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« Răspuns #15 : 18 Iunie 2007, 23:31:11 »
Pluto status suffers another blow


Pluto has suffered yet another blow to its status.
Not only has it been demoted from planet to "dwarf planet", research now shows that it cannot even lay claim to being the biggest of these.
A study has confirmed that the dwarf planet Eris - whose discovery prompted Pluto's relegation from planet to dwarf - outranks it in mass.
The US team, whose work is published in the journal Science, described their finding as "Pluto's last stand".

Reclassification

The discovery of Eris, formerly known as 2003 UB313, marked the beginning of the end for Pluto as a planet.
Previous measurements from the Hubble Space Telescope confirmed that Eris was larger in diameter than Pluto, leading the International Astronomical Union (IAU) to rule in 2006 that Pluto could no longer be classed as a planet.

 ERIS - WORLD OF DISCORD
 
First seen in 2003 but finally recognised in 2005
Given the designation 2003 UB313 until formal naming
Highly elongated orbit around Sun lasting 560 years
Currently positioned some 14.5 billion km from Earth
Has extremely frigid surface temperature of -250C
May have thin atmosphere when closest to Sun
Is accompanied by a satellite called Dysnomia

A new category of dwarf planets was adopted, into which Pluto, Eris and another body called Ceres, which is located in the asteroid belt, were placed.
Eris lies some 14.5 billion km from Earth in a region of space known as the Kuiper Belt. It has a highly elongated orbit around the Sun that lasts 560 years.
It also has a moon, which is called Dysnomia, and scientists used this satellite, along with the Keck Observatory, Hubble Space Telescope to calculate its mass.
The researchers, led by Eris' discoverer Mike Brown from the California Institute of Technology, discovered that the more distant world has 27% more mass than Pluto.

They wrote: "In addition to being the largest, Eris is also the most massive known dwarf planet."
So if Pluto qualified as a full-fledged planet, then Eris certainly should too. Astronomers attending the International Astronomical Union meeting in 2006 worked to settle this dilemma. In the end, we lost a planet rather than gaining one. Pluto was demoted and reclassified as a dwarf planet along with Eris and the asteroid Ceres, the most massive member of the asteroid belt.

Adding insult to injury for the former ninth planet, Brown has now determined that Eris is also more massive than Pluto. This new detail was determined by observations of Eris’ tiny moon Dysnomia. The Hubble Space Telescope and Keck Observatory took images of the moon’s movement, from which Brown precisely calculated Eris to be 27 percent more massive than Pluto. In fact, if you scooped up all the asteroids in the asteroid belt they would fit inside Eris, with a lot of room to spare.

Currently, Eris is more than three times farther from the Sun than Pluto. It is so cold out there that the dwarf planet’s atmosphere has frozen onto the surface as a frosty glaze. The coating gleams brightly, reflecting as much sunlight as fresh fallen snow. The path Eris takes around the Sun is shaped like an oval rather than a circle. In about 290 years, Eris will move close enough to the Sun to partially thaw. Its icy veneer will melt away revealing a rocky, speckled landscape similar to Pluto’s.



Double Explosion Heralds The Death Of A Very Massive Star - imagine


 Eta Carinae may be about to explode. But no one knows when - it may be next year, it may be one million years from now. Eta Carinae's mass - about 100 times greater than our Sun - makes it an excellent candidate for a full blown supernova. Historical records do show that about 150 years ago Eta Carinae underwent an unusual outburst that made it one of the brightest stars in the southern sky. Eta Carinae, in the Keyhole Nebula, is the only star currently thought to emit natural LASER light. This image, taken in 1996, resulted from sophisticated image-processing procedures designed to bring out new details in the unusual nebula that surrounds this rogue star. Now clearly visible are two distinct lobes, a hot central region, and strange radial streaks. The lobes are filled with lanes of gas and dust which absorb the blue and ultraviolet light emitted near the center. The streaks remain unexplained. Will these clues tell us how the nebula was formed? Will they better indicate when Eta Carinae will explode?
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« Răspuns #16 : 21 Iunie 2007, 23:52:24 »
IS THIS THE 7TH ANGEL OF THE BOOK OF REVELATION ?

South is toward the top in this colorful close-up view of the Great Carina Nebula (NGC 3372), famous star-forming region of the southern sky. Covering an area surrounding the dusty Keyhole Nebula (NGC 3324) near picture center, the image spans about 40 light-years within the larger Carina Nebula at an estimated distance of 7,500 light-years. Like the more northerly Orion Nebula, the bright Carina Nebula is easily visible to the naked-eye. But the dramatic colors in this telescopic picture are mapped colors, based on three exposures through narrow filters each intended to record the light emitted by specific atoms in the gaseous nebula. Sulfur is shown in blue, hydrogen in green and oxygen in red hues. The Carina Nebula is home to young, extremely massive stars, including the still enigmatic variable Eta Carinae, a star with well over 100 times the mass of the Sun. Highlighted by diffraction spikes, Eta is just above and right (east) of the Keyhole.
"This provides strong evidence that SN 2006gy was, in fact, the death of an extremely massive star," said Dave Pooley of the University of California at Berkeley, who led the Chandra observations.

The star that produced SN 2006gy apparently expelled a large amount of mass prior to exploding. This large mass loss is similar to that seen from Eta Carinae, a massive star in our galaxy, raising suspicion that Eta Carinae may be poised to explode as a supernova. Although SN 2006gy is intrinsically the brightest supernova ever, it is in the galaxy NGC 1260, some 240 million light years away. However, Eta Carinae is only about 7,500 light years away in our own Milky Way galaxy.


si acum... pentru cei care cred ca evenimentele cosmice au legatura cu Biblia - ori invers, sau orice tip de varianta - propun acest link:

http://www.hiddenmeanings.com/video2.htm  ,

TITLU: IS THIS THE 7TH ANGEL OF THE BOOK OF REVELATION ?  - PRIMELE DOUA FILMULETE
( We continue to study just what all of this means. Probably the most significant cosmic thing to ever happen in our life time. If this is what the ancient writers meant as the 7th Angel then indeed we are on the brink of a major event. Even if you cannot accept Eta Carina as the 7th Angel, be aware of the possibilities for earth when it explodes. There is nothing anyone can do about it, but we all should be aware)

Domnul acela spune ca,daca Eta Carinae va eploda, vom fi capabili sa citim noaptea fara sa aprindem luminnile...In plus, e posibil sa realizeze ceva ce noi nu am reusit inca: sa distruga stratul de ozon..
vizionare placuta!
« Ultima Modificare: 21 Iunie 2007, 23:54:34 de pri3st3ss »
Ii invat si ei se indeparteaza,
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« Răspuns #17 : 27 Iunie 2007, 13:19:38 »
NASA'S Swift Sees Double Supernova In Galaxy


 In just the past six weeks, two supernovae have flared up in an obscure galaxy in the constellation Hercules. Never before have astronomers observed two of these powerful stellar explosions occurring in the same galaxy so close together in time.

The galaxy, known as MCG +05-43-16, is 380 million light-years from Earth. Until this year, astronomers had never sighted a supernova popping off in this stellar congregation. A supernova is an extremely energetic and life-ending explosion of a star.

Making the event even more unusual is the fact that the two supernovae belong to different types. Supernova 2007ck is a Type II event – which is triggered when the core of a massive star runs out of nuclear fuel and collapses gravitationally, producing a shock wave that blows the star to smithereens. Supernova 2007ck was first observed on May 19.

In contrast, Supernova 2007co is a Type Ia event, which occurs when a white dwarf star accretes so much material from a binary companion star that it blows up like a giant thermonuclear bomb. It was discovered on June 4, 2007. A white dwarf is the exposed core of a star after it has ejected its atmosphere; it’s approximately the size of Earth but with the mass of our Sun.

"Most galaxies have a supernova every 25 to 100 years, so it’s remarkable to have a galaxy with two supernovae discovered just 16 days apart," says Stefan Immler of NASA’s Goddard Space Flight Center. In 2006 Immler used NASA’s Swift satellite to image two supernovae in the elliptical galaxy NGC 1316, but both of those explosions were Type Ia events, and they were discovered six months apart.

The simultaneous appearance of two supernovae in one galaxy is an extremely rare occurrence, but it’s merely a coincidence and does not imply anything unusual about MCG +05-43-16. Because the two supernovae are tens of thousands of light-years from each other, and because light travels at a finite speed, astronomers in the galaxy itself, or in a different galaxy, might record the two supernovae exploding thousands of years apart.


Supernova 2007ck  is a Type II event, and Supernova 2007co (right) is a Type Ia event. The image is a combination of red, green, and blue pictures taken on June 9 and 12 by the Ultraviolet/Optical Telescope on NASA's Swift satellite, which was designed primarily to study another type of stellar explosion gamma ray bursts. (Credit: Stefan Immler NASA/GSFC, Swift Science
Ii invat si ei se indeparteaza,
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« Răspuns #18 : 10 Iulie 2007, 21:53:13 »
o uimitoare cometa verde, VZ13  , trece pe langa constelatia Draco..uitati-va spre nord cu binoclul
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« Răspuns #19 : 11 Iulie 2007, 23:43:49 »
NASA's Spitzer Finds Water Vapor on Hot, Alien Planet


A scorching-hot gas planet beyond our solar system is steaming up with water vapor, according to new observations from NASA's Spitzer Space Telescope.

The planet, called HD 189733b, swelters as it zips closely around its star every two days or so. Astronomers had predicted that planets of this class, termed "hot Jupiters," would contain water vapor in their atmospheres. Yet finding solid evidence for this has been slippery. These latest data are the most convincing yet that hot Jupiters are "wet."

"We're thrilled to have identified clear signs of water on a planet that is trillions of miles away," said Giovanna Tinetti, a European Space Agency fellow at the Institute d'Astrophysique de Paris in France. " Tinetti is lead author of a paper on HD 189733b appearing today in Nature.

Although water is an essential ingredient to life as we know it, wet, hot Jupiters are not likely to harbor any creatures. Previous measurements from Spitzer indicate that HD 189733b is a fiery 1,000 Kelvin (1,340 degrees Fahrenheit) on average. Ultimately, astronomers hope to use instruments like those on Spitzer to find water on rocky, habitable planets like Earth.

"Finding water on this planet implies that other planets in the universe, possibly even rocky ones, could also have water," said co-author Sean Carey of NASA's Spitzer Science Center at the California Institute of Technology in Pasadena. "I'm excited to tell my nephews and niece about the discovery."

The new findings are part of a brand new field of science investigating the climate on exoplanets, or planets outside our solar system. Such faraway planets cannot be seen directly; however, in the past few years, astronomers have begun to glean information about their atmospheres by observing a subset of hot Jupiters that transit, or pass in front of, their stars as seen from Earth.

Earlier this year, Spitzer became the first telescope to analyze, or break apart, the light from two transiting hot Jupiters, HD 189733b and HD 209458b. One of its instruments, called a spectrometer, observed the planets as they dipped behind their stars in what is called the secondary eclipse. This led to the first-ever "fingerprint," or spectrum, of an exoplanet's light. Yet, the results came up "dry," probably because the structure of these planets' atmospheres makes finding water with this method difficult.

Later, a team of astronomers found hints of water in HD 209458b by analyzing visible-light data taken by NASA's Hubble Space Telescope. The Hubble data were captured as the planet crossed in front of the star, an event called the primary eclipse.

Now, Tinetti and her team have captured the best evidence yet for wet, hot Jupiters by watching HD 189733b's primary eclipse in infrared light with Spitzer. In this method, changes in infrared light from the star are measured as the planet slips by, filtering starlight through its outer atmosphere. The astronomers observed the eclipse with Spitzer's infrared array camera at three different infrared wavelengths and noticed that for each wavelength a different amount of light was absorbed by the planet. The pattern by which this absorption varies with wavelength matches that created by water.

"Water is the only molecule that can explain that behavior," said Tinetti. "Observing primary eclipses in infrared light is the best way to search for this molecule in exoplanets."

The water on HD 189733b is too hot to condense into clouds; however, previous observations of the planet from Spitzer and other ground and space-based telescopes suggest that it might have dry clouds, along with high winds and a hot, sun-facing side that is warmer than its dark side. HD 189733b is located 63 light-years away in the constellation Vulpecula.

Other authors of the Nature paper include Alfred Vidal-Madjar, Jean-Phillippe Beaulieu, David Sing and Nicole Allard of the Institute d'Astrophysique de Paris: Mao-Chang Liang of Caltech and the Academia Sinica, Taiwan; Yuk Yung of Caltech; Robert J. Barber and Jonathan Tennyson of University College London in England; Ignasi Ribas of the Institut de Ciències de l'Espai, Spain; Gilda E. Ballester of the University of Arizona, Tucson; and Franck Selsis of the Ecole Normale Supérieure, France. JPL manages the Spitzer Space Telescope mission for NASA's Science Mission Directorate, Washington. Science operations are conducted at the Spitzer Science Center at the California Institute of Technology, Pasadena. JPL is a division of Caltech. Spitzer's infrared array camera was built by NASA's Goddard Space Flight Center, Greenbelt, Md. The instrument's principal investigator is Giovanni Fazio of the Harvard-Smithsonian Center for Astrophysics in Cambridge, Mass.

 
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« Răspuns #20 : 12 Iulie 2007, 13:16:24 »
Astronomers claim galaxy record


 
The detections were made at the Keck Observatory
Astronomers say they may have detected the light from some of the earliest stars to form in the Universe.
They have pictures of what appear to be very faint galaxies that shone more than 13 billion years ago, a mere 500 million years after the Big Bang.
The remarkable claim dramatically exceeds the current, broadly accepted record for the most distant detection.
The Caltech-led team behind the work recognises there will be sceptics but says it believes its data is strong.
It has published details in The Astrophysical Journal; and the group leader, Professor Richard Ellis, has been arguing the case at a conference in London, UK.
"We've had these galaxies for over a year and we have gone back to the telescope and revisited them, to prove their signals are robust," he explained.
"We feel confident now that we have done all that is humanly possibly to show the community that these galaxies are at these great distances," Professor Ellis told BBC News.


Big zoom

The international team of astronomers found its six "candidate" galaxies using one of the 10m Keck telescope twins sited on Mauna Kea, Hawaii.
The researchers employed a technique known as gravitational lensing to achieve the detections.
This makes use of the gravity of relatively nearby objects (in this case galaxy clusters) to magnify the light coming from much more distant objects (the six candidates).


More details
 
Astronomers from Caltech (California Institute of Technology) have helped pioneer this field; and they say they know how to select just the right "zoom lens" to see back into the required period in cosmic history.  - im 1
The team then further refined its search by only looking for a very narrow wavelength of light where its target galaxies - if they existed - would be expected to shine.

It has taken three years' painstaking work to make and check the observations.
"Using Keck II, we have detected six faint star-forming galaxies whose signal has been boosted about 20 times by the magnifying effect of a foreground cluster," said Caltech co-worker Dan Stark.
"That we should find so many distant galaxies in our small survey area suggests they are very numerous indeed."


It's a crowd

This is perhaps the most significant implication of the study.
Astronomy is now engaged in a major drive to tie down the timings of key events in the early Universe.
Scientists would like to see extensive evidence for the very first populations of stars. These hot, blue giants would have grown out of the cold neutral gas that pervaded the young cosmos.


Peering at a distant epoch 

The behemoths would likely have burned brilliant but brief lives, producing the very first heavy elements.
They would also have "fried" the neutral gas around them to produce the diffuse intergalactic plasma we detect between nearby stars today.
But this theory demands the earliest star-forming phase in the Universe was a busy one - and the significance of the latest study is that it suggests the numbers of stars required did indeed exist.
"The area of sky we surveyed was so small that for us to find anything at all suggests to us these objects must be very numerous," Professor Ellis told the BBC News website.
"Obviously it's a bit of a stretch to estimate a population from just six objects - but if you went out into a London street, looked at one piece of pavement and found six people standing there, I think you could reasonably conclude London was a crowded place."


Redshift hunters

It has been known for a while that the Caltech-led group had some very interesting pictures. In the past 12 months, knowledge of their existence has been shared at scientific conferences and hinted at by popular publications such as Time Magazine and the BBC News website.
But Ellis and colleagues have deliberately held back from formal publication of their work. Theirs is a field which has burned the reputations of others who have rushed forward with announcements that could not be confirmed by subsequent, independent observation.
Even so, to get an idea of how big a leap in detection is now being claimed can be illustrated by the "ruler" astronomers use to describe far-off sightings.
They will often be heard referring to "redshift". It is a measure of the degree to which light has been "stretched" by the expansion of the Universe. The greater the redshift, the more distant the object and the earlier it is being seen in cosmic history.
The current, widely accepted distance record-holder is the IOK-1 galaxy detection announced last year which had a redshift of 6.96. Its light was being seen when the Universe was little more than 700 million years old (Current estimates have the Universe coming into existence about 13.66 billion years ago as a "hot soup" of elementary particles).
Getting to this mark was a process of steady, incremental steps through redshifts in the lower-sixes and fives. The Caltech-led group has now suddenly jumped into the redshift region of eight to 10.

Dr Andy Bunker is a high-redshift hunter with Exeter University, UK. He has worked with the Ellis group in the past but was not involved in this study.
He commented: "Richard is a careful worker and he knows the burden of proof is very high.

"His group is aware of the history of the field and that's why they are being a little bit cagey; but I think this is a significant paper and unlike many that have gone before, I believe this will stand the test of time and at least some of the six candidates will be confirmed by others in due course."
The Caltech-led group hopes soon to get some confirmation of its own by looking at a different wavelength of light using the Spitzer Space Telescope and through the use of a new spectrograph instrument which is being installed at the Keck.
A refurbished Hubble Space Telescope is expected to be able to reach up to redshift 10; and its successor, the James Webb Space Telescope, due for launch early in the next decade, should be capable of redshift 15 observations.
Richard Ellis, the Steele Professor of Astronomy at Caltech, Pasadena, US, delivered a talk at the From IRAS to Herschel and Planck Conference. The meeting was organised to celebrate the 65th birthday of Royal Astronomical Society President Professor Michael Rowan-Robinson.  - im 2


 

im 1 - Images of the cluster fields with the newly located candidates marked. Three clusters gave up six candidates. Each foreground galaxy cluster acts as a "zoom lens". Magnification is predicted to be strong along "critical lines" (black lines). The Keck was used to search specifically these regions.

im 2 - Even the powerful Keck struggles to see the greatest distances
It uses a trick - a gravitational zoom lens to magnify far-off objects
The candidate galaxies are among the first to form in the Universe
Their stars would have helped end a period dubbed the 'Dark Ages'
In this cold phase the Universe was filled with neutral gas atoms
The stars of the 'Cosmic Renaissance' changed their environment
These giants' nuclear cores synthesised the first heavy elements
Their intense ultraviolet light also 'fried' the neutral gas atoms
The resulting plasma - free electrons and protons - is evident today
 
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« Răspuns #21 : 13 Iulie 2007, 13:50:34 »
The origin of perennial water-ice at the South Pole of Mars

 
Thanks to data from ESA's Mars Express mission, combined with models of the Martian climate, scientists can now suggest how the orbit of Mars around the Sun affects the deposition of water ice at the Martian South Pole.
Early during the mission, the OMEGA instrument (Visible and Infrared Mineralogical Mapping Spectrometer) on board Mars Express had already found previously undetected perennial deposits of water-ice. They are sitting on top of million-year old layered terrains and provide strong evidence for a recent glacial activity.
However, only now a realistic explanation for the age of the deposits and the mechanism of their formation could finally be suggested. This was achieved thanks to the OMEGA mapping and characterisation of these ice deposits, combined with the computer-generated Martian Global Climate Models (GCMs). 
The mapping and spectral analysis by OMEGA has shown that the perennial deposits on the Martian South Pole are of essentially three types: water-ice mixed with carbon dioxide (CO2) ice, tens-of-kilometres-wide patches of water-ice, and deposits covered by a thin layer of CO2 ice.
The discovery of the ice deposits of the first type confirms the long-standing hypothesis that CO2 acts as a cold-trap for water-ice. But how were the other two types of deposits, not ‘trapped’ by CO2, accumulated and preserved over time?
Franck Montmessin, from the Service d'Aéronomie du CNRS/IPSL (France) and lead author of the findings, explains how the deposits of water ice at the Martian's poles 'behave'. "We believe that the deposits of water-ice are juggled between Mars’ North and South Poles over a cycle that spans 51 000 years, corresponding to the time span in which the planet's precession is inverted." Precession is the phenomenon by which the rotation axis of a planet wobbles.Montmessin and colleagues came to the conclusion by turning back time in their Mars climate computer model. This was done by changing the precession together with other orbital information.  - fig 2
The scientists set the clock 21 000 years back, when the closest vicinity of the planet to the Sun corresponded to the northern summer – a situation opposite to that of today.
The model has shown that water at the North Pole was in an unstable condition and was easily transported to the South Pole in the form of water vapour, to then re-condense and freeze on the surface. Up to 1 millimetre of water ice was deposited at the South Pole every year. After Mars has spent more than 10 000 years in that climatic configuration, this accumulation led to a layer up to 6-metre thick.
About 10 000 years ago the precession cycle was inverted, and started to return to its current configuration. Water-ice at the South Pole became unstable, and was forced to progressively return back to the North.
About 1000 years ago, by a not-yet-well explained trigger mechanism, the erosion of the water-ice deposits at the South pole was blocked as soon as layers of CO2 ice were deposited on the water-ice and trapped it, as OMEGA has observed them.
 
 
Note for editors
 
Mars is currently experiencing 'Southern summer' – that is, water ice is more likely to accumulate at the North Pole.


Types of ice deposits at the South Pole of Mars - fig 1
Water-ice accumulation rate at Martian South Pole - fig 2
Recent evolution of water-ice at the south pole of Mars -  fig 3
 
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« Răspuns #22 : 13 Iulie 2007, 22:17:34 »
http://www.jpl.nasa.gov/videos/whatsup/whatsup20070713/?msource=mm071307&tr=y&auid=2836993 - cate ceva despre luna


in imagine : This  image was taken by the Far Infrared Surveyor instrument on Japan's Akari spacecraft. It shows star-forming regions in the constellation Cygnus, one of the brightest regions in the Milky Way.
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« Răspuns #23 : 18 Iulie 2007, 23:40:09 »
X-ray satellites discover the biggest collisions in the Universe



 The Bullet Cluster is a much-studied pair of galaxy clusters, which have collided head on. One has passed through the other, like a bullet travelling through an apple. In the Bullet Cluster, this is happening across our line of sight, so we can clearly see the two clusters.

The optical image from the Magellan and the Hubble Space Telescope shows galaxies in orange and white in the background. Hot gas, which contains the bulk of the normal matter in the cluster, is shown by the Chandra X-ray image, which showst the hot intracluster gas (pink). Gravitational lensing, the distortion of background images by mass in the cluster, reveals the mass of the cluster is dominated by dark matter (blue), an exotic form of matter abundant in the Universe, with very different properties compared to normal matter.

This was the first clear separation seen between normal and dark matter.

Credits: X-ray: NASA
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« Răspuns #24 : 19 Iulie 2007, 14:37:57 »
Ca efect estetic e mai mult decat bestial... in sensul bun al cuvantului, bineinteles...

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« Răspuns #25 : 24 Iulie 2007, 14:25:22 »
Astronomers Find Highly Elliptical Disk Around Young Star


Dust and debris parade in an extremely misshapen ring around the young star, HD 15115. The disk, seen edge-on with NASA's Hubble Space Telescope, is the dense blue line extending from the star to the upper right and lower left of the image. The disk appears thicker at upper right than at lower left, evidence of its lopsided structure. Astronomers think the disk's needle-like look is caused by dust particles following a highly elliptical orbit around the star
Astronomers using the Hubble Space Telescope and W. M. Keck Observatory have found a lopsided debris disk around a young star known as HD 15115. As seen from Earth, the edge-on disk resembles a needle sticking out from the star.
Astronomers think the disk's odd imbalanced look is caused by dust following a highly elliptical orbit about the star. The lopsided disk may have been caused by the gravity of planets sweeping up debris in the disk or by the gravity of a nearby star.

The observations were made by Paul Kalas, James Graham, and Michael P. Fitzgerald, all from the University of California at Berkeley. Their paper appeared in The Astrophysical Journal Letters.

"The lopsided disk presents a host of new challenges for theorists," said Kalas.

Debris disks are produced by dust from collisions among protoplanetary bodies, which are the building blocks of planets. These dusty disks can be affected by planets nearer to the star, much as Jupiter's gravity affects asteroids in the asteroid belt.

This discovery is consistent with models for planetary upheavals in our own solar system, where Neptune may have originally formed between Saturn and Uranus. Neptune was eventually kicked out to its present location by a gravitational dance between Saturn and Jupiter before their orbits stabilized. "Therefore, we speculate that if such a planetary upheaval were occurring around HD 15115 at the present time, it could explain the highly asymmetric disk," Kalas said.

This might happen through a powerful gravitational interaction between planets that kicks one or more planets into highly elliptical orbits, or even ejects them into interstellar space. When the planet's orbit becomes elliptical through a violent upheaval, the rest of the disk can be disturbed into an elliptical shape, according to Kalas.

Kalas also is studying whether the gravity of a star known as HIP 12545, located about 10 light-years from HD 15115, may have created the disk's lopsided shape due to a close encounter in the past.

Dusty disks are known to exist around at least 100 stars, but because of the difficulty in observing material within the glare of a star, less than a dozen have been studied closely.

HD 15115 and HIP 12545 are among nearly 30 stars that belong to the Beta Pictoris Moving Group. Moving groups are expanded clusters of stars believed to have a common birthplace and age that are traveling loosely together through space.

The dusty disk around HD 15115 was first inferred by observations at infrared wavelengths in 2000 and its existence confirmed in 2006 when the Hubble Space Telescope (HST) resolved the disk in reflected light for the first time. The disk was investigated further using Keck adaptive optics in 2006 and 2007.

"The disk was seen in the HST data, but its appearance was so extraordinary we could not be certain that it was real. It took follow-up observations at Keck to confirm that it was a real disk," Kalas said.

Credit: NASA, ESA, and P. Kalas (University of California, Berkeley)
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« Răspuns #26 : 31 Iulie 2007, 22:20:50 »
New Type Of Active Galaxy Discovered



An international team of astronomers using NASA’s Swift satellite and the Japanese/U.S. Suzaku X-ray observatory has discovered a new class of active galactic nuclei (AGN).

By now, you’d think that astronomers would have found all the different classes of AGN — extraordinarily energetic cores of galaxies powered by accreting supermassive black holes. AGN such as quasars, blazars, and Seyfert galaxies are among the most luminous objects in our Universe, often pouring out the energy of billions of stars from a region no larger than our solar system.

But by using Swift and Suzaku, the team has discovered that a relatively common class of AGN has escaped detection…until now. These objects are so heavily shrouded in gas and dust that virtually no light gets out.

"This is an important discovery because it will help us better understand why some supermassive black holes shine and others don’t," says astronomer and team member Jack Tueller of NASA’s Goddard Space Flight Center in Greenbelt, Md.

Evidence for this new type of AGN began surfacing over the past two years. Using Swift’s Burst Alert Telescope (BAT), a team led by Tueller has found several hundred relatively nearby AGNs that were previously missed because their visible and ultraviolet light was smothered by gas and dust. The BAT was able to detect high-energy X-rays from these heavily blanketed AGNs because, unlike visible light, high-energy X-rays can punch through thick gas and dust.

To follow up on this discovery, Yoshihiro Ueda of Kyoto University, Japan, Tueller, and a team of Japanese and American astronomers targeted two of these AGNs with Suzaku. They were hoping to determine whether these heavily obscured AGNs are basically the same type of objects as other AGN, or whether they are fundamentally different. The AGNs reside in the galaxies ESO 005-G004 and ESO 297-G018, which are about 80 million and 350 million light-years from Earth, respectively.

Suzaku covers a broader range of X-ray energies than BAT, so astronomers expected Suzaku to see X-rays across a wide swath of the X-ray spectum. But despite Suzaku’s high sensitivity, it detected very few low- or medium-energy X-rays from these two AGN, which explains why previous X-ray AGN surveys missed them.

According to popular models, AGNs are surrounded by a donut-shaped ring of material, which partially obscures our view of the black hole. Our viewing angle with respect to the donut determines what type of object we see. But team member Richard Mushotzky, also at NASA Goddard, thinks these newly discovered AGN are completely surrounded by a shell of obscuring material. "We can see visible light from other types of AGN because there is scattered light," says Mushotzky. "But in these two galaxies, all the light coming from the nucleus is totally blocked."

Another possibility is that these AGN have little gas in their vicinity. In other AGN, the gas scatters light at other wavelengths, which makes the AGN visible even if they are shrouded in obscuring material.

"Our results imply that there must be a large number of yet unrecognized obscured AGNs in the local universe," says Ueda.

In fact, these objects might comprise about 20 percent of point sources comprising the X-ray background, a glow of X-ray radiation that pervades our Universe. NASA’s Chandra X-ray Observatory has found that this background is actually produced by huge numbers of AGNs, but Chandra was unable to identify the nature of all the sources.

By missing this new class, previous AGN surveys were heavily biased, and thus gave an incomplete picture of how supermassive black holes and their host galaxies have evolved over cosmic history. "We think these black holes have played a crucial role in controlling the formation of galaxies, and they control the flow of matter into clusters," says Tueller. "You can’t understand the universe without understanding giant black holes and what they’re doing. To complete our understanding we must have an unbiased sample."In the newly discovered type of AGN, the disk and torus surrounding the black hole are so deeply obscured by gas and dust that no visible light escapes, making them very difficult to detect. (Credit: Aurore Simonnet, Sonoma State University.)

The discovery paper will appear in the August 1st issue of the Astrophysical Journal Letters.

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Raspuns: DE-ALE COSMOSULUI...ECLIPSA
« Răspuns #27 : 20 Februarie 2008, 21:57:20 »
In noaptea zilei de 20/21 februarie 2008 va avea loc prima eclipsa a anului 2008 vizibila din Romania si ultima eclipsa totala de Luna a deceniului intai din secolul XXI. Aceasta eclipsa va fi deosebit de frumoasa, faza de totalitate durand aproape 50 de minute. In Romania eclipsa este asteptata cu nerabdare urmand eclipsei din 3/4 martie 2007 cand conditiile meteorologice nu au permis observarea eclipsei dar si pentru ca dupa aceasta eclipsa urmatoarea eclipsa totala de Luna vizibila din Romania se va produce pe 15 iunie 2011.

Seria Saros

Eclipsa de Luna din 21 februarie face parte din seria Saros 133 fiind a 26-a eclipsa din cele 71 ale seriei. In aceasta serie eclipsa din 21 februarie 2008 este a 6-a eclipsa totala. In total seria produce 21 de eclipse totale
In noaptea de 20/21 februarie Luna se va afla pe teritoriul constelatiei Leo si va trece printre stelele Regulus (alfa Leonis, m=+1.35) si 31 Leonis (m=+4.37). De asemenea la doar 3° nord-est de Luna se va afla planeta Saturn (m=+0.2). Discul lunar va avea diametrul aparent de 31.5'. Luna va rasari in seara zilei de miercuri, 20 februarie la ora 17.15 la est-nord-est. Apoi, Luna va trece la meridian la ora 00.27 avand altitudinea maxima de 53°. Eclipsa de Luna va incepe sa fie vizibila in jurul orei 03.00 cand pe discul lunar va incepe sa fie observata penumbra terestra. De precizat ca pentru a observa penumbra terestra e nevoie de un cer bun si experienta in domeniu. Dupa acest moment eclipsa se va desfasura conform datelor din tabelul urmator:

Momentul eclipsei Ora de iarna
Intrarea Lunii in penumbra 02h36m35s
Inceputul eclipsei partiale 03h43m19s
Inceputul eclipsei totale 05h01m10s
Faza maxima  05h26m05s
Sfarsitul eclipsei totale 05h50m57s
Sfarsitul eclipsei partiale  07h08m47s
Iesirea Lunii din penumbra  08h15m39s

Eclipsa totala de Luna din 21 februarie 2008 va avea un farmec deosebit pentru ca se produce la sfarsitul noptii terminandu-se cu apusul Lunii in crepusculul de dimineata. Astfel in Romania Luna va apune cand penumbra Pamantului se va afla inca pe discul acesteia. Totusi in zonele cu orizont vestic inalt (munti, vegetatie, etc) Luna va disparea inca in eclipsa partiala.

Desfasurarea eclipsei

Eclipsa de Luna din 21 februarie 2008 va debuta la ora 02.37 cand Luna va incepe sa se cufunde in penumbra terestra. Totusi, cum am amintit si mai inainte, penumbra nu se va putea observa pe discul lunar numai in jurul orei 03.00 cand va acoperi o suprafata suficient de mare pentru a iesi in evidenta nuanta mai inchisa a zonelor aflate in eclipsa. In acest moment Luna se va afla la sud-vest la o altitudine de 41°. Dupa aceasta, eclipsa va fi tot mai evidenta prin scaderea luminozitatii discului lunar dinspre est.

Eclipsa prin umbra incepe la ora 03.43 cand estul discului lunar dispare in intuneric. Din acest moment eclipsa a inceput in adevaratul sens al cuvantului si poate fi observata de oricine si din orice loc cu cer senin si cu Luna pe cer. In acest moment Luna a mai coborat pe cer avand o altitudine de 35° si aflandu-se foarte aproape de steaua 31 Leonis. Mai precis la ora 03.45 steaua se va afla la doar 24' de centrul discului lunar si la numai 8' de limbul sud-vestic al astrului noptii. Cu ochiul liber steaua 31 Leonis se va gasi exact sub Luna aflata in eclipsa. In continuare eclipsa avanseaza si umbra Pamantului va parea ca inainteaza tot mai mult pe discul Lunii dinspre est. In realitate, in spatiu Luna se cufunda in interiorul umbrei planetei noastre apropiindu-se de eclipsa totala. Odata cu trecerea minutelor, lumina dimprejur va scadea treptat, cerul se va intuneca iar obiectele mai putin stralucitoare vor deveni tot mai evidente. Astfel, obiectele deep-sky (galaxiile, nebuloasele, roiurile de stele) se vor putea observa in conditii mai bune.

Putin dupa ora 5 (mai precis la ora 05.01) incepe eclipsa totala. Intreg discul lunar se va afla cufundat in interiorul umbrei Pamantului. Din acest moment cerul va fi la fel de negru ca intr-o noapte fara Luna si va recomand sa mai aruncati cate un ochi la obiectele deep-sky prezente pe cer. Discul lunar va avea o culoare rosiatica insa nuanta sau nuantele exacte nu se pot calcula. Culoarea exacta a Lunii in timpul eclipsei totale depinde foarte mult de starea, din acel moment, a atmosferei terestre care poate permite mai mult sau mai putin trecerea luminii rosii in interiorul conului de umbra. De-a lungul timpului au fost observate eclipse totale de Luna in care culoarea discului lunar a variat de la galben-orange, la rosu, maroniu sau chiar negru. Sa vedem ce surpriza ne rezerva aceasta eclipsa de Luna.

Faza maxima a eclipsei se va produce la ora 05.26. Luna se va afla cel mai aproape de centrul petei de umbra a Pamantului: limbul nordic se va gasi la 7' sud de axa conului de umbra in timp ce limbul sudic se va afla la doar 3' de limita sudica umbrei terestre. Astfel in acest moment pe discul lunar lumina va fi mai intensa in zona sudica iar culoarea acestuia nu va fi uniforma. De asemenea aspectul Lunii eclipsate poate varia odata cu trecerea timpului de aceea va recomand sa estimati valoarea Danjon a eclipsei de mai multe ori in timpul totalitatii. Magnitudinea eclipsei in faza maxima va fi de 1.1062. Luna se va afla deasupra orizontului vestic la o altitudine de 18°.

Dupa aproape 50 de minute de eclipsa totala, la ora 05.50, Luna incepe sa paraseasca umbra terestra iar faza totala a eclipsei se termina. Discul lunar incepe sa reapara in zona estica a acestuia. Luna mai coboara spre orizont ajungand la altitudinea de 15° deasupra orizontului vestic. Simultan cu cresterea luminii Lunii la vest, la est va creste lumina crepusculului de dimineata care a inceput la ora 05.39. Cu trecerea minutelor Luna ia din nou aspectul unei seceri si se apropie tot mai mult de orizontul vestic.

La ora 6.30 Luna stapaneste orizontul vestic de la o altitudine de 6° fiind inca acoperita in raport de 50% de umbra terestra. Luna se apropie incet de apus dar si de sfarsitul eclipsei partiale. Acesta se produce la ora 07.09 dar, pentru unele zone ale tarii la aceasta ora Luna deja va fi apus (in functie de locatie si de orizontul vestic). Apusul Lunii se produce in jurul orei 07.15. Tot in jurul acestui moment la sud-est va rasari Soarele.

Eclipsa de Luna va continua si dupa apusul Lunii pana la ora 08.15 cand Luna va parasi si penumbra terestra. Cu aceasta ia sfarsit eclipsa totala de Luna din 21 februarie 2008.

Sfaturi pentru observarea eclipsei

Pentru a observa in conditii bune eclipsa de Luna din 21 februarie 2008 trebuie sa va alegeti un loc de observare unde orizontul vestic sa fie cat mai jos. Astfel veti putea observa faza partiala finala a eclipsei cat mai mult inainte de apusul Lunii. De asemenea pentru a putea admira cu adevarat spectacolul cerului din noaptea de 20/21 februarie va recomand sa va deplasati in afara localitatilor, in locuri cu poluare luminoasa cat mai mica.

In timpul eclipsei constelatiile de primavara sunt bine plasate pentru a fi observate. Astfel cerul va fi vegheat de stelele Regulus, Spica, Arcturus, Alphard (alfa Hydrae), Antares, Vega, Deneb si Altair. De asemenea si planetele vor fi prezente pe cer in timpul eclipsei: Saturn se va afla destul de aproape de Luna, Marte apune la 04.30, Jupiter rasare la 05.10, Mercur si Venus in jurul orei 06.15 fiind la o distanta de doar 4°.

Pentru observarea eclipsei recomand folosirea unui instrument de orice fel: binoclu, luneta sau telescop. Bineinteles ca si cu ochiul liber totul va arata superb insa instrumentele vor arata detalii fine ale fenomenului. Incercati sa folositi grosismente cat mai mici pentru a avea o imagine de ansamblu. Eu recomand sa observati eclipsa la 30-40x dar puteti sa mergeti pana pe la 75x. E bine sa aveti campul in telescop macar 50'-55' (cam 1.7-1.8 diametre aparente lunare).

sursa  : http://www.astroclubul.org


P.S. : rog varcolacii sa nu consume luna cu prea mult sare,zahar si alcool :-D :wink:
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« Răspuns #28 : 22 Martie 2008, 20:27:23 »
spiral galaxy NGC 4565

This image was created by median combining 7 x 90 second unfiltered images taken with a Takahashi Epsilon 250 with SBIG ST-8XE CCD. The image has been cut down to be 20 x 20 arc minutes in size.The edge-on spiral galaxy NGC 4565 is a celestial showpiece - far superior to some of the Messier entries. This view resembles what we would see of our own Milky Way if seen from outside near its galactic equatorial plane. NGC 4565 is about 31 million light years distant.
( im 1 )



Star explodes halfway across universe

The explosion of a star halfway across the universe was so huge it set a record for the most distant object that could be seen on Earth by the naked eye.
A star 7.5 billion light years away exploded, giving off the brightest gamma-ray burst afterglow ever seen.
 The aging star, in a previously unknown galaxy, exploded in a gamma ray burst 7.5 billion light years away, its light finally reaching Earth early Wednesday.
The gamma rays were detected by NASA's Swift satellite at 2:12 a.m. "We'd never seen one before so bright and at such a distance," NASA's Neil Gehrels said.
It was bright enough to be seen with the naked eye.
However, NASA has no reports that any skywatchers spotted the burst, which lasted less than an hour.
Telescopic measurements show that the burst -- which occurred when the universe was about half its current age -- was bright enough to be seen without a telescope.
"Someone would have had to run out and look at it with a naked eye, but didn't," said Gehrels, chief of NASA's astroparticles physics lab at Goddard Space Flight Center in Greenbelt, Md.
The starburst would have appeared as bright as some of the stars in the handle of the Little Dipper constellation, said Penn State University astronomer David Burrows. How it looked wasn't remarkable, but the distance traveled was.The 7.5 billion light years away far eclipses the previous naked eye record of 2.5 million light years. One light year is 5.9 trillion miles.
"This is roughly halfway to the edge of the universe," Burrows said.
Before it exploded, the star was about 40 times bigger than our sun. The explosion vaporized any planet nearby, Gehrels said
im2

sursa: cnn.com
« Ultima Modificare: 22 Martie 2008, 20:29:38 de pri3st3ss »
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« Răspuns #29 : 23 Martie 2008, 19:38:26 »
Un pas inainte in cautarea vietii extraterestre


NASA a identificat, in premiera, o molecula organica pe o planeta din afara sistemului nostru solar. Poarta numele de HD 189733b, are dimensiunea lui Jupiter si este situata la 63 de ani-lumina, in constelatia Vulpecula (Vulpea). Un corp ceresc ca oricare altul, pina cind a devenit, gratie unor cercetatori NASA, prima planeta extrasolara in atmosfera careia s-a gasit o molecula organica. Mai mult, molecula in cauza este cea de metan (combinatie de carbon si hidrogen), substanta care, in anumite conditii, joaca un rol crucial in chimia prebiotica, adica in reatiile chimice considerate necesare pentru ca viata, asa cum o stim, sa apara. Descoperirea, realizata cu ajutorul telescopului spatial Hubble, apartine unei echipe conduse de Mark Swain, de la Laboratorului NASA de Propulsie Jet din Pasadena, California, care-i mai include pe Gautam Vasisht, de la acelasi institut, si pe Giovanna Tinetti, astrobiolog in cadrul University College London. Rezultatele cercetatarii au aparut in editia de azi a publicatiei “Nature”, noteaza site-ul NASA.

Pe linga metan, atmosfera planetei contine si apa, insa oamenii de stiinta exclud posibilitatea prezentei vreunei forme de viata, deoarece HD 189733b are o orbita mai apropiata de steaua careia ii da tircoale decit cea pe care este inscrisa planeta Mercur (prima planeta din sitemul solar) fata de Soare. In consecinta, atmosfera planetei se ridica la peste 900 de grade Celsius, temperatura apropiata de punctul de topire al argintului. Viata n-ar rezista in asemenea conditii, explica Giovanna Tinetti, citata de “BBC Online”: “Desi metanul descoperit este un produs organic, n-a fost generat de organisme vii. Este mult prea cald acolo pentru asa ceva”. Chiar daca nu au dat de viata, cercetatorii n-au de gind sa se lase cu una, cu doua, asa cum explica astrobiologul: “Am fi prea aroganti sa ne imaginam ca sintem singurele creaturi din univers”.

Studiul celor trei reprezinta trecerea de la simpla identificare a exoplanetelor (planetele situate in afara sistemului nostru solar), la determinarea compozitiei chimice a atmosferei lor. “Putem acum sa analizam structura chimica a atmosferei exoplanetelor. Este o descoperire foarte importanta”, a declarat, ieri, Mark Swain, in cadrul unei conferinte de presa, dupa cum noteaza “New York Times”. Mai mult, el a subliniat, pentru “The Telegraph”, ca “masuratorile efectuate sint un pas important spre scopul final, acela de a stabili toate conditiile atmosferice ale unei planete, precum temperatura, presiunea, intensitatea vintului si caracteristicile straturilor de nori”. In prezent, oamenii de stiinta cunosc doar masa si orbitele celor in 270 de exoplanete descoperite. “La 13 ani dupa descoperirea primei exoplanete, incepem sa adunam suficiente date despre corpurile ceresti pentru a le putea acorda titlul de lumi”, a declarat profesorul Adam Showman, de la Universitatea Arizona, care nu a participat la proiect. El a subliniat ca, pentru ca viata sa fie posibila, metanul trebuie sa fie insotit de oxigen, lucru care nu este valabil in cazul HD 189733b.

Pentru a determina compozitia atmosferica a planetei, cercetatorii au asteptat ca ea sa se pozitioneze in fata stelei pe care o inconjoara, din punctul de vedere al unui observator terestru. Cind razele stelei au maturat planeta, gazele atmosferice si-au lasat amprenta pe respectivul flux de lumina. Metoda numita spetroscopie, care separa lumina in componentele din care este alcatuita, a dezvaluit amprenta chimica a metanului. “Spetroscopia va fi aplicata, eventual, si in cazul unei planete mai reci, potential locuibile”, a spus Swain. Scopul ultim al echipei pe care o conduce este sa identifice molecule prebiotice in atmosfera planetelor situate in “zonele locuibile”, unde temperaturile sint potrivite pentru ca apa sa se pastreze in stare lichida, si nu sa se evapore sau sa inghete.



Cercetatorii cauta Evul Intunecat al cosmosului

Oamenii de stiinta vor incerca sa studieze perioada in care universul nu primea lumina de la nici un astru, pentru a-i intelege evolutia.O echipa de cercetatori si ingineri condusi de Laboratorul de Cercetare Navala din SUA va studia, in cadrul proiectului Dark Ages Lunar Interferometer (DALI), cum sa conceapa un telescop pe Luna care sa descoasa ultima era neexplorata din istoria universului, mai precis primele 100 de milioane de ani din tineretea sa, anunta publicatia „Science Daily“.
Desi cerul de noapte este plin de stele, acestea nu s-au format imediat dupa Big Bang. A existat o perioada, botezata Evul Intunecat, in care universul nu era luminat de nici o stea. Cel mai abundent element din cosmos, materie prima pentru formarea stelelor, planetelor si a oamenilor, este hidrogenul. Din fericire, atomul de hidrogen poate produce un semnal in spectrul undelor radio la 21 cm, lungime de unda mult mai mare decit poate cuprinde ochiul uman. Daca aceste prime semnale ale atomilor de hidrogen din Evul Intunecat pot fi detectate, astronomii pot proba cum au evoluat primele stele, primele galaxii, precum si universul modern. Intrucit universul se extinde, semnalele venite de la acesti atomi de hidrogen indepartati in timp vor fi extinse la lungimi de unda mai mari, de citiva metri.
Desi observatiile astronomice bazate pe lungimi de unda radio au o istorie lunga in spate, aceasta portiune a spectrului electromagnetic este folosita masiv pentru diferite transmisiuni civile si militare, toate fiind de milioane de ori mai limpezi decit semnalul hidrogenului cautat de astronomi. In plus, straturile superioare ale atmosferei Pamintului sint ionizate, ceea ce distorsioneaza semnalele astronomice in drumul lor spre telescoapele pamintene. Fara atmosfera si scuturi din partea Pamintului, partea indepartata a Lunii prezinta un mediu ideal pentru un telescop care sa studieze Evul Intunecat. In cadrul proiectului DALI, oamenii de stiinta si inginerii vor investiga constructia de noi antene si de dispozitive electronice care sa supravietuiasca conditiilor aspre de pe Luna si configurarea unei tehnologii pentru ridicarea telescopului selenar in viitorii zece ani.

Harta oxigenului din Soare
Oamenii de stiinta au masurat compozitia de oxigen de la nasterea sistemului solar, descoperire vitala pentru reconstituirea evolutiei mediului nostru cosmic inconjurator, informeaza BBC. Naveta spatiala Genesis de la NASA a petrecut mai mult de doi ani in spatiu colectind oxigen din cele mai indepartate straturi ale Soarelui, care reflecta compozitia norului de praf si gaze, cunoscut sub numele de nebuloasa solara, din care sistemul solar s-a format acum 4,6 miliarde de ani.
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