ikenbot:

New Research Confirms The Existence of Dark Matter

Image: Don Dixon

Fans of dark matter can rest easy. A study published last month raised eyebrows by suggesting that our cosmic neighbourhood is empty of the extra mass needed to hold the galaxy together. But a re-analysis shows that the dark matter was there all along.

Dark matter is the mysterious, invisible stuff that makes up 83 per cent of the matter in the universe. It is responsible for keeping galaxies from flying apart despite their high spinning speeds, and has aided our understanding of how structures in the universe formed.

The most popular theories say that dark matter is a hitherto undetected particle called a WIMP (weakly interacting massive particle) that is shy of interacting with ordinary matter through any force except gravity.

But several underground detectors waiting for WIMPs have come up empty, or with conflicting results. If the galaxy is so full of dark matter, why hasn’t it shown up yet?

In April, a team led by Christian Moni-Bidin of the University of Concepcion in Chile thought they had a solution: the WIMPs aren’t actually there.

The team tracked the motions of more than 400 stars within 13,000 light years of Earth to estimate the mass of matter – visible and dark – in the sun’s local neighbourhood. They concluded that the mass they found could be explained by the visible matter alone, with no need for dark matter.

But the team made a subtle error, say Jo Bovy and Scott Tremaine of the Institute for Advanced Study in Princeton, New Jersey.

Moni-Bidin and colleagues considered stars whose orbits take them far above or below the Milky Way’s main bright disc, and used the speed at which they orbit the centre of the galaxy to figure out how much of a pull they feel from the nearby mass of stars and dark matter. They assumed that the stars’ speeds would be the same no matter how far they were from the galactic centre. Observations of dust clumps have shown that this assumption is true for young stars orbiting in the galactic disc, which mostly move in a near-perfect circle.

But the stars that orbit high above or far below the disc can’t have circular orbits, Bovy says. The only stars that reach such great heights have been kicked away from the disc by matter in the galaxy’s spiral arms, which sent them on highly elliptical orbits.

Full Article: Crisis averted: Dark matter was there all along

ikenbot:

GALEX presents The Andromeda Galaxy

A mere 2.5 million light-years away, the Andromeda Galaxy really is just next door as large galaxy’s go.

So close, and spanning some 260,000 light-years, it took 11 different image fields from the Galaxy Evolution Explorer (GALEX) satellite’s telescope to produce this gorgeous portrait of the spiral galaxy in ultraviolet light.

While its spiral arms stand out in visible light images of Andromeda (also known as M31), the arms look more like rings in the GALEX ultraviolet view, dominated by hot, young, massive stars.

As sites of intense star formation, the rings have been interpreted has evidence Andromeda collided with its smaller neighboring elliptical galaxy M32 more than 200 million years ago. The large Andromeda galaxy and our own Milky Way are the dominant members of the local galaxy group.

ikenbot:

Monster Sunspot Fires Off Powerful Solar Flares

A huge sunspot that dwarfs the Earth is unleashing a series of powerful solar flares as it moves across the surface of the sun, NASA scientists say.

The sunspot AR 1476 was detected by space telescopes on May 5. The huge sunspot is 60,000 miles (100,000 kilometers) across, so large that when it was first seen in views from NASA’s Solar Dynamics Observatory spacecraft, mission scientists dubbed it a “monster sunspot.”

Earlier this week, space weather scientists predicted the sunspot would erupt with powerful solar flares, and those predictions have since come true. So far, the sunspot has fired off several flares, including a strong solar storm early Thursday (May 10).

“Solar activity has been at high levels for the past 24 hours with multiple M-class solar flares observed,” stated an update Thursday from the Space Weather Prediction Center, a joint service of NOAA and the National Weather Service. Sunspot region AR 1476 was responsible for nearly all of the sun’s storm activity, center officials said.

On Thursday, sunspot AR 1476 unleashed a powerful flare at 12:18 a.m. EDT (0418 GMT) that registered as a class M5.7 eruption. M-class solar flares are medium-strength sun storms that can still unleash powerful blasts of radiation and magnetic solar plasma. So far, the sunspot has not triggered huge explosions from the sun, which scientists call coronal mass ejections.

Continue..

ikenbot:

Light from Alien Super-Earth Seen for 1st Time

Light from an alien “super-Earth” twice the size of our own Earth has been detected by a NASA space telescope for the first time in what astronomers are calling a historic achievement.

NASA’s infrared Spitzer Space Telescope spotted light from the alien planet 55 Cancri e, which orbits a star 41 light-years from Earth. A day on the extrasolar planet lasts just 18 hours.

The planet 55 Cancri e was first discovered in 2004 and is not a habitable world. Instead, it is known as a super-Earth because of its size: The world is about twice the width of Earth and is super-dense, with about eight times the mass of Earth.

But until now, scientists have never managed to detect the infrared light from the super-Earth world.

Continue..

thenewenlightenmentage:

Uncovering the Secret Origin of Brown Dwarfs

The origin of brown dwarfs is one of the great unsolved mysteries facing astrophysicists today. In a new study published in The Astrophysical Journal (http://stacks.iop.org/0004-637X/750/30), Western University’s Shantanu Basu and University of Vienna’s Eduard Vorobyov present a new model of brown dwarf formation that unites the best parts of existing theories and has far-reaching implications for understanding the population of low mass objects in the Universe. Studying how brown dwarfs form and evolve can help astrobiologists understand their potential for supporting orbiting worlds that are habitable for life as we know it.

Brown dwarfs are astronomical objects that have too little mass to be called stars and too much mass to be called planets. Only a theoretical concept until discovered in the mid-1990s, several hundred brown dwarfs have now been identified through infrared telescopes and surveys.

“There could be significant mass in the universe that is locked up in brown dwarfs and contribute at least part of the budget for the universe’s missing dark matter,” says Basu, a professor in Western’s Department of Physics and Astronomy. “And the common idea that the first stars in the early Universe were only of very high mass may also need revision.”

One leading theory suggests that brown dwarfs form like stars through the direct collapse of low mass interstellar gas cloud fragments while another speculates that they are formed after the collapse of more massive cloud fragments yield multiple bodies including brown dwarfs that are ejected due to the mutual interaction of the bodies. Both scenarios produce conceptual and theoretical problems and are equally challenged and supported by scientists.

Employing numerical hydrodynamic simulations — carried out in part by utilizing the high performance computing capabilities of Western’s SHARCNET — Basu and Vorobyov show that the evolution of the swirling nebular disc of gas around a newly formed protostar (or a star that is still forming) is critical to brown dwarf formation. Such a disc of gas has long been postulated to exist around the early Sun and the planets in the Solar System are thought to have condensed out of such a disc.

In the study, Basu and Vorobyov prove that the early life of a disc is characterized by the formation of multiple fragments that orbit the central protostar and that the interaction of fragments leads to the ejection of some brown dwarf fragments that have yet to fully form. The ejection speeds in this mechanism are much lower than in a model where ejections occur only for fully formed brown dwarfs and provide a more favorable comparison with observations that show that brown dwarfs are present in close proximity to young stars.

thenewenlightenmentage:

“The Demon Star” —Cairo Calendar Shows Egyptians Discovered Binary Algol 3200 Years Ago

Algol, aka the Demon Star, is actually a binary star in the Perseus constellation, and has been discovered by a group of Finnish researchers to be  first noted by the Egyptians some 3200 years ago. It is one of the best known eclipsing binaries, the first such star to be discovered, and also one of the first (non-nova) variable stars to be discovered. 

Continue reading “”The Demon Star” —Cairo Calendar Shows Egyptians Discovered Binary Algol 3200 Years Ago” »

thenewenlightenmentage:

When the Stars Go Blue

Credit: Canada-France-Hawaii Telescope/Coelum

Monday, April 30, 2012: Giant blue stars ionizing hydrogen gas give dwarf galaxy IC 10 its signature blue glow, and signal ongoing star formation. IC 10 is one of tens of dwarf galaxies in our Local Group, which is dominated by the giant Milky Way (our galaxy) and Andromeda Galaxy.

— Tom Chao

fyeahuniverse:

^{Pure Water Ice & Minerals on Europa}

^{Jupiter’s moon, Europa has been found to have pure water ice. Through the use of the Galileo Spacecraft, this image has been snapped using the Near Infrared Mapping Spectrometer (NIMS). With it we can see that the areas appear bright (red, orange, yellow) are due to surface compositions of pure water ice, and mixtures of water and other minerals.}

^{(Image credit: NASA/JPL)}

fyeahuniverse:

^{Trailing Hemisphere of Europa in “natural” and false colour}

^{“This image shows two views of the trailing hemisphere of Jupiter’s ice-covered satellite, Europa. The left image shows the approximate natural color appearance of Europa. The image on the right is a false-color composite version combining violet, green and infrared images to enhance color differences in the predominantly water-ice crust of Europa. Dark brown areas represent rocky material derived from the interior, implanted by impact, or from a combination of interior and exterior sources. Bright plains in the polar areas (top and bottom) are shown in tones of blue to distinguish possibly coarse-grained ice (dark blue) from fine-grained ice (light blue). Long, dark lines are fractures in the crust, some of which are more than 3,000 kilometers (1,850 miles) long. The bright feature containing a central dark spot in the lower third of the image is a young impact crater some 50 kilometers (31 miles) in diameter. This crater has been provisionally named ‘Pwyll’ for the Celtic god of the underworld.” - via NSSDC Photo Gallery}

^{(Image credit: NASA/JPL)}