What will happen when our sun dies?

Scientists agree the sun will die in approximately 10 billion years, but they weren't sure what would happen next...until now.

A team of international astronomers, including Professor Albert Zijlstra from the University of Manchester, predict it will turn into a massive ring of luminous, interstellar gas and dust, known as a planetary nebula.

A planetary nebula marks the end of 90% of all stars active lives and traces the star's transition from a red giant to a degenerate white dwarf. But, for years, scientists weren't sure if the sun in our galaxy would follow the same fate: it was thought to have too low mass to create a visible planetary nebula.

To find out the team developed a new stellar, data-model that predicts the lifecycle of stars. The model was used to predict the brightness (or luminosity) of the ejected envelope, for stars of different masses and ages.

The research is being published in Nature Astronomy on Monday 7th May.

Prof Zijslra explains: "When a star dies it ejects a mass of gas and dust -- known as its envelope -- into space. The envelope can be as much as half the star's mass. This reveals the star's core, which by this point in the star's life is running out of fuel, eventually turning off and before finally dying.

"It is only then the hot core makes the ejected envelope shine brightly for around 10,000 years -- a brief period in astronomy. This is what makes the planetary nebula visible. Some are so bright that they can be seen from extremely large distances measuring tens of millions of light years, where the star itself would have been much too faint to see."

The model also solves another problem that has been perplexing astronomers for a quarter of a century.

Approximately 25 years ago astronomers discovered that if you look at planetary nebulae in another galaxy, the brightest ones always have the same brightness. It was found that it was possible to see how far away a galaxy was just from the appearance of its brightest planetary nebulae. In theory it worked in any of type galaxy.

But whilst the data suggested this was correct, the scientific models claimed otherwise. Prof Zijlstra adds: "Old, low mass stars should make much fainter planetary nebulae than young, more massive stars. This has become a source of conflict for the past for 25 years.

"The data said you could get bright planetary nebulae from low mass stars like the sun, the models said that was not possible, anything less than about twice the mass of the sun would give a planetary nebula too faint to see."

The new models show that after the ejection of the envelope, the stars heat up three times faster than found in older models. This makes it much easier for a low mass star, such as the sun, to form a bright planetary nebula. The team found that in the new models, the sun is almost exactly the lowest mass star that still produces a visible, though faint, planetary nebula. Stars even a few per cent smaller do not.

Professor Zijlstra added: "We found that stars with mass less than 1.1 times the mass of the sun produce fainter nebula, and stars more massive than 3 solar masses brighter nebulae, but for the rest the predicted brightness is very close to what had been observed. Problem solved, after 25 years!

"This is a nice result. Not only do we now have a way to measure the presence of stars of ages a few billion years in distant galaxies, which is a range that is remarkably difficult to measure, we even have found out what the sun will do when it dies!"

Officials Detect 2,000 Planets Outside Milky Way For First Time

For the first time ever, astrophysicists have discovered a large group of exoplanets outside of the Milky Way galaxy, according to a study published Friday in The Astrophysical Journal Letters.

University of Oklahoma researchers were able to detect an estimated 2,000 planets, ranging in mass from the size of Earth's moon to the mass of the Jupiter, by examining data gathered by the National Aeronautics and Space Administration's Chandra X-ray Observatory.

Though exoplanets have been found before, what distinguishes this find from previous ones is that this is the first time that there has been confirmed evidence of planets outside of our galaxy.

Researchers managed to detect the extragalactic planets by using gravitational microlensing, an astronomical phenomenon that allows scientists to find objects in space by using light bent by a gravitational field.

"We are very excited about this discovery, this is the first time anyone has discovered planets outside our galaxy," Xinyu Dai, lead researcher of the study, said in a statement. "These small planets are the best candidate for the signature we observed in this study using the microlensing technique. We analyzed the high frequency of the signature by modeling the data to determine the mass."

In a separate statement, fellow study author Eduardo Guerras indicated that the planets are in a galaxy roughly 3.8 billion light years away.

"This galaxy is located 3.8 billion light years away and there is not the slightest chance of observing these planets directly, not even with the best telescope one can imagine in a science fiction scenario," Guerras noted. "However, we are able to study them, unveil their presence and even have an idea of their masses."

"This is very cool science," he added.

In addition to using the Chandra observatory, Dai and Guerras also used microlensing models designed at the university's OU Supercomputing Center for Education and Research.

Moon has a water-rich interior

A new study of satellite data finds that numerous volcanic deposits distributed across the surface of the Moon contain unusually high amounts of trapped water compared with surrounding terrains. The finding of water in these ancient deposits, which are believed to consist of glass beads formed by the explosive eruption of magma coming from the deep lunar interior, bolsters the idea that the lunar mantle is surprisingly water-rich.

Scientists had assumed for years that the interior of the Moon had been largely depleted of water and other volatile compounds. That began to change in 2008, when a research team including Brown University geologist Alberto Saal detected trace amounts of water in some of the volcanic glass beads brought back to Earth from the Apollo 15 and 17 missions to the Moon. In 2011, further study of tiny crystalline formations within those beads revealed that they actually contain similar amounts of water as some basalts on Earth. That suggests that the Moon's mantle -- parts of it, at least -- contain as much water as Earth's.

"The key question is whether those Apollo samples represent the bulk conditions of the lunar interior or instead represent unusual or perhaps anomalous water-rich regions within an otherwise 'dry' mantle," said Ralph Milliken, lead author of the new research and an associate professor in Brown's Department of Earth, Environmental and Planetary Sciences. "By looking at the orbital data, we can examine the large pyroclastic deposits on the Moon that were never sampled by the Apollo or Luna missions. The fact that nearly all of them exhibit signatures of water suggests that the Apollo samples are not anomalous, so it may be that the bulk interior of the Moon is wet."

The research, which Milliken co-authored with Shuai Li, a postdoctoral researcher at the University of Hawaii and a recent Brown Ph.D. graduate, is published in Nature Geoscience.

Detecting the water content of lunar volcanic deposits using orbital instruments is no easy task. Scientists use orbital spectrometers to measure the light that bounces off a planetary surface. By looking at which wavelengths of light are absorbed or reflected by the surface, scientists can get an idea of which minerals and other compounds are present.

The problem is that the lunar surface heats up over the course of a day, especially at the latitudes where these pyroclastic deposits are located. That means that in addition to the light reflected from the surface, the spectrometer also ends up measuring heat.

"That thermally emitted radiation happens at the same wavelengths that we need to use to look for water," Milliken said. "So in order to say with any confidence that water is present, we first need to account for and remove the thermally emitted component."

To do that, Li and Milliken used laboratory-based measurements of samples returned from the Apollo missions, combined with a detailed temperature profile of the areas of interest on the Moon's surface. Using the new thermal correction, the researchers looked at data from the Moon Mineralogy Mapper, an imaging spectrometer that flew aboard India's Chandrayaan-1 lunar orbiter.

The researchers found evidence of water in nearly all of the large pyroclastic deposits that had been previously mapped across the Moon's surface, including deposits near the Apollo 15 and 17 landing sites where the water-bearing glass bead samples were collected.

"The distribution of these water-rich deposits is the key thing," Milliken said. "They're spread across the surface, which tells us that the water found in the Apollo samples isn't a one-off. Lunar pyroclastics seem to be universally water-rich, which suggests the same may be true of the mantle."

The idea that the interior of the Moon is water-rich raises interesting questions about the Moon's formation. Scientists think the Moon formed from debris left behind after an object about the size of Mars slammed into the Earth very early in solar system history. One of the reasons scientists had assumed the Moon's interior should be dry is that it seems unlikely that any of the hydrogen needed to form water could have survived the heat of that impact.

"The growing evidence for water inside the Moon suggest that water did somehow survive, or that it was brought in shortly after the impact by asteroids or comets before the Moon had completely solidified," Li said. "The exact origin of water in the lunar interior is still a big question."

In addition to shedding light on the water story in the early solar system, the research could also have implications for future lunar exploration. The volcanic beads don't contain a lot of water -- about .05 percent by weight, the researchers say -- but the deposits are large, and the water could potentially be extracted.

"Other studies have suggested the presence of water ice in shadowed regions at the lunar poles, but the pyroclastic deposits are at locations that may be easier to access," Li said. "Anything that helps save future lunar explorers from having to bring lots of water from home is a big step forward, and our results suggest a new alternative."

The research was funded by the NASA Lunar Advanced Science and Exploration Research Program (NNX12AO63G).


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Under pressure: Extreme atmosphere stripping may limit exoplanets' habitability

New models of massive stellar eruptions hint at an extra layer of complexity when considering whether an exoplanet may be habitable or not. Models developed for our own Sun have now been applied to cool stars favoured by exoplanet hunters, in research presented by Dr Christina Kay, of the NASA Goddard Flight Center, on Monday 3rd July at the National Astronomy Meeting at the University of Hull.

Coronal mass ejections (CMEs) are huge explosions of plasma and magnetic field that routinely erupt from the Sun and other stars. They are a fundamental factor in so called "space weather," and are already known to potentially disrupt satellites and other electronic equipment on Earth. However, scientists have shown that the effects of space weather may also have a significant impact on the potential habitability of planets around cool, low mass stars -- a popular target in the search for Earth-like exoplanets.

Traditionally an exoplanet is considered "habitable" if its orbit corresponds to a temperature where liquid water can exist. Low mass stars are cooler, and therefore should have habitable zones much closer in to the star than in our own solar system, but their CMEs should be much stronger due to their enhanced magnetic fields.

When a CME impacts a planet, it compresses the planet's magnetosphere, a protective magnetic bubble shielding the planet. Extreme CMEs can exert enough pressure to shrink a magnetosphere so much that it exposes a planet's atmosphere, which can then be swept away from the planet. This could in turn leave the planetary surface and any potential developing lifeforms exposed to harmful X-rays from the nearby host star.

The team built on recent work done at Boston University, taking information about CMEs in our own solar system and applying it to a cool star system.

"We figured that the CMEs would be more powerful and more frequent than solar CMEs, but what was unexpected was where the CMEs ended up" said Christina Kay, who led the research during her PhD work.

The team modelled the trajectory of theoretical CMEs from the cool star V374 Pegasi and found that the strong magnetic fields of the star push most CMEs down to the Astrophysical Current Sheet (ACS), the surface corresponding to the minimum magnetic field strength at each distance, where they remain trapped.

"While these cool stars may be the most abundant, and seem to offer the best prospects for finding life elsewhere, we find that they can be a lot more dangerous to live around due to their CMEs" said Marc Kornbleuth, a graduate student involved in the project.

The results suggest that an exoplanet would need a magnetic field ten to several thousand times that of Earth's to shield their atmosphere from the cool star's CMEs. As many as five impacts a day could occur for planets near the ACS, but the rate decreases to one every other day for planets with an inclined orbit.

Merav Opher, who advised the work, commented, "This work is pioneering in the sense that we are just now starting to explore space weather effects on exoplanets, which will have to be taken into account when discussing the habitability of planets near very active stars."

NASA's Cassini Spacecraft Captures Stunning Photos of Saturn's Changing Seasons

NASA's Cassini spacecraft made new pictures of Saturn and the famous storm at its north pole on the second day of the planet's solstice, NASA reported.

Cassini observed how a huge storm has appeared and encircled Saturn over the last seven years of its mission. Scientists believe that such storms are influenced by seasonal effects of sunlight on Saturn's atmosphere.

"Reaching the solstice, and observing seasonal changes in the Saturn system along the way was a primary goal of Cassini's Solstice Mission," NASA's website reported.

Saturn's north-polar region in June 2013 and April 2017
Saturn's north-polar region in June 2013 and April 2017 / © Photo: NASA/JPL-Caltech/Space Science Institute/Hampton University

Basically, the spacecraft was able to follow the complete change of all seasons on Saturn, with the whole planet's system dramatically changing with the start of summer and the end of winter.

"The Saturn system undergoes dramatic transitions from winter to summer, and thanks to Cassini, we had a ringside seat," Dr. Linda Spilker, the scientific leader of the mission, was quoted as saying.

NASA: Cassini's First Fantastic Dive Past Saturn
 
Many of the things, which scientists know now, could have never been registered by Cassini if NASA had not decided to extend the mission. For example, five years ago, Cassini first "saw" how Saturn's atmosphere was covered with a giant hurricane at the beginning of autumn and how a haze of hydrocarbons appeared in the planet's atmosphere.

The main achievement of the Cassini mission was the discovery that geysers located on Saturn's sixth moon — Enceladus — can ejecthot water that is generally suitable for the birth and maintenance of life. This discovery urged NASA to consider sending another mission to Saturn and Enceladus in the future.

The Cassini space mission was launched in October 1997 and arrived at Saturn in July 2004. The mission has seen two extensions and is set to end on September 15, 2017. Its observations have generated hundreds of scientific articles.

Huge ‘potentially hazardous’ asteroid hurtling towards Earth

A huge 1km-wide asteroid is hurtling towards Earth, prompting astronomers to label it “potentially hazardous”. But don’t pack for Mars just yet – the giant space rock, ‘2014 JO25’, is expected to pass by our planet safely.

According to NASA the encounter on April 19 will be the closest the asteroid comes to Earth in 400 years, and no projected future encounters will be as close for at least another 480 years.

However, another fly-by is expected in 2091 and the space rock also makes regular close approaches to Mercury and Venus.

 
An asteroid of this size won't have as close an encounter with Earth for more than 10 years. "The next known flyby by an object with a comparable or larger diameter will occur when 800-meter-diameter asteroid ‘1999 AN10’ approaches within one lunar distance in August 2027," NASA said.

The asteroid was discovered by the Mt. Lemmon Survey in May 2014. Astronomers describe it as a “bright object” and believe it will be among the best targets for radar observations this year.

READ MORE: Risk of catastrophic asteroid impact ‘real’ – White House

‘2014 JO25’ has been designated as a potentially hazardous asteroid (PHA) by the Minor Planet Center. PHA’s are asteroids larger than 100 meters that can come closer to Earth than 7,495,839km (about 4,658,000 miles), which is equal to 19.5 ‘Lunar distances’.

Asteroid Hazards, Part 1: What Makes an Asteroid a Hazard?

Despite 2014 JO25’s designation as a PHA, projections predict it will pass by Earth at a safe distance of about 1.8 million km (4.57 lunar distances).

@BadAstronomer Pic of a 10-meter rock that passed inside the Moon’s orbit a couple of hours ago. Amazing we can find these things. http://www.virtualtelescope.eu/2017/04/02/near-earth-asteroid-2017-fu102-close-encounter-image-2-apr-2017/ 


 
 
 

Two other big asteroids, ‘2003 BD44’ and ‘1999 CU3’, which are both nearly 2km wide, will also pass by our planet shortly, however they won’t come as close as 2014.

Astrowatch report 1,781 PHAs were detected on Sunday, however – happily – none of them is on a projected collision course with Earth.

Oldest-ever fossils show life existed on Earth at its infancy - study

Ancient fossils discovered in Canada are “direct evidence” that life existed on Earth 4 billion years ago, scientists wrote in a newly-released study, believing the emergence of life could be simple enough to begin on other planets.

Researchers believe the microfossils – discovered in Canada's Nuvvuagittuq Supracrustal Belt, which hosts some of the oldest sedimentary rocks known on Earth – are between 3.77 billion and 4.29 billion years old.

The discovery has led scientists to believe that life was present during the infancy of the planet, which is thought to be around 4.57 billion years old.

If the dating is accurate, it would represent an “almost instantaneous emergence of life” after ocean formation, lead author Matthew Dodd said, as quoted by Reuters.

READ MORE World's oldest fossils unearthed (UCL)

The tiny microfossils were found to be half the width of a human hair and up to half-a-millimeter in length. Their appearance is of blood-red tubes and filaments, formed by ocean-dwelling bacteria that fed on iron.

The dating puts the fossils “within a few hundred million years of the acceleration of the solar system,” University College London Professor Dominic Papineau, who made the discovery, said in a video statement cited by AFP.

Even at the lower end of the range, “the microfossils we discovered are about 300 million years older” than any runners-up, Papineau said.

Locked inside white quartz structures, the microfossils were found in what were once warm-water vents on the ocean floor, most often in deep waters.

The finding has prompted scientists to hypothesize that such vents may have been some of the earliest habitable environments on the planet.

However, one of the researchers acknowledged skepticism about whether such fossils are biological in nature, or merely natural mineral formations.

“One of the big questions when it comes to early life studies is whether or not the organic carbon we find in these rocks is actually biological in origin,” Dodd said, as quoted by AFP.

Dodd and his colleagues used several methods to determine the answer to that question, including laser-imaging to analyze the minerals associated with the organic material.

They concluded that the presence of two minerals in particular – apatite and carbonite – provide strong evidence for life.

Moreover, the scientists noted that the microfossils’ structure closely resembles modern bacteria that dwell near iron-rich hydrothermal vents.

The possibility that the microfossils were formed by temperature and pressure changes as the sediment formed were also examined and excluded.

Perhaps the most intriguing piece of the research is that Dodd believes there’s no reason to rule out similar evidence of early life being found on other planets.

READ MORE: 500mn years old & boasting 30 legs: ‘Worm’ fossil offers insight into ancient species (VIDEO)

“We could expect to find evidence for past life on Mars 4 billion years ago,” Dodd said, stating that Earth and Mars had liquid on their surfaces at the same time.

“If life happened so quickly on Earth, then could we expect it to be a simple process that could start on other planets?” he said.

He admitted, however, that Earth could be “just a special case.”

The discovery represents a significant milestone, as the oldest microfossils previously reported were found in Western Australia and dated to 3.46 billion years old. However, some scientists say they are not biological in origin.

Researchers from various institutions, including the US Geological Survey, took part in the study. The results were published in the journal Nature on Wednesday.

NASA has discovered 7 Earth-like planets orbiting a star just 40 light-years away

This tiny star has 7 planets that potentially could be suitable for life.

The first step in finding life outside our own planet is to find a planet like our own: small, rocky, and at just the right distance from the star that liquid water could exist on its surface.

That’s why an announcement today from NASA is so exciting: The space agency, along with partners around the world, has found seven potentially Earth-like planets orbiting a star 40 light-years away.

“It’s the first time that so many planets of this kind are found around a same star,” Michaël Gillon, the lead author of the Nature paper announcing the discovery, said in a press conference. “The seven planets … could have some liquid water and maybe life on the surface.”

Three of the planets are directly in the star’s habitable zone, meaning water can mostly likely exist on the surface of them. One of them, Gillon said, has a mass “strongly to suggest a water-rich composition.” And it’s possible that the other four could have liquid water, too, depending on the composition of their atmospheres, the astronomers said.

 The planets “e,” “f,” and “g” — marked in green are directly in the “habitable zone” of this star system. NASA

The exoplanets orbit a star in the constellation Aquarius called Trappist-1. And it’s a solar system very different from our own.

For one, Trappist-1 is a tiny, “ultra-cool” dwarf star. It’s cool because it’s small: just about a tenth of the mass of our sun and about one-thousandth as bright. But its low mass allows its planets to orbit it very closely and remain in the habitable zone.

The distance at which the planets orbit Trappist-1 is comparable to the distance of Jupiter to its moons. All the planets are believed to be rocky, and are all believed to be around the size of Earth, give or take 10 to 20 percent.

The star’s dimness is actually what led to the discoveries of these planets. When astronomers search for exoplanets, they typically look for a temporary dimming of a star — an indication that a planet has passed in front of it. This method makes it hard to find small, rocky worlds orbiting big, bright stars. If the planets are too small, they’ll get washed out.

“Maybe the most exciting thing here is that these seven planets are very well suited for detailed atmospheric study,” Gillon said. The James Webb Space Telescope, set to launch in 2018, will have the ability to measure the chemical composition of exoplanet atmospheres. If the atmospheres contain telltale gases like ozone, oxygen, or methane, life could exist there. “We can expect that in a few years, we will know a lot more about these [seven] planets,” Amaury Triaud, another of the paper’s co-authors, said.

If this all sounds a bit familiar, it’s because astronomers announced three potentially habitable planets around Trappist-1 in May. Today’s reveal adds four more to the mix.

Right now, the astronomers are beginning to study the planets’ atmospheres with the telescopes they have. And from these observations, they feel fairly confident that the worlds are rocky. “For detailed characterization, we will need James Webb,” Triaud said.

In the meantime, we just have our imaginations to fill in the gap. This is an artist’s rendition of what the fifth planet in this bizarre solar system might look like. These planets are believed to be tidally locked to the star, each has a permanent day side and a permanent nice side. And because the planets are so close together, they’d appear in the sky like moons.

 This artist's concept allows us to imagine what it would be like to stand on the surface of the exoplanet Trappist-1f. Dream vacation? NASA/JPL-Caltech

The more Earth-like exoplanets astronomers find in the galaxy, the more they update their estimates of how many Earth-like planets could be out there. “For every transiting planet found, there should be a multitude of similar planets (20–100 times more) that, seen from Earth, never pass in front of their host star,” Nature reporter Ignas Snellen explains in a feature article. And the more exoplanets there are, the more likely it is that life exists on at least one of them.

“With this discovery we’ve made a giant, accelerated leap forward in our search for habitable worlds and life on other worlds potentially,” Sara Seager, a leading exoplanet expert at MIT, said during the announcement. This one star system, she said, gives astronomers many chances to look for life, and refine their understanding of exoplanets in small-star systems.

Also promising: Tiny, cool stars like Trappist-1 are some of the most common in the galaxy. Investigating them will likely yield more exoplanet discoveries. Which will help get us closer to finding places like Earth.

As NASA associate administrator Thomas Zurbuchen said, “Finding another Earth-like planet isn't a matter of if but when.“

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