Chandra X-ray Observatory goes into safe mode

It's been a bad couple weeks in space. A week ago, technical difficulties forced engineers to put the Hubble Space Telescope's science mission on hold. Now, the Chandra X-ray Observatory is in safe mode, too. In a statement released on Friday, NASA confirmed Chandra, one of the most powerful telescopes in space, transitioned to safe mode earlier this week. During safe mode, the observatory's mirrors are pointed away from the sun and its solar panels are turned directly toward the sun. The satellite's most critical hardware is transferred to backup drives. "Analysis of available data indicates the transition to safe mode was normal behavior for such an event," according to NASA. "All systems functioned as expected and the scientific instruments are safe." Engineers are still working to determine why Chandra went into safe mode. As Chandra's Twitter account reminded readers, the powerful X-ray telescope is getting up its in age: "Chandra is 19 years old, which is well beyond the original design lifetime of 5 years." In a separate release, NASA confirmed Hubble is still in safe mode. Last week, NASA and European Space Agency engineers suspended the telescopes' scientific activities after one of its gyroscopes failed. Scientists turned on a replacement gyro, but the backup didn't perform as hoped.

"This past week, tests were conducted to assess the condition of that backup gyro. The tests showed that the gyro is properly tracking Hubble's movement, but the rates reported are consistently higher than the true rates," according to NASA.

Because the gyro is reading rates of changes at a greater magnitude, it can't be used to monitor smaller changes. Normally, when fixed on an observation target, Hubble's gyros operate on low-mode.

"The extremely high rates currently being reported exceed the upper limit of the gyro in this low mode, preventing the gyro from reporting the spacecraft's small movements," NASA reported.

If followup troubleshooting efforts fail, Hubble will be forced to shut down all but a single gyroscope. Previous tests showed Hubble can conduct observation using a single gyro.

Hubble and Chandra aren't the only spacecraft in trouble. Earlier this week, NASA astronaut Nick Hague and Roscosmos cosmonaut Alexey Ovchinin were forced to abort their mission to the space station just moments after launch, ejecting their Soyuz capsule from the rocket and executing an emergency "ballistic descent."

And as NASA reported this week, the Mars rover Opportunity is still silent. Engineers haven't communicated with the rover for four months.

A universe aglow: lyman-alpha emission across the entire sky

Deep observations made with the MUSE spectrograph on ESO's Very Large Telescope have uncovered vast cosmic reservoirs of atomic hydrogen surrounding distant galaxies. The exquisite sensitivity of MUSE allowed for direct observations of dim clouds of hydrogen glowing with Lyman-alpha emission in the early Universe?-?revealing that almost the whole night sky is invisibly aglow. An unexpected abundance of Lyman-alpha emission in the Hubble Ultra Deep Field (HUDF) region was discovered by an international team of astronomers using the MUSE instrument on ESO's Very Large Telescope (VLT). The discovered emission covers nearly the entire field of view - leading the team to extrapolate that almost all of the sky is invisibly glowing with Lyman-alpha emission from the early Universe. Astronomers have long been accustomed to the sky looking wildly different at different wavelengths, but the extent of the observed Lyman-alpha emission was still surprising. "Realising that the whole sky glows in optical when observing the Lyman-alpha emission from distant clouds of hydrogen was a literally eye-opening surprise," explained Kasper Borello Schmidt, a member of the team of astronomers behind this result. "This is a great discovery!" added team member Themiya Nanayakkara. "Next time you look at the moonless night sky and see the stars, imagine the unseen glow of hydrogen: the first building block of the universe, illuminating the whole night sky."

The HUDF region the team observed is an otherwise unremarkable area in the constellation of Fornax (the Furnace), which was famously mapped by the NASA/ESA Hubble Space Telescope in 2004, when Hubble spent more than 270 hours of precious observing time looking deeper than ever before into this region of space.

The HUDF observations revealed thousands of galaxies scattered across what appeared to be a dark patch of sky, giving us a humbling view of the scale of the Universe. Now, the outstanding capabilities of MUSE have allowed us to peer even deeper.

The detection of Lyman-alpha emission in the HUDF is the first time astronomers have been able to see this faint emission from the gaseous envelopes of the earliest galaxies. This composite image shows the Lyman-alpha radiation in blue superimposed on the iconic HUDF image.

MUSE, the instrument behind these latest observations, is a state-of-the-art integral field spectrograph installed on Unit Telescope 4 of the VLT at ESO's Paranal Observatory.

When MUSE observes the sky, it sees the distribution of wavelengths in the light striking every pixel in its detector. Looking at the full spectrum of light from astronomical objects provides us with deep insights into the astrophysical processes occurring in the Universe.

"With these MUSE observations, we get a completely new view on the diffuse gas 'cocoons' that surround galaxies in the early Universe," commented Philipp Richter, another member of the team.

The international team of astronomers who made these observations have tentatively identified what is causing these distant clouds of hydrogen to emit Lyman-alpha, but the precise cause remains a mystery. However, as this faint omnipresent glow is thought to be ubiquitous in the night sky, future research is expected to shed light on its origin.

"In the future, we plan to make even more sensitive measurements," concluded Lutz Wisotzki, leader of the team. "We want to find out the details of how these vast cosmic reservoirs of atomic hydrogen are distributed in space."

Extremely distant Solar System object found

Carnegie's Scott Sheppard and his colleagues - Northern Arizona University's Chad Trujillo, and the University of Hawaii's David Tholen - are once again redefining our solar system's edge. They discovered a new extremely distant object far beyond Pluto with an orbit that supports the presence of an even-farther-out, super-Earth or larger Planet X. The newly found object, called 2015 TG387, will be announced Tuesday by the International Astronomical Union's Minor Planet Center. A paper with the full details of the discovery has also been submitted to The Astronomical Journal. 2015 TG387 was discovered about 80 astronomical units (AU) from the Sun, a measurement defined as the distance between the Earth and Sun. For context, Pluto is around 34 AU, so 2015 TG387 is about two and a half times further away from the Sun than Pluto is right now. The new object is on a very elongated orbit and never comes closer to the Sun, a point called perihelion, than about 65 AU. Only 2012 VP113 and Sedna at 80 and 76 AU respectively have more-distant perihelia than 2015 TG387. Though 2015 TG387 has the third-most-distant perihelion, its orbital semi-major axis is larger than 2012 VP113 and Sedna's, meaning it travels much farther from the Sun than they do. At its furthest point, it reaches all the way out to about 2,300 AU. 2015 TG387 is one of the few known objects that never comes close enough to the solar system's giant planets, like Neptune and Jupiter, to have significant gravitational interactions with them.

"These so-called Inner Oort Cloud objects like 2015 TG387, 2012 VP113, and Sedna are isolated from most of the solar system's known mass, which makes them immensely interesting," Sheppard explained. "They can be used as probes to understand what is happening at the edge of our solar system."

The object with the most-distant orbit at perihelion, 2012 VP113, was also discovered by Sheppard and Trujillo, who announced that find in 2014. The discovery of 2012 VP113 led Sheppard and Trujillo to notice similarities of the orbits of several extremely distant solar system objects, and they proposed the presence of an unknown planet several times larger than Earth - sometimes called Planet X or Planet 9 - orbiting the Sun well beyond Pluto at hundreds of AU.

"We think there could be thousands of small bodies like 2015 TG387 out on the solar system's fringes, but their distance makes finding them very difficult," Tholen said. "Currently we would only detect 2015 TG387 when it is near its closest approach to the Sun. For some 99 percent of its 40,000-year orbit, it would be too faint to see."

The object was discovered as part of the team's ongoing hunt for unknown dwarf planets and Planet X. It is the largest and deepest survey ever conducted for distant solar system objects.

"These distant objects are like breadcrumbs leading us to Planet X. The more of them we can find, the better we can understand the outer solar system and the possible planet that we think is shaping their orbits - a discovery that would redefine our knowledge of the solar system's evolution," Sheppard added.

It took the team a few years of observations to obtain a good orbit for 2015 TG387 because it moves so slowly and has such a long orbital period. They first observed 2015 TG387 in October of 2015 at the Japanese Subaru 8-meter telescope located atop Mauna Kea in Hawaii.

Follow-up observations at the Magellan telescope at Carnegie's Las Campanas Observatory in Chile and the Discovery Channel Telescope in Arizona were obtained in 2015, 2016, 2017 and 2018 to determine 2015 TG387's orbit.

2015 TG387 is likely on the small end of being a dwarf planet since it has a diameter near 300 kilometers. The location in the sky where 2015 TG387 reaches perihelion is similar to 2012 VP113, Sedna, and most other known extremely distant trans-Neptunian objects, suggesting that something is pushing them into similar types of orbits.

Trujillo and University of Oklahoma's Nathan Kaib ran computer simulations for how different hypothetical Planet X orbits would affect the orbit of 2015 TG387. The simulations included a super-Earth-mass planet at several hundred AU on an elongated orbit as proposed by Caltech's Konstantin Batygin and Michael Brown in 2016.

Most of the simulations showed that not only was 2015 TG387's orbit stable for the age of the solar system, but it was actually shepherded by Planet X's gravity, which keeps the smaller 2015 TG387 away from the massive planet.

This gravitational shepherding could explain why the most-distant objects in our solar system have similar orbits. These orbits keep them from ever approaching the proposed planet too closely, which is similar to how Pluto never gets too close to Neptune even though their orbits cross.

"What makes this result really interesting is that Planet X seems to affect 2015 TG387 the same way as all the other extremely distant solar system objects. These simulations do not prove that there's another massive planet in our solar system, but they are further evidence that something big could be out there," Trujillo concludes.

China Focus: World's largest telescope more powerful, popular after two years

His eyes brimming with excitement, seven-year-old Wang Jun ran to an exhibition stand to pick up a pair of headphones and started listening, leaving his father behind. "The Sound of Pulsar Stars collected by FAST," read a sign next to the stand. FAST, Five-hundred-meter Aperture Spherical Radio Telescope, is the world's largest single-dish radio telescope and was set up two years ago on this day in southwest China's Guizhou Province. It helps scientists understand the universe by receiving and recording pulsar and interstellar signals from extraterrestrial sources. Engineers and astronomers continuously try to perfect the telescope, making improvements to allow it to see farther into space. Meanwhile, those who visit the telescope find themselves in awe of the giant dish and its ability to lead to breakthrough discoveries. Since its trial operation in 2016, FAST has found some 50 stars which bear features similar to pulsars, with 44 confirmed, according to scientists in National Astronomical Observatories of China (NAOC). Pulsar observation can be used to conduct research on gravitational waves, black holes and to help solve many other major questions in physics. "We are still improving the system," said Jiang Peng, chief engineer of FAST with NAOC, during Xinhua's recent tour to the FAST observatory. "Now we have met many goals previously set for the telescope."

The sensitivity of a telescope is the minimum brightness that it can detect. The lower the number, the farther a telescope can see. In FAST's case, Jiang's team cut the number by 20 percent in the last two years, making it arguably the world's most sensitive telescope.

They have also extended its annual observation time from around 700 hours to more than 1,000 hours, which means more data for scientists to analyze.

The telescope will start formal operation and open to Chinese astronomers in 2019, according to NAOC.

"We often say the telescope was almost usable two years ago; now it is usable, and our goal is to make it good to use," Jiang said.

Silent Tourism

The state-of-art technology and the spectacle of the giant dish have become a magnet for tourists over the years.

"My son is interested in science and aliens," said Wang Lifa, Wang Jun's father. "We are here to satisfy his imagination."

Wang drove six hours from a neighboring province to Kedu township of Pingtang County, around 15 km away from the mega-telescope. Visitors gather here before they go for a closer view of the giant dish.

Tourism took off in the once-impoverished town surrounded by lush forests as wider roads, fancy hotels and bustling shops have sprung up.

In the first half of 2018, Pingtang County received 5.13 million visitors, up 40.58 percent. The tourists brought in 550 million yuan (around 80 million U.S. dollars) for the small county, according to the local newspaper Qiannan Daily.

The tourist surge has also stoked concerns that it might affect the telescope whose probe results can be compromised by radio signals from electronic devices carried by tourists.

Around FAST, a 30-km perimeter was set up as a "silent zone" where the frequencies and radio power are strictly limited.

To view the telescope, tourists go to a core zone with a radius of five km around the FAST. Restrictions are even more extreme in that area: no phones, laptops or cameras. Even the GPS system on the ferry to the site is disabled.

The local government has also developed plans to curb tourists.

Last Thursday, the scenic spot stopped selling onsite tickets for the ferry buses to FAST and museums and moved the operation to an online booking website.

The local government restricted the number of tourists to the site to 2,000 per day.

"So far, the protection against signal interferences in the core zone has turned out to be effective," said Jiang, the FAST chief engineer.

Astrophysicists measure precise rotation pattern of Sun-like stars for the first time

Sun-like stars rotate up to two and a half times faster at the equator than at higher latitudes, a finding by researchers at NYU Abu Dhabi that challenges current science on how stars rotate. Until now, little was known about the precise rotational patterns of Sun-like stars, only that the equator spins faster than at higher latitudes, similar to the Sun. Scientists at the NYU Abu Dhabi Center for Space Science used observations from NASA's Kepler mission and asteroseismology - the study of sound waves traveling inside stars - to determine with precision how Sun-like stars rotate, which no other scientific method has been able to achieve. Their study found that Sun-like stars, characterized as being like the Sun in mass and age, do indeed rotate in a similar manner as the Sun in that their equatorial regions rotate more rapidly than at mid- to high latitudes. But there's a key difference.The equator of the Sun rotates about 10 percent faster than its mid latitudes, while equators of Sun-like stars spin up to two and a half times faster than their mid latitudes. "This is very unexpected, and challenges current numerical simulations, which suggest that stars like these should not be able to sustain differential rotation of this magnitude," said Othman Benomar, research associate at the NYU Abu Dhabi Center for Space Science and lead author of the study published in Science.

"Understanding differential rotation - how fast one part of a star spins compared to the rest - is not only important for a complete understanding of how a star works, it will help us gain deeper insights about their magnetic fields," explained Katepalli Sreenivasan, principal investigator of the NYU Abu Dhabi Center for Space Science.

Magnetic fields on the Sun have been known to cause enormous solar storms that frequently disrupt orbiting space satellites and have knocked out power grids on Earth.

Scientists agree that the rotation of the Sun plays a crucial role in the generation of the solar magnetic field, but the exact details still remain a mystery, despite the Sun having been observed and studied in great detail.

Sreenivasan added, "learning more about how stars rotate and generate their own magnetic fields could help us gain further insight into the solar dynamo, the physical process that generates the Sun's magnetic field."

Magnetic waves are main force in star formation, researchers say

Magnetic waves are the main force in star formation in space, according to new research. This birth process leads to the formation of planets orbiting the sun and, ultimately, life on those planets, according Stella Offner, an assistant professor of astronomy at the University of Texas Austin. The new findings, which included using a supercomputer for models of the multitude of processes happening inside a cloud where stars are forming, was published this week in the journal Nature Astronomy. "These clouds are violent places," Stella Offner, assistant professor of astronomy, said in a press release. "It's an extreme environment with all kinds of different physics happening at once." This includes gravity and turbulence as well as radiation and winds from forming stars, which are called stellar feedback. Offner wanted to know: "Why are the motions in these clouds so violent?" The answer, according to some astronomers, are observed motions to gravitational collapse, or possibly turbulence and stellar feedback. Offner said it's virtually impossible to use telescopes to observe these clouds to find the influence of the various processes, she said.

"That's why we need computer models," Offner said.

Using the computer models, she noticed extra motions when comparing clouds with gravity, magnetic fields and stars.

Stellar winds interacting with the cloud magnetic field generated energy and influenced gas at great distances across the cloud more than previously thought.

"Think of the magnetic fields like rubber bands that stretch across the cloud," Offner said. "The winds push the field -- it's like rubber bands being plucked. The waves outrun the wind and cause distant motions."

This study focused on one area within star-forming clouds but Offner said she plans to study this process on larger scales in time and space.

Study of material surrounding distant stars shows Earth's ingredients 'pretty normal'

The Earth's building blocks seem to be built from 'pretty normal' ingredients, according to researchers working with the world's most powerful telescopes. Scientists have measured the compositions of 18 different planetary systems from up to 456 light years away and compared them to ours, and found that many elements are present in similar proportions to those found on Earth. This is amongst the largest examinations to measure the general composition of materials in other planetary systems, and begins to allow scientists to draw more general conclusions on how they are forged, and what this might mean for finding Earth-like bodies elsewhere. "Most of the building blocks we have looked at in other planetary systems have a composition broadly similar to that of the Earth", said researcher Dr Siyi Xu of the Gemini Observatory in Hawaii, who was presenting the work at the Goldschmidt conference in Boston. The first planets orbiting other stars were only found in 1992 (this was orbiting a pulsar), since then scientists have been trying to understand whether some of these stars and planets are similar to our own solar system. "It is difficult to examine these remote bodies directly. Because of the huge distances involved, their nearby star tends to drown out any electromagnetic signal, such as light or radio waves" said Siyi Xu. "So we needed to look at other methods".

Because of this, the team decided to look at how the planetary building blocks affect signals from white dwarf stars. These are stars which have burnt off most of their hydrogen and helium, and shrunk to be very small and dense - it is anticipated that our Sun will become a white dwarf in around 5 billion years.

Dr Xu continued, "White dwarfs' atmospheres are composed of either hydrogen or helium, which give out a pretty clear and clean spectroscopic signal. However, as the star cools, it begins to pull in material from the planets, asteroids, comets and so on which had been orbiting it, with some forming a dust disk, a little like the rings of Saturn.

"As this material approaches the star, it changes how we see the star. This change is measurable because it influences the star's spectroscopic signal, and allows us to identify the type and even the quantity of material surrounding the white dwarf. These measurements can be extremely sensitive, allowing bodies as small as an asteroid to be detected".

The team took measurements using spectrographs on the Keck telescope in Hawaii, the world's largest optical and infrared telescope, and on the Hubble Space Telescope.

Siyi Xu continued, "In this study, we have focused on the sample of white dwarfs with dust disks. We have been able to measure calcium, magnesium, and silicon content in most of these stars, and a few more elements in some stars. We may also have found water in one of the systems, but we have not yet quantified it: it's likely that there will be a lot of water in some of these worlds. For example, we've previously identified one star system, 170 light years away in the constellation Bootes, which was rich in carbon, nitrogen and water, giving a composition similar to that of Halley's Comet. In general though, their composition looks very similar to bulk Earth.

This would mean that the chemical elements, the building blocks of earth are common in other planetary systems. From what we can see, in terms of the presence and proportion of these elements, we're normal, pretty normal. And that means that we can probably expect to find Earth-like planets elsewhere in our Galaxy".

Dr Xu continued "This work is still on-going and the recent data release from the Gaia satellite, which so far has characterized 1.7 billion stars, has revolutionized the field. This means we will understand the white dwarfs a lot better. We hope to determine the chemical compositions of extrasolar planetary material to a much higher precision"

Professor Sara Seager, Professor of Planetary Science at Massachusetts Institute of Technology, is also the deputy science director of the recently-launched TESS (Transiting Exoplanet Survey Satellite) mission, which will search for exoplanets. She said:

"It's astonishing to me that the best way to study exoplanet interiors is by planets ripped apart and absorbed by their white dwarf host star. It is great to see progress in this research area and to have solid evidence that planets with Earth-like compositions are common--fueling our confidence that an Earth-like planet around a very nearby normal star is out there waiting to be found".

CALIFA renews the classification of galaxies

The objects within galaxies have two basic types of motions: orbiting around the galaxy centre in a regular organized disc, or in orbits oriented at random without a clear direction of rotaiton. If we imagined that galaxies behave in the same way as the Solar System we could think that as the objects move further away from the centre their orbital velocities decrease. However this is not necessarily the case for galaxies, as there are several factors which affect the rotational velocity of these objects, such as the dimensions of the galaxy, the gravitational pull of other galaxies, and the quantity of dark matter in a given galaxy. An international team of astrophysicists,among them IAC and Universidad de La Laguna researcher Jesus Falcon Barroso, coordinator of the CALIFa (Calar Alto Legacy Integral Field Area survey) at the IAC who is one of the authors of the article published in Nature Astronomy, has collected tat from 600 galaxies in the neighbourbhood of the Milky Way with the Potsday Multiple Aperture Spectrophotometer (PMAS) on the 3.6m telescope at the Calar Alto Observatory (Almeria, Spain). As part of this catalogue the scientists have made velocity maps of 300 galaxies showing the movements of their stars.

In this way they have defined three different groups among the sets of stellar orbits, which they have called "cold orfbits" "warm orbits" and "hot orbits", the latter typical of stars with random motions. When they analyzed tghe data they showed that circular orbits are frequent in lower mass galaxies, while the "hot orbits" are more often found in galaxies with higher mass. In addition tghey have found quite a number of "warm orbits", greater than that previously expected for this type of galaxies.

Using these maps of stellar motions one can obtain a lot of informatioin about the history of formation of these galaxies. They evolve and grow over thousands of millions of years, merging with other galaxies. Those which have absorbed other smaller galaxies generally have thin rotating discs, while when two galaxies with similar masses merge an elliptical galaxy is formed, in which the orbits are arranged in random directions.

Measuring the orbits in the galaxies analyzed allows us to distinguish between disc galaxies (with colder orbits) and elliptical galaxies (with hotter orbits) even when this difference cannot be detected when using images alone. This implies that by measuring the stellar orbits the researchers will be able to determine if the galaxy we observe is the result of internal evolution of an isolated object, a relatively calm series of mergers with smaller objects, or the product of a violent merger.

CALIFA, which with its 300 galaxy simple has become one of the biggest archives of data on galaxy dynamics up to now is the "first study to propose a scheme of galaxy classification base don the orbital distribution of their stars, which is different from the classical Hubble diagram , based on morphological classification" explains Falcon Barroso. This researcher also acknowledges that the results of this study " present some problems for current theories of formation and evolution of galaxies"

This new classification has been carefully prepared to produce a representative simple which will help astronomers to make models of the evolution of galaxies, and show whether their simulations produce valid predictions.

Research will help scientists understand how stars create elements

New research involving The Australian National University (ANU) has, for the first time, demonstrated a long-theorised nuclear effect, in a feat that will help scientists understand how stars evolve and produce elements such as gold and platinum. Physicists first predicted the effect, called Nuclear Excitation by Electron Capture (NEEC), more than 40 years ago, but this research was the first positive observation and has achieved the first quantified measurement of the phenomenon. Co-researcher Dr Greg Lane said the new research would improve scientific understanding of the nuclear reactions that occur in stars. "The abundance of the different elements in a star depends primarily on the structure and behaviour of atomic nuclei," said Dr Lane from the ANU Research School of Physics and Engineering. "The NEEC phenomenon modifies the nucleus lifetime so that it survives for a shorter amount of time in a star." The NEEC effect occurs when an ionised atom captures an electron, giving the atom's nucleus enough energy to transition to a higher excited state.

ANU and other research institutions in the United States, Poland and Russia supported the project, which was led by the U.S. Army Research Laboratory.

Dr Lane said the NEEC phenomenon could also potentially be harnessed as an energy source with 100,000 times greater energy density than chemical batteries.

"Our study demonstrated a new way to release the energy stored in a long-lived nuclear state, which the U.S. Army Research Laboratory is interested to explore further," he said.

The research team observed the NEEC effect by producing an exotic isotope, molybdenum-93, in an excited state with a half-life of about seven hours.

Dr Lane said the NEEC effect accelerated the isotope's decay through an excitation pathway with a unique set of gamma rays, different from the normal pathway, which are a signature of NEEC.

The Heavy Ion Accelerator Facility at ANU was used to confirm that the NEEC signature would be unique, in readiness for the discovery experiment that used the ATLAS Accelarator at Argonne National Laboratory in the United States.

The Heavy Ion Accelerator Facility uses electricity and magnets to guide particles and speed them up to extreme energies to study the internal make-up of atomic nuclei, and how they behave when they collide.
Understanding Conditions for Star Formation

Sapporo, Japan (SPX) Feb 06 - The mechanism by which hydrogen sulphide is released as gas in interstellar molecular clouds is described by scientists in Japan and Germany, in the journal Nature Astronomy. The process, known as chemical desorption, is more efficient than previously believed, and this has implications for our understanding of star formation in molecular clouds.

Molecular clouds are rare, but are important parts of the galaxy where molecules form and evolve. In the colder, denser areas, and under the right conditions, stars are formed. Theoretically, in molecular clouds at temperatures of 10 kelvin, all molecules except hydrogen and helium should be locked into ice on the surface of dust, not freely floating around. However, observations have shown this is not the case.

Understanding how molecules are released from dust at low temperatures is crucial to explaining how chemicals evolve in such cold clouds. The dissolution of particles from ice due to ultraviolet radiation, a process called photodesorption, has been demonstrated to play a role in some parts of the massive clouds. However, this would be inefficient in the darker, denser areas where stars are formed.

Researchers have supposed chemical desorption is at work in those areas, releasing particles using excess energy from a chemical reaction. The idea was first proposed 50 years ago, but scientists had not provided proof of the process until now.

The research team led by Yasuhiro Oba and Naoki Watanabe from Hokkaido University in Japan, in collaboration with the University of Stuttgart in Germany, set up the conditions to investigate.

Using an experimental system containing amorphous solid water at 10 kelvin and hydrogen sulphide (H2S), the team exposed the H2S to hydrogen and monitored the reaction with infrared absorption spectroscopy.

The experiment demonstrated that the desorption is caused by hydrogen interacting with H2S and the reaction is therefore a chemical one. They were able to quantify desorption after the reaction, and found it was a much more efficient process than previously estimated.

This work is the first infrared in-situ measurement of chemical desorption, and gives detailed descriptions during reactions which are key to understanding interstellar sulphur chemistry.

"Interstellar chemistry is of great importance to understanding the formation of stars, as well as water, methanol and possibly to more complex molecular species," says Watanabe. A significant step forward in the fields of astronomy and chemistry, the experimental setup can now be used to examine other molecules in the future.

Hubble Delivers First Insight Into Atmospheres Of Potentially Habitable Planets Orbiting Trappist-1

An international team of astronomers has used the NASA/ESA Hubble Space Telescope to look for atmospheres around four Earth-sized planets orbiting within or near TRAPPIST-1's habitable zone. The new results further support the terrestrial and potentially habitable nature of three of the studied planets. The results are published in Nature Astronomy. Seven Earth-sized planets orbit the ultracool dwarf star TRAPPIST-1, 40 light-years away from the Earth. This makes TRAPPIST-1 the planetary system with the largest number of Earth-sized planets discovered so far. These planets are also relatively temperate, making them a tantalizing place to search for signs of life beyond our Solar System. Now, an international team of astronomers has presented a study in which they used the NASA/ESA Hubble Space Telescope to screen four planets in the system - TRAPPIST-1d, e, f and g - to study their atmospheres. Three of the planets orbit within the system's habitable zone, the region at a distance from the star where liquid water - the key to life as we know it - could exist on the surface of a planet. The fourth planet orbits in a borderline region at the inner edge of the habitable zone. The data obtained rule out a cloud-free hydrogen-rich atmosphere for three of the planets - but for the fourth planet, TRAPPIST-1g, such an atmosphere could not be excluded.

Lead author Julien de Wit, from the Massachusetts Institute of Technology, USA, describes the positive implications of these measurements: "The presence of puffy, hydrogen-dominated atmospheres would have indicated that these planets are more likely gaseous worlds like Neptune. The lack of hydrogen in their atmospheres further supports theories about the planets being terrestrial in nature. This discovery is an important step towards determining if the planets might harbour liquid water on their surfaces, which could enable them to support living organisms."

The observations were made while the planets were in transit in front of TRAPPIST-1. In this configuration a small section of the star's light passes through the atmosphere of the exoplanet and interacts with the atoms and molecules in it. This leaves a weak fingerprint of the atmosphere in the spectrum of the star.

While the results rule out one type of atmosphere, many alternative atmospheric scenarios are still consistent with the data gathered by de Wit and his team. The exoplanets may possess a range of atmospheres, just like the terrestrial planets in our Solar System.

"Our results demonstrate Hubble's ability to study the atmospheres of Earth-sized planets. But the telescope is really working at the limit of what it can do," adds co-author Hannah Wakeford from the Space Telescope Science Institute, illustrating both the power and limitation of Hubble.

These latest findings complement the analysis of ultraviolet observations made with Hubble in 2017 (heic1713) and help us understand more about whether life might be possible in the TRAPPIST-1 system.

By ruling out the presence of a large abundance of hydrogen in the planets' atmospheres, Hubble is helping to pave the way for the NASA/ESA/CSA James Webb Space Telescope.

"Spectroscopic observations of the TRAPPIST-1 planets with the next generation of telescopes - including the James Webb Space Telescope - will allow us to probe deeper into their atmospheres," concludes Michael Gillon, from the University of Liege, Belgium.

"This will allow us to search for heavier gases such as carbon, methane, water, and oxygen, which could offer biosignatures for life."

Astronomers produce first detailed images of surface of giant star

An international team of astronomers has produced the first detailed images of the surface of a giant star outside our solar system, revealing a nearly circular, dust-free atmosphere with complex areas of moving material, known as convection cells or granules, according to a recent study.The giant star, named p1Gruis, is one of the stars in the constellation Grus (Latin for the crane, a type of bird), which can be observed in the southern hemisphere. An evolved star in the last major phase of life, p1Gruis is 350 times larger than the Sun and resembles what our Sun will become at the end of its life in five billion years. Studying this star gives scientists insight about the future activity, characteristics and appearance of the Sun. Convection, the transfer of heat due to the bulk movement of molecules within gases and liquids, plays a major role in astrophysical processes, such as energy transport, pulsation and winds.The Sun has about two million convective cells that are typically 2,000 kilometers across, but theorists believe giant and supergiant stars should only have a few large convective cells because of their low surface gravity. Determining the convection properties of most evolved and supergiant stars, such as the size of granules, has been challenging because their surfaces are frequently obscured by dust.

In this study, the researchers discovered the surface of the giant star p1Gruis had a complex convective pattern and the typical granule measured 1.2 x 10^11 meters horizontally or 27 percent of the diameter of the star. The findings are published in the journal Nature.

"This is the first time that we have such a giant star that is unambiguously imaged with that level of details," said Dr. Fabien Baron, assistant professor in the Department of Physics and Astronomy at Georgia State University.

"The reason is there's a limit to the details we can see based on the size of the telescope used for the observations. For this paper, we used an interferometer. The light from several telescopes is combined to overcome the limit of each telescope, thus achieving a resolution equivalent to that of a much larger telescope."

The star p1Gruis was observed with the PIONIER instrument, which has four combined telescopes, in Chile in September 2014. Baron, who specializes in making images, used interferometric data, image reconstruction software and algorithms to compose images of the star's surface.

Interferometry is relatively new to astronomy, and Georgia State's Center for High Angular Resolution Astronomy array was the first facility to use interferometry to image a star similar to the Sun in 2007.

This study was also the first to confirm theories about the characteristics of granules on giant stars.

"These images are important because the size and number of granules on the surface actually fit very well with models that predict what we should be seeing," Baron said.

"That tells us that our models of stars are not far from reality. We're probably on the right track to understand these kinds of stars."

The detailed images also showed different colors on the star's surface, which correspond to varying temperatures. A star doesn't have the same surface temperature throughout, and its surface provides our only clues to understand its internals. As temperatures rise and fall, the hotter, more fluid areas become brighter colors (such as white) and the cooler, more dense areas become darker colors (such as red).

In the future, the researchers would like to make even more detailed images of the surface of giant stars and follow the evolution of these granules continuously, instead of only getting snapshot images.

A New Approach for Detecting Planets in the Alpha Centauri System

Yale astronomers have taken a fresh look at the nearby Alpha Centauri star system and found new ways to narrow the search for habitable planets there. According to a study led by Professor Debra Fischer and graduate student Lily Zhao, there may be small, Earth-like planets in Alpha Centauri that have been overlooked. Meanwhile, the study ruled out the existence of a number of larger planets in the system that had popped up in previous models. "The universe has told us the most common types of planets are small planets, and our study shows these are exactly the ones that are most likely to be orbiting Alpha Centauri A and B," said Fischer, a leading expert on exoplanets who has devoted decades of research to the search for an Earth analog. The new study appears in the Astronomical Journal. Co-authors are John Brewer and Matt Giguere of Yale and Barbara Rojas-Ayala of Universidad Andres Bello in Chile. The Alpha Centauri system is located 1.3 parsecs (24.9 trillion miles) from Earth, making it our closest neighboring system. It has three stars: Centauri A, Centauri B, and Proxima Centauri. Last year, the discovery of an Earth-like planet orbiting Proxima Centauri set off a new wave of scientific and public interest in the system.

"Because Alpha Centauri is so close, it is our first stop outside our solar system," Fischer said. "There's almost certain to be small, rocky planets around Alpha Centauri A and B."

The findings are based on data coming in from a new wave of more advanced spectrographic instruments at observatories located in Chile: CHIRON, a spectrograph built by Fischer's team; HARPS, built by a team from Geneva; and UVES, part of the Very Large Telescope Array. "The precision of our instruments hasn't been good enough, until now," Fischer said.

The researchers set up a grid system for the Alpha Centauri system and asked, based on the spectrographic analysis, "If there was a small, rocky planet in the habitable zone, would we have been able to detect it?" Often, the answer came back: "No."

Zhao, the study's first author, determined that for Alpha Centauri A, there might still be orbiting planets that are smaller than 50 Earth masses. For Alpha Centauri B there might be orbiting planets than are smaller than 8 Earth masses; for Proxima Centauri, there might be orbiting planets that are less than one-half of Earth's mass.

In addition, the study eliminated the possibility of a number of larger planets. Zhao said this takes away the possibility of Jupiter-sized planets causing asteroids that might hit or change the orbits of smaller, Earth-like planets.

"This is a very green study in that it recycles existing data to draw new conclusions," said Zhao. "By using the data in a different way, we are able to rule out large planets that could endanger small, habitable worlds and narrow down the search area for future investigations."

This new information will help astronomers prioritize their efforts to detect additional planets in the system, the researchers said. Likewise, the continuing effort by Fischer and others to improve spectrographic technology will help identify and understand the composition of exoplanets.

Galaxy Orbits in the Local Supercluster

A team of astronomers from Maryland, Hawaii, Israel, and France has produced the most detailed map ever of the orbits of galaxies in our extended local neighborhood, showing the past motions of almost 1,400 galaxies within 100 million light-years of the Milky Way. The team reconstructed the galaxies' motions from 13 billion years in the past to the present day. The main gravitational attractor in the mapped area is the Virgo Cluster, with 600 trillion times the mass of the Sun, 50 million light-years from us. Over a thousand galaxies have already fallen into the Virgo Cluster, while in the future all galaxies that are currently within 40 million light-years of the cluster will be captured. Our Milky Way galaxy lies just outside this capture zone. However the Milky Way and Andromeda galaxies, each with 2 trillion times the mass of the Sun, are destined to collide and merge in 5 billion years.

"For the first time, we are not only visualizing the detailed structure of our local supercluster of galaxies but we are seeing how the structure developed over the history of the universe. An analogy is the study of the current geography of the Earth from the movement of plate tectonics," said co-author Brent Tully, from the University of Hawaii Institute for Astronomy.

These dramatic merger events are only part of a larger show. There are two overarching flow patterns within this volume of the universe. All galaxies in one hemisphere of the region - including our own Milky Way - are streaming toward a single flat sheet. In addition, essentially every galaxy over the whole volume is flowing, as a leaf would in a river, toward gravitational attractors at far greater distances.

Representations of the orbits can be seen in a video and, alternatively, with an interactive model.

With the interactive model, a viewer can pan, zoom, rotate, and pause/activate the time evolution of movement along orbits. The orbits are shown in a reference frame that removes the overall expansion of the universe. What we are seeing are the deviations from cosmic expansion caused by the interactions of local sources of gravity.

Measuring neutron star sizes by using thermonuclear explosion models

Neutron stars are made out of cold ultra-dense matter. How this matter behaves is one of the biggest mysteries in modern nuclear physics. Researchers developed a new method for measuring the radius of neutron stars which helps them to understand what happens to the matter inside the star under extreme pressure. A new method for measuring neutron star size was developed in a study led by a high-energy astrophysics research group at the University of Turku, Finland. The method relies on modelling how thermonuclear explosions taking place in the uppermost layers of the star emit X-rays to us. By comparing the observed X-ray radiation from neutron stars to the state-of-the-art theoretical radiation models, researchers were able to put constraints on the size of the emitting source. This new analysis suggests that the neutron star radius should be about 12.4 kilometers. "Previous measurements have shown that the radius of a neutron star is circa 10-16 kilometres. We constrained it to be around 12 kilometres with about 400 meters accuracy, or maybe 1000 meters if one wants to be really sure. Therefore, the new measurement is a clear improvement compared to that before, says Doctoral Candidate Joonas Nattila from the University of Turku who developed the method.

The new measurements help researchers to study what kind of nuclear-physical conditions exist inside extremely dense neutron stars. Researchers are particularly interested in determining equation of state of the neutron matter, which shows how compressible the matter is at extremely high densities.

"The density of neutron star matter is circa 100 million tons per cubic centimetre. At the moment, neutron stars are the only objects appearing in nature, with which these types of extreme states of matter can be studied," says Juri Poutanen, the leader of the research group.

The new results also help to understand the recently discovered gravitational waves that originated from the collision of two neutron stars. That is why the LIGO/VIRGO consortium that discovered these waves was quick to compare their recent observations with the new constraints obtained by the Finnish researchers.

"The specific shape of the gravitational wave signal is highly dependent on the radii and the equation of state of the neutron stars. It is very exciting how these two completely different measurements tell the same story about the composition of neutron stars. The next natural step is to combine these two results. We have already been having active discussions with our colleagues on how to do this," says Nattila.

The Most Powerful Magnets in the Universe Are Collapsed Stars

When a large star dies, sometimes it becomes a neutron star, a tiny, 12 mile across ball that's made almost entirely out of neutrons. These dead stars are incredibly dense, and spin incredibly fast. Just one thimbleful of neutron star would weigh 100 million tons. Magnetars are a variation of neutron stars, and they somehow manage to be even scarier. Neutron stars already have extremely strong magnetic fields--about 2 trillion times more powerful than Earth's. Yet magnetars have magnetic fields 1,000 times stronger than that. Yeah, that's a pretty intense field. Magnetars are not just insanely powerful--they're also very, very dangerous. If you were a mere 1,000 kilometers from a magnetar, your entire body would dissolve as the magnetic field rearranged the sequence of atoms in your body. 

In addition to their terrifying magnetic powers, magnetars also have something called starquakes, which function similarly to earthquakes here on Earth--except with much more intense results. A crack in the crust of a magnetar is responsible for the brightest light we've ever observed from space. And if a magnetar was closer to us, like 10 light years away, and blasted us with the radiation from a starquake, it would destroy our ozone layer and probably kill all life on Earth.

But don't worry--thankfully, there aren't any magnetars near Earth. The closest one is about 9,000 light years away. Let's pray that it stays that way.

Three New Gas Giants May Provide Hint Into Major Astronomical Mystery

European astronomers with the Super Wide Angle Search for Planets (SuperWASP) consortium of planet hunters have detected three new gas giant alien worlds.The SuperWASP is an international effort to use the Roque de los Muchachos Observatory in Spain and the South African Astronomical Observatory to discover exoplanets. Both observatories are equipped with eight wide-angle cameras that monitor the sky for planetary transit events (when planets pass in front of their stars, allowing them to be imaged by human telescopes). The three planets were discovered orbiting three stars also discovered by the SuperWASP program: WASP-151, WASP-153 and WASP-156. "In this paper, we report the discovery of three transiting exoplanets by the SuperWASP survey and the SOPHIE spectrograph with mass and radius determined with a precision better than 15 percent," wrote the astronomers, led by a team out of the University of Porto in Portugal.

Two of the planets are "hot Saturns," large but low-density gas giants that are very close to their stars. The larger of the two, WASP-153b, has a radius 1.86 times that of Saturn and is 1.3 times as dense. The smaller hot Saturn, WASP-151b, is 1.36 times larger than Saturn and is 1.03 times as dense. Both of them have orbital periods of less than a week.

Meanwhile, the third planet is a "super-Neptune:" a planet appreciably bigger than Neptune (2.5 times more massive in this case) but smaller than Saturn, which is about five times more massive than Neptune. This third planet, WASP-156b, only needs 3.83 days to complete a revolution around its star.

This third find is the exciting one to astronomers, as shockingly few super-Neptunes have been discovered — a dearth named the so-called "Neptunian Desert." Many terrestrial planets (like Earth and Venus), gas giants (like Jupiter and Saturn), and super-Earths (like Uranus and Neptune) have been discovered. Meanwhile 156b is only the ninth-ever super-Neptune to be found of the thousand-plus exoplanets confirmed — and nobody is sure why.

"These three planets also lie close to (WASP-151b and WASP-153b) or below (WASP-156b) the upper boundary of the Neptunian desert. (…) While a detailed analysis of the origin of the Neptunian desert is beyond the scope of this paper, it is still interesting to look into the similarities and differences between WASP-156b and WASP-151b/WASP-153b since they might provide useful hints on the nature of this desert," the paper reads.

We may have just seen the first comet from another solar system

The solar system may be hosting a visitor from the stars. A newly discovered comet is screaming away from Earth, and based on its weird orbital trajectory astronomers think it might be the first comet ever observed that came from interstellar space. A sky-surveying telescope in Hawaii spotted the fast-moving object, now called C/2017 U1, on 18 October, after its closest approach to the sun. During the next week, astronomers made 34 separate observations of the object and found it has a strange trajectory that is at an angle to the orbits of the planets and does not circle the sun. Now, astronomers are hoping more skywatchers will take a look and pin down whether it’s from our neighborhood or an interloper from beyond. Most comets follow ellipse-shaped orbits around the sun, swooping in from the distant Oort Cloud to kiss the inner solar system before heading back out again. This one, by contrast, will never return. Its orbital path suggests it sailed in from the direction of the constellation Lyra above the relatively flat plane of the solar system, looped around the sun, and is headed back out for eternity.

Lyra is near the direction the sun is moving within the Milky Way, says Luke Dones at the Southwest Research Institute in Boulder, Colorado. “That’s exactly what you’d expect; there should be more interstellar comets coming from the direction the sun is heading toward,” he says.
Just popping in

“It’s coming from very far away, but we can’t actually backtrack how far away it started. It could be that it’s coming from outside the solar system, but it’s really hard to tell,” says Simon Porter, also at the Southwest Research Institute. Further observations in the next couple weeks will make the picture clearer.

What’s more, a comet on such an extreme path doesn’t necessarily have to come from interstellar space. “It could have interacted with Jupiter or another planet in such a way that changed its orbit,” says Maria Womack at the University of South Florida in Tampa.

The comet’s origins are hard to pin down in part because of the nature of comets. “When you think of photos of comets, they’re a fuzzy blob. People have to make determinations of where they think the center is. Someone who is at the telescope has to make a call,” Womack says.

This necessary guesswork makes the measurements less precise, so astronomers want lots of observations before they’ll be convinced the comet really is from beyond our solar system, she adds.

Luckily, there are plenty of opportunities left to take a peek. The comet should be visible in powerful telescopes for at least another couple weeks, allowing amateurs and professionals alike to survey the icy visitor and determine its history.

Hubble Captures Massive Dead Disk Galaxy that Challenges Theories of Galaxy Evolution

By combining the power of a "natural lens" in space with the capability of NASA's Hubble Space Telescope, astronomers made a surprising discovery—the first example of a compact yet massive, fast-spinning, disk-shaped galaxy that stopped making stars only a few billion years after the big bang. Finding such a galaxy early in the history of the universe challenges the current understanding of how massive galaxies form and evolve, say researchers. When Hubble photographed the galaxy, astronomers expected to see a chaotic ball of stars formed through galaxies merging together. Instead, they saw evidence that the stars were born in a pancake-shaped disk.

Acting as a “natural telescope” in space, the gravity of the extremely massive foreground galaxy cluster MACS J2129-0741 magnifies, brightens, and distorts the far-distant background galaxy MACS2129-1, shown in the top box. The middle box is a blown-up view of the gravitationally lensed galaxy. In the bottom box is a reconstructed image, based on modeling that shows what the galaxy would look like if the galaxy cluster were not present. The galaxy appears red because it is so distant that its light is shifted into the red part of the spectrum.

Credits: NASA, ESA, S. Toft (University of Copenhagen), M. Postman (STScI), and the CLASH team

This is the first direct observational evidence that at least some of the earliest so-called "dead" galaxies — where star formation stopped — somehow evolve from a Milky Way-shaped disk into the giant elliptical galaxies we see today.

This is a surprise because elliptical galaxies contain older stars, while spiral galaxies typically contain younger blue stars. At least some of these early "dead" disk galaxies must have gone through major makeovers. They not only changed their structure, but also the motions of their stars to make a shape of an elliptical galaxy.

"This new insight may force us to rethink the whole cosmological context of how galaxies burn out early on and evolve into local elliptical-shaped galaxies," said study leader Sune Toft of the Dark Cosmology Center at the Niels Bohr Institute, University of Copenhagen, Denmark. "Perhaps we have been blind to the fact that early "dead" galaxies could in fact be disks, simply because we haven't been able to resolve them."

This artist's concept shows what the young, dead, disk galaxy MACS2129-1, right, would look like when compared with the Milky Way galaxy, left. Although three times as massive as the Milky Way, it is only half the size. MACS2129-1 is also spinning more than twice as fast as the Milky Way. Note that regions of Milky Way are blue from bursts of star formation, while the young, dead galaxy is yellow, signifying an older star population and no new star birth.

Credits: NASA, ESA, and Z. Levy (STScI)

Previous studies of distant dead galaxies have assumed that their structure is similar to the local elliptical galaxies they will evolve into. Confirming this assumption in principle requires more powerful space telescopes than are currently available.

However, through the phenomenon known as "gravitational lensing," a massive, foreground cluster of galaxies acts as a natural "zoom lens" in space by magnifying and stretching images of far more distant background galaxies. By joining this natural lens with the resolving power of Hubble, scientists were able to see into the center of the dead galaxy.

The remote galaxy is three times as massive as the Milky Way but only half the size. Rotational velocity measurements made with the European Southern Observatory's Very Large Telescope (VLT) showed that the disk galaxy is spinning more than twice as fast as the Milky Way.

Using archival data from the Cluster Lensing And Supernova survey with Hubble (CLASH), Toft and his team were able to determine the stellar mass, star-formation rate, and the ages of the stars.

Why this galaxy stopped forming stars is still unknown. It may be the result of an active galactic nucleus, where energy is gushing from a supermassive black hole. This energy inhibits star formation by heating the gas or expelling it from the galaxy. Or it may be the result of the cold gas streaming onto the galaxy being rapidly compressed and heated up, preventing it from cooling down into star-forming clouds in the galaxy's center.

But how do these young, massive, compact disks evolve into the elliptical galaxies we see in the present-day universe? "Probably through mergers," Toft said. "If these galaxies grow through merging with minor companions, and these minor companions come in large numbers and from all sorts of different angles onto the galaxy, this would eventually randomize the orbits of stars in the galaxies. You could also imagine major mergers. This would definitely also destroy the ordered motion of the stars."

The findings are published in the June 22 issue of the journal Nature. Toft and his team hope to use NASA's upcoming James Webb Space Telescope to look for a larger sample of such galaxies.

The Hubble Space Telescope is a project of international cooperation between NASA and ESA (European Space Agency). NASA's Goddard Space Flight Center in Greenbelt, Maryland, manages the telescope. The Space Telescope Science Institute (STScI) in Baltimore, Maryland, conducts Hubble science operations. STScI is operated for NASA by the Association of Universities for Research in Astronomy, Inc., in Washington, D.C.

The Very Large Telescope is a telescope facility operated by the European Southern Observatory on Cerro Paranal in the Atacama Desert of Northern Chile.