can simulate electron diffusion regions; they just don’t have the computing power to do it,” says Forrest Mozer, University of California, Berkeley, who led the investigation of the Cluster data.

The data will provide invaluable insights into the process of magnetic reconnection. The phenomenon occurs throughout the Universe on many different scales, anywhere there are tangled magnetic fields. In these complex situations, the magnetic fields occasionally collapse into more stable configurations. This is the reconnection and releases energy through electron diffusion regions. On the Sun, magnetic reconnection drives the solar flares that occasionally release enormous amounts of energy above sunspots.

This work may also have an important bearing on solving energy needs on Earth. Nuclear physicists trying to build fusion generators attempt to create stable magnetic fields in their reactors but are plagued by reconnection events that ruin their configurations. If the process of reconnection can be understood, perhaps ways of preventing it in nuclear reactors will become clear.

However, that still lies in the future. “We need to do a lot more science before we fully understand reconnection,” says Mozer, whose aim is now to understand which solar wind conditions trigger the reconnection events and their associated electron diffusion regions seen by Cluster.

Original Source: ESA Portal

Posted on by Fraser Cain

Massive Stars Slowed Early Galaxy Growth

An illustartion of an early dwarf galaxy surrounded by red hydrogen gas. Image credit: David A. Aguilar/CfA. Click to enlarge
Shortly after the Big Bang, large clouds of hydrogen collapsed easily into the first galaxies and stars. These weren’t stars like our Sun; however, they were hot, massive and very short lived – blasting their environment with ultraviolet radiation. But after the first 100 million years of the Universe, it became very difficult for these dwarf galaxies to grow any larger as this radiation sabotaged further growth. Only the gravity of the largest galaxies could overcome this heat and pressure to grow into larger galaxies over time.

The first galaxies were small – about 10,000 times less massive than the Milky Way. Billions of years ago, those mini-furnaces forged a multitude of hot, massive stars. In the process, they sowed the seeds for their own destruction by bathing the universe in ultraviolet radiation. According to theory, that radiation shut off further dwarf galaxy formation by both ionizing and heating surrounding hydrogen gas. Now, astronomers Stuart Wyithe (University of Melbourne) and Avi Loeb (Harvard-Smithsonian Center for Astrophysics) are presenting direct evidence in support of this theory.

Wyithe and Loeb showed that fewer, larger galaxies, rather than more numerous, smaller galaxies, dominated the billion-year-old universe. Dwarf galaxy formation essentially shut off only a few hundred million years after the Big Bang.

“The first dwarf galaxies sabotaged their own growth and that of their siblings,” says Loeb. “This was theoretically expected, but we identified the first observational evidence for the self-destructive behavior of early galaxies.”

Their research is being reported in the May 18, 2006 issue of Nature.

Nearly 14 billion years ago, the Big Bang filled the universe with hot matter in the form of electrons and hydrogen and helium ions. As space expanded and cooled, electrons and ions combined to form neutral atoms. Those atoms efficiently absorbed light, yielding a pervasive dark fog throughout space. Astronomers have dubbed this era the “Dark Ages.”

The first generation of stars began clearing that fog by bathing the universe in ultraviolet radiation. UV radiation splits atoms into negatively charged electrons and positively charged ions in a process called ionization. Since the Big Bang created an ionized universe that later became neutral, this second phase of ionization by stars is known as the “epoch of reionization.” It took place in the first few hundred million years of existence.

“We want to study this time period because that’s when the primordial soup evolved into the rich zoo of objects we now see,” said Loeb.

During this key epoch in the history of the universe, gas was not only ionized, but also heated. While cool gas easily clumps together to form stars and galaxies, hot gas refuses to be constrained. The hotter the gas, the more massive a galactic “seed” must be to attract enough matter to become a galaxy.

Before the epoch of reionization, galaxies containing only 100 million solar masses of material could form easily. After the epoch of reionization, galaxies required more than 10 billion solar masses of material to be assembled.

To determine typical galaxy masses, Wyithe and Loeb looked at light from quasars – powerful light sources visible across vast distances. The light from the farthest known quasars left them nearly 13 billion years ago, when the universe was a fraction of its present age. Quasar light is absorbed by intervening clouds of hydrogen associated with early galaxies, leaving telltale bumps and wiggles in the quasar’s spectrum.

By comparing the spectra of different quasars along different lines of sight, Wyithe and Loeb determined typical galaxy sizes in the infant universe. The presence of fewer, larger galaxies leads to more variation in the absorption seen along various lines of sight. Statistically, large variation is exactly what Wyithe and Loeb found.

“As an analogy, suppose you are in a room where everybody is talking,” explains Wyithe. “If this room is sparsely populated, then the background noise is louder in some parts of the room than others. However if the room is crowded, then the background noise is the same everywhere. The fact that we see fluctuations in the light from quasars implies that the early universe was more like the sparse room than the crowded room.”

Astronomers hope to confirm the suppression of dwarf galaxy formation using the next generation of telescopes – both radio telescopes that can detect distant hydrogen and infrared telescopes that can directly image young galaxies. Within the next decade, researchers using these new instruments will illuminate the “Dark Ages” of the universe.

Headquartered in Cambridge, Mass., the Harvard-Smithsonian Center for Astrophysics (CfA) is a joint collaboration between the Smithsonian Astrophysical Observatory and the Harvard College Observatory. CfA scientists, organized into six research divisions, study the origin, evolution and ultimate fate of the universe.

Original Source: CfA News Release

Posted on by Fraser Cain

Amateur Team Finds an Extrasolar Planet

Artist’s Concept of Transiting Planet XO-1b. Image credit: NASA/ESA/STScI. Click to enlarge
Amateur astronomers have used inexpensive equipment to discover a Jupiter-sized planet orbiting a Sun-like star 600 light-years away. The team used the “transit method”, to watch how a star dims slightly as a planet passes in front. An automated telescope observed tens of thousands of bright stars, and then the team chose a few dozen promising candidates. The new planet, dubbed X0-1b is the 10th planet ever discovered using the transit method.

An international team of professional and amateur astronomers, using simple off-the-shelf equipment to trawl the skies for planets outside our solar system, has hauled in its first “catch.”

The astronomers discovered a Jupiter-sized planet orbiting a Sun-like star 600 light-years from Earth in the constellation Corona Borealis. The team, led by Peter McCullough of the Space Telescope Science Institute in Baltimore, Md., includes four amateur astronomers from North America and Europe.

Using modest telescopes to search for extrasolar planets allows for a productive collaboration between professional and amateur astronomers that could accelerate the planet quest.

“This discovery suggests that a fleet of modest telescopes and the help of amateur astronomers can search for transiting extrasolar planets many times faster than we are now,” McCullough said. The finding has been accepted for publication in the Astrophysical Journal.

McCullough deployed a relatively inexpensive telescope made from commercial equipment to scan the skies for extrasolar planets. Called the XO telescope, it consists of two 200-millimeter telephoto camera lenses and looks like a pair of binoculars. The telescope is on the summit of the Haleakala volcano, in Hawaii.

“To replicate the XO prototype telescope would cost $60,000,” McCullough explained. “We have spent far more than that on software, in particular on designing and operating the system and extracting this planet from the data.”

McCullough’s team found the planet, dubbed X0-1b, by noticing slight dips in the star’s light output when the planet passed in front of the star, called a transit. The light from the star, called XO-1, dips by approximately 2 percent when the planet XO-1b passes in front of it. The observation also revealed that X0-1b is in a tight four-day orbit around its parent star.

Although astronomers have detected more than 180 extrasolar planets, X0-1b is only the tenth planet discovered using the transit method. It is the second planet found using telephoto lenses. The first, dubbed TrES-1, was reported in 2004. The transit method allows astronomers to determine a planet’s mass and size. Astronomers use this information to deduce the planet’s characteristics, such as its density.

The team confirmed the planet’s existence by using the Harlan J. Smith Telescope and the Hobby-Eberly Telescope at the University of Texas’s McDonald Observatory to measure the slight wobble induced by the planet on its parent star. This so-called radial-velocity method allowed the team to calculate a precise mass for the planet, which is slightly less than that of Jupiter (about 0.9 Jupiter masses). The planet also is much larger than its mass would suggest. “Of the planets that pass in front of their stars, XO-1b is the most similar to Jupiter yet known, and the star XO-1 is the most similar to the Sun,” McCullough said, although he was quick to add, “but XO-1b is much, much closer to its star than Jupiter is to the Sun.”

The astronomer’s innovative technique of using relatively inexpensive telescopes to look for eclipsing planets favors finding planets orbiting close to their parent stars. The planet also must be large enough to produce a measurable dip in starlight.

The planet is the first discovered in McCullough’s three-year search for transiting extrasolar planets. The planet quest is underwritten by a grant from NASA’s Origins program.

McCullough’s planet-finding technique involves nightly sweeps of the sky using the XO telescope in Hawaii to note the brightness of the stars it encounters. A computer software program sifts through many thousands of stars every two months looking for tiny dips in the stars’ light, the signature of a possible planetary transit. The computer comes up with a few hundred possibilities. From those candidates, McCullough and his team select a few dozen promising leads. He passes these stars on to the four amateur astronomers to study the possible transits more carefully.

From September 2003 to September 2005, the XO telescope observed tens of thousands of bright stars. In that time, his team of amateur astronomers studied a few dozen promising candidate stars identified by McCullough and his team. The star X0-1 was pegged as a promising candidate in June 2005. The amateur astronomers observed it in June and July 2005, confirming that a planet-sized object was eclipsing the star. McCullough’s team then turned to the McDonald Observatory in Texas to obtain the object’s mass and verify it as a planet. He received the news of the telescope’s observation at 12:06 a.m. Feb. 16, 2006, from Chris Johns-Krull, a friend and colleague at Rice University.

“It was a wonderful feeling because the team had worked for three years to find this one planet,” McCullough explained. “The discovery represents a few bytes out of nearly a terabyte of data: It’s like trying to distill gold out of seawater.”

The discovery also has special familial significance for the astronomer. “My father’s mentor was Harlan J. Smith, the man whose ambition and hard work produced the telescope that we used to acquire the verifying data.”

McCullough believes the newly found planet is a perfect candidate for study by the Hubble and Spitzer space telescopes. Hubble can measure precisely the star’s distance and the planet’s size. Spitzer can actually see the infrared radiation from the planet. By timing the disappearance of the planet behind the star, Spitzer also can measure the “ellipticity,” or “out-of-roundness,” of the planet’s orbit. If the orbit is elliptical, then the varying gravitational force would result in extra heating of the planet, expanding its atmosphere and perhaps explaining why the object’s diameter seems especially large for a body of its calculated mass.

“By timing the planet’s passages across the star, both amateur and professional astronomers might be lucky enough to detect the presence of another planet in the XO-1 system by its gravitational tugs on XO-1b,” McCullough said. “It’s even possible that such a planet could be similar to Earth.”

Original Source: HubbleSite News Release

Posted on by Fraser Cain

Three Neptunes Orbiting Another Star

An artist’s impression of a planetary system around HD 69830. Image credit: ESO. Click to enlarge
Astronomers have discovered a nearby star that’s home to three Neptune-sized planets; no super-Jupiters here. The star, HD 69830, is located 41 light-years away in the constellation of Puppis. With magnitude 5.95, it’s just possible to see with the unaided eye. The discovery was made using the European Southern Observatory’s 3.6 metre telescope at La Silla in Chile. The planets orbit their star in 8.67, 31.6 and 197 days respectively.

Using the ultra-precise HARPS spectrograph on ESO’s 3.6-m telescope at La Silla (Chile), a team of European astronomers have discovered that a nearby star is host to three Neptune-mass planets. The innermost planet is most probably rocky, while the outermost is the first known Neptune-mass planet to reside in the habitable zone. This unique system is likely further enriched by an asteroid belt.

“For the first time, we have discovered a planetary system composed of several Neptune-mass planets”, said Christophe Lovis, from the Geneva Observatory and lead-author of the paper presenting the results.

During more than two years, the astronomers carefully studied HD 69830, a rather inconspicuous nearby star slightly less massive than the Sun. Located 41 light-years away towards the constellation of Puppis (the Stern), it is, with a visual magnitude of 5.95, just visible with the unaided eye. The astronomers’ precise radial-velocity measurements allowed them to discover the presence of three tiny companions orbiting their parent star in 8.67, 31.6 and 197 days.

“Only ESO’s HARPS instrument installed at the La Silla Observatory, Chile, made it possible to uncover these planets”, said Michel Mayor, also from Geneva Observatory, and HARPS Principal Investigator. “Without any doubt, it is presently the world’s most precise planet-hunting machine”.

The detected velocity variations are between 2 and 3 metres per second, corresponding to about 9 km/h! That’s the speed of a person walking briskly. Such tiny signals could not have been distinguished from ‘simple noise’ by most of today’s available spectrographs.

The newly found planets have minimum masses between 10 and 18 times the mass of the Earth. Extensive theoretical simulations favour an essentially rocky composition for the inner planet, and a rocky/gas structure for the middle one. The outer planet has probably accreted some ice during its formation, and is likely to be made of a rocky/icy core surrounded by a quite massive envelope. Further calculations have also shown that the system is in a dynamically stable configuration.

The outer planet also appears to be located near the inner edge of the habitable zone, where liquid water can exist at the surface of rocky/icy bodies. Although this planet is probably not Earth-like due to its heavy mass, its discovery opens the way to exciting perspectives.

“This alone makes this system already exceptional”, said Willy Benz, from Bern University, and co-author. “But the recent discovery by the Spitzer Space Telescope that the star most likely hosts an asteroid belt is adding the cherry to the cake.”

With three roughly equal-mass planets, one being in the habitable zone, and an asteroid belt, this planetary system shares many properties with our own solar system.

“The planetary system around HD 69830 clearly represents a Rosetta stone in our understanding of how planets form”, said Michel Mayor. “No doubt it will help us better understand the huge diversity we have observed since the first extra-solar planet was found 11 years ago.”

Original Source: ESO News Release

Posted on by Fraser Cain

Before the Big Bang

Researchers have developed a model of a shrinking universe that existed prior to the Big Bang. Image credit: NASA. Click to enlarge
The Big Bang describes how the Universe began as a single point 13.7 billion years ago, and has been expanding ever since, but it doesn’t explain what happened before that. Researchers from Penn State University believe that there should be traces of evidence in our current universe that could used to look back before the Big Bang. According to their research, there was a contracting universe with similar space-time geometry to our expanding universe. The universe collapsed and then “bounced” as the Big Bang.

According to Einstein’s general theory of relativity, the Big Bang represents The Beginning, the grand event at which not only matter but space-time itself was born. While classical theories offer no clues about existence before that moment, a research team at Penn State has used quantum gravitational calculations to find threads that lead to an earlier time. “General relativity can be used to describe the universe back to a point at which matter becomes so dense that its equations don’t hold up,” says Abhay Ashtekar, Holder of the Eberly Family Chair in Physics and Director of the Institute for Gravitational Physics and Geometry at Penn State. “Beyond that point, we needed to apply quantum tools that were not available to Einstein.” By combining quantum physics with general relativity, Ashtekar and two of his post-doctoral researchers, Tomasz Pawlowski and Parmpreet Singh, were able to develop a model that traces through the Big Bang to a shrinking universe that exhibits physics similar to ours.

In research reported in the current issue of Physical Review Letters, the team shows that, prior to the Big Bang, there was a contracting universe with space-time geometry that otherwise is similar to that of our current expanding universe. As gravitational forces pulled this previous universe inward, it reached a point at which the quantum properties of space-time cause gravity to become repulsive, rather than attractive. “Using quantum modifications of Einstein’s cosmological equations, we have shown that in place of a classical Big Bang there is in fact a quantum Bounce,” says Ashtekar. “We were so surprised by the finding that there is another classical, pre-Big Bang universe that we repeated the simulations with different parameter values over several months, but we found that the Big Bounce scenario is robust.”

While the general idea of another universe existing prior to the Big Bang has been proposed before, this is the first mathematical description that systematically establishes its existence and deduces properties of space-time geometry in that universe.

The research team used loop quantum gravity, a leading approach to the problem of the unification of general relativity with quantum physics, which also was pioneered at the Penn State Institute of Gravitational Physics and Geometry. In this theory, space-time geometry itself has a discrete ‘atomic’ structure and the familiar continuum is only an approximation. The fabric of space is literally woven by one-dimensional quantum threads. Near the Big-Bang, this fabric is violently torn and the quantum nature of geometry becomes important. It makes gravity strongly repulsive, giving rise to the Big Bounce.

“Our initial work assumes a homogenous model of our universe,” says Ashtekar. “However, it has given us confidence in the underlying ideas of loop quantum gravity. We will continue to refine the model to better portray the universe as we know it and to better understand the features of quantum gravity.”

The research was sponsored by the National Science Foundation, the Alexander von Humboldt Foundation, and the Penn State Eberly College of Science.

Original Source: PSU News Release

Posted on by Fraser Cain

Searching For Crater Chains on the Earth

Aorounga impact crater. Image credit: NASA/JPL. Click to enlarge
Comet 73P/Schwassmann Wachmann 3 is a beautiful sight in the night sky, especially now that it’s fractured into many pieces. There’s evidence for these kinds of impacts on several planets and moons in the Solar System, and astronomers watched 23 fragments of Comet Shoemaker-Levy 9 smash into Jupiter in 1993. What if a string of comet fragments like this hit the Earth? There are only a few examples of these kinds of impacts on the Earth; unfortunately, wind, rain and tectonic forces work to hide the evidence.

As the fragments of shattered comet 73P/Schwassmann Wachmann 3 glide harmlessly past Earth this month in full view of backyard telescopes, onlookers can’t help but wonder, what if a comet like that didn’t miss, but actually hit our planet?

For the answer to that question, we look to the Sahara desert.

In a remote windswept area named Aorounga, in Chad, there are three craters in a row, each about 10 km in diameter. “We believe this is a ‘crater chain’ formed by the impact of a fragmented comet or asteroid about 400 million years ago in the Late Devonian period,” explains Adriana Ocampo of NASA headquarters.

Ocampo and colleagues discovered the chain in 1996. The main crater “Aorounga South” had been known for many years?it sticks out of the sand and can be seen from airplanes and satellites. But a second and possibly third crater were buried. They lay hidden until radar onboard the space shuttle (SIR-C) penetrated the sandy ground, revealing their ragged outlines.

“Here on Earth, crater chains are rare,” says Ocampo, but they are common in other parts of the solar system.

The first crater chains were discovered by NASA’s Voyager 1 spacecraft. In 1979 when the probe flew past Jupiter’s moon Callisto, cameras recorded a line of craters, at least fifteen long, evenly spaced as if someone had strafed the moon with a Gatling gun. Eventually, eight chains were found on Callisto and three more on Ganymede.

At first the chains were a puzzle. Were they volcanic? Had an asteroid skipped along the surface of Callisto like a stone skipping across a pond?

The mystery was solved in 1993 with the discovery of Comet Shoemaker-Levy 9. SL-9 was not a single comet, but a “string of pearls,” a chain of 21 comet fragments created a year earlier when Jupiter’s gravity ripped the original comet apart. SL-9 struck back in 1994, crashing into Jupiter. Onlookers watched titanic explosions in the giant planet’s atmosphere, and it only took a little imagination to visualize the result if Jupiter had had a solid surface: a chain of craters.

Astronomers have since realized that fragmented comets and rubble-pile asteroids are commonplace. Comets fall apart rather easily; sunlight alone can shatter their fragile nuclei. Furthermore, there is mounting evidence that many seemingly solid asteroids are assemblages of boulders, dust and rock held together by feeble gravity. When these things hit, they make chains.

In 1994, researchers Jay Melosh and Ewen Whitaker announced their finding of two crater chains on the Moon. One, on the floor of the crater Davy, is spectacular–an almost perfect line of 23 pockmarks each a few miles in diameter. This proved that crater chains exist in the Earth-Moon system.

But where on Earth are they?

Earth tends to hide its craters. “Wind and rain erode them, sediments fill them in, and the tectonic recycling of Earth’s crust completely obliterates them,” says Ocampo. On the Moon, there are millions of well-preserved craters. On Earth, “so far we’ve managed to find only about 174.”

Sounds like a job for Google. Seriously. Amateur astronomer Emilio Gonzalez pioneered the technique in March 2006. “I use Google Earth,” he explains. Google Earth is a digital map of our planet made of stitched-together satellite images. You can zoom in and out, fly around and inspect the landscape in impressive detail. It’s a bit like a video game-except it is real.

Gonzalez began by calling up Kebira impact crater in Libya?the Sahara’s largest. It was so easy to see, he recalls, “I decided to look around for more.” Minutes later he was “flying” over the Libya-Chad border when another crater appeared. And then another. They both had multiple rings and a central peak, the telltale splash of a high-energy impact. “It couldn’t be this easy!” he marveled.

But it was. At least one of the craters had never been catalogued before, and both, almost incredibly, lined up with the Aorounga crater 200 km away: map. In less than 30 minutes, Gonzalez had found two good impact candidates and possibly multiplied the length of the Aorounga chain. Hours of additional searching produced no new results. “Beginner’s luck,” he laughs. (If you would like to hunt for your own craters online, Gonzalez offers these tips.)

Ocampo doubts that these new craters are related to Aorounga. “They don’t appear to be the same age.” But she can’t rule it out either.

“We need to do some fieldwork,” she says. To prove a crater is a crater-and not, say, a volcano-researchers must visit the site to look for signs of extraterrestrial impact such as “shatter cones” and other minerals forged by intense heat and pressure. This kind of geological study can also reveal the age of an impact site, marking it as part of a chain or an independent event.

Answers may have to wait. Civil war in Chad and the possibility of war between Chad and Sudan prevent scientists from mounting an expedition. Meanwhile, researchers are scrutinizing candidate chains in Missouri and Spain. Although those sites are more accessible than Chad, researchers still can’t decide if they are chains or not. It’s difficult work.

Ocampo believes it’s worth the effort. “The history of Earth is shaped by impacts,” she says. “Crater chains can tell us important things about our planet.”

And so the search goes on.

Original Source: NASA News Release