Astronomers from Keio University, Japan, have observed what looks like the largest intermediate-mass black hole within the Milky Way. The object is estimated to weigh 100,000 times the mass of the Sun and is located near the center of the galaxy.

The study, published in Nature Astronomy, focused on a large molecular gas cloud almost 200 light-years from the center of the Milky Way. The team was able to study how the gas is moving, which is consistent with having a massive compact object at its center, which they named CO–0.40–0.22*.

The researchers also noticed how the emissions from the gas cloud resemble the core of the Milky Way, where the supermassive black hole of our galaxy is located, although 500 times less luminous. There’s also quite a difference in size as the Milky Way’s supermassive black hole, called Sagittarius A*, is over 4 million times the mass of the Sun.

“This is the first detection of an intermediate-mass black hole (IMBH) candidate in our Milky Way Galaxy,” lead author Dr Tomoharu Oka told IFLScience. “This supports the merging scenario of the formation/evolution of supermassive black holes in galactic centers.”

The team already suspected the cloud hosted an IMBH, but this is the first detection of a point-like radio source. The new observations were possible thanks to Atacama Large Millimeter/Submillimeter Array whose sensitive antennas were ideal to pick up the extremely cold emissions of interstellar carbon monoxide clouds. The team compared the observations to numerical simulations of the gas cloud and they agreed with the idea of an intermediate-mass black hole hiding within. The team believes CO–0.40–0.22* to be one of the most promising candidates for an intermediate-mass black hole yet.

The discovery of potential new black hole is always an exciting affair but this is particularly important because it provides us with important clues to how supermassive black holes formed. Black holes form in supernova explosions but their size is very much related to their stellar progenitors. So how can black holes exist that are millions, if not billions, of times the mass of our Sun?

One main theory suggests that in the early universe black holes formed a lot more often because the stars were a lot bigger and burned through their fuel more quickly. These black holes would merge, eventually reaching hundreds of solar masses in size. At that point, they would merge with other similar sized black holes and become supermassive black holes.

The team is continuing observations of the source, and they hope that within just a decade of observations they’ll be able to describe how it’s moving across the galaxy and if it’s going to merge with Sagittarius A*.  

Read more: http://www.iflscience.com/space/black-hole-100000-times-the-mass-of-the-sun-discovered-in-our-own-galaxy/

A star just 10 light-years away may provide a fascinating glimpse into the beginnings of our own Solar System.

The star, called Epsilon Eridani, is similar to our Sun but about one-fifth the age, and contains debris disks that are the hallmark of the formation of a planetary system.

A new study by Iowa State University, published in The Astronomical Journal, examined the disks of debris around the star. They found that the star has separate inner and outer disk structures, similar to the asteroid belt between Earth and Mars and the Kuiper Belt beyond Neptune in our own Solar System.

This star hosts a planetary system currently undergoing the same cataclysmic processes that happened to the Solar System in its youth, at the time in which theMoon gained most of its craters, Earth acquired the water in its oceans, and the conditions favorable for life on our planet were set, co-author Massimo Marengo said in a summary of the study.

This period is known as the late heavy bombardment (LHB), when its thought that comets from the Kuiper Belt and possibly the Oort Cloud further out too were sent flying inwards. This is thought to have happened between 4.1 and 3.8 billion years ago in our Solar System, which is about 4.6 billion years old.

We can see evidence for this period today in the age of craters on the Moon and other bodies. Samples from the Apollo missions found that many lunar craters heralded from this time period. The migration of Jupiter and Saturn to different orbits is thought to have caused the event, kicking Neptune further out and sending comets inwards.

^{A model of epsilon Eridani compared to our own Solar System.NASA/SOFIA/Lynette Cook}

Its not clear what process is taking place in Epsilon Eridani. But we do know theres a Jupiter-mass planet there, called Epsilon Eridani b, at the edge of an inner asteroid belt roughly at the same position as our own. A second asteroid belt is at about the same position as the orbit of Uranus in our system.

The similarity of the structure of the Epsilon Eridani system to our Solar System is remarkable, although Epsilon Eridani is much younger than our Sun, NASA said in a statement.

These latest findings were made using NASAs Stratospheric Observatory for Infrared Astronomy (SOFIA), a plane equipped with a telescope that flies at about 13,700 meters (45,000 feet) to observe the universe.

[W]e can now say with great confidence that there is a separation between the stars inner and outer belts, Marengo said ina statement. There is a gap most likely created by planets. We havent detected them yet, but I would be surprised if they are not there.

Read more: http://www.iflscience.com/space/nearby-star-may-be-a-young-version-of-our-solar-system/

Researchers have finally been able to produce metallic hydrogen, a complex and elusive state that was firstly theorized more than 80 years ago.

Dr Ranga Dias and Professor Isaac Silvera from Harvard University were able to achieve this impressive feat by cooling down hydrogen to 5.5 Kelvin (-268C/-450F), while compressing it to astaggering pressure of 4.8 million atmospheres. The breakthrough is reported this week in Science.

The incredibly high pressure was achieved by using diamond anvil cells. But it was not a straightforward approach. Scientists have been trying to get to this pressure for many years, and although they’vealmost got there, only now have scientists got the right set up.

“Metallic hydrogenwas never made before because diamonds failed before a sufficiently high pressure was attained,” Professor Silvera told IFLScience. “We do not use natural diamonds but rather synthetics which are very homogeneous, while naturals have inhomogeneities and internal defects and impurities.”

In its standard form, hydrogen is a molecular gas with its atoms bound in pairs, each sharing an electron with theother. When hydrogen was placed between the anvils, the pressure mounts and things get weird.

At a pressure of 3.2 million atmospheres, hydrogen becomes opaque (hence the nickname black hydrogen) and is also a semiconductor. But only a much higher pressure can break the molecular bonds and create the metallic hydrogen phase. The gas was turned into a metal, with the expected properties an atomic metal has. The two researchersbelieve metallic hydrogen is a solid, but the team wasnt able to confirm itexperimentally.

^{Photos and molecular representation of the compressed hydrogen going from transparent gas to black molecular to metallic hydrogen. R. Dias and I.F. Silvera}

This peculiar phase of hydrogen was first predicted in 1935 by E. Wigner and H.B. Huntington, and since then achieving this has become the holy grail of high-pressure physics. But Wigner and Huntington were wrong in their estimation of the necessary pressures. They thought metallic hydrogen could be achieved with a pressure of 250,000 atmospheres, almost 20 times smaller than what has been necessary to make it in real life.

Creating metallic hydrogen is not just a triumph of science for the sake of science. Understanding the metallic properties of the most abundant element in the universe has a multi-disciplinary impact. Metallic hydrogen is thought to be metastable at room temperature after the pressure is removed, so it could be used in nuclear fusion.

It is also believed to be a high-temperature superconductor, which would be an incredible breakthrough if confirmed. And even astronomy might benefit from this the core of Jupiter, Saturn, and exoplanets could be made of metallic hydrogen.

Read more: http://www.iflscience.com/physics/metallic-hydrogen-achieved-for-the-first-time/

In twelve years time the universe looks set to offer us an exceptionally rare opportunity to discover if there are any planets orbiting Alpha Centauri A, one of the two nearest Sun-like stars to our own.

General relativity predicts that gravity can distort the path of light. When correctly positioned, a heavy object bends light around it to act as a lens, giving us a better view of whatever is behind it. The nature of the bending also tells us a lot about the distorting object. One of the ways we have discovered planets around other stars is by watching the parent star act as a gravitational lens for objects towards the center of the galaxy, and noticed the extra blip provided by the planet itself.

Usually, however, even the closer star is a long way from Earth. Discovering their planets has been useful in building statistics on planetary size and locations, but interest in individual discoveries was more muted. One of the closest stars to Earth passing in front of an object that would allow it to act as a gravitational lens would be a different matter entirely.

In Astronomy and Astrophysics, a team led by Professor Pierre Kervella of the Universidad de Chile decided to see whether Alpha Centauri will give us any such opportunities before 2050.

Kervella’s team plotted the movements of both stars in the double system across our field of view. They made an extensive study of the background objects they will pass, and concluded that in May 2028 Alpha Centauri A will pass almost directly in front of the star 2MASS 14392160-6049528 (nicknamed S5). The timing is particularly fortuitous, since Alpha Centauri will be high in the sky at night, and the two stars will be widelyseparated, so that Alpha Centauri B’s light will not interfere.

^{The paths of Alpha Centauri A (orange) and B (red) across the sky, with the objects one or the other star will pass in front of marked. Kervella et al Astronomy and Astrophysics}

Little is known about S5, a previously disregarded star whose magnitude of 7.8 makes it visible in binoculars or small telescopes. It is thought to be a red giant at a distance of several thousand light-years.

As seen from Earth, Alpha Centauri A is predicted to pass just 0.015 arc seconds from S5, creating a lensing effect sharp enough that we should be able to detect any large planets near it at the same time. Kervella estimates a 45 percent chance of the approach being close enough to produce an Einstein Ring, the most dramatic form of lensing.

There will be four previous times when one of Alpha Centauri’s stars pass in front of a background object, and many more before 2050. These are at least a thirty times fainter, greatly reducing the chance of detecting planets, although some may prove useful as test runs.

^{Trajectories of Centauri A (orange curve) and B (red curve) superimposed on an image Alpha Centauri. Kervella et al/Astronomy and Astrophysics}

The recent discovery of a planet orbiting Proxima Centauri has put the focus on our nearest stellar neighbor, but the twin stars of Alpha Centauri A and B are almost as close, and bear a much greater resemblance to the Sun.

Kervella’s technique could be applied to other nearby stars. However, Alpha Centauri’s location near the galactic plane means that it will pass in front of stars that are bright enough to be useful unusually often. For planet-hunting astronomers, 2028 could be a true once in a lifetime opportunity.

[H/T:The Register]

Read more: http://www.iflscience.com/space/2028-to-provide-rare-opportunity-for-planet-hunting-around-alpha-centauri/

The release of a catalog of more than 70 galactic gamma-ray sources has been accompanied by a flurry of papers. One proposes a young, very hot star might be a powerful gamma-ray emitter, which would force a rethink of ideas about the conditions around one of the rarest categories of stars.

Gamma rays are the highest-energy part of the electromagnetic spectrum, which has radio waves at the opposite end and visible light towards the middle. As such, their astronomical sources include the most powerful objects in the universe, such as neutron stars and the births of black holes. For the last 15 years, the High Energy Stereoscopic System (HESS) has been surveying the Milky Way at extreme gamma-ray frequencies from Namibia.

The results have been reported in Astronomy and Astrophysics, along with 14 papers discussing some of the most interesting new finds. One paper deals with a strong gamma-ray source in a cluster of stars that includes LBV 1806-20, a blue giant star some 20-30 times the mass of the Sun, one of only a dozen luminous blue variable stars in the entire galaxy.

“The cluster of stars also harbors a rare, extremely magnetic, neutron star known as a magnetar,” Dr Gavin Rowell of the University of Adelaide said in a statement. Magnetars are major gamma-ray sources; “but we think the gamma-ray emission could be linked to the luminous blue variable star. If the source is the luminous blue variable star, it is the first time that gamma-ray emission has been linked to such a massive star.”

Rowell explained to IFLScience that the distribution of gamma-ray intensity HESS found closely matches the distribution of radio waves, where LBV 1806-20 is known to be the dominant local source. This makes it, rather than the magnetar, the most likely source. Rowell added that stars similar to LBV 1806-20 have been seen associated with gamma-ray emissions before, but since these stars usually exist in clusters with other extreme objects, such as supernova remnants, astronomers have attributed the emissions to known sources. This case could shake that belief.

LBV 1806-20 has a stellar wind 10,000 times as powerful as the Sun’s. Rowell told IFLScience there was speculation decades ago such winds could accelerate particles to the speeds needed to release gamma rays when they collide. Since then attention has shifted to other possible sources, but Rowell thinks it might be time to revive that work.

Among the associated papers, Rowell highlights one describing three new circular features that are invisible to telescopes operating at other wavelengths. Rowell described these as a mystery, but said they might reflect the energy from supernova remnant shockwaves, possibly indicating a previously unknown stage in the evolution of supernova remnants.

Read more: http://www.iflscience.com/space/young-very-hot-stars-may-be-a-new-source-of-gamma-rays/