Posted on by Fraser Cain

Progress Docks with Station

Image credit: NASA
An unpiloted Russian Progress cargo craft successfully linked up with the International Space Station (ISS) today. The 17th Progress mission to the ISS automatically docked to the aft port of the Zvezda Service Module at 2:10 p.m. EST, as the Station flew 225 statute miles over the equator west of Africa.

The flawless docking completed a two-day journey for the craft since its liftoff Monday from the Baikonur Cosmodrome, Kazakhstan. As the Progress approached the ISS, Expedition 10 Flight Engineer Salizhan Sharipov was at the controls of a manual docking system. He was ready to take over the final approach if the automated docking system encountered problems. Station Commander and NASA Science Officer Leroy Chiao took video and still photos of the arrival. The crew will open the Progress hatch later today to begin unloading.

The Progress carried 386 pounds of propellant, 242 pounds of oxygen and air, 1,071 pounds of water and more than 2,900 pounds of spare parts, life support system components and experiment hardware. The manifest included 86 containers of food, about a six-month supply, to supplement items already in the Station’s pantry.

The Progress carried a new heat exchanger device to replace a faulty component in the U.S. airlock needed for the resumption of spacewalks in U.S. space suits this summer. It also carried cameras and lenses for the next Station crew, Expedition 11, to capture digital images of the Thermal Protection System on the Shuttle Discovery during its approach to the ISS during the STS-114 mission in May.

Information about crew activities on the ISS, future launch dates and sighting opportunities from Earth, is available on the Internet at: http://spaceflight.nasa.gov/

Original Source: ISS News Release

Posted on by Fraser Cain

Opportunity Breaks Driving Records

On three consecutive days, NASA’s Mars Exploration Rover Opportunity accomplished unprecedented feats of martian motion, covering more total ground in that period than either Opportunity or its twin, Spirit, did in their first 70 days on Mars.

Spirit, meanwhile, has uncovered soil that is more than half salt, adding to the evidence for Mars’ wet past. The golf-cart-size robots successfully completed their three-month primary missions in April 2004 and are continuing extended mission operations.

Opportunity set a one-day distance record for martian driving, 177.5 meters (582 feet), on Feb. 19. That was the first day of a three-day plan transmitted to the rover as a combined set of weekend instructions. During the preceding week, engineers at NASA’s Jet Propulsion Laboratory had sent Opportunity and Spirit an upgrade of the rovers’ software, onboard intelligence the rovers use for carrying out day-to-day commands.

The new record exceeded a two-week old former best by 13 percent. As on all previous long drives by either rover, the traverse began with “blind” driving, in which the rover followed a route determined in advance by rover planners at JPL using stereo images. That portion lasted an hour and covered most of the day’s distance. Then Opportunity switched to “autonomous” driving for two and a half hours, pausing every 2 meters (6.6 feet) to look ahead for obstacles as it chose its own route ahead.

The next day, Opportunity used its new software to start another drive navigating for itself. “This is the first time either rover has picked up on a second day with continued autonomous driving,” said Dr. Mark Maimone, rover mobility software engineer at JPL. “It’s good to sit back and let the rover do the driving for us.”

Not only did Opportunity avoid obstacles for four hours of driving, it covered more ground than a football field. Opportunity has a favorable power situation, due to relatively clean solar panels and increasing minutes of daylight each day as spring approaches in Mars’ southern hemisphere. This allows several hours of operations daily.

On the third day of the three-day plan, the robotic geologist continued navigating itself and drove even farther, 109 meters (357 feet), pushing the three-day total to 390 meters (nearly a quarter mile). In one long weekend, Opportunity covered a distance equivalent to more than half of the 600 meters that had been part of each rover’s original mission-success criteria during their first three months on Mars.

Opportunity has now driven 3,014 meters (1.87 miles) since landing; Spirit even farther, 4,157 meters (2.58 miles). Opportunity is heading south toward a rugged landscape called “etched terrain,” where it might find exposures of deeper layers of bedrock than it has seen so far. Spirit is climbing “Husband Hill,” with a pause on a ridge overlooking a valley north of the summit to see whether any potential targets below warrant a side trip.

As Spirit struggled up the slope approaching the ridgeline, the rover’s wheels churned up soil that grabbed scientists’ attention. “This was an absolutely serendipitous discovery,” said Dr. Steve Squyres of Cornell University, Ithaca, N.Y., principal investigator for the rovers’ science instruments. “We said, ‘My gosh, that soil looks very bright. Before we go away, we should at least take a taste.”

The bright patch of disturbed soil, dubbed “Paso Robles,” has the highest salt concentration of any rock or soil ever examined on Mars. Combined information gained from inspecting it with Spirit’s three spectrometers and panoramic camera suggests its main ingredient is an iron sulfate salt with water molecules bound into the mineral. The soil patch is also rich in phosphorus, but not otherwise like a high-phosphorus rock, called “Wishstone,” that Spirit examined in December. “We’re still trying to work out what this means, but clearly, with this much salt around, water had a hand here,” Squyres said.

Meanwhile, scientists are re-calibrating data from both rovers’ alpha particle X-ray spectrometers. These instruments are used to assess targets’ elemental composition. The sensor heads for the two instruments were switched before launch. Therefore, data that Opportunity’s spectrometer has collected have been analyzed using calibration files for Spirit’s, and vice-versa. Fortunately, because the sensor heads are nearly identical, the effect on the elemental abundances determined by the instruments was very small. The scientists have taken this opportunity to go back and review the results for the mission so far and re-compute using correct calibration files. “The effect in all cases was less than the uncertainties in results, so none of our science conclusions are affected,” Squyres said.

JPL, a division of the California Institute of Technology in Pasadena, has managed NASA’s Mars Exploration Rover project since it began in 2000. Images and additional information about the rovers and their discoveries are available on the Internet at http://www.nasa.gov/vision/universe/solarsystem/mer_main.html and http://marsrovers.jpl.nasa.gov.

Original Source: NASA/JPL News Release

Posted on by Fraser Cain

Galaxy Headed for a Cosmic Collision

What happens when a galaxy falls in with the wrong crowd? The irregular galaxy NGC 1427A is a spectacular example of the resulting stellar rumble. Under the gravitational grasp of a large gang of galaxies, called the Fornax cluster, the small bluish galaxy is plunging headlong into the group at 600 kilometers per second or nearly 400 miles per second.

NGC 1427A, which is located some 62 million light-years away from Earth in the direction of the constellation Fornax, shows numerous hot, blue stars in this newly released image obtained by the Hubble Space Telescope. These blue stars have been formed very recently, showing that star formation is occurring extensively throughout the galaxy.

Galaxy clusters, like the Fornax cluster, contain hundreds or even thousands of individual galaxies. Within the Fornax cluster, there is a considerable amount of gas lying between the galaxies. When the gas within NGC 1427A collides with the Fornax gas, it is compressed to the point that it starts to collapse under its own gravity. This leads to formation of the myriad of new stars seen across NGC 1427A, which give the galaxy an overall arrowhead shape that appears to point in the direction of the galaxy’s high-velocity motion. The tidal forces of nearby galaxies in the cluster may also play a role in triggering star formation on such a massive scale.

NGC 1427A will not survive long as an identifiable galaxy passing through the cluster. Within the next billion years, it will be completely disrupted, spilling its stars and remaining gas into intergalactic space within the Fornax cluster.

To the upper left of NGC 1427A is a background galaxy that happens to lie near Hubble’s line of sight but is some 25 times further away. In contrast to the irregularly shaped NGC 1427A, the background galaxy is a magnificent spiral, somewhat similar to our own Milky Way. Stars are forming in its symmetric pinwheel-shaped spiral arms, which can be traced into the galaxy’s bright nucleus. This galaxy is, however, less dominated by very young stars than NGC 1427A, giving it an overall yellower color. At even greater distances background galaxies of various shapes and colors are scattered across the Hubble image.

The Hubble Space Telescope’s Advanced Camera for Surveys was used to obtain images of NGC 1427A in visible (green), red, and infrared filters in January 2003. These images were then combined by the Hubble Heritage team to create the color rendition shown here. Astronomers are using the data to investigate the star-formation patterns throughout the object, to verify a prediction that there should be a relation between the ages of stars and their positions within the galaxy. This will help them understand how the gravitational influence of the cluster has affected the internal workings of this galaxy, and how this galaxy has responded to passing through the cluster environment.

The disruption of objects like NGC 1427A, and even larger galaxies like our own Milky Way, is an integral part of the formation and evolution of galaxy clusters. Such events are believed to have been very common during the early evolution of the universe, but the rate of galaxy destruction is tapering off at the present time. Thus the impending destruction of NGC 1427A provides a glimpse of an early and much more chaotic time in our universe.

Original Source: Hubble News Release

Posted on by Fraser Cain

Jupiter-Sized Star Found

An international team of astronomers have accurately determined the radius and mass of the smallest core-burning star known until now.

The observations were performed in March 2004 with the FLAMES multi-fibre spectrograph on the 8.2-m VLT Kueyen telescope at the ESO Paranal Observatory (Chile). They are part of a large programme aimed at measuring accurate radial velocities for sixty stars for which a temporary brightness “dip” has been detected during the OGLE survey.

The astronomers find that the dip seen in the light curve of the star known as OGLE-TR-122 is caused by a very small stellar companion, eclipsing this solar-like star once every 7.3 days.

This companion is 96 times heavier than planet Jupiter but only 16% larger. It is the first time that direct observations demonstrate that stars less massive than 1/10th of the solar mass are of nearly the same size as giant planets. This fact will obviously have to be taken into account during the current search for transiting exoplanets.

In addition, the observations with the Very Large Telescope have led to the discovery of seven new eclipsing binaries, that harbour stars with masses below one-third the mass of the Sun, a real bonanza for the astronomers.

The OGLE Survey
When a planet happens to pass in front of its parent star (as seen from the Earth), it blocks a small fraction of the star’s light from our view [1].

These “planetary transits” are of great interest as they allow astronomers to measure in a unique way the mass and the radius of exoplanets. Several surveys are therefore underway which attempt to find these faint signatures of other worlds.

One of these programmes is the OGLE survey which was originally devised to detect microlensing events by monitoring the brightness of a very large number of stars over extended time intervals. During the past years, it has also included a search for periodic, very shallow “dips” in the brightness of stars, caused by the regular transit of small orbiting objects (small stars, brown dwarfs [2] or Jupiter-size planets). The OGLE team has since announced 177 “planetary transit candidates” from their survey of several hundred thousand stars in three southern sky fields, one in the direction of the Galactic Centre, another within the Carina constellation and the third within the Centaurus/Musca constellations.

The nature of the transiting object can however only be established by subsequent radial-velocity observations of the parent star. The size of the velocity variations (the amplitude) is directly related to the mass of the companion object and therefore allows discrimination between stars and planets as the cause of the observed brightness “dip”.

A Bonanza of Low-Mass Stars
An international team of astronomers [3] has made use of the 8.2-m VLT Kueyen telescope for this work. Profiting from the multiplex capacity of the FLAMES/UVES facility that permits to obtain high-resolution spectra of up to 8 objects simultaneously, they have looked at 60 OGLE transit candidate stars, measuring their radial velocities with an accuracy of about 50 m/s [4].

This ambitious programme has so far resulted in the discovery of five new transiting exoplanets (see, e.g., ESO PR 11/04 for the announcement of two of those).

Most of the other transit candidates identified by OGLE have turned out to be eclipsing binaries, that is, in most cases common, small and low-mass stars passing in front of a solar-like star. This additional wealth of data on small and light stars is a real bonanza for the astronomers.

Constraining the Relation Between Mass and Radius
Low-mass stars are exceptionally interesting objects, also because the physical conditions in their interiors have much in common with those of giant planets, like Jupiter in our solar system. Moreover, a determination of the sizes of the smallest stars provides indirect, crucial information about the behaviour of matter under extreme conditions [5].

Until recently, very few observations had been made and little was known about low-mass stars. At this moment, exact values of the radii are known only for four stars with masses less than one-third of the mass of the Sun (cf. ESO PR 22/02 for measurements made with the Very Large Telescope Interferometer) and none at all for masses below one-eighth of a solar mass.

This situation is now changing dramatically. Indeed, observations with the Very Large Telescope have so far led to the discovery of seven new eclipsing binaries, that harbour stars with masses below one-third the mass of the Sun.

This new set of observations thus almost triples the number of low-mass stars for which precise radii and masses are known. And even better – one of these stars now turns out to be the smallest known!

Planet-Sized Stars
The newly found stellar gnome is the companion of OGLE-TR-122, a rather remote star in the Milky Way galaxy, seen in the direction of the southern constellation Carina.

The OGLE programme revealed that OGLE-TR-122 experiences a 1.5 per cent brightness dip once every 7 days 6 hours and 27 minutes, each time lasting just over 3 hours (about 188 min). The FLAMES/UVES measurements, made during 6 nights in March 2004, reveal radial velocity variations of this period with an amplitude of about 20 km/s. This is the clear signature of a very low-mass star, close to the Hydrogen-burning limit, orbiting OGLE-TR-122. This companion received the name OGLE-TR-122b.

As Fran?ois Bouchy of the Observatoire Astronomique Marseille Provence (France) explains: “Combined with the information collected by OGLE, our spectroscopic data now allow us to determine the nature of the more massive star in the system, which appears to be solar-like”.

This information can then be used to determine the mass and radius of the much smaller companion OGLE-TR-122b. Indeed, the depth (brightness decrease) of the transit gives a direct estimate of the ratio between the radii of the two stars, and the spectroscopic orbit provides a unique value of the mass of the companion, once the mass of the larger star is known.

The astronomers find that OGLE-TR-122b weighs one-eleventh of the mass of the Sun and has a diameter that is only one-eighth of the solar one. Thus, although the star is still 96 times as massive as Jupiter, it is only 16% larger than this giant planet!

A Dense Star
“Imagine that you add 95 times its own mass to Jupiter and nevertheless end up with a star that is only slightly larger”, suggests Claudio Melo from ESO and member of the team of astronomers who made the study. “The object just shrinks to make room for the additional matter, becoming more and more dense.”

The density of such a star is more than 50 times the density of the Sun.

“This result shows the existence of stars that look strikingly like planets, even from close by”, emphasizes Frederic Pont of the Geneva Observatory (Switzerland). “Isn’t it strange to imagine that even if we were to receive images from a future space probe approaching such an object at close range, it wouldn’t be easy to discern whether it is a star or a planet?”

As all stars, OGLE-TR-122b produces indeed energy in its interior by means of nuclear reactions. However, because of its low mass, this internal energy production is very small, especially compared to the energy produced by its solar-like companion star.

Not less striking is the fact that exoplanets which are orbiting very close to their host star, the so-called “hot Jupiters”, have radii which may be larger than the newly found star. The radius of exoplanet HD209458b, for example, is about 30% larger than that of Jupiter. It is thus substantially larger than OGLE-TR-122b!

Masqueraders
This discovery also has profound implications for the ongoing search for exoplanets. These observations clearly demonstrate that some stellar objects can produce precisely the same photometric signals (brightness changes) as transiting Jupiter-like planets [6]. What’s more, the present study has shown that such stars are not rare.

Stars like OGLE-TR-122b are thus masqueraders among giant exoplanets and the outermost care is required to differentiate them from their planetary cousins. Uncovering such small stars can only be done with follow-up high-resolution spectral measurements with the largest telescopes. There is more work ahead for the Very Large Telescope!

More information
The information contained in this press release is based on a research article to appear soon as a Letter to the Editor in the leading research journal “Astronomy & Astrophysics” (“A planet-sized transiting star around OGLE-TR-122” by F. Pont et al.). The paper is available in PDF format on the A&A website.

Notes
[1]: Brown dwarfs, or “failed stars”, are objects which are up to 75 times more massive than Jupiter. They are too small for major nuclear fusion processes to have ignited in its interior.

[2]: The radius of a Jupiter-size planet is about 10 times smaller than that of a solar-type star, i.e. it covers about 1/100 of the surface of that star and hence it blocks about 1 % of the stellar light during the transit.

[3]: The team consists of Fr?d?ric Pont, Michel Mayor, Didier Queloz and St?phane Udry of the Geneva Observatory in Switzerland, Claudio Melo of ESO-Chile, Fran?ois Bouchy at Observatoire Astronomique Marseille Provence in France, and Nuno Santos of the Lisbon Astronomical Observatory, Portugal.

[4]: This amounts to measuring a speed of 180 km/h. By comparison, the motion of the Sun induced by Jupiter is about 13 m/s or 47 km/h. This motion is proportional to the mass of the planet and inversely proportional to the square root of its distance from the star.

[5]: For a normal star like the Sun whose matter behaves like a perfect gas, the stellar size is proportional to the mass. However, for low-mass stars, quantum effects become important and the stellar matter becomes “degenerate”, resisting compression much more than does a perfect gas. For objects with a mass below 75 times the mass of Jupiter, i.e. brown dwarfs, the matter is fully degenerate and their size does not depend on the mass.

[6]: Note that a distant transiting object – star or planet – will always produce a brightness “dip”, however bright it is itself. Before and after the transit, the recorded brightness equals the sum of the brightness of the central star and that of the orbiting object. During the transit, the recorded brightness is this sum minus the light emitted by that part of the central star that is obscured.

Original Source: ESO News Release

Posted on by Fraser Cain

Giant Planets Created Primitive Meteorites

Scientists now believe that the formation of Jupiter, the heavy-weight champion of the Solar System?s planets, may have spawned some of the tiniest and oldest constituents of our Solar System?millimeter-sized spheres called chondrules, the major component of primitive meteorites. The study, by theorists Dr. Alan Boss of the Carnegie Institution and Prof. Richard H. Durisen of Indiana University, is published in the March 10, 2005, issue of The Astrophysical Journal (Letters).

?Understanding what formed the chondrules has been one of the biggest problems in the field for over a century,? commented Boss. ?Scientists realized several years ago that a shock wave was probably responsible for generating the heat that cooked these meteoritic components. But no one could explain convincingly how the shock front was generated in the solar nebula some 4.6 billion years ago. These latest calculations show how a shock front could have formed as a result of spiral arms roiling the solar nebula at Jupiter?s orbit. The shock front extended into the inner solar nebula, where the compressed gas and radiation heated the dust particles as they struck the shock front at 20,000 mph, thereby creating chondrules,? he explained.

?This calculation has probably removed the last obstacle to acceptance of how chondrules were melted,? remarked theorist Dr. Steven Desch of Arizona State University, who showed several years ago that shock waves could do the job. ?Meteoriticists have recognized that the ways chondrules are melted by shocks are consistent with everything we know about chondrules. But without a proven source of shocks, they have remained mostly unconvinced about how chondrules were melted. The work of Boss and Durisen demonstrates that our early solar nebula experienced the right types of shocks, at the right times, and at the right places in the nebula to melt chondrules. I think for many meteoriticists, this closes the deal. With nebular shocks identified as the culprit, we can finally begin to understand what the chondrules are telling us about the earliest stages of our Solar System’s evolution,? he concluded.

?Our calculation shows how the 3-dimensional gravitational forces associated with spiral arms in a gravitationally unstable disk at Jupiter?s distance from the Sun (5 times the Earth-Sun distance), would produce a shock wave in the inner solar system (2.5 times the Earth-Sun distance, i.e., in the asteroid belt),? Boss continued. ?It would have heated dust aggregates to the temperature required to melt them and form tiny droplets.? Durisen and his research group at Indiana have independently made calculations of gravitationally unstable disks that also support this picture.

While Boss is well known as a proponent of the rapid formation of gas giant planets by the disk instability process, the same argument for chondrule formation works for the slower process of core accretion. In order to make Jupiter in either process, the solar nebula had to have been at least marginally gravitationally unstable, so that it would have developed spiral arms early on and resembled a spiral galaxy. Once Jupiter formed by either mechanism, it would have continued to drive shock fronts at asteroidal distances, at least so long as the solar nebula was still around. In both cases, chondrules would have been formed at the very earliest times, and continued to form for a few million years, until the solar nebula disappeared. Late-forming chondrules are thus the last grin of the Cheshire Cat that formed our planetary system.

Boss?s research is supported in part by the NASA Planetary Geology and Geophysics Program and the NASA Origins of Solar Systems Program. The calculations were performed on the Carnegie Alpha Cluster, the purchase of which was supported in part by the NSF Major Research Instrumentation Program. Durisen?s research was also supported in part by the NASA Origins of Solar Systems Program.

Original Source: Carnegie Institute News Release

What is the biggest planet?

Posted on by Fraser Cain

Young Star Has Grown Up Quickly

Something weird is happening inside a nearby stellar nursery. An embryonic star is giving off a healthy glow?in X-rays. Like a precocious child, the developing star (protostar) is far too young for that kind of behavior.

New stars are born when a cloud of dust and gas in interstellar space collapses under its own gravity, or so we thought. The strange behavior of this protostar reveals that something else might help gravity turn a bunch of gas and dust into a star.

Scientists have pierced through a dusty stellar nursery to capture the earliest and most detailed view of a collapsing gas cloud turning into a star, analogous to a baby’s first ultrasound.

The observation, made primarily with the European Space Agency’s XMM-Newton observatory, suggests that some unrealized, energetic process — likely related to magnetic fields — is superheating the surface of the cloud core, nudging the cloud ever closer to becoming a star.

The observation marks the first clear detection of X-rays from a nascent yet frigid precursor to a star, called a Class 0 protostar, far earlier in a star’s evolution than most experts in this field thought possible. X-rays are produced in space by processes that release a lot of energy and heat. The surprise detection of X-rays from such a cold object reveals that matter is falling toward the protostar core 10 times faster than expected from gravity alone.

“We are seeing star formation at its embryonic stage,” said Dr. Kenji Hamaguchi, a NASA-funded researcher at NASA’s Goddard Space Flight Center in Greenbelt, Md., lead author on a report in The Astrophysical Journal. “Previous observations have captured the shape of such gas clouds but have never been able to peer inside. The detection of X-rays this early indicates that gravity alone is not the only force shaping young stars.”

Supporting data came from NASA’s Chandra X-ray Observatory, Japan’s Subaru telescope in Hawaii, and the University of Hawaii 88-inch telescope.

Hamaguchi’s team discovered X-rays from a Class 0 protostar in the R Corona Australis star-forming region, about 500 light years from Earth.

Class 0 is the youngest class of protostellar object, about 10,000 to 100,000 years into the assimilation process. The cloud temperature is about 400 degrees below zero Fahrenheit (minus 240 Celsius). After a few million years, nuclear fusion ignites at the center of the collapsing protostellar cloud, and a new star is formed.

The team speculates that magnetic fields in the spinning protostar core accelerate infalling matter to high speeds, producing high temperatures and X-rays in the process. These X- rays can penetrate the dusty region to reveal the core.

“This is no gentle freefall of gas,” said Dr. Michael Corcoran of NASA Goddard, a co-author on the report. “The X-ray emission shows that forces appear to be accelerating matter to high speeds, heating regions of this cold gas cloud to 100 million degrees Fahrenheit. The X-ray emission from the core gives us a window to probe the hidden processes by which cold gas clouds collapse to stars.”

Hamaguchi likened the generation of X-rays in the Class 0 protostar to what happens during solar flares on our Sun. The solar surface has lots of magnetic loops, which sometimes get tangled and release large amounts of energy. This energy can accelerate electrically-charged particles (electrons and ionized atoms) to velocities of 7 million miles an hour. The particles smash against the solar surface and create X-rays. Similarly tangled magnetic fields might be responsible for X-rays observed by Hamaguchi and his collaborators.

The detection of magnetic fields from an extremely young Class 0 protostar provides a crucial link in understanding the star formation process, because magnetic field loops are believed to play a critical role in moderating the cloud collapse. Only electrically-charged particles, called ions, respond to magnetic fields. The scientists are not sure where the magnetic fields or ions come from. However, X-rays will ionize atoms, creating more ions to be accelerated through magnetic activity and create more X-rays.

The team used XMM-Newton for its powerful light-collecting capability, necessary for this type of observation where so few X-rays penetrate the dusty region, and the exquisite resolving power of Chandra to pinpoint the X-ray source position. The team used the infrared Subaru telescope to determine the protostar’s age.

“The age is based on a well-established chart of spectra, or characteristics of the infrared light, as the protostar evolves over the course of a million years,” said Ko Nedachi, a doctoral student at the University of Tokyo who led the Subaru observation.

The science team also includes Drs. Rob Petre and Nicholas White of NASA Goddard, Dr. Beate Stelzer of the Astronomy Observatory in Palermo, Italy, and Dr. Naoto Kobayashi of University of Tokyo. Kenji Hamaguchi is funded through the National Research Council; Michael Corcoran is funded through Universities Space Research Association.

Original Source: NASA News Release

Posted on by Fraser Cain

Young Universe Was Surprisingly Structured

Combining observations with ESO’s Very Large Telescope and ESA’s XMM-Newton X-ray observatory, astronomers have discovered the most distant, very massive structure in the Universe known so far.

It is a remote cluster of galaxies that is found to weigh as much as several thousand galaxies like our own Milky Way and is located no less than 9,000 million light-years away.

The VLT images reveal that it contains reddish and elliptical, i.e. old, galaxies. Interestingly, the cluster itself appears to be in a very advanced state of development. It must therefore have formed when the Universe was less than one third of its present age.

The discovery of such a complex and mature structure so early in the history of the Universe is highly surprising. Indeed, until recently it would even have been deemed impossible.

Serendipitous discovery
Clusters of galaxies are gigantic structures containing hundreds to thousands of galaxies. They are the fundamental building blocks of the Universe and their study thus provides unique information about the underlying architecture of the Universe as a whole.

About one-fifth of the optically invisible mass of a cluster is in the form of a diffuse, very hot gas with a temperature of several tens of millions of degrees. This gas emits powerful X-ray radiation and clusters of galaxies are therefore best discovered by means of X-ray satellites (cf. ESO PR 18/03 and 15/04).

It is for this reason that a team of astronomers [1] has initiated a search for distant, X-ray luminous clusters “lying dormant” in archive data from ESA’s XMM-Newton satellite observatory.

Studying XMM-Newton observations targeted at the nearby active galaxy NGC 7314, the astronomers found evidence of a galaxy cluster in the background, far out in space. This source, now named XMMU J2235.3-2557, appeared extended and very faint: no more than 280 X-ray photons were detected over the entire 12 hour-long observations.

A Mature Cluster at Redshift 1.4
Knowing where to look, the astronomers then used the European Southern Observatory’s Very Large Telescope (VLT) at Paranal (Chile) to obtain images in the visible wavelength region. They confirmed the nature of this cluster and it was possible to identify 12 comparatively bright member galaxies on the images (see ESO PR Photo 05b/05).

The galaxies appear reddish and are of the elliptical type. They are full of old, red stars. All of this indicates that these galaxies are already several thousand million years old. Moreover, the cluster itself has a largely spherical shape, also a sign that it is already a very mature structure.

In order to determine the distance of the cluster – and hence its age – Christopher Mullis, former European Southern Observatory post-doctoral fellow and now at the University of Michigan in the USA, and his colleagues used again the VLT, now in the spectroscopic mode. By means of one of the FORS multi-mode instruments, the astronomers zoomed-in on the individual galaxies in the field, taking spectral measurements that reveal their overall characteristics, in particular their redshift and hence, distance [2].

The FORS instruments are among the most efficient and versatile available anywhere for this delicate work, obtaining on the average quite detailed spectra of 30 or more galaxies at a time.

The VLT data measured the redshift of this cluster as 1.4, indicating a distance of 9,000 million light-years, 500 million light years farther out than the previous record holding cluster.

This means that the present cluster must have formed when the Universe was less than one third of its present age. The Universe is now believed to be 13,700 million years old.

“We are quite surprised to see that a fully-fledged structure like this could exist at such an early epoch,” says Christopher Mullis. “We see an entire network of stars and galaxies in place, just a few thousand million years after the Big Bang”.

“We seem to have underestimated how quickly the early Universe matured into its present-day state,” adds Piero Rosati of ESO, another member of the team. “The Universe did grow up fast!”

Towards a Larger Sample
This discovery was relative easy to make, once the space-based XMM and the ground-based VLT observations were combined. As an impressive result of the present pilot programme that is specifically focused on the identification of very distant galaxy clusters, it makes the astronomers very optimistic about their future searches. The team is now carrying out detailed follow-up observations both from ground- and space-based observatories. They hope to find many more exceedingly distant clusters, which would then allow them to test competing theories of the formation and evolution of such large structures.

“This discovery encourages us to search for additional distant clusters by means of this very efficient technique,” says Axel Schwope, team leader at the Astrophysical Institute Potsdam (Germany) and responsible for the source detection from the XMM-Newton archival data. Hans B?hringer of the Max Planck Institute for Extraterrestrial Physics (MPE) in Garching, another member of the team, adds: “Our result also confirms the great promise inherent in other facilities to come, such as APEX (Atacama Pathfinder Experiment) at Chajnantor, the site of the future Atacama Large Millimeter Array. These intense searches will ultimately place strong constraints on some of the most fundamental properties of the Universe.”

Notes
[1]: The team is composed of Chris Mullis (University of Michigan, USA), Piero Rosati (ESO Garching, Germany), Georg Lamer and Axel Schwope (Astrophysical Institute, Postdam, Germany), Hans B?hringer, Rene Fassbender, and Peter Schuecker (Max-Planck Institute for Extra-terrestrial Physics, Garching, Germany).

[2]: In astronomy, the “redshift” denotes the fraction by which the lines in the spectrum of an object are shifted towards longer wavelengths. Since the redshift of a cosmological object increases with distance, the observed redshift of a remote galaxy also provides an estimate of its distance.

Original Source: ESO News Release

Posted on by Fraser Cain

Spitzer Finds Hidden Galaxies

How do you hide something as big and bright as a galaxy? You smother it in cosmic dust. NASA’s Spitzer Space Telescope saw through such dust to uncover a hidden population of monstrously bright galaxies approximately 11 billion light-years away.

These strange galaxies are among the most luminous in the universe, shining with the equivalent light of 10 trillion suns. But, they are so far away and so drenched in dust, it took Spitzer’s highly sensitive infrared eyes to find them.

“We are seeing galaxies that are essentially invisible,” said Dr. Dan Weedman of Cornell University, Ithaca, N.Y., co-author of the study detailing the discovery, published in today’s issue of the Astrophysical Journal Letters. “Past infrared missions hinted at the presence of similarly dusty galaxies over 20 years ago, but those galaxies were closer. We had to wait for Spitzer to peer far enough into the distant universe to find these.”

Where is all this dust coming from? The answer is not quite clear. Dust is churned out by stars, but it is not known how the dust wound up sprinkled all around the galaxies. Another mystery is the exceptional brightness of the galaxies. Astronomers speculate that a new breed of unusually dusty quasars, the most luminous objects in the universe, may be lurking inside. Quasars are like giant light bulbs at the centers of galaxies, powered by huge black holes.

Astronomers would also like to determine whether dusty, bright galaxies like these eventually evolved into fainter, less murky ones like our own Milky Way. “It’s possible stars like our Sun grew up in dustier, brighter neighborhoods, but we really don’t know. By studying these galaxies, we’ll get a better idea of our own galaxy’s history,” said Cornell’s Dr. James Houck, lead author of the study.

The Cornell-led team first scanned a portion of the night sky for signs of invisible galaxies using an instrument on Spitzer called the multiband imaging photometer. The team then compared the thousands of galaxies seen in this infrared data to the deepest available ground-based optical images of the same region, obtained by the National Optical Astronomy Observatory Deep Wide-Field Survey. This led to identification of 31 galaxies that can be seen only by Spitzer. “This large area took us many months to survey from the ground,” said Dr. Buell Jannuzi, co-principal investigator for the Deep Wide-Field Survey, “so the dusty galaxies Spitzer found truly are needles in a cosmic haystack.”

Further observations using Spitzer’s infrared spectrograph revealed the presence of silicate dust in 17 of these 31 galaxies. Silicate dust grains are planetary building blocks like sand, only smaller. This is the furthest back in time that silicate dust has been detected around a galaxy. “Finding silicate dust at this very early epoch is important for understanding when planetary systems like our own arose in the evolution of galaxies,” said Dr. Thomas Soifer, study co-author, director of the Spitzer Science Center, Pasadena, Calif., and professor of physics at the California Institute of Technology, also in Pasadena.

This silicate dust also helped astronomers determine how far away the galaxies are from Earth. “We can break apart the light from a distant galaxy using a spectrograph, but only if we see a recognizable signature from a mineral like silicate, can we figure out the distance to that galaxy,” Soifer said.

In this case, the galaxies were dated back to a time when the universe was only three billion years old, less than one-quarter of its present age of 13.5 billion years. Galaxies similar to these in dustiness, but much closer to Earth, were first hinted at in 1983 via observations made by the joint NASA-European Infrared Astronomical Satellite. Later, the European Space Agency’s Infrared Space Observatory faintly recorded comparable, nearby objects. It took Spitzer’s improved sensitivity, 100 times greater than past missions, to finally seek out the dusty galaxies at great distances.

The National Optical Astronomy Observatory Deep Wide-Field Survey used the National Science Foundation’s 4-meter (13-foot) telescope at Kitt Peak National Observatory, located southwest of Tucson, Ariz.

NASA’s Jet Propulsion Laboratory, Pasadena, Calif., manages the Spitzer Space Telescope mission for NASA’s Science Mission Directorate, Washington, D.C. Science operations are conducted at the Spitzer Science Center. JPL is a division of Caltech. The infrared spectrograph was built by Ball Aerospace Corporation, Boulder, Colo., and Cornell; its development was led by Houck. The multiband imaging photometer was built by Ball Aerospace Corporation, the University of Arizona, Tucson, Ariz., and Boeing North American, Canoga Park, Calif.; its development was led by Dr. George Rieke of the University of Arizona.

The Infrared Astronomical Satellite was a joint effort between NASA, the Science and Engineering Research Council, United Kingdom and the Netherlands Agency for Aerospace Programmes, the Netherlands.

Artist’s conceptions, images and additional information about the Spitzer Space Telescope are available at http://www.spitzer.caltech.edu.

Original Source: Spitzer News Release

Posted on by Fraser Cain

Jupiter’s Auroras Helped by Io

Scientists have obtained new insight into the unique power source for many of Jupiter’s auroras, the most spectacular and active auroras in the Solar System. Extended monitoring of the giant planet with NASA’s Chandra X-ray Observatory detected the presence of highly charged particles crashing into the atmosphere above its poles.

X-ray spectra measured by Chandra showed that the auroral activity was produced by ions of oxygen and other elements that were stripped of most of their electrons. This implies that these particles were accelerated to high energies in a multimillion-volt environment above the planet’s poles. The presence of these energetic ions indicates that the cause of many of Jupiter’s auroras is different from auroras produced on Earth or Saturn.

“Spacecraft have not explored the region above the poles of Jupiter, so X-ray observations provide one of the few ways to probe that environment,” said Ron Elsner of the NASA Marshall Space Center in Huntsville, Alabama, and lead author on a recently published paper describing these results in the Journal for Geophysical Research. “These results will help scientists to understand the mechanism for the power output from Jupiter’s auroras, which are a thousand times more powerful than those on Earth.”

Electric voltages of about 10 million volts, and currents of 10 million amps – a hundred times greater than the most powerful lightning bolts – are required to explain the X-ray observations. These voltages would also explain the radio emission from energetic electrons observed near Jupiter by the Ulysses spacecraft.

On Earth, auroras are triggered by solar storms of energetic particles, which disturb Earth’s magnetic field. Gusts of particles from the Sun can also produce auroras on Jupiter, but unlike Earth, Jupiter has another way of producing auroras. Jupiter’s rapid rotation, intense magnetic field, and an abundant source of particles from its volcanically active moon, Io, create a huge reservoir of electrons and ions. These charged particles, trapped in Jupiter’s magnetic field, are continually accelerated down into the atmosphere above the polar regions where they collide with gases to produce the aurora, which are almost always active on Jupiter.

If the particles responsible for the aurora came from the Sun, they should have been accompanied by large number of protons, which would have produced an intense ultraviolet aurora. Hubble ultraviolet observations made during the Chandra monitoring period showed relatively weak ultraviolet flaring. The combined Chandra and Hubble data indicate that this auroral activity was caused by the acceleration of charged ions of oxygen and other elements trapped in the polar magnetic field high above Jupiter’s atmosphere.

Chandra observed Jupiter in February 2003 for four rotations of the planet (approximately 40 hours) during intense auroral activity. These Chandra observations, taken with its Advanced CCD Imaging Spectrometer, were accompanied by one-and-a-half hours of Hubble Space Telescope observations at ultraviolet wavelengths.

The research team also included Noe Lugaz, Hunter Waite, and Tariq Majeed (University of Michigan, Ann Arbor), Thomas Cravens (University of Kansas, Lawrence), Randy Gladstone (Southwest Research Institute, San Antonio, Texas), Peter Ford (Massachusetts Institute of Technology, Cambridge), Denis Grodent (University of Liege, Belgium), Anil Bhardwaj (Marshall Space Flight Center) and Robert MacDowell and Michael Desch (Goddard Space Flight Center, Greenbelt, Md.)

NASA’s Marshall Space Flight Center, Huntsville, Ala., manages the Chandra program for NASA’s Office of Space Science, Washington. Northrop Grumman of Redondo Beach, Calif., formerly TRW, Inc., was the prime development contractor for the observatory. The Smithsonian Astrophysical Observatory controls science and flight operations from the Chandra X-ray Center in Cambridge, Mass.

Additional information and images are available at: http://chandra.harvard.edu and http://chandra.nasa.gov

Original Source: Chandra News Release

Posted on by Fraser Cain

Are We Alone?

Image Credit: “Seeking” ?1998
Lynette Cook. Used with Permission.
“All truth passes through three stages. First, it is ridiculed. Second, it is violently opposed. Third, it is accepted as being self-evident.”
– German philosopher Arthur Schopenhauer (1788 – 1860)

Are we alone? Given the immensity of the Cosmos, a mathematical impossibility. Will we ever come to know we are not alone? That’s a tougher question. But should first contact occur today we could be in for a shock1. So right now may be a good time to prepare. And perhaps the best way to prepare is to imagine the possibility…

Numerous psychological studies have shown that “imagining a thing” makes us more receptive to the possibility. In fact many of the great breakthroughs in scientific thought came about as a result of the proper use of the creative imagination. Sir Isaac Newton saw the motions of all moons and planets everywhere in the simple fall of a ripe apple from the boughs of a tree. Albert Einstein perceived the relativity of all time and space while contemplating the accelerated motion of a trolley car moving away from the face of a public clocktower. We human beings might want to take a few moments and think about how we will respond should ET make an appearence in our small corner of the cosmos.

So, take a moment and relax. (Yes it’s true, deep breathing does help!) Imagine a universe populated with many and diverse forms of intelligent life. Extend yourself through time and space toward distant systems of suns and planets. See simple organisms thrilling to the rhythms of light and matter working in harmony to develop ever more sophisticated life-forms. Follow the earliest interstellar craft as they move tirelessly from system to system toward some distant beckoning beacon of promise. Surf beams of radiant energy flung like arrows from far away lighthouses upon the Ocean of Space.

Someday such imaginings may be confirmed by rock solid science – perhaps SETI will detect an indisputable signal from beyond, or “Michael Rennie” emerges as an emissary from the Galactic Federation of Planetary Systems trailed by Gort – the Wonder Robot.

Given the likelihood that such space-faring or highly communicative intelligences exist, and given all the billions of years for off-world intelligence to develop the means to travel and communicate, plus our own recent efforts to find them out, why don’t we know already?

One, and possibly the very best answer is “We aren’t ready.”

The human imagination also has its down-side: Imagine the initial shock and ridicule as we humans attempt to upright a world overturned by what for many will be an impossible event. Consider also how governments and institutions, groups and individuals, have responded to similar reports in the past. Remember “Mars-rock”? Do we hear much of it now? And what about pilot Hap Arnold’s “flying saucer” report. Can we really say that we have taken clear-headed, scientific looks at such things? Or is our normal response one of incredulity and ridicule? Hmmmm…

To know is to see truth wherever it may be found. No, we’re not saying that UFO’s have visited the Earth. What we are saying is that our response to those who make such claims is often one of ridicule and disrespect. Is it not possible that compassion and open-mindedness would be more appropriate?

So let’s seek truth where it can be found – right here on Earth. We can start by looking for unsuspected signs of intelligence around us2. Let’s take a clear-eyed look at our animal friends by setting aside prejudices concerning their intelligence. Those goldfish in the aquarium can be surprisingly sensitive about things. Walk near the tank during the day and they ignore you. Come feeding time, and you are the most interesting thing in the world to them.

To be sure we are very unlikely to learn that the universe is suffused with intelligence until we get past our own anthrocentrism. It took a lot of hard work (and self-sacrifice) by Copernicus, Kepler, and Galileo just to get western society to finally step “up to the edge” and see that the Blue Planet is most definitely not flat nor does it act as the axis around which all things celestial swing.

And even with the signs of intelligence abounding on our homeworld today we persist in thinking that all creatures exist for us, our amusement, our purposes. Under such conditions can we possibly appreciate how truly intelligent they are? And to be more germane, do we really think ET might want to come out and play with us under such circumstances?

Today we don’t seem to be ready to accept anything other than the myth of being alone. Yes, one way to tell this does have to do with how we relate to other creatures on the Blue Planet, but there are other reasons to doubt our readiness as well. Consider our political institutions; Why is it that our leaders and their associates spend so much time “down-playing” the truth of things, presenting specious arguments to motivate behavior, or putting controversial issues into the spin cycle? Is it because of hidden political or economic agendas? Or possibly because they don’t believe we can handle reality3?

Meanwhile high overhead, ET approaches the Earth – third stone from the Sun – and initiates a scan of the EM spectrum. Newscasts portray crisis after crisis, violence, conflict, bloodshed, environmental degradation. How would you – an intelligent being from elsewhere respond?

Personally, I’d activate the cloaking device.

ET is no dummy – he/she/it is after all an intelligent life-form possessed of advanced technology. One scan of Earth’s broadcast media and ET soon comes to see that this is not a place to be trifled with: The natives are restless. Emotion overrules reason. Reaction upstages proaction. Nations practice deception and ill-will in relationships – internal and external. Angry voices shout each other down – not just on the streets but in the houses of governance as well. We are not a happy bunch.

And yet the future remains always a bright star of possibility. Hope springs eternal in ET’s breast (or left antibular thorax as the case may be…)

ET of course, has seen such things before. Countless worlds of lesser and greater advancement have been encountered. Before ET learned the wisdom of keeping a safe distance, he-she-it actually tried to help a few troubled worlds such as our own. In the end ET may have had to overcome shock, ignorance, even bloody insurgencies. Costs were great, rewards few. Now ET waits – waits for us to pass certain tests – tests defined in some intragalactic protocol: “The Prime Directive”.

So the hailing frequencies are locked down. ET goes stealth. “Subspace” signals are transmitted to ET Central: “Earthlings are still at it. Planet approaching ecological crisis. Species dying off. The few have much, many have little. Schedule re-visit next solar maximum. Report over and out.”

Today our instruments can peer back to the very threshold of the Big Bang – nearly 13.7 million lightyears distant in time and space, millions and millions of galaxies, billions and billions of Suns. Who knows how many planets – many equal to or superior to our own in fecundity and arability. Some populated as yet only by single-cell organisms. Others by beings possessed of no organic form whatsoever. It doesn’t even take the imagination to see the possibility anymore. Those of us interested in astronomy also read and watch science fiction. All the heavy lifting has been done for us. Fantastic lifeforms dwell in fabulous environs undergoing incredible adventures: Star Trek, Star Wars, Babylon Five – you name it – we’ve seen it. And yes, many of us believe in our hearts – but even so, we want to know.

Even now we scan the heavens seeking proof. The SETI project is bringing its array of parallel narrow-band scanning recievers on line. We hope against hope that some not-too-circumspect intelligence is out there broadcasting narrowband signals intentionally (or not) seeking to conclusively demonstrate their presence in our universe.

Will SETI find them out? And if so, how will we respond to the reality?

It is possible to uncover intelligence in this way, but intelligent life-forms not only learn from experience but in advance of experience as well. Do we here on Earth choose to project our presence intentionally into the interstellar medium4?

No – that particular notion has already been discarded and perhaps wisely so. We know what we are like – others could be worse!

Psychology plays a big role in choices made by intelligent creatures. When they don’t trust others, they “down-play” the truth or offer specious arguments. When they make mistakes, they put things in the “spin cycle”. When they see other intelligences doing these kinds of things with great regularity they know that contact is to be avoided. Perhaps this is at essence in first contact protocol. Until truth is welcomed – even at the expense of notions held dear – a world is not ready. Otherwise the cost of engagement is too high, benefits too low, and outcomes too unpredictable – or worse – dangerous.

But we may detect extraterrestial intelligence in other ways. It’s a solid assumption that all advancing technologies pass through a broadband em broadcast phase. During such an era civilizations “leak” evidence of their existence. Unfortunately, even our largest radio telescope would be hard pressed to detect broadband transmissions – such as Earth’s – from as close as the Alpha Centauri system. Meanwhile the window on em broadcast may even be closing here on earth. How many of us watch television programs delivered by antenna today? Less than a half-century ago every house had its own “rabbit ears”. One-hundred years from now we may be EM mute…

We might also intercept a signal in transit between two worlds. Such an event would be serendipitous – luck would play a huge role. First we would have to be more or less line of sight. Why? Because the tighter such a signal is foused the further it travels without attenuation. Although laser (and maser) transmissions do diffract over great distances, we would still need to be well-placed to pick one up. Meanwhile such signals may not necessarily be narrow band in frequency. Why? Because phase-modulated transmission may be the most efficient way to transmit pictures, sounds, and data across space5.

Despite all these barriers to revelation what practical steps can we now take to prepare for some future “first contact”?

Assisted by writers of science fiction and purveyors of motion pictures, we’ve already made a start by imagining the possibility. Animal behaviorists have helped prepare us by investigating various types and degrees of intelligence in the natural world. Psychologists and socioligists have done the same thing in the realms of our own species.

Meanwhile on an individual basis we can all learn to pay more attention to intelligence as seen within our families, among friends, associates – and even strangers. (Perhaps especially strangers.) All this makes us more aware of what intelligence is and how it is communicated.

On the broadest possible levels we must all further our ability to welcome and speak truth – despite any pain it may leave in its wake.

Having done our own personal work, “homeworld work” can go forward. Collectively we can work together to expunge the seeds and uproot the weeds of war on the planet. Although this means holstering our weapons, it also means overcoming a persistent propensity toward propaganda, religious strife, scientific contention, and undue corporate economic advantage.

And of great importance at this time is the need to be more supportive of other homeworld species – irrespective of intelligence. Ecology teaches us that every creature plays an important role in Earth’s biosphere. Perhaps it should become a matter of human education, demographical planning, economics, and political activity to ensure that this particular insight truly guides our choices and behavior. After all so long as we remain exploitative of lesser species no truly intelligent extraterrerestial species is likely to have much to do with us. Scarier still, if there are any “bad boys” out there, they could easily rationalize “taking over the joint”.

So let’s say we clean up our act. What happens next?

Isn’t that enough? To live in a world where truth multiplies, nature is respected, intelligence is recognized, and peace reigns supreme is actually quite appealing in itself – for most intelligences worthy of interstellar relations.

But this article is not about social transformation per se – it’s about the very real possibility of first contact – something that could transpire even before our children take a leading role in the unfolding story of human history.

Are we ready to get ready?

If intelligence can germinate here, it can flower elsewhere. Why, of course, it’s all so – “self-evident!”

1 The 1997 hit movie “Contact” (based on a novel by Carl Sagan) portrayed the many and varied ways in which human beings responded to scientific proof of the existence of advanced extraterrestrial intelligence.

2 According to a BBC News article a captive African grey parrot named N’kisi has a vocabulary of almost one thousand words, shows evidence of a sense of humour, and devises new words and concocts phrases as needed.

3 Irrespective of its overall merits, US efforts to topple an Iraqi dictatorship were found to be based on overstated evidence. (See Conclusions of Senate’s Iraq report) Such misuses of information often occur when a government is unable to speak plainly to its citizens concerning matters of importance.

4 In an article published by the title Quantum Communication Between the Stars? SETI Institute member Seth Shostak recalls the heated response of England’s Astronomer Royal to the ad hoc messaging of M13 during a 1974 ceremonial at the Arecibo radio telescope in Puerto Rico.

5 The narrower the frequency used to transmit data through space the higher the signal-to-noise ratio. The most efficient mode of such transmission is to digitally switch a carrier frequency “on and off”. Such serial modes of transmission however, are very slow at transfering large amounts of data through space in short amounts of time. Such signals are however very useful for saying things like “look at me I am here!”.

About The Author: Inspired by the early 1900’s masterpiece: “The Sky Through Three, Four, and Five Inch Telescopes”, Jeff Barbour got a start in astronomy and space science at the age of seven. Currently Jeff devotes much of his time observing the heavens and maintaining the website Astro.Geekjoy.