Athena to study the hot and energetic universe

Artist's impression of an active galaxy

The European Space Agency (ESA) has selected the Athena advanced telescope for high-energy astrophysics as its second “large-class” science mission.

The observatory will study the hot and energetic universe and take the “L2” slot in ESA’s Cosmic Vision 2015–25 plan with a launch foreseen in 2028.

By combining a large X-ray telescope with state-of-the-art scientific instruments, Athena will address key questions in astrophysics, including how and why ordinary matter assembles into the galaxies and galactic clusters that we see today as well as how black holes grow and influence their surroundings.

Scientists believe that black holes lurk at the center of almost all galaxies and that they play a fundamental role in their formation and evolution.

To investigate this connection, Athena will observe X-ray emission from very hot material just before it is swallowed by a black hole, measuring distortions due to gravitational light-bending and time-delay effects in this extreme environment. Athena also will be able to determine the spin of the black hole itself.

Athena’s powerful instruments also will allow unprecedented studies of a wide range of astronomical phenomena. These include distant gamma-ray bursts, the hot gas found in the space around clusters of galaxies, the magnetic interplay between exoplanets and their parent stars, Jupiter’s aurorae, and comets in our solar system.

“Athena will be a state-of-the-art observatory that will provide a significant leap forward in scientific capabilities compared with previous X-ray missions and will address fundamental open questions in astrophysics,” said Alvaro Giménez from ESA. “Its selection ensures that Europe’s success in the field of X-ray astronomy is maintained far beyond the lifetime of our flagship observatory, XMM-Newton.”

The selection process for L2 began in March 2013 when ESA issued a call to the European science community to suggest the scientific themes to be pursued by the Cosmic Vision program’s second and third Large missions.

In November 2013, the theme of “the hot and energetic universe” was selected for L2 for a launch in 2028, with “the gravitational universe” selected for L3 and a planned launch in 2034.

Now officially selected for L2, Athena moves into a study phase. Once the mission design and costing have been completed, it will eventually be proposed for “adoption” in around 2019 before the start of construction.

After launch, Athena will travel to its operational orbit around the gravitationally semistable location in space some 1 million miles (1.5 million kilometers) beyond Earth as seen from the Sun — a position coincidentally known as L2. ESA’s Herschel, Planck, and Gaia missions also have used L2 orbits.

Astronomers Discover Rare Triple Supermassive Black Hole System

A team of scientists led by Dr Roger Deane from the University of Cape Town in South Africa has discovered a system of three supermassive black holes – with two of them orbiting each other rather like binary stars – in a galaxy more than 4 billion light-years away from Earth. The discovery could help astronomers in the search for gravitational waves (the ripples in space-time) predicted by Albert Einstein.

Radio images of the triple supermassive black holes system J1502P/SE/SW in the galaxy SDSS J150243.09+1111557.3 and its binary component. Image credit: R.P.Deane et al.

“Einstein’s General Relativity predicts that merging black holes are sources of gravitational waves and in this work we have managed to spot three black holes packed about as tightly together as they could be before spiraling into each other and merging,” said Prof Matt Jarvis from the University of Oxford, who is a co-author of the discovery paper published in the journal Nature.

“The idea that we might be able to find more of these potential sources of gravitational waves is very encouraging as knowing where such signals should originate will help us try to detect these ripples in space-time as they warp the Universe.”

In their study, Dr Deane, Prof Jarvis and co-authors examined six galaxies thought to contain binary supermassive black hole systems.

The astronomers found that one of these galaxies, SDSS J150243.09+1111557.3 (J1502 for short), they thought contained two black holes (J1502P and J1502S) actually contained a triple system with a very compact double supermassive black hole.

They then used the European Very Long Baseline Interferometry Network and the 305-m Arecibo Observatory in Puerto Rico to observe the inner two black holes, J1502SE and J1502SW.

“Very little is actually known about black hole systems that are so close to one another that they emit detectable gravitational waves,” the scientists said.

“This discovery not only suggests that close-pair black hole systems emitting at radio wavelengths are much more common than previously expected,” Prof Jarvis said.

“This exciting discovery perfectly illustrates the power of the Very Long Baseline Interferometry technique, whose exquisite sharpness of view allows us to see deep into the hearts of distant galaxies,” said co-author Dr Keith Grainge from the University of Manchester.

Swiftly moving gas streamer eclipses supermassive black hole

This is the galaxy known as NGC 5548. At its heart, though not visible here, is a supermassive black hole behaving in a strange and unexpected manner. Researchers detected a clumpy gas stream flowing quickly outward and blocking 90 percent of the X-rays emitted by the black hole. This activity could provide insights into how supermassive black holes interact with their host galaxies.

Researchers detected a clumpy gas stream flowing quickly outward and blocking 90 percent of the X-rays emitted by the black hole in NGC 5548.
Astronomers have discovered strange and unexpected behavior around the supermassive black hole at the heart of galaxy NGC 5548. The international team of researchers detected a clumpy gas stream flowing quickly outward and blocking 90 percent of the X-rays emitted by the black hole. This activity could provide insights into how supermassive black holes interact with their host galaxies.

The discovery of the unusual behavior in NGC 5548 is the result of an intensive observing campaign using major European Space Agency and NASA observatories, including the NASA/ESA Hubble Space Telescope. In 2013 and 2014, the international team carried out the most extensive monitoring campaign of an active galaxy ever conducted.

There are other galaxies that show gas streams near a black hole, but this is the first time that a stream like this has been seen to move into the line of sight.

The researchers say that this is the first direct evidence for the long-predicted shielding process that is needed to accelerate powerful gas streams, or winds, to high speeds. “This is a milestone in understanding how supermassive black holes interact with their host galaxies,” said Jelle Kaastra of the SRON Netherlands Institute for Space Research. “We were very lucky. You don’t normally see this kind of event with objects like this. It tells us more about the powerful ionized winds that allow supermassive black holes in the nuclei of active galaxies to expel large amounts of matter. In larger quasars than NGC 5548, these winds can regulate the growth of both the black hole and its host galaxy.”

As matter spirals down into a black hole, it forms a flat disk known as an accretion disk. The disk is heated so much that it emits X-rays near the black hole and less energetic ultraviolet radiation farther out. The ultraviolet radiation can create winds strong enough to blow gas away from the black hole, which otherwise would have fallen into it. But the winds only come into existence if their starting point is shielded from X-rays.

Earlier observations had seen the effects of both X-rays and ultraviolet radiation on a region of warm gas far away from the black hole, but these most recent observations have shown the presence of a new gas stream between the disk and the original cloud. The newly discovered gas stream in the archetypal Seyfert galaxy (NGC 5548) — one of the best-studied sources of this type over the past half-century — absorbs most of the X-ray radiation before it reaches the original cloud, shielding it from X-rays and leaving only the ultraviolet radiation. The same stream shields gas closer to the accretion disk. This makes the strong winds possible, and it appears that the shielding has been going on for at least three years.

Directly after Hubble had observed NGC 5548 on June 22, 2013, the team discovered unexpected features in the data. “There were dramatic changes since the last observation with Hubble in 2011. We saw signatures of much colder gas than was present before, indicating that the wind had cooled down, due to a strong decrease in the ionizing X-ray radiation from the nucleus,” said team member Gerard Kriss of the Space Telescope Science Institute in Baltimore.

After combining and analyzing data from the six observatories involved, the team was able to put the pieces of the puzzle together. NGC 5548’s persistent wind, which scientists have known about for two decades, reaches velocities exceeding 2.2 million mph (3.5 million km/h). But a new wind has arisen that is much stronger and faster than the persistent wind.

“The new wind reaches speeds of up to 18 million km/h [11 million mph] but is much closer to the nucleus than the persistent wind,” said Kaastra. “The new gas outflow blocks 90 percent of the low-energy X-rays that come from close to the black hole, and it obscures up to a third of the region that emits the ultraviolet radiation at a distance of a few light-days from the black hole.”

Strong X-ray absorption by ionized gas has been seen in several other sources, and it has been attributed for instance to passing clouds. “However, in our case, thanks to the combined XMM-Newton and Hubble data, we know this is a fast stream of outflowing gas very close to the nucleus,” said Massimo Cappi of INAF-IASF Bologna. “It may even originate from the accretion disk,” added team member Pierre-Olivier Petrucci of CNRS, IPAG Grenoble.

Swift satellite tallies water production of Mars-bound comet

This composite of C/2013 A1 (Siding Spring) merges Swift UVOT images taken between May 27 and 29, 2014. Sunlight reflected from the comet's dust, which produces most of the light in this image, appears yellow; violet shows ultraviolet light produced by hydroxyl (OH), a molecular fragment of water.

Observations reveal how rapidly Comet Siding Spring is producing water and allow astronomers to better estimate its size.
In late May, NASA’s Swift satellite imaged comet Siding Spring, which will brush astonishingly close to Mars later this year. These optical and ultraviolet observations are the first to reveal how rapidly the comet is producing water and allow astronomers to better estimate its size.

“Comet Siding Spring is making its first passage through the inner solar system and is experiencing its first strong heating from the Sun,” said Dennis Bodewits from the University of Maryland, College Park (UMCP). “These observations are part of a two-year-long Swift campaign to watch how the comet’s activity develops during its travels.”

“Fresh” comets like Siding Spring, which is formally known as C/2013 A1, contain some of the most ancient material scientists can study. The solid part of a comet, called its nucleus, is a clump of frozen gases mixed with dust and is often described as a “dirty snowball.” Comets cast off gas and dust whenever they venture near enough to the Sun.

What powers this activity is the transformation of frozen material from solid ice to gas, a process called sublimation. As the comet approaches the Sun and becomes heated, different gases stream from the nucleus, carrying with them large quantities of dust that reflect sunlight and brighten the comet. By about two and a half times Earth’s distance from the Sun (2.5 astronomical units, or AU), the comet has warmed enough that water becomes the primary gas emitted by the nucleus.

Between May 27 and 29, Swift’s Ultraviolet/Optical Telescope (UVOT) captured a sequence of images as Comet Siding Spring cruised through the constellation Eridanus at a distance of about 229 million miles (368 million kilometers) from the Sun. While the UVOT cannot detect water molecules directly, it can detect light emitted by fragments formed when ultraviolet sunlight breaks up water, specifically hydrogen atoms and hydroxyl (OH) molecules.

“Based on our observations, we calculate that at the time of the observations the comet was producing about 2 billion billion billion water molecules, equivalent to about 13 gallons or 49 liters, each second,” said Tony Farnham from UMCP. At this rate, Comet Siding Spring could fill an Olympic-size swimming pool in about 14 hours. Impressive as it sounds, though, this is relatively modest water emission compared to other comets Swift has observed.

Based on these measurements, the team concludes that the icy nucleus of Comet Siding Spring is only about 2,300 feet (700 meters) across, placing it at the lower end of a size range estimated from earlier observations by other spacecraft.

The comet makes its closest approach to Mars on October 19, passing just 86,000 miles (138,000km) from the Red Planet — so close that gas and dust in the outermost reaches of the comet’s atmosphere, or coma, will interact with the atmosphere of Mars.

For comparison, the closest recorded Earth approach by a comet was by the now-defunct Comet Lexell, which on July 1, 1770, swept to within 1.4 million miles (2.3 million km), or about six times farther than the Moon. During its Mars flyby, Comet Siding Spring will pass more than 16 times closer than this.

Scientists have established that the comet poses no danger to spacecraft now in orbit around Mars. These missions will be pressed into service as a provisional comet observation fleet to take advantage of this unprecedented opportunity.

The Swift observations are part of a larger study to investigate the activity and evolution of new comets, which show distinct brightening characteristics as they approach the Sun not seen in other comets. Bodewits and his colleagues single out comets that can be observed by Swift at distances where water has not yet become the primary gas and repeatedly observe them as they course through the inner solar system. This systematic study will help astronomers better understand how comet activity changes with repeated solar heating.

Molecule vital for creating water exists in dying sun-like stars

Herschel image of the Helix Nebula using the SPIRE instrument at wavelengths around 250 micrometres, superimposed on Hubble image of the nebula. The spectrum corresponds to the outer region of the Helix Nebula outlined on the SPIRE image. It identifies the OH+ molecular ion, which is needed for the formation of water. ESA’s Herschel space observatory is the first to detect this molecule in planetary nebulas – the product of dying Sun-like stars.

Using ESA's Herschel space observatory, astronomers have discovered that a molecule vital for creating water exists in the burning embers of dying Sun-like stars.

When low- to middleweight stars like our Sun approach the end of their lives, they eventually become dense, white dwarf stars. In doing so, they cast off their outer layers of dust and gas into space, creating a kaleidoscope of intricate patterns known as planetary nebulas.

These actually have nothing to do with planets, but were named in the late 18th century by astronomer William Herschel, because they appeared as fuzzy circular objects through his telescope, somewhat like the planets in our Solar System.

Over two centuries later, planetary nebulas studied with William Herschel's namesake, the Herschel space observatory, have yielded a surprising discovery.

Like the dramatic supernova explosions of weightier stars, the death cries of the stars responsible for planetary nebulas also enrich the local interstellar environment with elements from which the next generations of stars are born.

While supernovas are capable of forging the heaviest elements, planetary nebulas contain a large proportion of the lighter 'elements of life' such as carbon, nitrogen, and oxygen, made by nuclear fusion in the parent star.

A star like the Sun steadily burns hydrogen in its core for billions of years. But once the fuel begins to run out, the central star swells into a red giant, becoming unstable and shedding its outer layers to form a planetary nebula.

The remaining core of the star eventually becomes a hot white dwarf pouring out ultraviolet radiation into its surroundings.

This intense radiation may destroy molecules that had previously been ejected by the star and that are bound up in the clumps or rings of material seen in the periphery of planetary nebulas.

The harsh radiation was also assumed to restrict the formation of new molecules in those regions.

But in two separate studies using Herschel astronomers have discovered that a molecule vital to the formation of water seems to rather like this harsh environment, and perhaps even depends upon it to form. The molecule, known as OH+, is a positively charged combination of single oxygen and hydrogen atoms.

In one study, led by Dr Isabel Aleman of the University of Leiden, the Netherlands, 11 planetary nebulas were analysed and the molecule was found in just three.

What links the three is that they host the hottest stars, with temperatures exceeding 100,000ºC.

"We think that a critical clue is in the presence of the dense clumps of gas and dust, which are illuminated by UV and X-ray radiation emitted by the hot central star," says Dr Aleman.

"This high-energy radiation interacts with the clumps to trigger chemical reactions that leads to the formation of the molecules."

Meanwhile, another study, led by Dr Mireya Etxaluze of the Instituto de Ciencia de los Materiales de Madrid, Spain, focused on the Helix Nebula, one of the nearest planetary nebulas to our Solar System, at a distance of 700 light years.

The central star is about half the mass of our Sun, but has a far higher temperature of about 120,000ºC. The expelled shells of the star, which in optical images appear reminiscent of a human eye, are known to contain a rich variety of molecules.

Herschel mapped the presence of the crucial molecule across the Helix Nebula, and found it to be most abundant in locations where carbon monoxide molecules, previously ejected by the star, are most likely to be destroyed by the strong UV radiation.

Once oxygen atoms have been liberated from the carbon monoxide, they are available to make the oxygen-hydrogen molecules, further bolstering the hypothesis that the UV radiation may be promoting their creation.

The two studies are the first to identify in planetary nebulas this critical molecule needed for the formation of water, although it remains to be seen if the conditions would actually allow water formation to proceed.

"The proximity of the Helix Nebula means we have a natural laboratory on our cosmic doorstep to study in more detail the chemistry of these objects and their role in recycling molecules through the interstellar medium," says Dr Etxaluze.

"Herschel has traced water across the Universe, from star-forming clouds to the asteroid belt in our own Solar System," says Göran Pilbratt, ESA's Herschel project scientist.

"Now we have even found that stars like our Sun could contribute to the formation of water in the Universe, even as they are in their death throes."

"Herschel planetary nebula survey (HerPlaNS). First detection of OH⁺ in planetary nebulae," by I. Aleman et al., and "Herschel spectral-mapping of the Helix Nebula (NGC 7293): extended CO photodissociation and OH⁺ emission," by M. Etxaluze et al., are published in Astronomy & Astrophysics.

HerPlaNS (The Herschel Planetary Nebulae Survey) is a survey of 11 planetary nebulas aiming the study the formation and evolution of the circumstellar material by tracing the dust and gas components. The HerPlaNS team is led by Toshiya Ueta from the University of Denver.

The MESS (Mass loss of Evolved StarS) consortium studies a wide variety of evolved stars (including planetary nebulas) to better understand the mass loss in these objects, the dust and gas chemistry in the ejected material, and the processes shaping the nebulae. The MESS consortium is led by Martin Groenewegen (Royal Observatory of Belgium) and the study of planetary nebulas within the group is led by Peter van Hoof (Royal Observatory of Belgium).

Giant telescopes pair up to image near-Earth asteroid

NASA scientists used Earth-based radar to produce these sharp views of the asteroid designated 2014 HQ124 on June 8, 2014.

NASA scientists using Earth-based radar have produced sharp views of a recently discovered asteroid as it slid silently past our planet. Captured on June 8, 2014, the new views of the object designated 2014 HQ124 are some of the most detailed radar images of a near-Earth asteroid ever obtained.

Scientists Marina Brozovic and Lance Benner of NASA’s Jet Propulsion Laboratory (JPL) in Pasadena, California, led the radar observations. The researchers worked closely with Michael Nolan, Patrick Taylor, Ellen Howell, and Alessondra Springmann at Arecibo Observatory in Puerto Rico to plan and execute the observations.

2014 HQ124 appears to be an elongated, irregular object that is at least 1,200 feet (370 meters) wide on its long axis. “This may be a double object, or ‘contact binary,’ consisting of two objects that form a single asteroid with a lobed shape,” Benner said. The images reveal a wealth of other features, including a puzzling pointy hill near the object’s middle, on top as seen in the images.

The 21 radar images were taken over a span of 4.5 hours. During that interval, the asteroid rotated a few degrees per frame, suggesting its rotation period is slightly less than 24 hours.

At its closest approach to Earth on June 8, the asteroid came within 776,000 miles (1.25 million kilometers), or slightly more than three times the distance to the Moon. Scientists began observations of 2014 HQ124 shortly after the closest approach when the asteroid was between about 864,000–902,000 miles (1.39–1.45 million kilometers) from Earth.

Each image in the collage and movie represents 10 minutes of data.

The new views show features as small as about 12 feet (3.75 meters) wide. This is the highest resolution currently possible using scientific radar antennas to produce images. Such sharp views for this asteroid were made possible by linking together two giant radio telescopes to enhance their capabilities.

To obtain the new views, researchers paired the 230-foot (70m) Deep Space Network antenna at Goldstone, California, with two other radio telescopes, one at a time. Using this technique, the Goldstone antenna beams a radar signal at an asteroid and the other antenna receives the reflections. The technique dramatically improves the amount of detail that can be seen in radar images.

To image 2014 HQ124, the researchers first paired the large Goldstone antenna with the 1,000-foot (305m) Arecibo radio telescope in Puerto Rico. They later paired the large Goldstone dish with a smaller companion, a 112-foot (34m) antenna, located about 20 miles (32km) away.

A recent equipment upgrade at Arecibo enabled the two facilities to work in tandem to obtain images with this fine level of detail for the first time.

“By itself, the Goldstone antenna can obtain images that show features as small as the width of a traffic lane on the highway,” said Benner. “With Arecibo now able to receive our highest-resolution Goldstone signals, we can create a single system that improves the overall quality of the images.”

The first five images in the new sequence — the top row in the collage — represent the data collected by Arecibo and are 30 times brighter than what Goldstone can produce observing on its own.

Scientists were fortunate to be able to make these radar observations at all, as this particular asteroid was only recently discovered. NASA’s NEOWISE mission, a space telescope adapted for scouting the skies for the infrared light emitted by asteroids and comets, first spotted the space rock April 23, 2014.

For asteroids, as well as comets, radar is a powerful tool for studying the objects’ sizes, shapes, rotation, surface features, and orbits. Radar measurements of asteroid distances and velocities enable researchers to compute orbits much further into the future than if radar observations were not available.

NASA detects, tracks, and characterizes asteroids and comets passing close to Earth using both ground- and space-based telescopes. The Near-Earth Object Program, commonly called “Spaceguard,” discovers these objects, characterizes a subset of them, and identifies their orbits to determine if any could be potentially hazardous to our planet. To date, U.S. assets have discovered more than 98 percent of the known near-Earth objects.

Along with the resources NASA puts into understanding asteroids, it also partners with other U.S. government agencies, university-based astronomers, and space science institutes across the country that are working to find, track, and understand these objects better. In addition, NASA values the work of numerous highly skilled amateur astronomers, whose accurate observational data helps improve asteroid orbits after they are found.

Cracks in Pluto's moon could indicate it once had an underground ocean

This artist concept shows Pluto and some of its moons, as viewed from the surface of one of the moons. Pluto is the large disk at center. Charon is the smaller disk to the right.

If the icy surface of Pluto's giant moon Charon is cracked, analysis of the fractures could reveal if its interior was warm, perhaps warm enough to have maintained a subterranean ocean of liquid water, according to a new NASA-funded study.

Pluto is an extremely distant world, orbiting the sun more than 29 times farther than Earth. With a surface temperature estimated to be about 380 degrees below zero Fahrenheit (around minus 229 degrees Celsius), the environment at Pluto is far too cold to allow liquid water on its surface. Pluto's moons are in the same frigid environment.

Pluto's remoteness and small size make it difficult to observe, but in July of 2015, NASA's New Horizons spacecraft will be the first to visit Pluto and Charon, and will provide the most detailed observations to date.

"Our model predicts different fracture patterns on the surface of Charon depending on the thickness of its surface ice, the structure of the moon's interior and how easily it deforms, and how its orbit evolved," said Alyssa Rhoden of NASA's Goddard Space Flight Center in Greenbelt, Maryland. "By comparing the actual New Horizons observations of Charon to the various predictions, we can see what fits best and discover if Charon could have had a subsurface ocean in its past, driven by high eccentricity." Rhoden is lead author of a paper on this research now available online in the journal Icarus.

Some moons around the gas giant planets in the outer solar system have cracked surfaces with evidence for ocean interiors -- Jupiter's moon Europa and Saturn's moon Enceladus are two examples.

As Europa and Enceladus move in their orbits, a gravitational tug-of-war between their respective parent planets and neighboring moons keeps their orbits from becoming circular. Instead, these moons have eccentric (slightly oval-shaped) orbits, which raise daily tides that flex the interior and stress the surface. It is thought that tidal heating has extended the lifetimes of subsurface oceans on Europa and Enceladus by keeping their interiors warm.

In Charon's case, this study finds that a past high eccentricity could have generated large tides, causing friction and surface fractures. The moon is unusually massive compared to its planet, about one-eighth of Pluto's mass, a solar system record. It is thought to have formed much closer to Pluto, after a giant impact ejected material off the planet's surface. The material went into orbit around Pluto and coalesced under its own gravity to form Charon and several smaller moons.

Initially, there would have been strong tides on both worlds as gravity between Pluto and Charon caused their surfaces to bulge toward each other, generating friction in their interiors. This friction would have also caused the tides to slightly lag behind their orbital positions. The lag would act like a brake on Pluto, causing its rotation to slow while transferring that rotational energy to Charon, making it speed up and move farther away from Pluto.

"Depending on exactly how Charon's orbit evolved, particularly if it went through a high-eccentricity phase, there may have been enough heat from tidal deformation to maintain liquid water beneath the surface of Charon for some time," said Rhoden. "Using plausible interior structure models that include an ocean, we found it wouldn't have taken much eccentricity (less than 0.01) to generate surface fractures like we are seeing on Europa."

"Since it's so easy to get fractures, if we get to Charon and there are none, it puts a very strong constraint on how high the eccentricity could have been and how warm the interior ever could have been," adds Rhoden. "This research gives us a head start on the New Horizons arrival -- what should we look for and what can we learn from it. We're going to Pluto and Pluto is fascinating, but Charon is also going to be fascinating."

Based on observations from telescopes, Charon's orbit is now in a stable end state: a circular orbit with the rotation of both Pluto and Charon slowed to the point where they always show the same side to each other. Its current orbit is not expected to generate significant tides, so any ancient underground ocean may be frozen by now, according to Rhoden.

Since liquid water is a necessary ingredient for known forms of life, the oceans of Europa and Enceladus are considered to be places where extraterrestrial life might be found. However, life also requires a useable energy source and an ample supply of many key elements, such as carbon, nitrogen, and phosphorus. It is unknown if those oceans harbor these additional ingredients, or if they have existed long enough for life to form. The same questions would apply to any ancient ocean that may have existed beneath the icy crust of Charon.

This research was funded by the NASA Postdoctoral Program at the NASA Goddard Space Flight Center, administered by Oak Ridge Associated Universities, and NASA Headquarters through the Science Innovation Fund.

Planet bonanza hints at worlds similar to our own

A team of astronomers has used data from NASA’s Kepler space telescope to uncover 715 new exoplanets and the first Earth-sized planet in the habitable zone of its star, Kepler-186f, this year.

The artist concept depicts multiple-transiting planet systems, which are stars with more than one planet. The planets eclipse or transit their host star from the vantage point of the observer. This angle is called edge-on.

For planet hunters, this has been a bountiful year. A team of astronomers at the SETI Institute in Mountain View, California, and NASA Ames Research Center in Moffett Field, California, has used data from NASA's Kepler space telescope to uncover 715 new exoplanets. The newly verified objects orbit 305 different stars and therefore include multiworld systems that are reminiscent of the Sun's planetary family. The announcement of these discoveries was followed by news that Kepler had also found the first Earth-sized planet in the habitable zone of its star, Kepler-186f. This is a significant milestone in the task of determining the prevalence of terrestrial planets in the Milky Way Galaxy.

"These results are showing us that not only are Earth-sized planets common, but so are multiplanet systems containing potentially habitable worlds," said Jason Rowe from the SETI Institute. "Most of the new planets orbit their host star much closer than Mercury, but a few are beginning to bear a similarity to our own solar system."

The deluge of new planets has been intensified by a new analysis scheme called verification by multiplicity. This technique can be applied to many planets at once, allowing the researchers to verify hundreds of new planetary systems in wholesale fashion, rather than teasing them from the Kepler data one-by-one as done in the past. The new technique uses probability arguments based on the recognition that, of the 150,000 stars observed by Kepler, hundreds were found that have multiple planet candidates. On this basis, the researchers are assured that their results are not distorted by binary stars that can mimic a multiworld system. The new discoveries increase the total number of known exoplanets to over 1,700.

"From this work, we've also learned that planets in these multiple systems are small, and their orbits are flat and circular, much like our own solar system," Rowe said.

On April 17, the Kepler team announced the discovery of Kepler-186f, the first Earth-sized planet found in the habitable zone of its host star, marking a major milestone in determining the frequency of Earth-like planets in the Milky Way Galaxy.

"Uncovering these worlds and showing that habitable worlds could be very common has increased the likelihood that there is life — perhaps abundant life — elsewhere in the cosmos," said David Black from the SETI Institute.

Data collection from the Kepler mission ended in the spring of last year due to the failure of a second onboard reaction wheel, essential to accurate pointing of the telescope. However, on May 20, NASA announced the approval of the K2 mission, which intended to repurpose Kepler to use the pressure of sunlight hitting the side of the spacecraft to act as a third wheel.

"We can't continue to look at the original Kepler star field," said Douglas Caldwell from the SETI Institute, "but spacecraft are built and operated by very smart people, and thanks to the hard work of the entire Kepler team, we can now search for planets in a wide variety of environments and conditions, including star forming regions. Doing so will teach us more about how our own planetary system formed and evolved."

"The more we explore, the more we find worlds among the stars that remind us of home," Rowe said.

Milky Way may bear 100 million life-giving planets

There are some 100 million other places in the Milky Way galaxy that could support complex life, report a group of university astronomers in the journal Challenges. They have developed a new computation method to examine data from planets orbiting other stars in the universe.

A new computation method to examine planets orbiting other stars suggests the Milky Way galaxy may house 100 million other places that could support complex life.

Their study provides the first quantitative estimate of the number of worlds in our galaxy that could harbor life above the microbial level.

"This study does not indicate that complex life exists on that many planets. We're saying that there are planetary conditions that could support it. Origin of life questions are not addressed -- only the conditions to support life," according to the paper's authors Alberto Fairén, Cornell research associate; Louis Irwin, University of Texas at El Paso (lead author); Abel Méndez, University of Puerto Rico at Arecibo; and Dirk Schulze-Makuch, Washington State University.

"Complex life doesn't mean intelligent life -- though it doesn't rule it out or even animal life -- but simply that organisms larger and more complex than microbes could exist in a number of different forms. For example, organisms that form stable food webs like those found in ecosystems on Earth," the researchers explain in an auxiliary statement.

The scientists surveyed more than 1,000 planets and used a formula that considers planet density, temperature, substrate (liquid, solid or gas), chemistry, distance from its central star and age. From this information, they developed and computed the Biological Complexity Index (BCI).

The BCI calculation revealed that 1 to 2 percent of the planets showed a BCI rating higher than Europa, a moon of Jupiter thought to have a subsurface global ocean that may harbor forms of life. With about 10 billion stars in the Milky Way galaxy, the BCI yields 100 million plausible planets.

Despite the large number of planets that could harbor complex life, the Milky Way is so vast that planets with high BCI values are very far apart, according to the scientists. One of the closest and most promising extrasolar systems, called Gliese 581, has two planets with the apparent, possible capacity to host complex biospheres. The distance from Earth to Gliese 581 is about 20 light years.

"It seems highly unlikely that we are alone," say the researchers. "We are likely so far away from life at our level of complexity that a meeting with such alien forms might be improbable for the foreseeable future."

The research, "Assessing the Possibility of Biological Complexity on Other Worlds, With an Estimate of the Occurrence of Complex Life in the Milky Way Galaxy," inChallenges, received no external funding.

'Hello, world!' NASA beams video from space station via laser

"Helllo, World!" came the message from the International Space Station as NASA successfully beamed high-definition video via laser from space to ground on Thursday, June 5. The 175-megabit video transmission was the first of its kind for the Optical Payload for Lasercomm Science (OPALS) with the goal of improving the way we receive data from orbit and beyond. In fact, this emerging technology of optical communications--or lasercomm--is likened to an upgrade from dial-up to DSL.

This artist's concept shows how the Optical Payload for Lasercomm Science (OPALS) laser beams data to Earth from the International Space Station.

"It's incredible to see this magnificent beam of light arriving from our tiny payload on the space station," said Matt Abrahamson, OPALS mission manager at NASA's Jet Propulsion Laboratory (JPL) in Pasadena, California.

OPALS launched to the space station aboard the SpaceX Dragon earlier this spring. This technology demonstration furthers NASA's exploration of higher-bandwidth methods of communicating with future spacecraft. Optical communications tools like OPALS use focused laser energy to achieve data rates 10 to 1,000 times higher than current space communications, which rely on radio portions of the electromagnetic spectrum.

OPALS' success also is an important step in improving communication rates with spacecraft beyond low-Earth orbit. The instrument allows for communications rates to keep pace with the ever-increasing data generation produced by scientific instruments. The capability could replace the Federally-regulated radio frequencies currently in use from orbit to meet the needs anticipated by researchers for future missions, like Mars.

"We look forward to experimenting with OPALS over the coming months in hopes that our findings will lead to optical communications capabilities for future deep space exploration missions," Abrahamson said.

The space station moves through Earth's sky at approximately 17,500 mph. This speed requires extreme precise pointing ability. It's equivalent to a person aiming a laser pointer at the end of a human hair 30 feet away and keeping it there while walking. To achieve this precision, OPALS locked onto a ground beacon emitted by the Optical Communications Telescope Laboratory ground station at the Table Mountain Observatory in Wrightwood, California.

Once locked onto the signal, OPALS began to modulate the beam from its 2.5-Watt 1,550-nanometer laser to transmit the video. The entire transmission lasted 148 seconds and achieved a maximum data rate of 50 megabits per second. It took OPALS 3.5 seconds to transmit a single copy of the "Hello World!" video message, which would have taken more than 10 minutes using traditional downlink methods. The message was sent multiple times during the transmission.

The OPALS instrument was built at JPL as part of the Phaeton hands-on training program and is slated to run for a prime mission of 90 days. The OPALS Project Office is based at JPL, a division of the California Institute of Technology in Pasadena. During these transmissions, NASA also will train personnel in optical communication systems operations, leading to improved optical communication instrument design.

Commercial ventures can likewise take note of the project, as it proves the use of lasercomm for optimized communications from space. This may mean higher definition video feeds from near-Earth assets, such as satellites, as well as those in deep space, like future Mars rovers. This improves the interaction and experience with the stakeholders, whether they be researchers, engineers or consumers. And if you remember the days of having to leave the room to download a video when using DSL, you know that higher-speed downloads are definitely the way to go!

Chandra captures galaxy sparkling in X-rays

A decade of Whirlpool Galaxy observations provide critical information about how X-ray sources containing black holes behave over time.

A new Chandra image of M51 contains nearly a million seconds of observing time. The data reveal hundreds of point-like X-ray sources within what is nicknamed the "Whirlpool Galaxy." Most of these point sources are X-ray binary systems with either a neutron star or black hole orbiting a Sun-like star. The composite image consists of X-rays from Chandra (purple) and optical data from Hubble (red, green, and blue).

Nearly a million seconds of observing time with NASA’s Chandra X-ray Observatory has revealed a spiral galaxy similar to the Milky Way, glittering with hundreds of X-ray points of light.

The galaxy is officially named Messier 51 (M51) or NGC 5194 but often goes by its nickname of the “Whirlpool Galaxy.” Like the Milky Way, the Whirlpool is a spiral galaxy with spectacular arms of stars and dust. M51 is located 30 million light-years from Earth, and its face-on orientation to Earth gives us a perspective that we can never get of our own spiral galactic home.

By using Chandra, astronomers can peer into the Whirlpool to uncover things that can only be detected in X-rays. In this new composite image, Chandra data are shown in purple. Optical data from the Hubble Space Telescope are red, green, and blue.

Most of the X-ray sources are X-ray binaries (XRBs). These systems consist of pairs of objects where a compact star, either a neutron star or, more rarely, a black hole, is capturing material from an orbiting companion star. The infalling material is accelerated by the intense gravitational field of the compact star and heated to millions of degrees, producing a luminous X-ray source. The Chandra observations reveal that at least 10 of the XRBs in M51 are bright enough to contain black holes. In eight of these systems, the black holes are likely capturing material from companion stars that are much more massive than the Sun.

Because astronomers have been observing M51 for about a decade with Chandra, they have critical information about how X-ray sources containing black holes behave over time. The black holes with massive stellar companions are consistently bright over the 10 years of Chandra observations. These results suggest that the high-mass stars in these X-ray sources also have strong winds that allow for a steady stream of material to flow onto the black hole.

A difference between the Milky Way and the Whirlpool Galaxy is that M51 is in the midst of merging with a smaller companion galaxy seen in the upper left of the image. Scientists think this galactic interaction is triggering waves of star formation. The most massive of the newly formed stars will race through their evolution in a few million years and collapse to form neutron stars or black holes. Most of the XRBs containing black holes in M51 are located close to regions where stars are forming, showing their connection to the oncoming galactic collision.

Previous studies of the Whirlpool Galaxy with Chandra revealed just over 100 X-ray sources. The new data set, equivalent to about 900,000 seconds of Chandra observing time, reveals nearly 500 X-ray sources. About 400 of these sources are thought to be within M51, with the remaining either being in front of or behind the galaxy itself.

Much of the diffuse, or fuzzy, X-ray emission in M51 comes from gas that has been superheated by supernova explosions of massive stars.

New isotopic evidence supporting moon formation via Earth collision with planet-sized body

A new series of measurements of oxygen isotopes provides increasing evidence that the Moon formed from the collision of Earth with another large, planet-sized astronomical body, around 4.5 billion years ago.

The moon. A new series of measurements of oxygen isotopes provides increasing evidence that the moon formed from the collision of the Earth with another large, planet-sized astronomical body, around 4.5 billion years ago.

This work will be published in Science on 6th June, and will be presented to the Goldschmidt geochemistry conference in California on 11th June.

Most planetary scientists believe that the Moon formed from an impact between  Earth and a planet-sized body, which has been given the name Theia. Efforts to confirm that the impact had taken place had centred on measuring the ratios between the isotopes of oxygen, titanium, silicon and others. These ratios are known to vary throughout the solar system, but their close similarity between Earth and Moon conflicted with theoretical models of the collision that indicated that the Moon would form mostly from Theia, and thus would be expected to be compositionally different from Earth.

Now a group of German researchers, led by Dr. Daniel Herwartz, have used more refined techniques to compare the ratios of 17O/16O in lunar samples, with those from Earth. The team initially used lunar samples which had arrived on Earth via meteorites, but as these samples had exchanged their isotopes with water from Earth, fresher samples were sought. These were provided by NASA from the Apollo 11, 12 and 16 missions; they were found to contain significantly higher levels of 17O/16O than their Earthly counterparts.

Dr Herwartz said "The differences are small and difficult to detect, but they are there. This means two things; firstly we can now be reasonably sure that the Giant collision took place. Secondly, it gives us an idea of the geochemistry of Theia. Theia seems to have been similar to what we call E-type chondrites.If this is true, we can now predict the geochemical and isotopic composition of the Moon, because the present Moon is a mixture of Theia and the early Earth. The next goal is to find out how much material of Theia is in the Moon."

Most models estimate that the Moon it is composed of around 70% to 90% material from Theia, with the remaining 10% to 30% coming from the early Earth. However, some models argue for as little as 8% Theia in the Moon. Dr Herwartz said that the new data indicate that a 50:50 mixture seems possible, but this needs to be confirmed.

The team used an advanced sample preparation technique before measuring the samples via stable isotope ratio mass spectrometry, which showed a 12 parts per million (± 3 ppm) difference in 17O/16O ratio between Earth and Moon.

Astronomers discover ancient worlds next door

An artist's impression of the red dwarf Kapteyn's star superimposed on a diagram showing its ejection from a nearby dwarf galaxy.

An international team of scientists, led by astronomers at Queen Mary University of London (QMUL), report of two new planets orbiting Kapteyn’s star, one of the oldest stars found near the Sun. One of the newly discovered planets could be ripe for life as it orbits at the right distance to the star to allow liquid water on its surface.

Discovered at the end of the 19th century and named after the Dutch astronomer who discovered it (Jacobus Kapteyn), Kapteyn’s star is the second-fastest moving star in the sky and belongs to the galactic halo, an extended cloud of stars orbiting our galaxy. With a third of the mass of the Sun, this red dwarf star can be seen in the southern constellation of Pictor with an amateur telescope.

The astronomers used new data from the HARPS spectrometer at the European Southern Observatory's La Silla Observatory in Chile to measure tiny periodic changes in the motion of the star. Using the Doppler effect, which shifts the star’s light spectrum depending on its velocity, the scientists can work out some properties of these planets, such as their masses and periods of orbit.

The study also combined data from two more high-precision spectrometers to secure the detection: HIRES at Keck Observatory and PFS at Magellan/Las Campanas Observatory.

“We were surprised to find planets orbiting Kapteyn’s star. Previous data showed some moderate excess of variability, so we were looking for very short-period planets when the new signals showed up loud and clear,” explains lead author Guillem Anglada-Escude from QMUL’s School of Physics and Astronomy.

Based on the data collected, the planet Kapetyn b is at least five times as massive as Earth and orbits its host star every 48 days. This means the planet is warm enough for liquid water to be present on its surface. The second planet, Kapteyn c, is a more massive super-Earth and quite different: Its year lasts for 121 days, and astronomers think it’s too cold to support liquid water.

At the moment, only a few properties of the planets are known: approximate masses, orbital periods, and distances to the star. By measuring the atmosphere of these planets with next-generation instruments, scientists will try to find out whether they can bear water.

Typical planetary systems detected by NASA's Kepler mission are hundreds of light-years away. In contrast, Kapteyn's star is the 25th nearest star to the sun and is only 13 light-years away from Earth.

What makes this discovery different however, is the peculiar story of the star. Kapteyn's star was born in a dwarf galaxy absorbed and disrupted by the early Milky Way. This galactic disruption event put the star in its fast halo orbit. The likely remnant core of the original dwarf galaxy is Omega Centauri, an enigmatic globular cluster 16,000 light-years from Earth that contains hundreds of thousands of similarly old suns. This sets the most likely age of the planets at 11.5 billion years, which is 2.5 times older than Earth and "only" 2 billion years younger than the universe itself (around 13.7 billion years).

Anglada-Escude adds: “It does make you wonder what kind of life could have evolved on those planets over such a long time.”

Richard Nelson, head of the Astronomy Unit at QMUL, who didn't participate in the research, commented: "This discovery is very exciting. It suggests that many potentially habitable worlds will be found in the next years around nearby stars by ground-based and space-based observatories, such as PLATO. Until we have detected a larger number of them, the properties and possible habitability of the near-most planetary systems will remain mysterious."

For the simulation video go to https://www.youtube.com/watch?v=MDouqzqfLYU