Hubble and the Queen's hair

A spectacular new image of an unusual spiral galaxy in the Coma Galaxy Cluster has been created from data taken by the Advanced Camera for Surveys on the NASA/ESA Hubble Space Telescope. It reveals fine details of the galaxy, NGC 4921, as well as an extraordinary rich background of more remote galaxies stretching back to the early Universe.

The Coma Galaxy Cluster, in the northern constellation of Coma Berenices, is one of the closest very rich collections of galaxies in the nearby Universe.

Its name means "Berenice's Hair", and refers to the legend of Queen Berenice II of Egypt: around 246 BC Berenice married Ptolemy III, king of Egypt, and became Queen Berenice II. Shortly after they married, Ptolemy set off on a campaign to support his sister in the Third Syrian War.

The legend tells that Berenice vowed to the gods she would offer one of her amber hair locks in the temple of Arsinoe at Zypherium, if her husband would safely return from his military expedition.

The king returned victorious in 245 BC, and Berenice cut off one of her locks and placed it in the Temple's shrine. The next day the amber hair lock had disappeared. Conon from Samos, a mathematician and astronomer who worked at the court, declared to the king and his wife that the gods had placed the lost hair lock in the heavens. It could be seen as a new constellation between Virgo and Bootes: "Coma Berenice" (Berenice's Hair).

Anyway the cluster, also known as Abell 1656, is about 320 million light-years from Earth and contains more than 1000 members. The brightest galaxies, including NGC 4921 shown here, were discovered back in the late 18th century by William Herschel.

The galaxies in rich clusters undergo many interactions and mergers that tend to gradually turn gas-rich spirals into elliptical systems without much active star formation. As a result there are far more ellipticals and fewer spirals in the Coma Cluster than are found in quieter corners of the Universe.

NGC 4921 is one of the rare spirals in Coma, and a rather unusual one — it is an example of an "anaemic spiral" where the normal vigorous star formation that creates a spiral galaxy’s familiar bright arms is much less intense. As a result there is just a delicate swirl of dust in a ring around the galaxy, accompanied by some bright young blue stars that are clearly separated out by Hubble’s sharp vision. Much of the pale spiral structure in the outer parts of the galaxy is unusually smooth and gives the whole galaxy the ghostly look of a vast translucent jellyfish.

The long exposure times and sharp vision of Hubble also allowed it to not just image NGC 4921 in exquisite detail but also to see far beyond into the distant Universe. All around, and even through the galaxy itself, thousands of much more remote galaxies of all shapes, sizes and colours are visible. Many have the spotty and ragged appearance of galaxies at a time before the familiar division into spirals and ellipticals had become established.

The Hubble images used to make this picture were originally obtained by a team led by Kem Cook (Lawrence Livermore National Laboratory, California). The team was using Hubble to search for Cepheid variable stars in NGC 4921 that could be used to measure the distance to the Coma Cluster and hence the expansion rate of the Universe. Unfortunately the failure of the Advanced Camera for Surveys in early 2007 meant that they had insufficient data to complete their original programme, although they hope to continue after the servicing mission. Very deep imaging data like this, which is available to anyone from the Hubble archives, may also be used for other interesting scientific explorations of this galaxy and its surroundings.

This image was created from 50 separate exposures through a yellow filter and another 30 exposures through a near-infrared filter using the Wide Field Channel of the Advanced Camera for Surveys on Hubble. The total exposure times were approximately seventeen hours and ten hours respectively.



Source: ESA


Having fun? So visit our main page clicking HERE

Plenty of pure water in Mars

A large ice cap found at Mars' northern pole is "of a very high degree of purity," according to an international study reported on Tuesday by French researchers.

Radar data sent back by the SHARAD radar (Shallow Subsurface Radar) on the US Mars Reconnaissance Orbiter (MRO) point to 95 percent purity in this deposit, France's National Institute of Sciences of the Universe (Insu) said in a press release.

SHARAD looks for liquid or frozen water in the first few hundreds of feet (up to 1 kilometer) of Mars' crust by using subsurface sounding. It can detect liquid water and profile ice by probing the subsurface using radar waves within a 15- to 25-megahertz frequency band to get the desired, high-depth resolution.

The Martian polar regions are believed to hold the equivalent of two to three million cubic kilometres" (0.47-0.72 million cu. miles) of ice, it said.

That makes it roughly 100 times more than the total volume of North America's Great Lakes, which is 22,684 cu. kms (5,439 miles).

The study appears in the journal Geophysical Research Letters, published by the American Geophysical Union.



Source: Physorg



Having fun? So visit our main page clicking HERE

More...

The Swedish Meteorite

Remember the "Canadian Fireball"? Now is Sweden's time...

On Saturday (January 17) at 7:09 pm (UTC) a meteorite entered the Earth's atmosphere over Sweden and illuminated the whole sky (magnitude -10, at least) for about 4 seconds.

Luckily some cameras recorded the event, just as happened in Canada before. I hope that somebody could find the debris this time too...


Having fun? So visit our main page clicking HERE

Proportions

The Sun is extremely big - for us. But if you compare our local star with others the Sun is microscopic.

It is interesting to see how what we perceive as "huge" depends, in fact, from our momentary perspective .

Watch this animation, which compares our Sun to the biggest known star, VY Canis Majoris, to understand what I am talking about.

Having fun? So visit our main page clicking HERE

3D Mars

This is really cool...

Exactly 362 amazing anaglyph images from Mars are available at Uiversity of Arizona's HiRISE (High Resolution Imaging Science Experiment) webpage.

In these images - taken by the HiRISE Camera on board the Mars Reconnaissance Orbiter - you can see features as small as one meter (40 inches) across. In other words, you get transported to the Martian surface...


The image above shows some of the canyons of Arabia Terra, a large upland region in the north of Mars.

All you need to enjoy the show: 3D glasses like those at right. You can buy them, but if you prefer you can make them: find instructions HERE.

HiRISE website: LINK

Enjoy!


Having fun? So visit our main page clicking HERE

More...

The Moon: closer, brighter, bigger

In 2004, Greek amateur astronomer Anthony Ayiomamitis photographed an apogee Moon and a perigee Moon, and set the images side by side to show the difference.

No, you can not see Neil Armstrong's footprint. But go ahead and look: The full Moon of Dec. 12th is the biggest and brightest full Moon of the year.


It's no illusion. Some full Moons are genuinely larger than others and this Friday's is a whopper. Why? The Moon's orbit is an ellipse with one side 50,000 km closer to Earth than the other: diagram. In the language of astronomy, the two extremes are called "apogee" (far away) and "perigee" (nearby). On Dec. 12th, the Moon becomes full a scant 4 hours after reaching perigee, making it 14% bigger and 30% brighter than lesser full Moons we've seen earlier in 2008.

A perigee Moon brings with it extra-high "perigean tides," but this is nothing to worry about, according to NOAA. In most places, lunar gravity at perigee pulls tide waters only a few centimeters (an inch or so) higher than usual. Local geography can amplify the effect to about 15 centimeters (six inches)--not exactly a great flood.

Okay, the Moon is 14% bigger, but can you actually tell the difference? It's tricky. There are no rulers floating in the sky to measure lunar diameters. Hanging high overhead with no reference points to provide a sense of scale, one full Moon looks much like any other.

The best time to look is when the Moon is near the horizon. That is when illusion mixes with reality to produce a truly stunning view. For reasons not fully understood by astronomers or psychologists, low-hanging Moons look unnaturally large when they beam through trees, buildings and other foreground objects. On Friday, why not let the "Moon illusion" amplify a full Moon that's extra-big to begin with? The swollen orb rising in the east at sunset may seem so nearby, you can almost reach out and touch it.

Via NASA

Having fun? So visit our main page clicking HERE

More...

Hubble finds carbon dioxide on an extrasolar planet

The NASA/ESA Hubble Space Telescope has discovered carbon dioxide in the atmosphere of a planet orbiting another star. This is an important step along the trail of finding the chemical biotracers of extraterrestrial life, as we know it.


The Jupiter-sized planet, called HD 189733b, is too hot for life. But new Hubble observations are a proof-of-concept demonstration that the basic chemistry for life can be measured on planets orbiting other stars. Organic compounds can also be a by-product of life processes and their detection on an Earth-like planet may someday provide the first evidence of life beyond Earth.

Previous observations of HD 189733b by Hubble and the Spitzer Space Telescope found water vapour. Earlier this year Hubble found methane in the planet’s atmosphere.
"This is exciting because Hubble is allowing us to see molecules that probe the conditions, chemistry, and composition of atmospheres on other planets," says first author Mark Swain of The Jet Propulsion Laboratory in Pasadena, USA. "Thanks to Hubble we're entering an era where we are rapidly going to expand the number of molecules we know about on other planets."

The international team of astronomers used Hubble's Near Infrared Camera and Multi-Object Spectrometer (NICMOS) to study infrared light emitted from the planet, which lies 63 light-years away. Gases in the planet's atmosphere absorb certain wavelengths of light from the planet's hot glowing interior. The team identified not only carbon dioxide, but also carbon monoxide. The molecules leave their own unique spectral fingerprint on the radiation from the planet that reaches Earth. This is the first time a near-infrared emission spectrum has been obtained for an extrasolar planet.

"The carbon dioxide is kind of the main focus of the excitement, because that is a molecule that under the right circumstances could have a connection to biological activity as it does on Earth," Swain says. "The very fact that we're able to detect it, and estimate its abundance, is significant for the long-term effort of characterizing planets both to find out what they’re made of and to find out if they could be a possible host for life."

This type of observation is best done for planets with orbits tilted edge-on to Earth. They routinely pass in front of and then behind their parent stars, phenomena known as eclipses. The planet HD 189733b passes behind its companion star once every 2.2 days. This allows an opportunity to subtract the light of the star alone (when the planet is blocked) from that of the star and planet together prior to eclipse), thus isolating the emission of the planet alone and making possible a chemical analysis of its "day-side" atmosphere.

In this way, Swain explains that he's using the eclipse of the planet behind the star to probe the planet's day side, which contains the hottest portions of its atmosphere. "We're starting to find the molecules and to figure out how many of them there are to see the changes between the day side and the night side,”Swain says.

This successful demonstration of looking at near-infrared light emitted from a planet is very encouraging for astronomers planning to use the NASA/ESA/CSA James Webb Space Telescope when it is launched in 2013. These biomarkers are best seen at near-infrared wavelengths.

Astronomers look forward to using JWST to spectroscopically look for biomarkers on a terrestrial planet the size of Earth, or a "super-Earth" several times our planet's mass.

Swain and colleagues next plans to search for molecules in the atmospheres of other extrasolar planets, as well as trying to increase the number of molecules detected in extrasolar planet atmospheres. He also plans to use molecules to study changes that may be present in extrasolar planet atmospheres to learn something about the weather on these distant worlds.

Co-author Giovanna Tinetti from University College London adds: "In the terrestrial planets of our solar system, carbon dioxide plays a crucial role for the stability of climate. On Earth, carbon dioxide is one of the ingredients of the photosynthesis and a key element for the carbon cycle. Our observations represent a great opportunity to understand the role of carbon dioxide in the atmospheres of hot Jupiter type planets".


Source: ESA

Having fun? So visit our main page clicking HERE

More...

Solar System Visualizer

This is really interesting: the Solar System Visualizer shows the orbits of several planet's satellites (planets from our Solar System and some from extrasolar systems).


The Solar System Visualizer could be reached through this LINK.

It's simple, easy, objective and fun...

The Solar System Visualizer was created by Michael VanDaniker and Andrew Lund as a part of an independent study under Douglas Hamilton at the University of Maryland.

If you like this kind of thing you might be interested to see THIS too.



Having fun? So visit our main page clicking HERE

More...

Time travel: an explosion first seen in 1572 is being watched again

Astronomers at the Subaru Telescope went back in time and observed light from a “new star” that originally was seen on 11 November 1572 by astronomer Tycho Brahe and others. What Brahe observed as a bright star in the constellation Cassiopeia, outshining even Venus, was actually a rare supernova event where the violent death of a star sends out an extremely bright outburst of energy. He studied the brightness and color of the “new star” until March 1572 when it faded from view. The remains of this milestone event are seen today as Tycho’s supernova remnant (picture above).

A team of international astronomers recently completed a study at Subaru that focused on ‘light echos’ from Tycho’s supernova to determine its origin and exact type, and relate that information to what we see from its remnant today. A ‘light echo’ is light from the original supernova event that bounces off dust particles in surrounding interstellar clouds and reaches Earth many years after the direct light passes by; in this case, 436 years ago.



This same team used similar methods to uncover the origin of supernova remnant Cassiopeia A in 2007. Lead project astronomer at Subaru, Dr. Tomonori Usuda, said “using light echoes in supernova remnants is time-travelling in a way, in that it allows us to go back hundreds of years to observe the first light from a supernova event. We got to relive a significant historical moment and see it as famed astronomer Tycho Brahe did hundreds of years ago. More importantly, we get to see how a supernova in our own galaxy behaves from its origin.”

The view of the light echoes from Tycho’s supernova. The optical light arrived at Earth in 1572 (sky blue arrow). Optical light was scattered by dust cloud around the supernova arrived in 2008 (yellow arrows). Since the emitting regions were apparently shifted from 23 August 2008 to September 24, the optical lights were confirmed as light echoes.

On 24 September 2008, using the Faint Object Camera and Spectrograph (FOCAS) instrument at Subaru, the light echoes were broken apart into the signatures of atoms (spectra) present when Supernova 1572 exploded, bearing all the information about the nature of the original blast. The results showed clear absorption of once-ionized silicon and absence of the hydrogen H-alpha emission. The findings were very typical of a Type Ia supernova observed at maximum brightness of its outburst.

During the study, the astronomers tested theories of the explosion mechanism and the nature of the supernova progenitor. For Type Ia supernovae, a white dwarf star in a close binary system is the typical source, and as the gas of the companion star accumulates onto the white dwarf, the white dwarf is progressively compressed, and eventually sets off a runaway nuclear reaction inside that eventually leads to a cataclysmic supernova outburst. However, as Type Ia supernovae with luminosity brighter/fainter than standard ones have been reported recently, the understanding of the supernova outburst mechanism has come under debate. In order to explain the diversity of the Type Ia supernovae, the Subaru team studied the outburst mechanisms in detail.

What they discovered is that Supernova 1572 shows indications of an aspherical/nonsymmetrical explosion, which, in turn, puts limits on explosion models for future studies. In addition, follow-up comparisons with template spectra of Type Ia supernovae found outside our Galaxy shows that Tycho's supernova belongs to the majority class of Normal Type Ia, and, as such, is now the first confirmed and precisely classified supernova in our galaxy. This finding is significant because Type Ia supernovae are the primary source of heavy elements in the Universe, and play an important role as cosmological distance indicators, serving as ‘standard candles’ because the level of the luminosity is always the same for this type of supernova.

This observational study at Subaru established how light echoes can be used in a spectroscopic manner to study supernovae outburst that occurred hundreds of years ago. The light echoes, when observed at different position angles from the source, enabled the team to look at the supernova in a three dimensional view. For the future, this 3D aspect will accelerate the study of the outburst mechanism of supernova based on their spatial structure, which, to date, has been impossible with distant supernovae in galaxies outside the Milky Way.

Fonte: National Astronomical Observatory of Japan

Having fun? So visit our main page clicking HERE

More...

It's tonight!

Remember the spectacular conjunction? It's going to happen tonight!

Enjoy...




Having fun? So visit our main page clicking HERE

Spectacular conjunction

This story ends with the best sky show of the year - a spectacular three-way conjunction of Venus, Jupiter and the crescent Moon.

On Nov. 29th the two planets will be less than 3 degrees apart and you'll think to yourself "surely it can't get any better than this."

And then it will. On Nov. 30th a slender 10% crescent Moon leaps up from the horizon to join the show. The delicate crescent hovering just below Venus-Jupiter will have cameras clicking around the world.

Dec. 1st (sky map, above) is the best night of all. The now-15% crescent Moon moves in closer to form an isosceles triangle with Venus and Jupiter as opposing vertices. The three brightest objects in the night sky will be gathered so tightly together, you can hide them all behind your thumb held at arm's length.

The celestial triangle will be visible from all parts of the world, even from light-polluted cities. People in New York and Hong Kong will see it just as clearly as astronomers watching from remote mountaintops. Only cloudy weather or a midnight sun (sorry Antarctica!) can spoil the show.

Although you can see the triangle with naked eyes--indeed, you can't miss it—a small telescope will make the evening even more enjoyable. In one quick triangular sweep, you can see the moons and cloud-belts of Jupiter, the gibbous phase of Venus (69% full), and craters and mountains on the Moon. It's a Grand Tour you won't soon forget.

Finally, look up from the eyepiece and run your eyes across the Moon. Do you see a ghostly image of the full Moon inside the bright horns of the crescent? That's called "Earthshine" or sometimes "the da Vinci glow" because Leonardo da Vinci was the first person to explain it: Sunlight hits Earth and ricochets to the Moon, casting a sheen of light across the dark lunar terrain.

Via NASA



Having fun? So visit our main page clicking HERE

Meteor over Canada

Beautiful meteor exploding over Alberta, Canada, on November 20.

The fireball was filmed by a police car dashboard camera (first video) and a security camera (second video).

The fireball was attributed to a re-entering piece of rocket from a Soyuz launch on November 14th, but it appears that any rocket debris left over from Soyuz is still being tracked in space and has not re-entered. The Saskatchewan fireball is therefore assumed to be a naturally occurring meteoroid, possibly as large as a grapefruit car.

Having fun? So visit our main page clicking HERE

Top 50 NASA photos of all time

Amazing gallery with NASA's top 50 photos of all time, by Smithsonian Institution's Air & Space Magazine.

If you enjoy this theme you can't miss... To get there use this LINK.



Having fun? So visit our main page clicking HERE

Mystery aurora above Saturn's hexagon

Not only does Saturn have a mysterious hexagonal shape etched into the bands of cloud above its north pole, it also has a unique magnetic structure. This is suggested by recent results recorded by the NASA Cassini probe that passed over the pole to see a huge active auroral region, much larger and more dynamic than expected (picture above, click to enlarge).


According to Tom Stallard, a scientist working with Cassini data at the University of Leicester: “We’ve never seen an aurora like this elsewhere. It’s not just a ring of auroras like those we’ve seen at Jupiter or Earth. This aurora covers an enormous area across the pole. Our current ideas on what forms Saturn’s aurora predict that this region should be empty, so finding such a bright aurora here is a fantastic surprise."



It isn't stablished yet any relation between the hexagon and the aurora - but since the aurora occurs exactly above the hexagon this a possibility to be analyzed. Saturn's hexagon was spotted by the first time in 1980, when Voyager I first captured images of the phenomena - and since then the hexagon remains there. Below you can see some new images of both Saturn's poles:



The aurora now became part of Saturn's collection of mysteries, along with the North pole's hexagon and the massive cyclone that lies in the South pole (the following pictures).




Finally, take a look at this extremely interesting video.

Sources: NASA , astroengine

Having fun? So visit our main page clicking HERE

More...

Google Moon, Google Mars

Maybe you don't know but there are two Google Earth-like apps for the Moon and Mars, both from Google.

Images above are from Google Moon (top) and from Google Mars. Click the images to access each website.



Having fun? So visit our main page clicking HERE

Interactive 3D map of our interstellar neighbourhood

Try this one... it's a great work from Krystian Majewski:

A spatial representation of every star within 14 light-years of the Solar System in orthographic projection. There are 32 stars in this region, including the Sun.

The stars are colored according to the spectral type, which may not reflect the actual color. Each grid square represents 1 square light year. The grid is aligned to the ecliptic. Planets are not shown on this map because they would be indistinguishable at this scale.

Click HERE to access the map.


Having fun? So visit our main page clicking HERE

This page in Portuguese: AQUI

Hubble is back in business

The European Space Agency has just released this information: the Hubble Space Telescope is working properly again and already sent a fantastic snapshot (above - click to enlarge).

Just a couple of days after the orbiting observatory was brought back online, Hubble aimed its prime working camera, the Wide Field Planetary Camera 2 (WFPC2), at a particularly intriguing target, a pair of gravitationally interacting galaxies called Arp 147.

The pair Arp 147 lies in the constellation of Cetus (Whale), and in this image both galaxies are in a beautiful alignment.

Via esa




Having fun? So visit our main page clicking HERE

How is the view of Earth from Mars?

Like this... (click to enlarge)



Via Boston College



Having fun? So visit our main page clicking HERE