These images are a comparison of outflows from telescope observation and computer simulation. CREDIT Tiago Costa

Two teams of astronomers led by researchers at the University of Cambridge have looked back nearly 13 billion years, when the Universe was less than 10 percent its present age, to determine how quasars - extremely luminous objects powered by supermassive black holes with the mass of a billion suns - regulate the formation of stars and the build-up of the most massive galaxies.

Using a combination of data gathered from powerful radio telescopes and supercomputer simulations, the teams found that a quasar spits out cold gas at speeds up to 2000 kilometres per second, and across distances of nearly 200,000 light years - much farther than has been observed before.

How this cold gas - the raw material for star formation in galaxies - can be accelerated to such high speeds had remained a mystery. Detailed comparison of new observations and supercomputer simulations has only now allowed researchers to understand how this can happen: the gas is first heated to temperatures of tens of millions of degrees by the energy released by the supermassive black hole powering the quasar. This enormous build-up of pressure accelerates the hot gas and pushes it to the outskirts of the galaxy.

The supercomputer simulations show that on its way out of the parent galaxy, there is just enough time for some of the hot gas to cool to temperatures low enough to be observable with radio telescopes. The results are presented in two separate papers published today (16 January) in the journals Monthly Notices of the Royal Astronomical Society and Astronomy & Astrophysics.

Quasars are amongst the most luminous objects in the Universe, and the most distant quasars are so far away that they allow us to peer back billions of years in time. They are powered by supermassive black holes at the centre of galaxies, surrounded by a rapidly spinning disk-like region of gas. As the black hole pulls in matter from its surroundings, huge amounts of energy are released.

"It is the first time that we have seen outflowing cold gas moving at these large speeds at such large distances from the supermassive black hole," said Claudia Cicone, a PhD student at Cambridge's Cavendish Laboratory and Kavli Institute for Cosmology, and lead author on the first of the two papers. "It is very difficult to have matter with temperatures this low move as fast as we observed."

Cicone's observations allowed the second team of researchers specializing in supercomputer simulations to develop a detailed theoretical model of the outflowing gas around a bright quasar.

"We found that while gas is launched out of the quasar at very high temperatures, there is enough time for some of it to cool through radiative cooling - similar to how the Earth cools down on a cloudless night," said Tiago Costa, a PhD student at the Institute of Astronomy and the Kavli Institute for Cosmology, and lead author on the second paper. "The amazing thing is that in this distant galaxy in the young Universe the conditions are just right for enough of the fast moving hot gas to cool to the low temperatures that Claudia and her team have found."

Working at the IRAM Plateau De Bure interferometer in the French Alps, the researchers gathered data in the millimetre band, which allows observation of the emission from the cold gas which is the primary fuel for star formation and main ingredient of galaxies, but is almost invisible at other wavelengths.

The research was supported by the UK Science and Technology Facilities Council (STFC), the Isaac Newton Trust and the European Research Council (ERC). The supercomputer simulations were run using the SuperComputer Cluster DARWIN, operated by the University of Cambridge High Performance Computing Service, as part of STFCs DiRAC supercomputer facility.

At least two unknown planets could exist in our solar system beyond Pluto.

There could be at least two unknown planets hidden well beyond Pluto, whose gravitational influence determines the orbits and strange distribution of objects observed beyond Neptune. This has been revealed by numerical calculations made by researchers at the Complutense University of Madrid and the University of Cambridge. If confirmed, this hypothesis would revolutionise solar system models.

Astronomers have spent decades debating whether some dark trans-Plutonian planet remains to be discovered within the solar system. According to the calculations of scientists at the Complutense University of Madrid (UCM, Spain) and the University of Cambridge (United Kingdom) not only one, but at least two planets must exist to explain the orbital behaviour of extreme trans-Neptunian objects (ETNO).

The most accepted theory establishes that the orbits of these objects, which travel beyond Neptune, should be distributed randomly, and by an observational bias, their paths must fulfil a series of characteristics: have a semi-major axis with a value close to 150 AU (astronomical units or times the distance between the Earth and the Sun), an inclination of almost 0° and an argument or angle of perihelion (closest point of the orbit to our Sun) also close to 0° or 180°.

Yet what is observed in a dozen of these bodies is quite different: the values of the semi-major axis are very disperse (between 150 AU and 525 AU), the average inclination of their orbit is around 20° and argument of Perihelion -31°, without appearing in any case close to 180°.

"This excess of objects with unexpected orbital parameters makes us believe that some invisible forces are altering the distribution of the orbital elements of the ETNO and we consider that the most probable explanation is that other unknown planets exist beyond Neptune and Pluto," explains Carlos de la Fuente Marcos, scientist at the UCM and co-author of the study.

"The exact number is uncertain, given that the data that we have is limited, but our calculations suggest that there are at least two planets, and probably more, within the confines of our solar system," adds the astrophysicist.

To carry out the study, which is published as two articles in the journal 'Monthly Notices of the Royal Astronomical Society Letters', the researchers have analysed the effects of the so-called 'Kozai mechanism', related to the gravitational perturbation that a large body exerts on the orbit of another much smaller and further away object. As a reference they have considered how this mechanism works in the case of comet 96P/Machholz1 under the influence of Jupiter.

Two problems to solve

Despite their surprising results, the authors recognise that their data comes up against two problems. On the one hand, their proposal goes against the predictions of current models on the formation of the solar system, which state that there are no other planets moving in circular orbits beyond Neptune.

However, the recent discovery by the ALMA radio telescope of a planet-forming disk more than 100 astronomical units from the star HL Tauri, which is younger than the Sun and more massive, suggests that planets can form several hundred astronomical units away from the centre of the system.

On the other hand, the team recognises that the analysis is based on a sample with few objects (specifically 13), but they point out that in the coming months more results are going to be published, making the sample larger. "If it is confirmed, our results may be truly revolutionary for astronomy," says de la Fuente Marcos.

Last year two researchers from the United States discovered a dwarf planet called 2012 VP113 in the Oort cloud, just beyond our solar system. The discoverers consider that its orbit is influenced by the possible presence of a dark and icy super-Earth, up to ten times larger than our planet.

NASA has selected 11 university-led proposals for the study of innovative, early stage technologies that address high priority needs of America's space program.

The selected proposals address unique, disruptive, or transformational technologies, including: advanced thermal protection materials modeling, computational materials, in situ utilization of asteroid materials, mobile robotic surface probe concepts for planetary exploration, and kinetic penetrators for icy planetary moons. Selection criteria required technology research that will provide dramatic improvements over existing capabilities for future science and human exploration missions.

"Research in these critical technology areas will enable science and exploration of our home planet, future deep space missions and our journey to Mars," said Michael Gazarik, associate administrator for NASA's Space Technology Mission Directorate in Washington. "New space technology enables exploration while providing real world economic benefits to the American people right here on Earth, right now."

Universities selected for NASA's Early Stage Innovation grants, and the titles of their proposals, are:

    --  Iowa State University, Ames: Computational Modeling of Nondestructive
        Evaluation, Defect Detection, and Defect Identification for CFRP
        Composite Materials
    --  Missouri University of Science and Technology, Rolla. Laboratory
        Demonstration and Test of Solar Thermal Asteroid ISRU
    --  Montana State University, Bozeman: Uncovering the Chemical Processes
        during Atmospheric Entry of a Carbon/Phenolic Ablator: Laboratory
        Studies by In Situ Mass Spectrometric and Molecular Beam Techniques
    --  Stanford University, Stanford, California: Asteroid Surface Resource
        Characterization Through Distributed Plasma Analysis of Meteoroid Impact
        Ejecta
    --  Texas A&M University, College Station: Control of Variability in the
        Performance of Selective Laser Melting (SLM) Parts through
        Microstructure Control and Design
    --  University of California, Berkeley: Precision Hopping/Rolling Robotic
        Surface Probe Based on Tensegrity Structures
    --  University of California, Davis: Development of Physics-Based Numerical
        Models for Uncertainty Quantification of Selective Laser Melting
        Processes
    --  University of Kentucky, Lexington: Model Development and Experimental
        Validation of Reactive Gas and Pyrolysis Product Interactions with Hot
        Carbon Chars
    --  University of Vermont, Burlington: Experimental and Numerical
        Investigation of Ablation Kinetics
    --  University of Washington, Seattle: Europa Kinetic Ice Penetrator (EKIP)
    --  West Virginia University, Morgantown: Robotic In-Situ Surface
        Exploration System (RISES)
The awards from NASA's Space Technology Research Grants Program are worth as much as $500,000 each, with technology research and development efforts taking place over two to three years.

Aligned with NASA's Space Technology Roadmaps, and priorities identified by the National Research Council, the agency's technology research areas lend themselves to the early stage innovative approaches U.S. universities can offer for solving tough space technology challenges.

NASA's Early Stage Innovations efforts are an element of the agency's Space Technology Research Grants Program. This program is designed to accelerate the development of technologies originating in academia that support the future science and exploration needs of NASA, other government agencies, and the commercial space sector.

For more information about NASA's Space Technology Research Grants Program, visit: http://go.usa.gov/X9eP

This is Eta Carinae's great eruption in the 1840s created the billowing Homunculus Nebula, imaged here by Hubble. Now about a light-year long, the expanding cloud contains enough material to make at least 10 copies of our sun. Astronomers cannot yet explain what caused this eruption.

Eta Carinae, the most luminous and massive stellar system within 10,000 light-years of Earth, is known for its surprising behavior, erupting twice in the 19th century for reasons scientists still don't understand. A long-term study led by astronomers at NASA's Goddard Space Flight Center in Greenbelt, Maryland, used NASA satellites, ground-based telescopes and theoretical modeling to produce the most comprehensive picture of Eta Carinae to date. New findings include Hubble Space Telescope images that show decade-old shells of ionized gas racing away from the largest star at a million miles an hour, and new 3-D models that reveal never-before-seen features of the stars' interactions.

"We are coming to understand the present state and complex environment of this remarkable object, but we have a long way to go to explain Eta Carinae's past eruptions or to predict its future behavior," said Goddard astrophysicist Ted Gull, who coordinates a research group that has monitored the star for more than a decade.

Located about 7,500 light-years away in the southern constellation of Carina, Eta Carinae comprises two massive stars whose eccentric orbits bring them unusually close every 5.5 years. Both produce powerful gaseous outflows called stellar winds, which enshroud the stars and stymy efforts to directly measure their properties. Astronomers have established that the brighter, cooler primary star has about 90 times the mass of the sun and outshines it by 5 million times. While the properties of its smaller, hotter companion are more contested, Gull and his colleagues think the star has about 30 solar masses and emits a million times the sun's light.

Speaking at a press conference at the American Astronomical Society meeting in Seattle on Wednesday, the Goddard researchers discussed recent observations of Eta Carinae and how they fit with the group's current understanding of the system.

At closest approach, or periastron, the stars are 140 million miles (225 million kilometers) apart, or about the average distance between Mars and the sun. Astronomers observe dramatic changes in the system during the months before and after periastron. These include X-ray flares, followed by a sudden decline and eventual recovery of X-ray emission; the disappearance and re-emergence of structures near the stars detected at specific wavelengths of visible light; and even a play of light and shadow as the smaller star swings around the primary.

During the past 11 years, spanning three periastron passages, the Goddard group has developed a model based on routine observations of the stars using ground-based telescopes and multiple NASA satellites. "We used past observations to construct a computer simulation, which helped us predict what we would see during the next cycle, and then we feed new observations back into the model to further refine it," said Thomas Madura, a NASA Postdoctoral Program Fellow at Goddard and a theorist on the Eta Carinae team.

According to this model, the interaction of the two stellar winds accounts for many of the periodic changes observed in the system. The winds from each star have markedly different properties: thick and slow for the primary, lean and fast for the hotter companion. The primary's wind blows at nearly 1 million mph and is especially dense, carrying away the equivalent mass of our sun every thousand years. By contrast, the companion's wind carries off about 100 times less material than the primary's, but it races outward as much as six times faster.

Madura's simulations, which were performed on the Pleiades supercomputer at NASA's Ames Research Center in Moffett Field, California, reveal the complexity of the wind interaction. When the companion star rapidly swings around the primary, its faster wind carves out a spiral cavity in the dense outflow of the larger star. To better visualize this interaction, Madura converted the supercomputer simulations to 3-D digital models and made solid versions using a consumer-grade 3-D printer. This process revealed lengthy spine-like protrusions in the gas flow along the edges of the cavity, features that hadn't been noticed before.

"We think these structures are real and that they form as a result of instabilities in the flow in the months around closest approach," Madura said. "I wanted to make 3-D prints of the simulations to better visualize them, which turned out to be far more successful than I ever imagined." A paper detailing this research has been submitted to the journal Monthly Notices of the Royal Astronomical Society.

The team detailed a few key observations that expose some of the system's inner workings. For the past three periastron passages, ground-based telescopes in Brazil, Chile, Australia and New Zealand have monitored a single wavelength of blue light emitted by helium atoms that have lost a single electron. According to the model, the helium emission tracks conditions in the primary star's wind. The Space Telescope Imaging Spectrograph (STIS) aboard Hubble captures a different wavelength of blue light emitted by iron atoms that have lost two electrons, which uniquely reveals where gas from the primary star is set aglow by the intense ultraviolet light of its companion. Lastly, X-rays from the system carry information directly from the wind collision zone, where the opposing winds create shock waves that heat the gas to hundreds of millions of degrees.

"Changes in the X-rays are a direct probe of the collision zone and reflect changes in how these stars lose mass," said Michael Corcoran, an astrophysicist with the Universities Space Research Association headquartered in Columbia, Maryland. He and his colleagues compared periastron emission measured over the past 20 years by NASA's Rossi X-ray Timing Explorer, which ceased operation in 2012, and the X-ray Telescope aboard NASA's Swift satellite. In July 2014, as the stars rushed toward each other, Swift observed a series of flares culminating in the brightest X-ray emission yet seen from Eta Carinae. This implies a change in mass loss by one of the stars, but X-rays alone cannot determine which one.

Goddard's Mairan Teodoro led the ground-based campaign tracking the helium emission. "The 2014 emission is nearly identical to what we saw at the previous periastron in 2009, which suggests the primary wind has been constant and that the companion's wind is responsible for the X-ray flares," he explained.

After NASA astronauts repaired the Hubble Space Telescope's STIS instrument in 2009, Gull and his collaborators requested to use it to observe Eta Carinae. By separating the stars' light into a rainbow-like spectrum, STIS reveals the chemical make-up of their environment. But the spectrum also showed wispy structures near the stars that suggested the instrument could be used to map a region close to the binary system in never-before-seen detail.

STIS views its targets through a single narrow slit to limit contamination from other sources. Since December 2010, Gull's team has regularly mapped a region centered on the binary by capturing spectra at 41 different locations, an effort similar to building up a panoramic picture from a series of snapshots. The view spans about 430 billion miles (670 billion km), or about 4,600 times the average Earth-sun distance.

The resulting images, revealed for the first time on Wednesday, show that the doubly ionized iron emission comes from a complex gaseous structure nearly a tenth of a light-year across, which Gull likens to Maryland blue crab. By stepping through the STIS images, vast shells of gas representing the crab's "claws" can be seen racing away from the stars with measured speeds of about 1 million mph (1.6 million km/h). With each close approach, a spiral cavity forms in the larger star's wind and then expands outward along with it, creating the moving shells.

"These gas shells persist over thousands of times the distance between Earth and the sun," Gull explained. "Backtracking them, we find the shells began moving away from the primary star about 11 years or three periastron passages ago, providing us with an additional way to glimpse what occurred in the recent past."

When the stars approach, the companion becomes immersed in the thickest part of the primary's wind, which absorbs its UV light and prevents the radiation from reaching the distant gas shells. Without this energy to excite it, the doubly ionized iron stops emitting light and the crab structure disappears at this wavelength. Once the companion swings around the primary and clears the densest wind, its UV light escapes, re-energizes iron atoms in the shells, and the crab returns.

Both of the massive stars of Eta Carinae may one day end their lives in supernova explosions. For stars, mass is destiny, and what will determine their ultimate fate is how much matter they can lose -- through stellar winds or as-yet-inexplicable eruptions -- before they run out of fuel and collapse under their own weight.

For now, the researchers say, there is no evidence to suggest an imminent demise of either star. They are exploring the rich dataset from the 2014 periastron passage to make new predictions, which will be tested when the stars again race together in February 2020.

NASA is exploring our solar system and beyond to understand the universe and our place in it. We seek to unravel the secrets of our universe, its origins and evolution, and search for life among the stars. 

A 3-D map of bedrock beneath Jakobshavn Glacier generated with ice-penetrating radar data. Image Credit: Center for Remote Sensing of Ice Sheets

Thanks in part to support from NASA and the National Science Foundation, scientists have produced the first-ever detailed maps of bedrock beneath glaciers in Greenland and Antarctica. This new data will help researchers better project future changes to glaciers and ice sheets, and ultimately, sea level.

Researchers at the Center for Remote Sensing of Ice Sheets, or CReSIS, at the University of Kansas in Lawrence, Kansas, recently built detailed maps of the terrain beneath Greenland’s Jakobshavn Glacier and Byrd Glacier in Antarctica. The results of this study were published in the September issue of the Journal of Glaciology. CReSIS is a major participant in NASA’s Operation IceBridge, a NASA airborne science mission aimed at studying Arctic and Antarctica land and sea ice.

The edge of Greenland's Jakobshavn Glacier seen during an IceBridge survey flight on Apr. 19, 2014.
The edge of Greenland's Jakobshavn Glacier seen during an IceBridge survey flight on Apr. 19, 2014.
Image Credit: NASA / Jim Yungel

CReSIS researchers used supercomputer software to process and analyze data collected during field campaigns unrelated to IceBridge that were conducted in cooperation with NASA and NSF in 2008 and 2011 to build maps of the two glaciers. These data were from an ice-penetrating radar instrument known as the Multichannel Coherent Depth Sounder / Imager, or MCoRDS / I, which is similar to the instrument IceBridge has used since 2009. Bed topography data are vital for supercomputer models used to project future changes to ice sheets and their contribution to sea level rise. “Without bed topography you cannot build a decent ice sheet model,” said CReSIS director Prasad Gogineni.

Jakobshavn Glacier is of interest because it is the fastest-moving glacier in the world and drains about 7.5 percent of the Greenland Ice Sheet. Having a map of Jakobshavn’s bed has been a long-time goal of glaciologists. Byrd Glacier is also moving faster than average, but unlike many other glaciers, has been sounded in the past. Researchers mapped a previously unknown trench beneath Byrd Glacier and found that depth measurements from the 1970s were off by as much as a half mile in some places.

Ice-penetrating radar is one method for mapping bedrock topography. The instrument sends down radar waves, which reflect off of the ice surface, layers inside the ice sheet and bedrock back to the instrument, giving researchers a three-dimensional view. Ice-penetrating radar data from IceBridge flights helped build maps of Greenland and Antarctica’s bedrock and were even used to discover a large canyon beneath the ice in northern Greenland.

Earth RIght Now: Your planet is changing. We're on it.
Five new NASA Earth science missions will join Landsat 8 in space this year to expand our understanding of Earth’s changing climate and environment.
 

Imaging rock beneath glaciers like Jakobshavn is important, but more difficult than mapping the ice sheet interior. The relatively warm ice and rough surfaces of outlet glaciers weaken and scatter radar signals, making the bed difficult to detect. To overcome these challenges, CReSIS used a sensitive radar instrument with a large antenna array and used several processing techniques to remove interference and build a view of sub-ice bedrock. “We showed that we have the technology to map beds,” said Gogineni.

The MCoRDS / I instrument can be traced back to an early ice-penetrating radar CReSIS designed and built in the mid-90s in cooperation with NASA and NSF. In the two decades since then CReSIS has refined this instrument and has flown on NASA aircraft and alongside NASA instruments.

Researchers continue to improve instrument hardware and data processing and are looking ahead to mapping more glaciers in the future, which will likely involve small, unmanned aerial vehicles. “Improving ice sheet models means we need even finer resolution,” Gogineni said. “To do this we need lines flown much closer together, which small UAVs would be well suited for.”

For more information on NASA's Operation Ice Bridge, visit:

www.nasa.gov/icebridge

For more information about the Center for Remote Sensing of Ice Sheets, visit:

https://www.cresis.ku.edu/

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