Tech's Corner

Scientists: Earth Has Two Moons

12/24/2011

This is view of how Earth would look like from its second moon.

A group of scientists proposed in a new scientific paper that Earth has two moons, the familiar one we see in the sky at night, influencing our planet's tides, and another one, only as big as a very small car.

The asteroid is not always the same, the team behind the paper believes. They say that there is a space rock around Earth at all times, an object at least 3.3 feet (1 meter) in diameter. However, any given rock flies away at one point, and is replaced by another with the same attributes.

According to the proposal – published in the December 20 issue of the scientific journal Icarus – a theoretical model they developed indicates the presence of such objects in donut-shaped orbits around Earth. However, this very path is what's constantly kicking them out of sync with the planet.

The simulation shows that Earth is capable of attracting some of the asteroids that make their way through the inner solar system, as they prepare to slingshot around the Sun and make their way to the outer edges of the system yet again.

Each of the companions our planet captures stays with us for about 9 months, completing 3 of the aforementioned orbits before being finally sent on its merry way. This scenario is not at all exaggerated, astronomers say, since they admit very little attention has been given to objects orbiting Earth.

Obviously, this is not the case with the Moon, but scientists always knew deep down inside that there must be other objects making their way around the planet. The research included Paris Observatory astronomer Jeremie Vauballion.

“There are lots of asteroids in the solar system, so chances for the Earth to capture one at any time is, in a sense, not surprising,” adds the expert, who is also a coauthor of the new study. He adds that this is one of the first models to try to simulate Earth's influence on surrounding asteroids, Space reports.

One of the temporary moons the team proposes was discovered by the Catalina Sky Survey, in Arizona, about 5 years ago, and was named 2006 RH120. The object was between 3 to 6 meters (10 and 20 feet) in diameter, and was most likely larger than other Earth companions before and after it.

Speaking about the smaller ones, Mikael Gravnik says that “objects of this size are too faint to be detected when being at a distance of, say, a few lunar distances from the Earth.” The expert, who is based at the University of Helsinki, is the lead author of the Icarus paper.

“When coming closer in during their orbit, they are moving too fast to be detected, because the limited amount of photons is spread over too many pixels,” he concludes.

Proba-2 Witnesses Large Solar Eruption

6/12/2011

This is the M2.5-class solar flare observed by Proba-2's SWAP instrument

On Tuesday, June 7, the Sun produced a large-scale solar flare, that observatories belonging to numerous space agencies were able to observe and analyze. The European Space Agency's (ESA) Proba-2 microsatellite was one of these spacecraft.

Our Sun is constantly being monitored by a number of dedicated telescopes, including the Solar Dynamics Observatory, STEREO, SOHO and others. Each of them focuses its observations on a specific wavelength or phenomenon, but together they provide a comprehensive view of the star.

Proba-2 is an European microsatellite, about a cubic meter in volume, which sports numerous innovations in terms of space-based instruments and capabilities. In addition to being able to conducting actual science, the spacecraft is also a technology testbed.

Its main mission is to survey the Sun, and it uses five instruments to do so. Two of them are dedicated specifically to monitoring the entire star. The first is the extreme ultraviolet wavelength (EUV) Sun Watcher using APS and Image Processing (SWAP) instrument.

The second one is called the Lyman Alpha Radiometer (LYRA). The three other are the Dual segmented Langmuir probe (DSLP), the Thermal Plasma Measurement Unit (TPMU) and the Science Grade Vector Magnetometer (SGVM). All three measure the basic properties of solar plasma.

Now that the Sun is finally reaching a maximum in its standard, 11-year-long cycle, the instruments spring into action more and more. The new solar flare again demonstrates that the star is starting to wake up, and to approach a period of intense activity, in 2012-2013.

Tuesday's event was a medium-class M2.5 solar flare, that triggered a coronal mass ejection (CME), otherwise known as a proton storm. The events were accompanied by a burst of radio energy.

The gas in the solar flare “was relatively cool – about 80 000ºC – which explains why it appears quite dark at the extreme ultraviolet wavelength of SWAP,” ESA officials say in a press release.

“Much of this gas then fell back to the Sun, with dark downflows that brighten as they fall, probably due to localized heating. This darkening actually caused a decrease in the average intensity seen by SWAP,” the document adds.

The 130-kilogram Proba-2 is the second of its series. With the Proba constellation, ESA aims to test the possibility of sending low-cost, low-weight, microsatellites to space, in order to conduct science that is generally conducted with much larger spacecraft.

Black Hole Twins Found in Nearby Galaxy

6/12/2011

A new scientific investigation has revealed the presence of yet another enormous black hole, at the core of a galaxy where experts had already discovered a supermassive black hole during previous studies.

The two cosmic giants apparently share the same home, experts say, inside the galaxy Markarian 739. The cosmic structure is located about 425 million light-years away from Earth, which is relatively near-by in astronomical terms.

Scientists operating the NASA Swift satellite and the NASA Chandra X-Ray Observatory were the ones who managed to identify the second black hole, orbiting close to the known one. The two may be in the process of merging with each other.

However, the objects are some distance away from each other, the new study also showed. Apparently, they are separated by 11,000 light-years, which is the equivalent of 33 percent of the distance separating our entire solar system from the core of our galaxy.

Both black holes have recently been cataloged as supermassive, which means that they can have the mass of billions of Suns. These objects are still extremely active, and thousands of times heavier than black holes produced via stellar collapses.

“At the hearts of most large galaxies, including our own Milky Way, lies a supermassiveblack hole weighing millions of times the Sun's mass,” explains researcher Michael Koss, the lead author of a new study detailing the findings.

“Some of them radiate billions of times as much energy as the Sun,” adds the expert, who holds joint appointments at the NASA Goddard Space Flight Center (GSFC), in Greenbelt, Maryland, and the University of Maryland in College Park.

He goes on to say that discovering two black holes capable of producing active galacticnuclei (AGN) in the same galaxy is extremely unusual. AGN are extremely rare as it is, and they can mostly be seen in distant galaxies powered by quasi-stellar radio sources(quasars).

Markarian 739 is not the only galaxy to display such twin, supermassive black holes. The galaxy NGC 6240, located approximately 330 million light-years from Earth, also has a similarly-active core, Space reports.

The Science Behind ExoMars' EDM

6/12/2011

This rendition shows the ExoMars orbiter ejecting the EDM

A group of officials at NASA and the European Space Agency (ESA) announce that they have finally decided on the science component of a demonstrator vehicle, that will be a part of the joint ExoMars mission to two agencies will be launching in 2016.

The ESA/NASA ExoMars Trace Gas Orbiter mission aims to put another spacecraft in Martian orbit, this time with the intent purpose of figuring out where the planet's methane supply is regenerated from.

But the new orbiter will also carry Entry, descent, and landing Demonstrator Module (EDM), a vehicle whose job will be to test new technologies that ESA has yet to develop. NASA has harnessed the science of Martian landings a long time ago, but Europe still lags behind.

When ExoMars enters orbit, it will deploy the EDM as pictured in the image attached to this article. The latter will then enter the Martian atmosphere, descent through it, and attempt a controlled landing.

During these three phases of its flight, the EDM will be opened for science. NASA and ESA recently concluded an analysis of the experiments scientists proposed for this short extraterrestrial flight.

Two experiments were selected for inclusion in the module – the Entry, Descent and Landing (EDL) Science and the Investigations During Entry and Atmospheric Science (IDEAS) instrument.

Together, the two might even return the first-ever data on electrical fields at the surface of our neighboring planet. No other mission has succeeded in doing so until now. EDL and IDEAS have now been combined into the Entry and Descent Science (EDS) program.

“The EDM will be landing during the dust storm season. This will provide a unique chance to characterise a dust-loaded atmosphere during entry and descent, and to conduct interesting surface measurements associated with a dust-rich environment,” ExoMars project scientist Jorge Vago says.

“The selection of these science investigations complements the technological goals of the EDM. This has been an important step that will allow our team to move on to the development of this important mission element,” the official adds.

ExoMars “will seek faint gaseous clues about possible life on Mars. This instrument, called the ExoMars Climate Sounder, will supply crucial context with its daily profiling of the atmosphere's changing structurem” NASA says on the mission website.

“The European Space Agency and NASA have selected five instruments for ExoMars Trace Gas Orbiter. The European Space Agency will provide one instrument and the spacecraft,” the statement adds.

“NASA will provide four instruments, including ExoMars Climate Sounder, which is coming from NASA's Jet Propulsion Laboratory, Pasadena, California,” it concludes.

Wolf-Rayet Stars Create Amazing 'Bubbles'

2/25/2011

Astronomers say that they may have finally found the origins of a series of interesting structural features that can be seen in NGC 2359, a formation also known as Thor's Helmet.

This is an emission nebula located in the constellation Canis Major, some 15,000 light-years away from our planet. The nebula itself is an estimated 30 light-years in diameter. For comparison, the entire Milky Way is about 100,000 light-years in diameter.

Inside this cosmic structure, astronomers have identified a number of bubbles and arcs, structures whose existence they could not explain. In a new study, they finally made some headway in this regard.

The experts say that the main culprit is a massive Wolf-Rayet star, that is located in the center of one of the bubbles, as evidenced in the attached image. This category of stars contains celestial fireballs that are both massive and highly luminous.

Wolf–Rayet stars (generally called WR stars) are objects that are relatively old and also very heavy. They tend to be 20 times the mass of our Sun, or more, and their main characteristic is that they are losing mass at very high rates.

The main mechanism through which this happens is via high-speed solar winds, which take matter out of the star at speeds reaching 2,000 kilometers per second. Average surface temperatures on WR stars are very high, at between 25,000 and 50,000 degrees Kelvin.

For comparison, the Sun is only about 5,800 degrees Kelvin on its surface. Granted, the corona is significantly hotter, reaching temperatures of millions of degrees, Daily Galaxy reports.

In the new scientific study, it was revealed that the massive amounts of matter that WR stars lose via solar winds are what cause the bubbles in Thor's Helmet and other similar nebulae.

However, the data also indicates that other mechanisms are at work inside NGC 2359 that are not visible in other similar locations. According to scientists, the observed differences could be accounted for if we consider the WR star in the nebula is moving at supersonic speeds.

At this point, this is only a supposition. Researchers plan to use advanced space telescopes to get a better view of the entire scene, and perhaps determine whether the star is moving, or if it's staying put.

Light Can Help Determine if Black Holes Spin

2/25/2011

For all their “popularity“ with scientists, black holes are still pretty much mysterious in every aspect, including when it comes to their basic properties. For instance, it's still unclear if they spin or not, but that could soon change. A team of scientists is already studying the issue via a new method.

The physics of black holes is still a matter of intense debate, primarily because most studies dealing with the issue are either theoretical, or they deal with the results of computer simulations.

But a team of investigators believes it may have discovered a way of telling if black holes actually spin or not. They say that this trait could be teased out by analyzing the way in which light is distorted as it moves past sch a dark behemoth.

Due to their tremendous gravitational pull, black holes not only draw in matter and light from their surroundings, but they also distort the very fabric of spacetime. But the way in which this fabric is distorted is influenced by many factors.

For example, there is a difference between the gravitational warp caused by a static object and a rotating one. The latter produces an effect called frame-dragging, which was first hypothesized by Albert Einstein in his theory on general relativity.

Its existence was inferred from the theory by Austrian physicists Josef Lense and Hans Thirring back in 1918, and so the phenomenon is also called the Lense–Thirring effect. Detecting it is however a tremendously complex task even around Earth.

However, it's not impossible. The NASA Gravity Probe B (GP-B) mission managed to detect the effect around our planet. Given that Earth deforms spacetime due to gravity and that it also spins, then objects in its orbit should theoretically be slightly drawn into the direction in which it rotates.

The same could be observed by analyzing light bent by black holes. The effect these structures have on light should theoretically differ if they spin, or if they are standing still.

“Light acquires kind of a spiral motion that carries information about the distorted space-time around a black hole. You can imagine that the light that approaches us from the black hole is not going in a straight line, but in spirals,” says scientist Bo Thidé.

He holds an appointment as a space physicist at the Swedish Institute of Space Physics in Uppsala. The expert, also the coauthor of the new investigation, says that this type of light could be easily analyzed, if astronomers have access to a very large telescope.

“This possibility of direct detection of swirling space and time around black holes is one that we think is quite exciting,” Thidé concludes, quoted by Space.

Details of the new study appear in the January 13 online issue of the esteemed journal Nature Physics.

The Universe Is 250 Times Bigger than What's Visible

2/19/2011

According to a new series of investigations, it would appear that the entire Universe, including both its visible and invisible components, is about 250 times than the visible Cosmos alone is.

There are several misconceptions going around about how old the Universe is. Cosmologists have been able to refine their results to prove that it is some 13.75 billion years old. This should theoretically mean that we cannot see things that are located further than 13.75 billion light-years away.

And this would be true too, were it not for Universal expansion. The visible parts of the Cosmos are not in fact nearly 28 billion years wide, but 90 billion years wide. This finding was made by analyzing background radiation permeating all space.

Some photons in the Cosmic Microwave Background (CMB) that have been detected here were determined to have traveled more than 45 billion years before finally reaching our location.

So, we know that the visible Universe is big, but cosmologists have been wondering for a long time how big the rest of it is. They are of course referring to its invisible part, which is undoubtedly much larger than we were led to believe.

University of Oxford investigator Mihran Vardanyan and his team discovered the answer by creating and studying interesting statistical models of the Cosmos as a whole. The researchers determined that it is some 250 times bigger than the Hubble volume.

This volume is comparable in size to that of the observable Universe. Thus far, conducting studies to analyze the volume of the thing has been very difficult, due to the fact that no one could really determine the curvature of the Universe, Technology Review reports.

Being able to do so is one of the most important steps in establishing the size of the Cosmos with certainty. Curvature places drastic limitation on size and volume, physicists say.

There are numerous methods being used in the international astronomical community today for establishing curvature, but the Oxford team used an approach called Bayesian model averaging to take them all into account.

Due to its elegance, this statistical method is bound to be used in other areas of cosmology as well, for placing limitations on a variety of parameters that are currently undetermined.

Dark Matter Doesn't Control Black Hole Growth

1/30/2011

Astronomers find it very funny that the two most important forces dominating the way a galaxy looks like, behaves and travels through space cannot be detected. Though not “in league” with each other, both dark matter and black holes exert their influences through the pull of gravity.

Dark matter is believed to be a peculiar form of matter that cannot be readily detected. Yet, its influence is made visible by witnessing the gravitational effects it causes on regular matter. Conglomerations of the stuff are believed to make up about 22 percent of the mass of the Universe.

On the other hand, black holes are points of infinite density and gravitational pull, that exert such a huge attraction on everything around them, that not even light can escape, despite its speed.

Black holes, either in their solar or supermassive configuration, can be found throughout the Universe, at the core of any and all galaxies. The cosmic structures influence the behavior of stars, stellar nurseries and planetary systems in their surroundings, also through gravity.

In the past, some experts proposed connections between the existence of supermassive black holes and huge halos of dark matter. Most large galaxies that contain dark behemoths at their cores also feature dense dark matter rings around them.

Back in 2002, a group of researchers proposed that the two were connected through a fairly simple mechanism – the mass of black holes is influenced by the outer rotation velocity of the galactic disk.

In turn, that velocity is controlled by the dark matter halo extending way beyond the edges of the galaxy, the paper went on to say. Therefore, a tight connection existed between the two hidden forces in the Milky Way.

But the size of black holes has also been linked to the mass of the bulge the galaxy hosting them has. At this point, it remains unclear which factor is most influential in determining black hole growth.

In a new study from the Max Planck Institute for Extraterrestrial Physics (MPIE), experts John Kormendy and Ralf Bender sought to determine which of the two factors is more important.

“They indeed found that galaxies without a bulge – even if they are embedded in massive dark matter halos – can at best contain very low mass black holes,” an MPIE statement reads.

“Thus, they could show that black hole growth is mostly connected to bulge formation and not to dark matter,” the document goes on to say.

“It is hard to conceive how the low-density, widely distributed non-baryonic dark matter could influence the growth of a black hole in a very tiny volume deep inside a galaxy,” explains Bender, who also holds an appointment at the University Observatory Munich.

“It seems much more plausible that black holes grow from the gas in their vicinity, primarily when the galaxies were forming,” concludes Kormendy, who is also based at the University of Texas, in the US.