Scientists confirm Einstein's supermassive black hole theory

FILE PHOTO: Artist's impression of the active galactic nucleus shows the supermassive black hole at the center of the accretion disk sending a narrow high-energy jet of matter into space, perpendicular to the disc in this image by Science Communication Lab in Kiel Germany, released on July 12, 2018. Courtesy DESY, Science Communication Lab/Handout via REUTERS

A team of international scientists observing a star in the Milky Way have for the first time confirmed Einstein's predictions of what happens to the motion of a star passing close to a supermassive black hole.

Einstein's 100-year-old general theory of relativity predicted that light from stars would be stretched to longer wavelengths by the extreme gravitational field of a black hole, and the star would appear redder, an effect known as gravitational red shift.

"This was the first time we could test directly Einstein's theory of general relativity near a supermassive black hole," Frank Eisenhauer, senior astronomer at the Max Planck Institute for Extraterrestrial Physics, told journalists.

"At the time of Einstein, he could not think or dream of what we are showing today," he said.

A team of scientists at the European Southern Observatory started monitoring the central area of the Milky Way using its Very Large Telescope to observe the motion of stars near the supermassive black hole 26 years ago.

The black hole is 26,000 light years away from Earth and has a mass 4 million times that of the Sun.

The scientists selected one star, S2, to follow. With an orbit of 16 years, they knew it would return close to the black hole in 2018.

Over 20 years, the accuracy of their instruments has improved and so in May 2018, they were able to take extremely precise measurements in conjunction with scientists from around the world.

This showed the star's orbital velocity increasing to more than 25 million kph (15.5 million mph) as it approached the black hole.

The star's wavelength stretched as it sought to escape the gravitational pull of the supermassive black hole, shifting its appearance from blue to red, Odele Straub from the Paris Observatory said.

The scientists now hope to observe other theories of black hole physics, she said.

"This is the first step on a long road that the team has done over many years and which we hope to continue in the next years," MPE's Reinhard Genzel, who led the international team, said.

New rare black holes spotted in space, evidence suggests

In a first, scientists have spotted the evidence of a rare intermediate-mass black hole - an elusive object whose existence has been hotly debated.

Scientists have been able to prove the existence of small black holes and those that are super-massive, but the existence of intermediate-mass black holes (IMBHs) was never proven.

Researchers from the University of New Hampshire (UNH) in the US found the strongest evidence to date that such middle-of-the-road black holes exist, by serendipitously capturing one in action devouring an encountering star.

"We feel very lucky to have spotted this object with a significant amount of high-quality data, which helps pinpoint the mass of the black hole and understand the nature of this spectacular event," said Dacheng Lin, a research assistant professor at UNH.

"Earlier research, including our own work, saw similar events, but they were either caught too late or were too far away," Lin said.

In the study, published in the journal Nature Astronomy, researchers used satellite imaging to detect for the first time this significant telltale sign of activity.

They found an enormous multiwavelength radiation flare from the outskirts of a distant galaxy. The brightness of the flare decayed over time exactly as expected by a star disrupting, or being devoured, by the black hole.

In this case, the star was disrupted in October 2003 and the radiation it created decayed over the next decade. The distribution of emitted photons over the energy depends on the size of the black hole.

This data provides one of the very few robust ways to weight, or determine the size of, the black hole.

Researchers used data from a trio of orbiting X-ray telescopes, NASA's Chandra X-ray Observatory and Swift Satellite as well as European Space Agency (ESA)'s XMM-Newton, to find the multiwavelength radiation flares that helped identify the otherwise uncommon IMBHs.

The characteristic of a long flare offers evidence of a star being torn apart and is known as a tidal disruption event (TDE).

Tidal forces, due to the intense gravity from the black hole, can destroy an object - such as a star - that wanders too close. During a TDE, some of the stellar debris is flung outward at high speeds, while the rest falls toward the black hole.

As it travels inward and is ingested by the black hole, the material heats up to millions of degrees and generates a distinct X-ray flare.

According to the researchers, these types of flares can easily reach the maximum luminosity and are one of the most effective ways to detect IMBHs.

"From the theory of galaxy formation, we expect a lot of wandering intermediate-mass black holes in star clusters," said Lin.

"But there are very, very few that we know of because they are normally unbelievably quiet and very hard to detect and energy bursts from encountering stars being shredded happen so rarely," he said.

Due to the very low occurrence rate of such star-triggered outbursts for an IMBH, the scientists believe that their discovery implies that there could be many IMBHs lurking in a dormant state in galaxy peripheries across the local universe.

Mercury mission to explore origin of Solar System

Is Mercury's core liquid or solid, and why -- on the smallest planet in our solar system -- is it so big? What can the planet closest to the Sun tell us about how our solar system came into being?

An unmanned European-Japanese space mission, dubbed BepiColombo, blasted off early Saturday morning from French Guiana, to probe these and other mysteries.

"BepiColombo is coming like a white knight with better and more precise data," said Alain Doressoundiram, an astronomer at the Paris Observatory.

"To understand how Earth was formed, we need to understand how all rocky planets formed," including Venus and Mars, he told AFP.

"Mercury stands apart and we don't know why."

First, however, the suite of instruments on board the Ariane 5 rocket will have to travel seven years and nine million kilometres (5.6 million miles) to reach their destination.

In a statement after the launch, ArianeGroup said the satellite had successfully escaped Earth's gravity field and was beginning its long journey where it will reach speeds of up to 40,000 kilometres (25,000 miles) an hour.

According to Pierre Bousquet, an engineer at France's National Centre for Space Research and head of the French team contributing to the mission, Mercury is "abnormally small," leading to speculation that it survived a massive collision in its youth.

"A huge crater visible on its surface could be the scar left over from that encounter," Bousquet told AFP. Finding out if this is true is on BepiColombo's "to do" list.

Going hot and cold

This scenario would explain why Mercury's core accounts for a whopping 55 percent of its mass, compared to 30 per cent for Earth.

Mercury is also the only rocky planet orbiting the Sun beside our own to have a magnetic field.

Magnetic fields are generated by a liquid core but given its size, Mercury's should have grown cold and solid by now, as did Mars.

This anomaly might be due to some feature of the core's composition, something BepiColombo's instruments will measure with much greater precision than has been possible so far.

On its surface, Mercury is a planet of extremes, vacillating between hot days of about 430 degrees Celsius (more than 800 degrees Fahrenheit) to super-frosty nights of minus 180C (minus 290F).

Those days and nights last nearly three Earth months each.

Earlier missions have detected evidence of ice in the deepest recesses of the planet's polar craters.

Scientists speculate that this may have accumulated from comets crashing onto Mercury's surface.

"If the presence of ice is confirmed, it means that some of those water samples date back nearly to the origin of the solar system," Doressoundiram said.

Lashed by solar winds

Mercury is 58 million kilometres (36 million miles) from the Sun, nearly three times closer than Earth.

"The planet is whipped by solar winds," a constant torrent of ionised particles bombarding the surface at 500 kilometres per second, said Bousquet.

The scientists will be able to study the impact of these winds -- 10 times stronger than the ones hitting Earth's atmosphere -- on Mercury's magnetic field.

The BepiColombo mission will deploy two spacecraft. The Mercury Planet Orbiter, built by ESA, will investigate planet's surface and interior composition.

The Mercury Magnetospheric Orbiter, made by the Japan Aerospace Exploration Agency, will study the region of space around the planet that is influenced by its magnetic field.

The mission will also look for tectonic activity, and seek to understand why spectroscopic observations show no iron even if it is thought to be one of the planet's major component elements.

Compared to Mars, Venus, and Saturn, Mercury has barely been explored. Only two spacecraft have ever paid it a visit.

NASA's Mariner 10 did three flybys in 1974 and 1975, providing the first up-close images. More than 30 years later, NASA's Messenger did the same, before settling into orbit around Mercury in 2011.

The new mission is named after Giuseppe (Bepi) Colombo, a brilliant Italian mathematician and engineer who first understood the relationship between Mercury's rotation and orbit.

Mars likely to have enough oxygen for life support

Salty water just below the surface of Mars could hold enough oxygen to support the kind of microbial life that emerged and flourished on Earth billions of years ago, researchers reported. In some locations, the amount of oxygen available could even keep alive a primitive, multicellular animal such as a sponge, they reported in the journal Nature Geosciences.  

"We discovered that brines" -- water with high concentrations of salt -- "on Mars can contain enough oxygen for microbes to breathe," said lead author Vlada Stamenkovic, a theoretical physicist at the Jet Propulsion Laboratory in California.

"This fully revolutionises our understanding of the potential for life on Mars, today and in the past," he told AFP. Up to now, it had been assumed that the trace amounts of oxygen on Mars were insufficient to sustain even microbial life.

"We never thought that oxygen could play a role for life on Mars due to its rarity in the atmosphere, about 0.14 per cent," Stamenkovic said. By comparison, the life-giving gas makes up 21 per cent of the air we breathe.

On Earth, aerobic -- that is, oxygen-breathing -- life forms evolved together with photosynthesis, which converts CO2 into O2. The gas played a critical role in the emergence of complex life, notable after the so-called Great Oxygenation Event some 2.35 billion years ago. But our planet also harbours microbes -- at the bottom of the ocean, in boiling hot springs -- that subsist in environments deprived of oxygen.

"That's why -- whenever we thought of life on Mars -- we studied the potential for anaerobic life," Stamenkovic.

The new study began with the discovery by NASA's Curiosity Mars rover of manganese oxides, which are chemical compounds that can only be produced with a lot of oxygen. Curiosity, along with Mars orbiters, also established the presence of brine deposits, with notable variations in the elements they contained.

A high salt content allows for water to remain liquid -- a necessary condition for oxygen to be dissolved -- at much lower temperatures, making brines a happy place for microbes. Depending on the region, season and time of day, temperatures on the Red Planet can vary between minus 195 and 20 degrees Celsius (minus 319 to 68 degrees Fahrenheit).

The researchers devised the first model to describe how oxygen dissolves in salty water at temperatures below freezing. A second model estimated climate changes on Mars over the last 20 million years, and over the next 10 million years. 

Taken together, the calculations showed which regions on the Red Planet are most likely to produce brine-based oxygen, data that could help determine the placement of future probes.

"Oxygen concentrations [on Mars] are orders of magnitude" -- several hundred times -- "greater than needed by aerobic, or oxygen-breathing -- microbes," the study concluded.

"Our results do not imply that there is life on Mars," Stamenkovic cautioned. "But they show that the Martian habitability is affected by the potential of dissolved oxygen."

NASA spacecraft makes 1st close approach to sun

 7th November, 2018 

A NASA spacecraft has made its first close approach to the sun, just 2 1/2 months after liftoff.

The Parker Solar Probe flew within 15 million miles (24 million kilometers) of the sun's surface Monday night. Its speed topped 213,000 mph (342,000 kph) relative to the sun, as it penetrated the outer solar atmosphere, or corona.

No spacecraft has ever gotten so close to our star.

NASA won't re-establish contact until Parker is far enough from the sun to avoid radio interference. NASA's Nicola Fox says scientists "can't wait to get the data." The observations could unlock some of the sun's mysteries.

Assuming it survives the harsh solar environment, the spacecraft will make 23 even closer approaches over the next seven years.

NASA discovers 10 new Earth-size exoplanets

NASA revealed Monday 10 new rocky, Earth-sized planets that could potentially have liquid water and support life.

 NASA’s Kepler space telescope team has identified 219 new planet candidates, 10 of which are near-Earth size and in the habitable zone of their star. Credits: NASA/JPL-Caltech

The Kepler mission team released a survey of 219 potential exoplanets -- planets outside of our solar system -- that had been detected by the space observatory launched in 2009 to scan the Milky Way galaxy.

Ten of the new discoveries were orbiting their suns at a distance similar to Earth's orbit around the sun, the so-called habitable zone that could potentially have liquid water and sustain life.

Kepler has already discovered 4,034 potential exoplanets, 2,335 of which have been confirmed by other telescopes as actual planets.

The 10 new Earth-size planets bring the total to 50 that exist in habitable zones around the galaxy.

"This carefully-measured catalog is the foundation for directly answering one of astronomy's most compelling questions -- how many planets like our Earth are in the galaxy?" said Susan Thompson, a Kepler research scientist and lead author of the latest study.

The latest findings were released at the Fourth Kepler and K2 science conference being held this week at NASA's Ames research center in California.

The Kepler telescope detects the presence of planets by registering minuscule drops in a star's brightness that occurs when a planet crosses in front of it, a movement known as a transit.

The findings were compiled from data gathered during the first four years of the mission, which scientists processed to determine the size and composition of the planets observed.

The scientists found that the newly discovered planets tended to fall into two distinct categories -- smaller, rocky planets that are usually around 75 percent bigger than Earth, and much larger, gaseous planets similar in size to Neptune.

NASA said the latest catalog is the most complete and detailed survey of potential exoplanets yet compiled. The telescope has studied some 150,000 stars in the Cygnus constellation, a survey which NASA said is now complete.

“The Kepler data set is unique, as it is the only one containing a population of these near Earth-analogs -- planets with roughly the same size and orbit as Earth,” said Mario Perez of NASA's Astrophysics Division. “Understanding their frequency in the galaxy will help inform the design of future NASA missions to directly image another Earth.”

The mission ran into technical problems in 2013 when mechanisms used to turn the spacecraft failed, but the telescope has continued searching for potentially habitable planets as part of its K2 project.

As of next year, NASA will continue its scan of the galaxy using Kepler's successor, the Transiting Exoplanet Survey Satellite, or TESS, which will spend two years observing the 200,000 brightest nearby stars for Earth-like worlds.

Scientists also hope the James Webb Space telescope, which will replace the Hubble telescope in 2018, will be able to detect the molecular make-up of atmospheres of exoplanets, including the possibility of finding signatures of potential life forms.

NASA captures images of strong solar flares

Two high-intensity solar flares were emitted Wednesday, the second of which was the most intense recorded since the start of this sun cycle in December 2008, NASA said.

This animation shows both the X2.2 and the X9.3 flares that the Sun emitted on Sept. 6, 2017.  The imagery was captured by NASA’s Solar Dynamics Observatory and shows light in the131 angstrom wavelength. Photo: NASA/Goddard/SDO 

These radiation flares, which can disrupt communications satellites, GPS and power grids by reaching the upper Earth atmosphere, were detected and captured by the US Space Agency's Solar Dynamics Observatory.

According to the Space Weather Prediction Center (SWPC), these so-called category X eruptions disrupted high-frequency radio communications for one hour on the Earth's side facing the sun and low-frequency communications used in navigation.

The two eruptions occurred in an active region of the sun where an eruption of average intensity occurred on September 4. The current cycle of the sun, which began in December 2008, saw the intensity of solar activity decline sharply, opening the way to the "solar minimum."

Solar cycles last on average eleven years. At the end of the active phase, these eruptions become increasingly rare but still can be powerful. 

Solar storms result from an accumulation of magnetic energy in some places.

These jets of ionized matter are projected -- at high speed into and beyond the crown of the sun -- hundreds of thousands of kilometers outward.

Astronomers bid farewell to Saturn spacecraft

Global astronomers bid farewell Friday to NASA's famed Cassini spacecraft, which launched 20 years ago to circle Saturn and transformed the way we think about life elsewhere in the solar system.

     Photo credit: NASA

Cassini, an international project that cost $3.9 billion and included scientists from 27 nations, has run out of rocket fuel as expected after a journey of some 4.9 billion miles (7.9 billion kilometers).

Its death plunge into the ringed gas giant -- the furthest planet visible from Earth with the naked eye -- is scheduled for shortly after the spacecraft's final contact with Earth at 7:55am (1155 GMT).

Cassini's well-planned demise is a way of preventing any damage to Saturn's ocean-bearing moons Titan and Enceladus, which scientists want to keep pristine for future exploration because they may contain some form of life.

"It will be sad to see Cassini go on Friday, especially as the instrument we built is still working perfectly," said Stanley Cowley, professor of solar planetary physics at the University of Leicester.

"But we recognize that it is important to bring the mission to an end in a tidy and controlled manner."

Three other spacecraft have flown by Saturn -- Pioneer 11 in 1979, followed by Voyager 1 and 2 in the 1980s.

But none have studied Saturn in such detail as Cassini, named after the French-Italian astronomer Giovanni Domenico Cassini, who discovered in the 17th century that Saturn had several moons and a gap in between its rings.

Discoveries

Cassini launched from Cape Canaveral, Florida in 1997, then spent seven years in transit followed by 13 years orbiting Saturn.

In that time, it discovered six more moons around Saturn, three-dimensional structures towering above Saturn's rings, and a giant storm that raged across the planet for nearly a year.

The 22 by 13 foot (6.7 by four meter) spacecraft is also credited with discovering icy geysers erupting from Saturn's moon Enceladus, and eerie hydrocarbon lakes made of ethane and methane on Saturn's largest moon, Titan.

In 2005, the Cassini orbiter released a lander called Huygens on Titan, marking the first and only such landing in the outer solar system, on a celestial body beyond the asteroid belt.

Huygens was a joint project of the European Space Agency, Italian Space Agency and NASA.

"The mission has changed the way we think of where life may have developed beyond our Earth," said Andrew Coates, head of the Planetary Science Group at Mullard Space Science Laboratory at University College London.

"As well as Mars, outer planet moons like Enceladus, Europa and even Titan are now top contenders for life elsewhere," he added.

"We've completely rewritten the textbooks about Saturn."

Some 4,000 scientific papers have been based on data from the mission, said Mathew Owens, professor of space physics at the University of Reading.

And its final plunge will reveal even more about the make-up of Saturn's atmosphere before Cassini disintegrates like a meteor.

"No doubt scientists will be analyzing the information from its final, one-way trip into Saturn's atmosphere for years to come," Owens said.

Mars had the ingredients needed for life

A NASA rover has detected a bonanza of organic compounds on the surface of Mars and seasonal fluctuations of atmospheric methane in findings released on Thursday that mark some of the strongest evidence ever that Earth's neighbor may have harbored life.

But National Aeronautics and Space Administration scientists emphasized there could be non-biological explanations for both discoveries made by the Curiosity rover at a site called Gale crater, leaving the issue of Martian life a tantalizing but unanswered question.

Three different types of organic molecules were discovered when the rover dug just 2-inches (5-cm) into roughly 3.5 billion-year-old mudstone, a fine-grained sedimentary rock, at Gale crater, apparently the site of a large lake when ancient Mars was warmer and wetter than the desolate planet it is today.

Curiosity also measured an unexpectedly large seasonal cycle in the low levels of atmospheric methane. About 95 percent of the methane in Earth's atmosphere is produced from biological activity, though the scientists said it is too soon to know if the Martian methane also is related to life.

Organic molecules are the building blocks of life, though they can also be produced by chemical reactions unrelated to life. The scientists said it is premature to know whether or not the compounds were created in biological processes.

Whether anywhere other than Earth has harbored life, perhaps even in microbial form, is one of the paramount questions in science.

"There's three possible sources for the organic material," said astrobiologist Jennifer Eigenbrode of NASA's Goddard Space Flight Center in Maryland. "The first one would be life, which we don't know about. The second would be meteorites. And the last one is geological processes, meaning the rock-forming processes themselves."

The rover, which has allowed scientists to explore whether Mars ever boasted conditions conducive to life, in 2014 made the first definitive detection of organic molecules, also in Gale crater rock formed from ancient lake sediment - but it was a much more limited set of compounds.

"What the organic detections in the rock do is to add to the story of habitability. It tells us that this ancient environment on Mars could have supported life," Eigenbrode said. "Everything that was needed to support life was there. But it doesn't tell us that life was there."

Christopher Webster, an atmospheric science research fellow at NASA's Jet Propulsion Laboratory in California, said it is possible existing microbes are contributing to the Martian atmospheric methane.

"With this new data, we again cannot rule out microbial activity as a potential source," Webster said.

The amount of methane peaked at the end of summer in the northern hemisphere at about 2.7 times the level of the lowest seasonal amount.

The scientists were surprised to find organic compounds, especially in the amounts detected, considering the harsh conditions, including bombardment of solar radiation on the Martian surface. After drilling, Curiosity heats the rock samples, releasing the compounds.

Referring to the findings regarding organic compounds and methane, Webster said, "They hint at an earlier time on Mars when water was present and the existence of primitive life forms was possible."

The scientists hope to find better preserved organic compounds with Curiosity or other rovers that would allow them to check for chemical signatures of life.