Category: Astronomy

The SuperNova/Acceleration Probe, SNAP. Image credit: Berkeley Lab Click to enlarge
What is the mysterious dark energy that’s causing the expansion of the universe to accelerate? Is it some form of Einstein’s famous cosmological constant, or is it an exotic repulsive force, dubbed “quintessence,” that could make up as much as three-quarters of the cosmos? Scientists from Lawrence Berkeley National Laboratory (Berkeley Lab) and Dartmouth College believe there is a way to find out.

In a paper to be published in Physical Review Letters, physicists Eric Linder of Berkeley Lab and Robert Caldwell of Dartmouth show that physics models of dark energy can be separated into distinct scenarios, which could be used to rule out Einstein’s cosmological constant and explain the nature of dark energy. What’s more, scientists should be able to determine which of these scenarios is correct with the experiments being planned for the Joint Dark Energy Mission (JDEM) that has been proposed by NASA and the U.S. Department of Energy.

“Scientists have been arguing the question ‘how precisely do we need to measure dark energy in order to know what it is?'” says Linder. “What we have done in our paper is suggest precision limits for the measurements. Fortunately, these limits should be within the range of the JDEM experiments.”

Linder and Caldwell are both members of the DOE-NASA science definition team for JDEM, which has the responsibility for drawing up the mission’s scientific requirements. Linder is the leader of the theory group for SNAP ? the SuperNova/Acceleration Probe, one of the proposed vehicles for carrying out the JDEM mission. Caldwell, a professor of physics and astronomy at Dartmouth, is one of the originators of the quintessence concept.

In their paper in Physical Review Letters Linder and Caldwell describe two scenarios, one they call “thawing” and one they call “freezing,” which point toward distinctly different fates for our permanently expanding universe. Under the thawing scenario, the acceleration of the expansion will gradually decrease and eventually come to a stop, like a car when the driver eases up on the gas pedal. Expansion may continue more slowly, or the universe may even recollapse. Under the freezing scenario, acceleration continues indefinitely, like a car with the gas pedal pushed to the floor. The universe would become increasingly diffuse, until eventually our galaxy would find itself alone in space.

Either of these two scenarios rules out Einstein’s cosmological constant. In their paper Linder and Caldwell show, for the first time, how to cleanly separate Einstein’s idea from other possibilities. Under any scenario, however, dark energy is a force that must be reckoned with.

Says Linder, “Because dark energy makes up about 70 percent of the content of the universe, it dominates over the matter content. That means dark energy will govern expansion and, ultimately, determine the fate of the universe.”

In 1998, two research groups rocked the field of cosmology with their independent announcements that the expansion of the universe is accelerating. By measuring the redshift of light from Type Ia supernovae, deep-space stars that explode with a characteristic energy, teams from the Supernova Cosmology Project headquartered at Berkeley Lab and the High-Z Supernova Search Team centered in Australia determined that the expansion of the universe is actually accelerating, not decelerating. The unknown force behind this accelerated expansion was given the name “dark energy.”

Prior to the discovery of dark energy, conventional scientific wisdom held that the Big Bang had resulted in an expansion of the universe that would gradually be slowed down by gravity. If the matter content in the universe provided enough gravity, one day the expansion would stop altogether and the universe would fall back on itself in a Big Crunch. If the gravity from matter was insufficient to completely stop the expansion, the universe would continue floating apart forever.

“From the announcements in 1998 and subsequent measurements, we now know that the accelerated expansion of the universe did not start until sometime in the last 10 billion years,” Caldwell says.

Cosmologists are now scrambling to determine what exactly dark energy is. In 1917 Einstein amended his General Theory of Relativity with a cosmological constant, which, if the value was right, would allow the universe to exist in a perfectly balanced, static state. Although history’s most famous physicist would later call the addition of this constant his “greatest blunder,” the discovery of dark energy has revived the idea.

“The cosmological constant was a vacuum energy (the energy of empty space) that kept gravity from pulling the universe in on itself,” says Linder. “A problem with the cosmological constant is that it is constant, with the same energy density, pressure, and equation of state over time. Dark energy, however, had to be negligible in the universe’s earliest stages; otherwise the galaxies and all their stars would never have formed.”

For Einstein’s cosmological constant to result in the universe we see today, the energy scale would have to be many orders of magnitude smaller than anything else in the universe. While this may be possible, Linder says, it does not seem likely. Enter the concept of “quintessence,” named after the fifth element of the ancient Greeks, in addition to air, earth, fire, and water; they believed it to be the force that held the moon and stars in place.

“Quintessence is a dynamic, time-evolving, and spatially dependent form of energy with negative pressure sufficient to drive the accelerating expansion,” says Caldwell. “Whereas the cosmological constant is a very specific form of energy ? vacuum energy ? quintessence encompasses a wide class of possibilities.”

To limit the possibilities for quintessence and provide firm targets for basic tests that would also confirm its candidacy as the source of dark energy, Linder and Caldwell used a scalar field as their model. A scalar field possesses a measure of value but not direction for all points in space. With this approach, the authors were able to show quintessence as a scalar field relaxing its potential energy down to a minimum value. Think of a set of springs under tension and exerting a negative pressure that counteracts the positive pressure of gravity.

“A quintessence scalar field is like a field of springs covering every point in space, with each spring stretched to a different length,” Linder said. “For Einstein’s cosmological constant, each spring would be the same length and motionless.”

Under their thawing scenario, the potential energy of the quintessence field was “frozen” in place until the decreasing material density of an expanding universe gradually released it. In the freezing scenario, the quintessence field has been rolling towards its minimum potential since the universe underwent inflation, but as it comes to dominate the universe it gradually becomes a constant value.

The SNAP proposal is in research and development by physicists, astronomers, and engineers at Berkeley Lab, in collaboration with colleagues from the University of California at Berkeley and many other institutions; it calls for a three-mirror, 2-meter reflecting telescope in deep-space orbit that would be used to find and measure thousands of Type Ia supernovae each year. These measurements should provide enough information to clearly point towards either the thawing or freezing scenario ? or to something else entirely new and unknown.

Says Linder, “If the results from measurements such as those that could be made with SNAP lie outside the thawing or freezing scenarios, then we may have to look beyond quintessence, perhaps to even more exotic physics, such as a modification of Einstein’s General Theory of Relativity to explain dark energy.”

Original Source: Berkeley Lab News Release

Similar close encounter last November. Image credit: Babak A. Tafreshi Click to enlarge
Something nice is happening in the sunset sky. Venus and Jupiter, the two brightest planets, are converging, and they’re going to be beautifully close together for the next two weeks.

Step outside tonight when the sun goes down and look west. If there are no trees or buildings in the way, you can’t miss Jupiter and Venus. They look like airplanes, hovering near the horizon with their lights on full blast. (Venus is the brighter of the two.) You can see them even from brightly-lit cities.

Try catching the pair just after sundown and just before the first stars appear. Venus and Jupiter pop into view while the sky is still twilight-blue. The scene has a special beauty.

When the sky darkens completely, look to the left of Jupiter for Spica, the brightest star in the constellation Virgo. Although it’s a bright star, Spica is completely outclassed by the two planets.

Venus and Jupiter are converging at the noticeable rate of 1o per day, with closest approach coming on September 1st when the two will be a little more than 1o apart. (How much is 1o? Hold your pinky finger at arm’s length. The tip is about 1o wide.)

When planets are so close together, not only do you notice them, you’ll have a hard time taking your eyes off them. They’re spellbinding.

There’s a biological reason for this phenomenon: In the back of your eye, near the center of the retina, lies a small patch of tissue called “the fovea” where cones are extra-densely packed. “Whatever you see with the fovea, you see in high-definition,” explains Stuart Hiroyasu, O.D., of Bishop, California. “The fovea is critical to reading, driving, watching television; it has the brain’s attention.” The field of view of the fovea is 5o. When two objects converge to, say, 1o as Venus and Jupiter will do, they can beam into your fovea simultaneously, signaling your brain?attention, please!

After September 1st, the two planets separate, but the show’s not over. On September 6th, with Jupiter and Venus still pleasingly close together, the slender crescent Moon will leap up from the sun’s glare and join the two planets. Together, they’ll form a compact triangle that will simply knock your socks off.

Feel like staring? Do.

Original Source: NASA News Release

GALEX , one of the telescopes that will study AE Aqr. Image credit: NASA Click to enlarge
Amateur astronomers are being asked to help a constellation of observatories unravel the mysteries of a puzzling binary star system.

On August 30-August 31, 2005 two space-based and four professional ground-based observatories are scheduled to observe the cataclysmic variable star AE Aqr. Each of the observatories covers a different wavelength of light and amateur astronomers have been asked to help cover the visible-light portion.

“This observing campaign will take place over nearly a full day, and since no single ground-based observatory can observe AE Aqr for that long due to Earth’s rotation, amateur astronomers can make a unique and invaluable contribution to this campaign,” said Dr. Christopher Mauche of Lawrence Livermore National Laboratory, the principal investigator of the project.

Because they are spaced all across the globe, amateur astronomers can observe this star and other celestial objects unhindered by nightfall or weather.

The Chandra and GALEX space telescopes will be working with the HESS, MAGIC, VLT, and VLA ground-based telescopes. Combined, they will provide coverage of AE Aqr from high-energy gamma-rays to low-energy radio waves. Such simultaneous multiwavelength coverage is required to provide the clearest picture of the locations, mass motions, energetics, and inter-relationships of the various emission regions in the star.

AE Aqr is an intermediate polar, a type of cataclysmic variable star. It actually consists of two stars – a red dwarf and rapidly spinning magnetic white dwarf. Material drawn off the red dwarf falls toward the white dwarf, but instead of landing on the white dwarf surface, it is flung out of the system by the white dwarf’s rapidly spinning magnetic field. This mechanism, which is uncommon but not unique to AE Aqr, is referred to as a magnetic propeller.

“Amateurs astronomers have been observing AE Aqr since 1944. Since then, they have recorded over 28,815 measurements of the star, most of them made with just a telescope and their eyes. This type of historical data is immensely valuable in studying variable stars and only amateurs can provide it,” Dr. Arne Henden, Director of the American Association of Variable Star Observers (AAVSO), said.

Amateur astronomers are being asked to observe AE Aqr every night possible until September 3. Those with CCD cameras on their telescopes are requested to make scientific brightness measurements, known as photometry, of the system as well. For information on how to measure the brightness of AE Aqr and submit results to professionals, visit the AAVSO web site at http://www.aavso.org/alertnotice .

The AAVSO is the world’s preeminent professional-amateur astronomical association. Specializing in the study of variable stars, the AAVSO’s International Database has over 11 million observations of variable stars dating back over 100 years. Founded in 1911 as part of the Harvard College Observatory, the AAVSO became independent in 1954 and currently has over 3,000 members and observers in over 40 countries.

Original Source: AAVSO News Release

NGC 520. Image credit: Gemini Click to enlarge
In the constellation of Pisces, some 100 million light-years from Earth, two galaxies are seen to collide – providing an eerie insight into the ultimate fate of our own planet when the Milky Way fatally merges with our neighbouring galaxy of Andromeda.

The image of the intertwined galaxies was captured on the night of 13-14th July 2005 by the Gemini Multi-Object Spectrograph [GMOS] instrument fitted to the 8-metre class Gemini North Observatory, sited on Mauna Kea, Hawaii.

Prof. Ian Robson, Director of the UK Astronomy Technology Centre which built GMOS in collaboration with other partners said,” This is quite scary. Since GMOS was installed on the telescope back in 2001 it has taken some amazing astronomical images of very faint, distant galaxies and star forming regions, providing a wealth of scientific data, but this one sends shivers down my spine. Our saving grace is that we have about 5 billion years left before we get swallowed up by Andromeda. Nevertheless, it’s amazing to see so far in advance how planet Earth and our own galaxy will ultimately end. Glad to say I won’t be around when the fireball happens”.

The image of the combined galaxies, which are known as NGC 520, may be fairly early in their galactic dance of death and it is likely that the situation has changed dramatically in the time it has taken for their light to reach Earth*.

Prof. Robson added, “Hints of new star formation taking place can be seen in the faint red glowing areas above and beneath the middle of the image. Perhaps even now the galaxies have totally combined to form a whole new galaxy with a brand new set of stars and associated planets – and maybe new life on one of those planets!”

The unique shape of NGC 520 is the result of the two galaxies colliding. One galaxy’s dust lane can be seen easily in the foreground and a distant tail is visible at the bottom centre. These features are the result of the gravitational interactions that have robbed both galaxies of their original shapes.

Original Source: PPARC News Release

Supernova 2005dh and NGC 1559. Image credit: ESO Click to enlarge
The southern Reticulum constellation certainly isn’t a big hit for amateur astronomers. This tiny, bleak and diamond-shaped constellation, not far on the sky from the Large Magellanic Cloud, is often overlooked. But recently, astronomers had a closer look at a galaxy situated inside it. And more precisely at an exploding star hosted by the spiral galaxy NGC 1559.

On the night of August 4, 2005, Australian amateur astronomer Reverend Robert Evans discovered a supernova just North of the galaxy with his 0.31-m telescope. The supernova – the explosion of a star – was of magnitude 13.8, that is, only 20 times fainter than the entire host galaxy. Being the 104th supernova discovered in 2005, it received the name SN 2005df. Noticeably, Evans had already discovered 2 other supernovae in the same galaxy: in 1984 (SN 1984J) and in 1986 (SN 1986L).

The following night, astronomer Marilena Salvo and her Australian colleagues classified the supernova as a somewhat unusual type Ia supernova, caught probably 10 days before it reached its maximum brightness. Such a supernova is thought to be the result of the explosion of a small and dense star – a white dwarf – inside a binary system. As its companion was continuously spilling matter onto the white dwarf, the white dwarf reached a critical mass, leading to a fatal instability and the supernova.

These are exactly a kind of supernovae in which Dietrich Baade, Ferdinando Patat (ESO), Lifan Wang (Lawrence Berkeley National Laboratory, USA), and their colleagues are interested. In particular, they study the polarization properties of this kind of supernova in order to learn more about their asphericity, which holds important clues to the detailed physics that governs this terminal catastrophe in the life of such stars.

Having an accepted observing programme that uses the FORS1 multi-mode instrument on Kueyen, one of the four Unit Telescopes of ESO’s 8.2m Very Large Telescope at Cerro Paranal, they triggered a Target of Opportunity request so that on-duty astronomers at the VLT could observe this supernova, which was done on August 6.

From a very first analysis of their data, Wang and his colleagues found that SN 2005df resembles closely another supernova they had studied before, SN 2001el, whose explosion they showed was significantly asymmetric.

NGC 1559 is a SBc(s)-type spiral galaxy located about 50 million light-years away, that weighs the equivalent of about 10,000 million of suns, and is about 7 times smaller than our Milky Way: on the sky, it measures about 4×2 arcmin2. Receding from us at a speed of about 1,300 km/s, it is a galaxy of the Seyfert type. Such galaxies are characterized by a bright nucleus that radiates strongly in the blue and in the ultraviolet. Astronomers think that about 2 solar masses of gas per year are transformed into stars in this galaxy. Like most galaxies, NGC 1559 probably contains a black hole in its centre, which should have a mass that is equivalent to 300,000 suns.

Original Source: ESO News Release

Artist’s impression of the Milky Way. Image credit: NASA/JPL-Caltech/R Click to enlarge
With the help of NASA’s Spitzer Space Telescope, astronomers have conducted the most comprehensive structural analysis of our galaxy and have found tantalizing new evidence that the Milky Way is much different from your ordinary spiral galaxy.

The survey using the orbiting infrared telescope provides the fine details of a long central bar feature that distinguishes the Milky Way from more pedestrian spiral galaxies.

“This is the best evidence ever for this long central bar in our galaxy,” says Ed Churchwell, a UW-Madison professor of astronomy and a senior author of a paper describing the new work in an upcoming edition of Astrophysical Journal Letters, a leading astronomy journal.

Using the orbiting infrared telescope, the group of astronomers surveyed some 30 million stars in the plane of the galaxy in an effort to build a detailed portrait of the inner regions of the Milky Way. The task, according to Churchwell, is like trying to describe the boundaries of a forest from a vantage point deep within the woods: “This is hard to do from within the galaxy.”

Spitzer’s capabilities, however, helped the astronomers cut through obscuring clouds of interstellar dust to gather infrared starlight from tens of millions of stars at the center of the galaxy. The new survey gives the most detailed picture to date of the inner regions of the Milky Way.

“We’re observing at wavelengths where the galaxy is more transparent, and we’re bringing tens of millions of objects into the equation,” says Robert Benjamin, the lead author of the new study and a professor of physics at the University of Wisconsin-Whitewater.

The possibility that the Milky Way Galaxy has a long stellar bar through its center has long been considered by astronomers, and such phenomena are not unheard of in galactic taxonomy. They are clearly evident in other galaxies, and it is a structural characteristic that adds definition beyond the swirling arms of typical spiral galaxies.

The new study provides the best estimates for the size and orientation of the bar, which are far different from previous estimates.

It shows a bar, consisting of relatively old and red stars, spanning the center of the galaxy roughly 27,000 light years in length – 7,000 light years longer than previously believed. It also shows that the bar is oriented at about a 45-degree angle relative to a line joining the sun and the center of the galaxy.

Previously, astronomers debated whether a presumed central feature of the galaxy would be a bar structure or a central ellipse – or both. The new research, the Wisconsin astronomers say, clearly shows a bar-like structure.

“To date, this is the best evidence for a long bar in our galaxy,” Benjamin asserts. “It’s hard to argue with this data.”

The Spitzer Space Telescope was lofted into orbit in August of 2003. It consists of a telescope and three science instruments, including the Infrared Array Camera, the primary instrument used for the new survey, known as GLIMPSE for Galactic Legacy Mid-Plane Survey Extraordinaire.

NASA’s Jet Propulsion Laboratory (JPL), 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 in Pasadena. JPL is a division of the California Institute of Technology.

Original Source: UW-Madison News Release

A wide-field view of NGC 300. Image credit: AAO-David Malin/Gemini Observatory. Click to enlarge
Like archaeologists unearthing a ‘lost city,’ astronomers using the 8-meter Gemini South telescope have revealed that the galaxy NGC 300 has a large, faint extended disk made of ancient stars, enlarging the known diameter of the galaxy by a factor of two or more.

The finding also implies that our own Milky Way Galaxy could be much larger than current textbooks say. Scientists will also need to explain the mystery of how galaxies like NGC 300 can form with stars so far from their centers.

The research, by an Australian and American team of scientists was just published in the August 10, 2005 issue of the Astrophysical Journal.

The team used the Gemini Multi-Object Spectrograph on the Gemini South telescope in Chile, and were able to clearly resolve extremely faint stars in the disk up to 47,000 light-years from the galaxy?s center?double the previously known radius of the disk. To detect these stars, images were obtained that went more than ten times ?deeper? than any previous images of this galaxy (Figure 1).

?A few billion years ago the outskirts of NGC 300 were brightly lit suburbs that would have shown up as clearly as its inner metropolis,? said the paper?s lead author, Professor Joss Bland-Hawthorn of the Anglo-Australian Observatory in Sydney, Australia. ?But the suburbs have dimmed with time, and are now inhabited only by faint, old stars?stars that need large telescopes such as Gemini South to detect them.?

The finding has profound implications for our own galaxy since most current estimates put the size of our Milky Way at about 100,000 light-years or about the size now estimated for NGC 300. ?However, the galaxy is much more massive and brighter than NGC 300 so on this basis, our galaxy is also probably much larger than we previously thought?perhaps as much as 200,000 light-years across,? said Bland-Hawthorn.

The Galaxy That Keeps On Keeping On!

Adding to these compelling findings is the fact that the team found no evidence for truncating, or an abrupt ?cutting-off’ of the star population as seen in many galaxies further from the central regions.

Team member Professor Bruce Draine of Princeton University explains: “It’s hard to understand how such an extensive stellar disk that falls off so smoothly in density could have formed ? this is really a huge surprise to us. Because it takes an incredibly long time to evenly disperse stars from a galaxy’s central disk to these extreme distances, it seems more likely that we are seeing the results of star formation that took place long ago, perhaps as much as ten billion years ago.”

?We now realize that there are distinctly different types of galaxy disks,? said team member Professor Ken Freeman of the Research School of Astronomy and Astrophysics at the Australian National University. ?Probably most galaxies are truncated?the density of stars in the disk drops off sharply. But NGC 300 just seems to go on forever. The density of stars in the disk falls off very smoothly and gradually.?

The observers traced NGC 300?s disk out to the point where the surface density of stars was equivalent to a one-thousandth of a sun per square light-year. ?This is the most extended and diffuse population of stars ever seen,? said Bland-Hawthorn.

NGC 300 is a spiral member of the Sculptor group of galaxies, the closest extragalactic cluster to us, and is about 6.1 million light-years away. Most of its stars lie in a fairly flat disk making it appear to be a very normal spiral galaxy like our Milky Way. NGC 300 is the first galaxy outside of our Local Group to be studied to this depth. There have only been two others studied to such faint levels, the Andromeda galaxy and its neighbor M33, both in our Local Group (see adjacent background information box).

The researchers have been granted more time on Gemini South to determine exactly what kind of stars they are seeing in the outskirts of NGC 300, and to make similar studies of other galaxies.

?We still have a lot to learn about how galaxies like ours formed,? said Bland-Hawthorn. ?Our next Gemini observations, that we have planned for later this year, should provide even more important clues and hopefully even more surprises!?

Original Source: Gemini Observatory

Spiral galaxy NGC 4565. Image credit: ESO Click to enlarge
How does the Galaxy in which we live look like?

It is almost certain that we will never be able to send a probe out of our Milky Way to take a snapshot, in the same way as the first satellites could do to give us striking images of planet Earth. But astronomers do not need this to imagine what our bigger home resembles. And they have a pretty good idea of it.

The Milky Way with its several hundreds of billion stars is thought to be a relatively flat disc -100,000 light-year across- with a central bulge lying in the direction of the constellation Sagittarius (The Archer) and six spiral arms. The Milky Way has most probably also a central bar made of young, bright stars.

If we can’t take pictures of the Milky Way, we may photograph others galaxies which astronomers think look similar to it. The two galaxies presented here are just two magnificient examples of barred spiral galaxies. One – Messier 83 – is seen face-on, and the other – NGC 4565 – appears edge-on. Together, they give us a nice idea of how the Milky Way may appear from outer space.

These images are based on data obtained with the twin FORS1 and FORS2 (FOcal Reducer and Spectrograph) instruments attached to two ESO’s 8.2-m Unit Telescopes of the Very Large Telescope Array located on Cerro Paranal. The data were extracted from the ESO Science Archive Facility, which contains approximately 50 Terabytes of scientific data and is, since April 1, 2005, open to the worldwide community. These invaluable data have already led to the publication of more than 1000 scientific papers. They also contains many nice examples of beautiful astronomical objects which could be the theme of as many midsummer’s dreams.

NGC 4565

The first galaxy pictured here is NGC 4565, which for obvious reasons is also called the Needle Galaxy. First spotted in 1785 by Uranus’ discoverer, Sir William Herschel (1738-1822), this is one of the most famous example of an edge-on spiral galaxy and is located some 30 million light-years away in the constellation Coma Berenices (Berenice’s Hair). It displays a bright yellowish central bulge that juts out above most impressive dust lanes.

Because it is relatively close (it is only 12 times farther away than Messier 31, the Andromeda galaxy, which is the major galaxy closest to us) and relatively large (roughly one third larger than the Milky Way), it does not fit entirely into the field of view of the FORS instrument (about 7 x 7 arcmin2).

Many background galaxies are also visible in this FORS image, giving full meaning to their nickname of “island universes”.

Messier 83

If our Milky Way were to resemble this one, we certainly would be proud of our home! The beautiful spiral galaxy Messier 83 is located in the southern constellation Hydra (the Water Snake) and is also known as NGC 5236 and as the Southern Pinwheel galaxy. Its distance is about 15 million light-years. Being about twice as small as the Milky Way, its size on the sky is 11×10 arcmin2.

The image show clumpy, well-defined spiral arms that are rich in young stars, while the disc reveals a complex system of intricate dust lanes. This galaxy is known to be a site of vigorous star formation.

Original Source: ESO News Release

Artist illustration of the newly discovered 10th planet. Image credit: NASA/JPL. Click to enlarge.
At the same time, another team led by astronomer Mike Brown of Caltech reported they had been observing 2003 EL61 for almost a year, but were waiting to analyze data from the Spitzer Space Telescope before announcing the discovery.

“There is no question that the Spanish group is rightly credited with discovery,” Brown stated on his personal website. “Even if they had found the object only this year and announced its existence, they would still be considered the rightful discovers. We took a chance that no one else would find it while we were awaiting our observations from the Spitzer Space Telescope. We were wrong! And we congratulate our colleagues on a very nice discovery.”

But just hours after that, Brown announced to the media the discovery of two other big TNOs, designated as 2003UB313 and 2005 FY9. Regarding the first one, he stated that it’s about three times as far from the Sun as Pluto, and “it’s definitely bigger” than the ninth planet.

Brown’s team discovered 2003 ub313 on January 8th, but wanted to further analyze their observations. However, they “were forced to announce their results on Friday evening because word had leaked out” he said.

“In mid-July, short abstracts of scientific talks to be given at a meeting in September became available on the web. We intended to talk about the object now known as 2003 EL61, which we had discovered around Christmas of 2004, and the abstracts were designed to whet the appetite of the scientists who were attending the meeting. In these abstracts we call the object a name that our software automatically assigned, K40506A -the first Kuiper belt object we discovered in data from 2004/05/06, May 6th-. Using this name was a very very bad idea on our part.”

“Unbeknownst to us, some of the telescopes that we had been using to study this object keep open logs of who has been observing, where they have been observing, and what they have been observing. A two-second Google search of “K40506A” immediately reveals these observing logs”.

According to Brown, from the moment the abstracts became public, anyone with an Internet connection and a little curiosity about the “K40506A” object could have found out where it was.

Brown was quick to point that he believes the fact that this discovery happened days after the data were potentially available on the Web is a coincidence. But “some people in the community privately expressed their concerns to me that this coincidence was too good to be true and wanted to know if there was any possible way that anyone could have found out the location of our object,” he added.

At this point, Brown contacted Brian Marsden at the International Astronomical Union’s Minor Planet Center (MPC). Brown told him confidentially about the two objects not yet announced (2003 UB313 and 2005 FY9), expressed his concerns that someone might be able to find their data and attempt to claim credit for discovering these objects, and sought advice.

Marden found that someone had already used the website of the MPC to access past observations of one of the objects and predict its location for that night. The past observations were precisely the logs from the telescope that Brown’s group had been using. “We had no choice but to hastily pull together a press conference which was held at 4pm on the last Friday in July, perhaps the single best time to announce news that you want no one to hear”, said Brown.

However, some astronomers have a very different opinion about Brown’s announcement.

“The group of Dr. Brown decided, as in previous cases, not to make public its detection until they finished their observations and their research work, and until the object was in conjunction with the Sun so that other people couldn’t observe it,” stated Dr. Javier Licandro in an e-mail sent to a Spanish-speaking astronomy mailing list. Licandro works at the Isaac Newton Group of Telescopes and the Instituto de Astrof?sica de Canarias, in Spain.

“They did it before with Sedna. But this time, by taking this ‘doubtful’ risk, they lost all the rights on the discovery of that object. Even more, their policy is, at least, criticizeable.”

“Due to the detection of 2003 EL61 by Ortiz et. al., and because of the fiasco that this has represented for Brown et. al., they decided to go public ‘ipso factum’ with their discoveries of two other objects that they knew at least from six months ago, 2005 FY y 2003 UB313,” said Licandro.

Contacted by AstronomiaOnline.com, Brown wouldn’t want to elaborate on Licandro’s comments. “I like Javier. It is unfortunate he feels the need to make such remarks,” he said.

But it didn’t take long for Ortiz to air his own feelings about the situation. “With technology many times more advanced than our own, Brown’s team had discovered three big objects many months ago, but they were hiding their findings from the international scientific community, as they did before with Quaoar and Sedna,” he declared to the Spaniard paper ABC.

“This secrecy was useful to Brown, as it allowed him to study the object in detail and exclusively. But his actions harm science and don’t follow the established procedures that imply notifying the existence of a new object to the astronomical community as soon as it’s discovered,” added Ortiz.

Brown indicated that he didn’t get that statement from Ortiz himself, so he would not want to comment on it directly. However, asked again by AstronomiaOnline.com, he said: “In general, there certainly are people who have that opinion, to which they are entitled. I, however, cannot think of any area of science in which an ‘established procedure’ is to announce a discovery with no time for thought and analysis. Anyone who feels otherwise is welcome to go and find these objects themselves -as did Ortiz- and get the credit for their own discoveries.”

Written by Ricardo J. Tohmé for Astronom?aOnline. If you want to read the original article in Spanish, click here.

A distant galaxy (yellow) that houses a quasar. Image credit: NASA Click to enlarge
Most of the biggest black holes in the universe have been eating cosmic meals behind closed doors ? until now.

With its sharp infrared eyes, NASA’s Spitzer Space Telescope peered through walls of galactic dust to uncover what may be the long-sought missing population of hungry black holes known as quasars.

“From past studies using X-rays, we expected there were a lot of hidden quasars, but we couldn’t find them,” said Alejo Martinez-Sansigre of the University of Oxford, England. He is lead author of a paper about the research in this week’s Nature. “We had to wait for Spitzer to find an entire population of these dust-obscured objects.”

Quasars are super-massive black holes that are circled by a giant ring of gas and dust. They live at the heart of distant galaxies and can consume up to the equivalent mass of one thousand stars in a single year. As their black holes suck in material from their dusty rings, the material lights up brilliantly, making quasars the brightest objects in the universe. This bright light comes in many forms, including X-rays, visible and infrared light.

Astronomers have puzzled for years over the question of how many of these cosmic behemoths are out there. One standard method for estimating the number is to measure the cosmic X-ray background. Quasars outshine everything else in the universe in X-rays. By counting the background buzz of X-rays, it is possible to predict the approximate total number of quasars.

But this estimate has not matched previous X-ray and visible-light observations of actual quasars, which number far fewer than expected. Astronomers thought this might be because most quasars are blocked from our view by gas and dust. They proposed that some quasars are positioned in such a way that their dusty rings hide their light, while others are buried in dust-drenched galaxies.

Spitzer appears to have found both types of missing quasars by looking in infrared light. Unlike X-rays and visible light, infrared light can travel through gas and dust.

Researchers found 21 examples of these quasars in a small patch of sky. All the objects were confirmed as quasars by the National Radio Astronomy Observatory’s Very Large Array radio telescope in New Mexico and by the Particle Physics and Astronomy Research Council’s William Herschel Telescope in Spain.

“If you extrapolate our 21 quasars out to the rest of the sky, you get a whole lot of quasars,” said Dr. Mark Lacy of the Spitzer Science Center, California Institute of Technology, Pasadena, Calif., a co-author of the Nature paper. “This means that, as suspected, most super-massive black hole growth is hidden by dust.”

The discovery will allow astronomers to put together a more complete picture of how and where quasars form in our universe. Of the 21 quasars uncovered by Spitzer, 10 are believed to be inside fairly mature, giant, elliptical galaxies. The rest are thought to be encased in thick, dusty galaxies that are still forming stars.

A team of researchers based at the University of Arizona, Tucson, found similar quasars using Spitzer. Their research is described at http://uanews.org/science.

Other authors of the Nature paper include Drs. Steve Rawlings and Matt Jarvis, University of Oxford; Drs. Dario Fadda and Francine Marleau, Spitzer Science Center; Dr. Chris Simpson, University of Durham, England; and Dr. Chris Willott, National Research Council Canada, Victoria.

The Jet Propulsion Laboratory, Pasadena, Calif., a division of Caltech, manages the Spitzer Space Telescope mission for NASA’s Science Mission Directorate, Washington. Science operations are conducted at the Spitzer Science Center at Caltech. Spitzer’s multiband imaging photometer, which observed the quasars, was built by Ball Aerospace Corporation, Boulder, Colo.; the University of Arizona; and Boeing North America, Canoga Park, Calif. Spitzer’s infrared array camera, which also observed the quasars, was built by NASA Goddard Space Flight Center, Greenbelt, Md.

A Spitzer false-colored picture of one of the newfound quasars is available at http://www.spitzer.caltech.edu/Media/index.shtml.

For information about NASA and agency programs visit http://www.nasa.gov/home/.

Original Source: NASA News Release