Friday, February 28, 2014

Hubble Monitors Supernova in Nearby Galaxy M82

Credit: NASA, ESA, A. Goobar (Stockholm University), 
and the Hubble Heritage Team (STScI/AURA)

This is a Hubble Space Telescope composite image of a supernova explosion designated SN 2014J in the galaxy M82. At a distance of approximately 11.5 million light-years from Earth it is the closest supernova of its type discovered in the past few decades. The explosion is categorized as a Type Ia supernova, which is theorized to be triggered in binary systems consisting of a white dwarf and another star — which could be a second white dwarf, a star like our Sun, or a giant star.

Astronomers using a ground-based telescope discovered the explosion on January 21, 2014. This Hubble photograph was taken on January 31, as the supernova approached its peak brightness. The Hubble data are expected to help astronomers refine distance measurements to Type Ia supernovae. In addition, the observations could yield insights into what kind of stars were involved in the explosion. Hubble's ultraviolet-light sensitivity will allow astronomers to probe the environment around the site of the supernova explosion and in the interstellar medium of the host galaxy.

Because of their consistent peak brightness, Type Ia supernovae are among the best tools to measure distances in the universe. They were fundamental to the 1998 discovery of the mysterious acceleration of the expanding universe. A hypothesized repulsive force, called dark energy, is thought to cause the acceleration.
The January 31 image, shown here as an inset, was taken in visible light with Hubble's Wide Field Camera 3. This image was superimposed into a photo mosaic of the entire galaxy taken in 2006 with Hubble's Advanced Camera for Surveys.

Among the other major NASA space-based observatories used in the M82 viewing campaign are Spitzer Space Telescope, Chandra X-ray Observatory, Nuclear Spectroscopic Telescope Array (NuSTAR), Fermi Gamma-ray Space Telescope, Swift Gamma-Ray Burst Explorer, and the Stratospheric Observatory for Infrared Astronomy (SOFIA).

Source: HubbleSite


Cloaked in red

Credit:  NASA, ESA, and D. Gouliermis (University of Heidelberg)
Acknowledgement: Luca Limatola

This stunning new Hubble image shows a small part of the Large Magellanic Cloud, one of the closest galaxies to our own. This collection of small baby stars, most weighing less than the Sun, form a young stellar cluster known as LH63. This cluster is still half-embedded in the cloud from which it was born, in a bright star-forming region known as the emission nebula LHA 120-N 51, or N51. This is just one of the hundreds of star-forming regions filled with young stars spread throughout the Large Magellanic Cloud.

The burning red intensity of the nebulae at the bottom of the picture illuminates wisps of gas and dark dust, each spanning many light-years. Moving up and across, bright stars become visible as sparse specks of light, giving the impression of pin-pricks in a cosmic cloak.

This patch of sky was the subject of observation by Hubble's WFPC2 camera. Looking for and at low-mass stars can help us to understand how stars behave when they are in the early stages of formation, and can give us an idea of how the Sun might have looked billions of years ago.

A version of this image was submitted to the Hubble's Hidden Treasures image processing competition by contestant Luca Limatola.




Thursday, February 27, 2014

SMA Unveils How Small Cosmic Seeds Grow Into Big Stars

These two panels show the Snake nebula as photographed by the Spitzer and Herschel space telescopes. At mid-infrared wavelengths (the upper panel taken by Spitzer), the thick nebular material blocks light from more distant stars. At far-infrared wavelengths, however (the lower panel taken by Herschel), the nebula glows due to emission from cold dust. The two boxed regions, P1 and P6, were examined in more detail by the Submillimeter Array (SMA).Spitzer/GLIMPSE/MIPS, Herschel/HiGal, Ke Wang (ESO). High Resolution (jpg) - Low Resolution (jpg)

These photos focus on the P1 star-forming region within the Snake nebula. The left panel shows a far-infrared view from the Herschel space telescope. Submillimeter views from the SMA are at center and right. The sensitive, high-resolution SMA images reveal small cosmic "seeds" spanning less than a tenth of a light-year, which will form one or a few massive stars. Herschel/EPoS, Sarah Ragan (MPIA); SMA, Ke Wang (ESO).  High Resolution (jpg) - Low Resolution (jpg)

Stretching across almost 100 light-years of space, the Snake nebula is located about 11,700 light-years from Earth in the direction of the constellation Ophiuchus. In images from NASA's Spitzer Space Telescope it appears as a sinuous, dark tendril against the starry background. It was targeted because it shows the potential to form many massive stars (stars heavier than 8 times our Sun).

"To learn how stars form, we have to catch them in their earliest phases, while they're still deeply embedded in clouds of gas and dust, and the SMA is an excellent telescope to do so," explained lead author Ke Wang of the European Southern Observatory (ESO), who started the research as a predoctoral fellow at the Harvard-Smithsonian Center for Astrophysics (CfA).

The team studied two specific spots within the Snake nebula, designated P1 and P6. Within those two regions they detected a total of 23 cosmic "seeds" - faintly glowing spots that will eventually birth one or a few stars. The seeds generally weigh between 5 and 25 times the mass of the Sun, and each spans only a few thousand astronomical units (the average Earth-Sun distance). The sensitive, high-resolution SMA images not only unveil the small seeds, but also differentiate them in age.

Previous theories proposed that high-mass stars form within very massive, isolated "cores" weighing at least 100 times the mass of the Sun. These new results show that that is not the case. The data also demonstrate that massive stars aren't born alone but in groups.

"High-mass stars form in villages," said co-author Qizhou Zhang of the CfA. "It's a family affair."

The team also was surprised to find that these two nebular patches had fragmented into individual star seeds so early in the star formation process.

They detected bipolar outflows and other signs of active, ongoing star formation. Eventually, the Snake nebula will dissolve and shine as a chain of several star clusters.

These results will be published in the Monthly Notices of the Royal Astronomical Society. The paper is available online.

Headquartered in Cambridge, Mass., the Harvard-Smithsonian Center for Astrophysics (CfA) is a joint collaboration between the Smithsonian Astrophysical Observatory and the Harvard College Observatory. CfA scientists, organized into six research divisions, study the origin, evolution and ultimate fate of the universe.

For more information, contact:

David A. Aguilar
Director of Public Affairs
Harvard-Smithsonian Center for Astrophysics
617-495-7462

daguilar@cfa.harvard.edu

Christine Pulliam
Public Affairs Specialist
Harvard-Smithsonian Center for Astrophysics
617-495-7463

cpulliam@cfa.harvard.edu



‘Super-Earths’ may be dead worlds

The mass of the initial rocky core determines whether the final planet is potentially habitable. On the top row of the diagram, the core has a mass of more than 1.5 times that of the Earth. The result is that it holds on to a thick atmosphere of hydrogen (H), deuterium (H2) and helium (He). The lower row shows the evolution of a smaller mass core, between 0.5 and 1.5 times the mass of the Earth. It holds on to far less of the lighter gases, making it much more likely to develop an atmosphere suitable for life. Credit: NASA / H. Lammer. Click here for a full resolution image

 In the last 20 years the search for Earth-like planets around other stars has accelerated, with the launch of missions like the Kepler space telescope. Using these and observatories on the ground, astronomers have found numerous worlds that at first sight have similarities with the Earth. A few of these are even in the ‘habitable zone’ where the temperature is just right for water to be in liquid form and so are prime targets in the search for life elsewhere in the universe.

Now a team of scientists have looked at how these worlds form and suggest that many of them may be a lot less clement than was though. They find that planets that form from less massive cores can become benign habitats for life, whereas the larger objects instead end up as ‘mini-Neptunes’ with thick atmospheres and probably stay sterile. The researchers, led by Dr. Helmut Lammer of the Space Research Institute (IWF) of the Austrian Academy of Sciences, publish their results in Monthly Notices of the Royal Astronomical Society. 

Planetary systems, including our own Solar system, are thought to form from hydrogen, helium and heavier elements that orbit their parent stars in a so-called protoplanetary disk. Dust and rocky material is thought to clump together over time, eventually forming rocky cores that go on to be planets. The gravity of these cores attracts hydrogen from the disk around them, some of which is stripped away by the ultraviolet light of the young star they orbit.

Dr. Lammer and his team modelled the balance of capture and removal of hydrogen for planetary cores between 0.1 and 5 times the mass of the Earth, located in the habitable zone of a Sun-like star. In their model, they found that protoplanets with the same density of the Earth, but less than 0.5 times its mass will not capture much gas from the disk.

Depending on the disk and assuming that the young star is much brighter in ultraviolet light than the Sun is today, planetary cores with a similar mass to the Earth can capture but also lose their enveloping hydrogen. But the highest mass cores, similar to the ‘super Earths’ found around many stars, hold on to almost all of their hydrogen. These planets end up as ‘mini Neptunes’ with far thicker atmospheres than our home planet.
The results suggest that for some of the recently discovered super-Earths, such as Kepler-62e and -62f, being in the habitable zone is not enough to make them habitats.

Dr. Lammer comments “Our results suggest that worlds like these two super-Earths may have captured the equivalent of between 100 and 1000 times the hydrogen in the Earth’s oceans, but may only lose a few percent of it over their lifetime. With such thick atmospheres, the pressure on the surfaces will be huge, making it almost impossible for life to exist.”

The ongoing discovery of low (average) density super-Earths supports the results of the study. Scientists will need to look even harder to find places where life could be found, setting a challenge for astronomers using the giant telescopes that will come into use in the next decade.
The study was carried out by researchers within the Austrian FWF Research Network “Pathways to Habitability”.


Media contact

Dr Robert Massey
Royal Astronomical Society
Tel: +44 (0)20 7734 3307 x214
Mob: +44 (0)794 124 8035

rm@ras.org.uk

Science contact

Dr Helmut Lammer
Mob: +43 316 4120 641

helmut.lammer@oeaw.ac.at


Further information




Notes for editors


The Royal Astronomical Society (RAS), founded in 1820, encourages and promotes the study of astronomy, solar-system science, geophysics and closely related branches of science. The RAS organizes scientific meetings, publishes international research and review journals, recognizes outstanding achievements by the award of medals and prizes, maintains an extensive library, supports education through grants and outreach activities and represents UK astronomy nationally and internationally. Its more than 3800 members (Fellows), a third based overseas, include scientific researchers in universities, observatories and laboratories as well as historians of astronomy and others.
Follow the RAS on Twitter via @royalastrosoc



Wednesday, February 26, 2014

Closing the ‘free will’ loophole

   Artist’s interpretation of ULAS J1120+0641, a very distant quasar.
Image: ESO/M. Kornmesser

CAMBRIDGE, Mass. — In a paper published this week in the journal Physical Review Letters, MIT researchers propose an experiment that may close the last major loophole of Bell’s inequality — a 50-year-old theorem that, if violated by experiments, would mean that our universe is based not on the textbook laws of classical physics, but on the less-tangible probabilities of quantum mechanics.

Such a quantum view would allow for seemingly counterintuitive phenomena such as entanglement, in which the measurement of one particle instantly affects another, even if those entangled particles are at opposite ends of the universe. Among other things, entanglement — a quantum feature Albert Einstein skeptically referred to as “spooky action at a distance”— seems to suggest that entangled particles can affect each other instantly, faster than the speed of light.

In 1964, physicist John Bell took on this seeming disparity between classical physics and quantum mechanics, stating that if the universe is based on classical physics, the measurement of one entangled particle should not affect the measurement of the other — a theory, known as locality, in which there is a limit to how correlated two particles can be. Bell devised a mathematical formula for locality, and presented scenarios that violated this formula, instead following predictions of quantum mechanics.

Since then, physicists have tested Bell’s theorem by measuring the properties of entangled quantum particles in the laboratory. Essentially all of these experiments have shown that such particles are correlated more strongly than would be expected under the laws of classical physics — findings that support quantum mechanics.

However, scientists have also identified several major loopholes in Bell’s theorem. These suggest that while the outcomes of such experiments may appear to support the predictions of quantum mechanics, they may actually reflect unknown “hidden variables” that give the illusion of a quantum outcome, but can still be explained in classical terms.

Though two major loopholes have since been closed, a third remains; physicists refer to it as “setting independence,” or more provocatively, “free will.” This loophole proposes that a particle detector’s settings may “conspire” with events in the shared causal past of the detectors themselves to determine which properties of the particle to measure — a scenario that, however far-fetched, implies that a physicist running the experiment does not have complete free will in choosing each detector’s setting. Such a scenario would result in biased measurements, suggesting that two particles are correlated more than they actually are, and giving more weight to quantum mechanics than classical physics.

“It sounds creepy, but people realized that’s a logical possibility that hasn’t been closed yet,” says MIT’s David Kaiser, the Germeshausen Professor of the History of Science and senior lecturer in the Department of Physics. “Before we make the leap to say the equations of quantum theory tell us the world is inescapably crazy and bizarre, have we closed every conceivable logical loophole, even if they may not seem plausible in the world we know today?”

Now Kaiser, along with MIT postdoc Andrew Friedman and Jason Gallicchio of the University of Chicago, have proposed an experiment to close this third loophole by determining a particle detector’s settings using some of the oldest light in the universe: distant quasars, or galactic nuclei, which formed billions of years ago.

The idea, essentially, is that if two quasars on opposite sides of the sky are sufficiently distant from each other, they would have been out of causal contact since the Big Bang some 14 billion years ago, with no possible means of any third party communicating with both of them since the beginning of the universe — an ideal scenario for determining each particle detector’s settings.

As Kaiser explains it, an experiment would go something like this: A laboratory setup would consist of a particle generator, such as a radioactive atom that spits out pairs of entangled particles. One detector measures a property of particle A, while another detector does the same for particle B. A split second after the particles are generated, but just before the detectors are set, scientists would use telescopic observations of distant quasars to determine which properties each detector will measure of a respective particle. In other words, quasar A determines the settings to detect particle A, and quasar B sets the detector for particle B.

The researchers reason that since each detector’s setting is determined by sources that have had no communication or shared history since the beginning of the universe, it would be virtually impossible for these detectors to “conspire” with anything in their shared past to give a biased measurement; the experimental setup could therefore close the “free will” loophole. If, after multiple measurements with this experimental setup, scientists found that the measurements of the particles were correlated more than predicted by the laws of classical physics, Kaiser says, then the universe as we see it must be based instead on quantum mechanics.

“I think it’s fair to say this [loophole] is the final frontier, logically speaking, that stands between this enormously impressive accumulated experimental evidence and the interpretation of that evidence saying the world is governed by quantum mechanics,” Kaiser says.

Now that the researchers have put forth an experimental approach, they hope that others will perform actual experiments, using observations of distant quasars.

“At first, we didn’t know if our setup would require constellations of futuristic space satellites, or 1,000-meter telescopes on the dark side of the moon,” Friedman says. “So we were naturally delighted when we discovered, much to our surprise, that our experiment was both feasible in the real world with present technology, and interesting enough to our experimentalist collaborators who actually want to make it happen in the next few years.”

Adds Kaiser, “We’ve said, ‘Let’s go for broke — let’s use the history of the cosmos since the Big Bang, darn it.’ And it is very exciting that it’s actually feasible.”

This research was funded by the National Science Foundation.


Written by: Jennifer Chu, MIT News Office 

Bullying black holes force galaxies to stay red and dead

Multi-wavelength view of the elliptical galaxy NGC 5044. Credits: Digitised Sky Survey/NASA Chandra/Southern Observatory for Astrophysical Research/Very Large Array (Robert Dunn et al. 2010).  Click here for 3 extra photos and captions (pdf)

Herschel has discovered massive elliptical galaxies in the nearby Universe containing plenty of cold gas, even though the galaxies fail to produce new stars. Comparison with other data suggests that, while hot gas cools down in these galaxies, stars do not form because jets from the central supermassive black hole heat or stir up the gas and prevent it from turning into stars.
 
Giant elliptical galaxies are the most puzzling type of galaxy in the Universe. Since they mysteriously shut down their star-forming activity and remain home only to the longest-lived of their stars - which are low-mass ones and appear red -  astronomers often call these galaxies 'red and dead'. 

Up until now, it was thought that red-and-dead galaxies were poor in cold gas - the vital raw material from which stars are born. While cold gas is abundant in spiral galaxies with lively star formation, the lack of it in giant ellipticals seemed to explain the absence of new stars. 

Astronomers have long been debating the physical processes leading to the end of their star formation. They speculated that these galaxies somehow expelled the cold gas, or that they had simply used it all to form stars in the past. Although the reason was uncertain, one thing seemed to have been established: these galaxies are red and dead because they no longer possess the means to sustain the production of stars. 

This view is being challenged by a new study based on data from ESA's Herschel Space Observatory. The results are published in Monthly Notices of the Royal Astronomical Society. 

"We looked at eight giant elliptical galaxies that nobody had looked at with Herschel before and we were delighted to find that, contrary to previous belief, six out of eight abound with cold gas", explains Norbert Werner from Stanford University in California, USA, who led the study. 

This is the first time that astronomers have seen large amounts of cold gas in red-and-dead galaxies that are not located at the centre of a massive galaxy cluster. 

The cold gas manifested itself through far-infrared emissions from carbon ions and oxygen atoms. Herschel's sensitivity at these wavelengths was instrumental to the discovery. 

"While we see cold gas, there is no sign of ongoing star formation," says co-author Raymond Oonk from ASTRON, the Netherlands Institute for Radio Astronomy. 

"This is bizarre: with plenty of cold gas at their disposal, why aren't these galaxies forming stars?" 

The astronomers proceeded to investigate their sample of galaxies across the electromagnetic spectrum, since gas at different temperatures shines brightly at different wavelengths. They used optical images to probe the warm gas - at slightly higher temperatures than the cold one detected with Herschel, and X-ray data from NASA's Chandra X-ray Observatory to trace the hot gas, up to tens of millions of K. 

"In the six galaxies that are rich in cold gas, the X-ray data show tell-tale signs that the hot gas is cooling," says Werner. 

This is consistent with theoretical expectations: once cooled, the hot gas would become the warm and cold gas that are observed at longer wavelengths. However, in these galaxies the cooling process somehow stopped, and the cold gas failed to condense and form stars. 

In the other two galaxies of the sample - the ones without cold gas - the hot gas does not appear to be cooling at all. 

"The contrasting behaviour of these galaxies may have a common explanation: the central supermassive black hole," adds Oonk. 

In some theoretical models, the level of a black hole's activity could explain why gas in a galaxy is able - or not able - to cool and form stars. And this seems to apply for the galaxies studied by Werner and his colleagues, too. 

While the six galaxies with plenty of cold gas harbour moderately active black holes at their centres, the other two show a marked difference. In the two galaxies without cold gas, the central black holes are accreting matter at frenzied pace, as confirmed by radio observations showing powerful jets of highly energetic particles that stem from their cores. 

The jets could be an effect of the hot gas cooling down, and flowing towards the centre of the galaxies. This inflow of cold gas can boost the black hole's accretion rate, launching the jets that are observed at radio wavelengths. 

The jets, in turn, have the potential to reheat the galaxy's reservoir of cold gas - or even to push it beyond the galaxy's reach. This scenario can explain the absence of star formation in all the galaxies observed in this study and, at the same time, the lack of cold gas in those with powerful jets. 

"These galaxies are red, but with the giant black holes pumping in their hearts, they are definitely not dead," comments Werner. 

"Once again, Herschel has detected something that was never seen before: significant amounts of cold gas in nearby red-and-dead galaxies," notes Göran Pilbratt, Herschel Project Scientist at ESA, "nevertheless, these galaxies do not form stars, and the culprit seems to be the black hole."
 

 
Background information
 
The study presented here is based on observations performed with the Photodetector Array Camera and Spectrometer (PACS) on board ESA's Herschel Space Observatory. 

In addition, the astronomers also used optical observations from the Southern Observatory for Astrophysical Research (SOAR) telescope in Chile and archival X-ray data from NASA's Chandra X-ray Observatory. 

Herschel is an ESA space observatory with science instruments provided by European-led Principal Investigator consortia and with important participation from NASA. 

The PACS instrument contains an imaging photometer (camera) and an imaging spectrometer. The camera operates in three bands centred on 70, 100, and 160 μm, respectively, and the spectrometer covers the wavelength range between 51 and 220 μm. PACS has been developed by a consortium of institutes led by MPE (Germany) and including UVIE (Austria); KU Leuven, CSL, IMEC (Belgium); CEA, LAM (France); MPIA (Germany); INAF-IFSI/OAA/OAP/OAT, LENS, SISSA (Italy); IAC (Spain). This development has been supported by the funding agencies BMVIT (Austria), ESA-PRODEX (Belgium), CEA/CNES (France), DLR (Germany), ASI/INAF (Italy), and CICYT/MCYT (Spain). 

Herschel was launched on 14 May 2009 and completed science observations on 29 April 2013.
 
Related publications (links on right-hand menu of web-page)
 
N. Werner, et al., "The origin of cold gas in giant elliptical galaxies and its role in fuelling radio-mode AGN feedback", 2014, Monthly Notices of the Royal Astronomical Society
 
Contacts
 
Norbert Werner
Kavli Institute for Particle Astrophysics and Cosmology and Department of Physics, Stanford University
Stanford, CA, USA
Email:
norbertw@stanford.edu
Phone: +81-90-6489-3142
 
J. B. Raymond Oonk
ASTRON, Netherlands Institute for Radio Astronomy
Dwingeloo, The Netherlands
Email:
oonk@astron.nl
Phone: +31-521-595-766
 
Göran Pilbratt
Herschel Project Scientist
Scientific Support Office
Science and Robotic Exploration Directorate
ESA, The Netherlands
Email:
gpilbratt@rssd.esa.int
Phone: +31-71-565-3621 



Tuesday, February 25, 2014

NASA's SDO Shows Images of Significant Solar Flare

The sun emitted a significant solar flare, peaking at 7:49 p.m. EST on Feb. 24, 2014. NASA's Solar Dynamics Observatory, which keeps a constant watch on the sun, captured images of the event.

An X-class solar flare erupted on the left side of the sun on the evening of Feb. 24, 2014. This composite image, captured at 7:59 p.m. EST, shows the sun in ultraviolet light with wavelengths of both 131 and 171 angstroms. Image Credit: NASA/SDO. Additional imagery from NASA Goddard's Scientific Visualization Studio

Solar flares are powerful bursts of radiation, appearing as giant flashes of light in the SDO images. Harmful radiation from a flare cannot pass through Earth's atmosphere to physically affect humans on the ground, however -- when intense enough -- they can disturb the atmosphere in the layer where GPS and communications signals travel.

To see how this event may impact Earth, please visit NOAA's Space Weather Prediction Center, the U.S. government's official source for space weather forecasts, alerts, watches and warnings.

These SDO images from 7:25 p.m. EST on Feb. 24, 2014, show the first moments of an X-class flare in different wavelengths of light -- seen as the bright spot that appears on the left limb of the sun. Hot solar material can be seen hovering above the active region in the sun's atmosphere, the corona. Image Credit: NASA/SDO. Additional imagery from NASA Goddard's Scientific Visualization Studio

This flare is classified as an X4.9-class flare. X-class denotes the most intense flares, while the number provides more information about its strength. An X2 is twice as intense as an X1, an X3 is three times as intense, etc.

Updates will be provided as needed.

Related Links

Karen C. Fox
NASA's Goddard Space Flight Center, Greenbelt, Md.


Limits on Binarity of Exoplanet Host Stars

Figure 1: Gemini DSSI speckle image of HD 168443 at a wavelength of 880 nanometers. Field of view is 2.8” across with north up and east to the left.

Figure 2. A top-down view of the HD 4203 system showing the orbits of the b planet and the newly discovered c planet. The orbits of the Solar System planets (from Mercury to Saturn) are shown as dashed lines for comparison.  

Though there are now many hundreds of confirmed exoplanets known, the number of exoplanet host stars that also have stellar companions is not well known. It is important to understand such binarity (or multiplicity) because this can have a profound effect on the way in which planets form and interact with one another. It is particularly important to examine the binarity of host stars that harbor a giant planet in a highly eccentric orbit since these are more likely to have had a dramatic dynamical history where the other star may have disrupted the orbit. 

New research by Stephen Kane (San Francisco State University) and collaborators shows that planets on highly eccentric (very non-circular) orbits are not necessarily explained by the presence of an additional star still present in the system. The observations that lead to this conclusion used the Differential Speckle Survey Instrument (DSSI) on the Gemini North telescope to rule out stellar companions to four known exoplanet host stars by obtaining high resolution images of the planet host stars and searching for very close stellar companions. These four stars were chosen because the eccentric planets in those systems also exhibit signs of being perturbed by an additional body. Ruling out stellar companions greatly implies that it is an additional planet rather than a star that is responsible for the non-circular orbit, one that is lurking beyond view. 

In addition to the Gemini result described above, the work also used data from the High Resolution Echelle Spectrometer (HIRES) on the Keck I telescope to confirm that one of the systems does indeed harbor another planet. The planet is the second planet found orbiting the star HD 4203 and so is called HD 4203c.

Together, these results represent a significant advance in understanding the dynamical interactions of planets with eccentric orbits. Full results will appear in and a preprint is now available at astro-ph

Monday, February 24, 2014

The Shocking Behavior of a Speedy Star

The red arc in this infrared image from NASA's Spitzer Space Telescope is a giant shock wave, created by a speeding star known as Kappa Cassiopeiae. Image Credit: NASA/JPL-Caltech. Large Image

Roguish runaway stars can have a big impact on their surroundings as they plunge through the Milky Way galaxy. Their high-speed encounters shock the galaxy, creating arcs, as seen in this newly released image from NASA’s Spitzer Space Telescope.

In this case, the speedster star is known as Kappa Cassiopeiae, or HD 2905 to astronomers. It is a massive, hot supergiant moving at around 2.5 million mph relative to its neighbors (1,100 kilometers per second). But what really makes the star stand out in this image is the surrounding, streaky red glow of material in its path. Such structures are called bow shocks, and they can often be seen in front of the fastest, most massive stars in the galaxy.
Bow shocks form where the magnetic fields and wind of particles flowing off a star collide with the diffuse, and usually invisible, gas and dust that fill the space between stars. How these shocks light up tells astronomers about the conditions around the star and in space. Slow-moving stars like our sun have bow shocks that are nearly invisible at all wavelengths of light, but fast stars like Kappa Cassiopeiae create shocks that can be seen by Spitzer’s infrared detectors.

Incredibly, this shock is created about 4 light-years ahead of Kappa Cassiopeiae, showing what a sizable impact this star has on its surroundings. (This is about the same distance that we are from Proxima Centauri, the nearest star beyond the sun.)

The Kappa Cassiopeiae bow shock shows up as a vividly red color. The faint green features in this image result from carbon molecules, called polycyclic aromatic hydrocarbons, in dust clouds along the line of sight that are illuminated by starlight.

Delicate red filaments run through this infrared nebula, crossing the bow shock. Some astronomers have suggested these filaments may be tracing out features of the magnetic field that runs throughout our galaxy. Since magnetic fields are completely invisible themselves, we rely on chance encounters like this to reveal a little of their structure as they interact with the surrounding dust and gas.

Kappa Cassiopeiae is visible to the naked eye in the Cassiopeia constellation (but its bow shock only shows up in infrared light.)

For this Spitzer image, infrared light at wavelengths of 3.6 and 4.5 microns is rendered in blue, 8.0 microns in green, and 24 microns in red.

NASA's Jet Propulsion Laboratory, Pasadena, Calif., manages the Spitzer Space Telescope mission for NASA's Science Mission Directorate, Washington. Science operations are conducted at the Spitzer Science Center at the California Institute of Technology in Pasadena. Spacecraft operations are based at Lockheed Martin Space Systems Company, Littleton, Colorado. Data are archived at the Infrared Science Archive housed at the Infrared Processing and Analysis Center at Caltech. Caltech manages JPL for NASA. For more information about Spitzer, visit http://spitzer.caltech.edu and http://www.nasa.gov/spitzer.


Whitney Clavin 818-354-4673
Jet Propulsion Laboratory, Pasadena, Calif.

whitney.clavin@jpl.nasa.gov

Sunday, February 23, 2014

Need to Track Organic Nano-Particles Across the Universe? NASA's Got an App for That

Image of a nebula taken by NASA’s Spitzer Space Telescope.
Image Credit: NASA/Jet Propulsion Laboratory
 
Scientists at NASA's Ames Research Center in Moffett Field, Calif., today released a significant expansion and upgrade to a public, online database that houses a unique and extensive collection of information about a family of complex, carbon-rich molecules that are both widespread and abundant throughout the universe. Scientists believe more than 20 percent of the carbon in the universe is tied up in this extensive family of compounds, collectively know as polycyclic aromatic hydrocarbons, or simply PAHs.

Using the Ames-developed PAH Infrared Spectroscopic Database, scientists will now have access to data on hundreds more compounds and several powerful new tools –including an advanced web app and a dedicated astronomical software package – to map the distribution of this life-essential element and track its role across the universe.

"Analyzing the PAH emission bands with the web app, new tools, and expanded database provides a powerful new way for astronomers to trace the evolution of cosmic carbon and, at the same time, probe conditions across the universe,” said Christiaan Boersma, a research fellow at Ames who designed and developed many parts of the web app and tools. "We have expanded the computational spectral collection to 700 spectra, including those of extremely large PAHs composed of hundreds of carbon atoms, and the experimental collection to 75 spectra."

Over the past 20 years, NASA scientists experimentally measured and computed PAH spectroscopic signatures to track and analyze the unexpected, widespread PAH emission originating from deep space. NASA made the original collection of spectra and accompanying software available online four years ago.

The approach of analyzing the infrared spectra emitted by everything from dying stars to clouds of gas and dust to entire galaxies using the one-two punch of known PAH spectra and the new, blind, algorithm-driven codes now available, provides a unique look into the evolution of cosmic PAHs.

In addition to substantially increasing the number of spectra available, the new version of the database includes powerful, astronomer-friendly tools that mimic the PAHs’ response to the local space environment and makes it possible to understand which types of PAHs are present in different regions of space. It also allows astronomers to tie these evolutionary changes to variations in local conditions such as those due to the radiation field, physical shape and history of the region.

"PAHs are so widespread and abundant in space that they don't just witness the conditions in their cosmic neighborhoods, they are active participants in many astronomical phenomena," said Louis Allamandola, an astrophysics researcher at Ames. "PAHs both are an important source of carbon for young, primordial planets, and influence how quickly they can form. For example, very bright PAH emission comes from places where new stars and exo-planets are forming."

NASA's Spitzer Space Telescope managed and operated by NASA's Jet Propulsion Laboratory in Pasadena, Calif., detected the PAH signature across the universe and showed PAHs were already forming only a couple of billion years after the Big Bang. Because their spectral signature is very sensitive to their local environment, especially radiation levels, the temperatures of PAHs in space can vary from nearly minus 450 degrees Fahrenheit to roughly 1,000 degrees, after which they break apart.

“Since PAHs are so sensitive to local conditions, analyzing the PAH bands as we did here represents a powerful new astronomical tool to trace the evolution of cosmic carbon and, at the same time, probe conditions in objects spanning the universe,” said Allamandola.

The upgraded database allows scientists to determine how the PAH signature changes across this vast range of temperatures. Astronomers need simply to upload the spectra of their favorite celestial object into the website and see which PAH classes are needed to reproduce their spectra.

"This capability is a major step forward because it allows astronomers to directly tie their astronomical spectra to the spectra of individual, bona-fide PAHs, not generic, model dependent, mythical, cosmic material," said Allamandola. "And they can do all this on their mobile devices like iPads and iPhones, as well as personal computers."

PAHs in space are probably made the same way soot is made in the combustion engines that power trucks and cars here on Earth. In addition to astronomical applications, the expanded PAH database and powerful new software also is a useful research tool for scientists, educators, policy makers, and consultants working in the fields of medicine, health, chemistry, fuel composition, engine design, environmental assessment, environmental monitoring and protection, and nanotechnology.

This work was supported by NASA's Astrobiology and Laboratory Astrophysics Programs and Carbon in the Galaxy Consortium under the auspices of the Astrophysics Research and Analysis Program.



Rachel Hoover
NASA's Ames Research Center, Moffett Field, Calif.



Rocks around the clock: asteroids pound tiny star

An artist's impression of an asteroid breaking up
Credit: NASA/JPL-Caltech 

As the star spins, its radio beam flashes over Earth again and again with the regularity of a clock. 

In 2008 Dr Shannon and a colleague predicted how an infalling asteroid would affect a pulsar. It would, they said, alter the slowing of the pulsar's spin rate and the shape of the radio pulse that we see on Earth.
"That is exactly what we see in this case," Dr Shannon said.

Scientists using CSIRO's Parkes telescope and another telescope in South Africa have found evidence that a tiny star called PSR J0738-4042 is being pounded by asteroids — large lumps of rock from space.

"One of these rocks seems to have had a mass of about a billion tonnes," CSIRO astronomer and member of the research team Dr Ryan Shannon said.

PSR J0738-4042 lies 37,000 light-years from Earth in the constellation of Puppis.

The environment around this star is especially harsh, full of radiation and violent winds of particles.

"If a large rocky object can form here, planets could form around any star. That's exciting," Dr Shannon said.
The star is a special one, a 'pulsar' that emits a beam of radio waves.

As the star spins, its radio beam flashes over Earth again and again with the regularity of a clock.

In 2008 Dr Shannon and a colleague predicted how an infalling asteroid would affect a pulsar. It would, they said, alter the slowing of the pulsar's spin rate and the shape of the radio pulse that we see on Earth.

"That is exactly what we see in this case," Dr Shannon said.

"We think the pulsar's radio beam zaps the asteroid, vaporising it. But the vaporised particles are electrically charged and they slightly alter the process that creates the pulsar's beam."

Asteroids around a pulsar could be created by the exploding star that formed the pulsar itself, the scientists say.

The material blasted out from the explosion could fall back towards the forming pulsar, forming a disk of debris.

Astronomers have found a dust disk around another pulsar called J0146+61.

"This sort of dust disk could provide the 'seeds' that grow into larger asteroids," said Mr Paul Brook, a PhD student co-supervised by the University of Oxford and CSIRO who led the study of PSR J0738-4042.

In 1992 two planet-sized objects were found around a pulsar called PSR 1257+12.  But these were probably formed by a different mechanism, the astronomers say.

The new study has been published as a paper in The Astrophysical Journal Letters, a leading journal of astronomical research: Evidence of an asteroid encountering a pulsar [external link].

Read more media releases in our Media section.

Contact Information 

Ms Helen Sim 
Media and Public Relations
Astronomy and Space Science
Phone: +61 2 9372 4251 
Alt Phone: +61 419 635 905
Email: Helen.Sim@csiro.au

Dr Ryan Shannon 
Postdoctoral Fellow
Astronomy and Space Science 
Phone: +61 2 9372 4326 
Alt Phone: +61 403 692 028
Email: Ryan.Shannon@csiro.au


Source: CSIRO


Saturday, February 22, 2014

NASA Researcher Finds Planet-Sized Space Weather Explosions at Venus

 
Giant perturbations called hot flow anomalies in the solar wind near Venus can pull the upper layers of its atmosphere, the ionosphere, up and away from the surface of the planet. Image Credit: NASA. Large Image

Researchers recently discovered that a common space weather phenomenon on the outskirts of Earth’s magnetic bubble, the magnetosphere, has much larger repercussions for Venus. The giant explosions, called hot flow anomalies, can be so large at Venus that they’re bigger than the entire planet and they can happen multiple times a day.

"Not only are they gigantic," said Glyn Collinson, a space scientist at NASA’s Goddard Space Flight Center in Greenbelt, Md. "But as Venus doesn’t have a magnetic field to protect itself, the hot flow anomalies happen right on top of the planet. They could swallow the planet whole."

Collinson is the first author of a paper on these results that appeared online in the Journal of Geophysical Research in February 2014. The work is based on observations from the European Space Agency's Venus Express. The results show just how large and how frequent this kind of space weather is at Venus.

Earth is protected from the constant streaming solar wind of radiation by its magnetosphere. Venus, however, has no such luck. A barren, inhospitable planet, with an atmosphere so dense that spacecraft landing there are crushed within hours, Venus has no magnetic protection.

Scientists like to compare the two: What happened differently at Earth to make it into the life-supporting planet it is today? What would Earth be like without its magnetic field?

At Earth, hot flow anomalies do not make it inside the magnetosphere, but they release so much energy just outside that the solar wind is deflected, and can be forced to move back toward the sun. Without a magnetosphere, what happens at Venus is very different.

Venus's only protection from the solar wind is the charged outer layer of its atmosphere called the ionosphere. A sensitive pressure balance exists between the ionosphere and the solar wind, a balance easily disrupted by the giant energy rush of a hot flow anomaly. The hot flow anomalies may create dramatic, planet-scale disruptions, possibly sucking the ionosphere up and away from the surface of the planet.

Karen C. Fox
NASA's Goddard Space Flight Center, Greenbelt, Md.



NASA's IRIS Spots Its Largest Solar Flare



On Jan. 28, 2014, NASA's newly-launched Interface Region Imaging Spectrometer, or IRIS, observed its strongest solar flare to date.Image Credit: NASA/IRIS/SDO/Goddard Space Flight Center.  Download high resolution video

On Jan. 28, 2014, NASA's IRIS witnessed its strongest solar flare since it launched in the summer of 2013. Image Credit: NASA/IRI. Large Image

On Jan. 28, 2014, NASA's Interface Region Imaging Spectrograph, or IRIS, witnessed its strongest solar flare since it launched in the summer of 2013. Solar flares are bursts of x-rays and light that stream out into space, but scientists don't yet know the fine details of what sets them off.

IRIS peers into a layer of the sun's lower atmosphere just above the surface, called the chromosphere, with unprecedented resolution. However, IRIS can't look at the entire sun at the same time, so the team must always make decisions about what region might provide useful observations. On Jan. 28, scientists spotted a magnetically active region on the sun and focused IRIS on it to see how the solar material behaved under intense magnetic forces. At 2:40 p.m. EST, a moderate flare, labeled an M-class flare -- which is the second strongest class flare after X-class – erupted from the area, sending light and x-rays into space.

IRIS studies the layer of the sun’s atmosphere called the chromosphere that is key to regulating the flow of energy and material as they travel from the sun's surface out into space. Along the way, the energy heats up the upper atmosphere, the corona, and sometimes powers solar events such as this flare.

IRIS is equipped with an instrument called a spectrograph that can separate out the light it sees into its individual wavelengths, which in turn correlates to material at different temperatures, velocities and densities. The spectrograph on IRIS was pointed right into the heart of this flare when it reached its peak, and so the data obtained can help determine how different temperatures of material flow, giving scientists more insight into how flares work.

The IRIS mission is managed by the Lockheed Martin Solar and Astrophysics Laboratory of the ATC in Palo Alto, Calif. NASA’s Ames Research Center in Moffett Field, Calif., is responsible for mission operations and the ground data system. The Ames Pleiades supercomputer is used to carry out many of the numerical simulations that are led by the University of Oslo. The IRIS telescope was designed and built by the Smithsonian Astrophysical Observatory while Montana State University faculty and students assisted in the design of the spectrograph. A large volume of science data is downlinked via Kongsberg Satellite Services, (KSAT) facilities through a cooperative agreement between NASA and the Norwegian Space Centre.  NASA’s Goddard Space Flight Center in Greenbelt, Md., oversees the Explorers Program from which IRIS evolved.

Karen C. Fox
NASA's Goddard Space Flight Center, Greenbelt, Md.

Friday, February 21, 2014

Supernovas Slosh Before Exploding

A longstanding mystery of astronomy, how supernovas explode, might finally have been solved with the help of NASA's Nuclear Spectroscopic Telescope Array (NuSTAR).  The high-energy X-ray observatory has mapped radioactive material in the supernova remnant Cassiopeia A (Cas A).  The map reveals how shock waves likely rip massive dying stars apart--by sloshing.

"Stars are spherical balls of gas, and so you might think that when they end their lives and explode, that explosion would look like a uniform ball expanding out with great power," said Fiona Harrison, the principal investigator of NuSTAR at Caltech. "Our new results show how the explosion's heart, or engine, is distorted, possibly because the inner regions literally slosh around before detonating."

Harrison is a co-author of a paper about the results appearing in the Feb. 20 issue of Nature.

In this false-color X-ray image of CAS A, blue traces the distribution of radioactive titanium-44, which is produced in the heart of the supernova. More

NuSTAR has helped decide between two competing models of supernova explosions: Jets vs. Sloshing. More

How supernovas explode has been a mystery for a long time: video. When researchers simulate supernova blasts using computers, as a massive star dies and collapses, the main shock wave often stalls out and the star fails to shatter. The latest findings strongly suggest the exploding star literally sloshed around, re-energizing the stalled shock wave and allowing the star to finally blast off its outer layers. 

NuSTAR's target, Cas A, was created when a massive star blew up as a supernova leaving a dense stellar corpse and its ejected remains. The light from the explosion reached Earth a few hundred years ago, so we are seeing the stellar remnant when it was fresh and young.

"With NuSTAR we have a new forensic tool to investigate the explosion," said the paper's lead author, Brian Grefenstette of Caltech. "Previously, it was hard to interpret what was going on in Cas A because the material that we could see only glows in X-rays when it's heated up. Now that we can see the radioactive material, which glows in X-rays no matter what, we are getting a more complete picture of what was going on at core of the explosion." 

NuSTAR is the first telescope capable of producing maps of radioactive elements in supernova remnants. In this case, the element is titanium-44, which has an unstable nucleus produced at the heart of the exploding star. The NuSTAR map of Cas A shows titanium concentrated in clumps at the remnant's center, which suggests a sloshing action. 

The NuSTAR map also casts doubt on other models of supernova explosions, in which the star is rapidly rotating just before it dies and launches narrow streams of gas that drive the stellar blast. Though imprints of jets have been seen before around Cas A, it was not known if they were triggering the explosion. NuSTAR did not see the titanium, essentially the radioactive ash from the explosion, in narrow regions matching the jets, so the jets were not the explosive trigger. 

"This is why we built NuSTAR," said Paul Hertz, director of NASA's astrophysics division in Washington. "To discover things we never knew -- and did not expect -- about the high-energy universe." 

Credits:
Production editor: Dr. Tony Phillips | Credit: Science@NASA

More information:
Why Won't the Supernova Explode?  -- this ScienceCast video explores the longstanding mystery of supernova explosions

Supernovas seed the universe with many elements, including the gold in jewelry, the calcium in bones and the iron in blood. While small stars like our sun die less violent deaths, stars at least eight times as massive as our sun blow up in supernova explosions. The high temperatures and particles created in the blast fuse light elements together to create heavier elements.  Learn more

Starbursts versus Monsters

Credit:ESA/Hubble & NASA
Acknowledgement: Judy Schmidt

The dominating figure in the middle of this new Hubble image is a galaxy known as MCG-03-04-014. It belongs to a class of galaxies called luminous infrared galaxies — galaxies that are incredibly bright in the infrared part of the spectrum.

This galaxy's status as a luminous infrared galaxy makes it part of an interesting astronomical question: starbursts versus monsters, a debate over how these galaxies are powered. Why are they so luminous in the infrared? Is it due to a recent burst of star formation, or a fiercely powerful "monster" black hole lurking at their core — or a mix of the two? The answer is still unclear.

This new image of MCG-03-04-014 shows bright sparks of star formation dotted throughout the galaxy, with murky dust lanes obscuring a bright central bulge. The galaxy seems to show evidence of disruption; at the top of the galaxy you can see bright wisps streaking into space, but the bottom is smooth and rounded. This asymmetrical appearance implies that another object is tugging at the galaxy and distorting its symmetry.

A version of this image was entered into the Hubble's Hidden Treasures image processing competition by contestant Judy Schmidt.

 Links





Thursday, February 20, 2014

ESA selects planet-hunting PLATO mission

Searching for exoplanetary systems
Copyright: ESA–C. Carreau

A space-based observatory to search for planets orbiting alien stars has been selected today as ESA’s third medium-class science mission. It is planned for launch by 2024. 

The PLATO – Planetary Transits and Oscillations of stars – mission was selected by ESA’s Science Programme Committee for implementation as part of its Cosmic Vision 2015–25 Programme. 

The mission will address two key themes of Cosmic Vision: what are the conditions for planet formation and the emergence of life, and how does the Solar System work? 

PLATO will monitor relatively nearby stars, searching for tiny, regular dips in brightness as their planets transit in front of them, temporarily blocking out a small fraction of the starlight. 

By using 34 separate small telescopes and cameras, PLATO will search for planets around up to a million stars spread over half of the sky. 

It will also investigate seismic activity in the stars, enabling a precise characterisation of the host sun of each planet discovered, including its mass, radius and age. 

When coupled with ground-based radial velocity observations, PLATO’s measurements will allow a planet’s mass and radius to be calculated, and therefore its density, providing an indication of its composition.
The mission will identify and study thousands of exoplanetary systems, with an emphasis on discovering and characterising Earth-sized planets and super-Earths in the habitable zone of their parent star – the distance from the star where liquid surface water could exist. 

“PLATO, with its unique ability to hunt for Sun–Earth analogue systems, will build on the expertise accumulated with a number of European missions, including CoRot and Cheops,” says Alvaro Giménez, ESA’s Director of Science and Robotic Exploration. 

“Its discoveries will help to place our own Solar System’s architecture in the context of other planetary systems. 

“All M3 mission candidates presented excellent opportunities for answering the major scientific questions that define our Cosmic Vision programme.” 

The four other mission concepts competing for the M3 launch opportunity were: EChO (the Exoplanet CHaracterisation Observatory), LOFT (the Large Observatory For x-ray Timing), MarcoPolo-R (to collect and return a sample from a near-Earth asteroid) and STE-Quest (Space-Time Explorer and QUantum Equivalence principle Space Test). 

PLATO joins Solar Orbiter and Euclid, which were chosen in 2011 as ESA’s first M-class missions. Solar Orbiter will be launched in 2017 to study the Sun and solar wind from a distance of less than 50 million km, while Euclid, to be launched in 2020, will focus on dark energy, dark matter and the structure of the Universe. 

PLATO will be launched on a Soyuz rocket from Europe’s Spaceport in Kourou by 2024 for an initial six-year mission. It will operate from L2, a virtual point in space 1.5 million km beyond Earth as seen from the Sun. 

Data from ESA’s recently launched Gaia mission will help PLATO to provide precise characteristics of thousands of exoplanet systems. These systems will provide natural targets for detailed follow-up observations by future large ground- and space-based observatories. 

For further information, please contact:

ESA Media Relations Office

Communication Department

Tel: + 33 1 53 69 72 99

Fax: + 33 1 53 69 76 90

Email:
media@esa.int  

Source: ESA



Clouds circling supermassive black holes

Artist's concept of a supermassive black hole at the centre of a galaxy. 
Credit: NASA / JPL / Caltec 

Astronomers see huge clouds of gas orbiting supermassive black holes at the centres of galaxies. Once thought to be a relatively uniform, fog-like ring, the accreting matter instead forms clumps dense enough to intermittently dim the intense radiation blazing forth as these enormous objects condense and consume matter.

The international team reports their sightings in a paper to be published in the Monthly Notices of the Royal Astronomical Society, available online now. Videos depicting the swirling clouds are posted to YouTube.

Evidence for the clouds comes from records collected over 16 years by NASA's Rossi X-ray Timing Explorer, a satellite in low-earth orbit equipped with instruments that measured variations in X-ray sources. Those sources include active galactic nuclei, brilliantly luminous objects powered by supermassive black holes as they gather and condense huge quantities of dust and gas.


By sifting through records for 55 active galactic nuclei Alex Markowitz, an astrophysicist at the University of California, San Diego and the Karl Remeis Observatory in Bamberg, Germany and colleagues found a dozen instances when the X-ray signal dimmed for periods of time ranging from hours to years, presumably when a cloud of dense gas passed between the source and satellite.

Mirko Krumpe of the European Southern Observatory in Garching, Germany and Robert Nikutta, of Andrés Bello University in Santiago, Chile co-authored the report, which confirms what recent models of these systems have predicted.

The clouds they observed orbit a few light-weeks to a few light-years from the centre of the active galactic nuclei. One, in a spiral galaxy in the direction of the constellation Centaurus designated NGC 3783, appeared to be in the midst of being torn apart by tidal forces.

Support for this research came from NASA's Astrophysics Data Analysis Program (NNX11AD07G) and the European Community's Seventh Framework Program (229517). Nikutta acknowledges support from ALMA-CONICYT (31110001). Video produced by the Scientific Visualization Studio, Goddard Spaceflight Centre, NASA, based in part on visualisations created by Wolfgang Steffen, Institute of Astronomy, National Autonomous University of Mexico.


Science contacts

Alex Markowitz, in Germany
almarkowitz@ucsd.edu (preferred)
Tel: +49 (0)951 95222 26
Available for interviews in English only


Mirko Krumpe, in California, U.S.
Tel: +1 858 822 3435

mkrumpe@eso.org
Available for interviews in German (preferred) or English

Robert Nikutta, in Chile
Tel: +56 9 7370 1865
Available for interviews in German or English



Animations

YouTube animations of clouds in orbit around a black hole are available from
http://www.youtube.com/watch?v=fUQ29PQBXhQ
http://www.youtube.com/watch?v=vdQm9VGj7g4 (with weather symbols)
http://www.youtube.com/watch?v=OCLpFTm01VA (with a diagram showing changing X-ray emission)

A NASA video with accompanying soundtrack is available from http://youtu.be/QA8nzRkjOE


Further information


The researchers publish their work in “First X-ray-based statistical tests for clumpy-torus models: eclipse events from 230 years of monitoring of Seyfert AGN”, A. G. Markowitz, M. Krumpe and R. Nikutta4, Monthly Notices of the Royal Astronomical Society. The paper is available from http://mnras.oxfordjournals.org/content/early/2014/02/04/mnras.stt2492


Notes for editors


The Royal Astronomical Society (RAS, www.ras.org.uk),  founded in 1820, encourages and promotes the study of astronomy, solar-system science, geophysics and closely related branches of science. The RAS organizes scientific meetings, publishes international research and review journals, recognizes outstanding achievements by the award of medals and prizes, maintains an extensive library, supports education through grants and outreach activities and represents UK astronomy nationally and internationally. Its more than 3800 members (Fellows), a third based overseas, include scientific researchers in universities, observatories and laboratories as well as historians of astronomy and others.


Follow the RAS on Twitter via @royalastrosoc