ESA Herschel: Young sun's violent history solves meteorite mystery

An illustration of the wind blown by a newborn star. 

When the energetic particles hit the surrounding material, they may collide with atoms that are present in the star's environment, break them apart and produce new elements. 

Credit: ESA/ATG medialab

Astronomers using ESA's Herschel space observatory to probe the turbulent beginnings of a Sun-like star have found evidence of mighty stellar winds that could solve a puzzling meteorite mystery in our own back yard.

In spite of their tranquil appearance in the night sky, stars are scorching furnaces that spring to life through tumultuous processes, and our 4.5 billion-year-old Sun is no exception.

To glimpse its harsh early days, astronomers gather clues not only in the Solar System but also by studying young stars elsewhere in our Galaxy.

Using Herschel to survey the chemical composition of regions where stars are being born today, a team of astronomers has noticed that one object in particular is different.

The unusual source is a prolific stellar nursery called OMC2 FIR4, a clump of new stars embedded in a gaseous and dusty cloud near to the famous Orion Nebula.

"To our great surprise, we found that the proportion of two chemical species, one based on carbon and oxygen and the other on nitrogen, is much smaller in this object than in any other protostar we know," says Dr Cecilia Ceccarelli, of the Institute de Planétologie et d'Astrophysique de Grenoble, France, who lead the study with Dr Carsten Dominik of the University of Amsterdam in the Netherlands.

In an extremely cold environment, the measured proportion could arise by one of the two compounds freezing onto dust grains and becoming undetectable.

However, at the relatively 'high' temperature of about –200°C found in star-forming regions like OMC2 FIR4, this should not occur.

"The most likely cause in this environment is a violent wind of very energetic particles, released by at least one of the embryonic stars taking shape in this proto-stellar cocoon," Dr Ceccarelli adds.

Orion A, a star-forming nebula lying about 1500 light-years from Earth, as viewed by ESA’s Herschel space observatory.

Orion A is located within the ‘sword of Orion,’ below the three main stars that form the belt of the Orion constellation. 

Embedded in the gaseous and dusty environment of this molecular cloud is the prolific stellar nursery called OMC2 FIR4 (highlighted with a red circle). 

Astronomers studying OMC2 FIR4 with Herschel have discovered that at least one of the embryo stars that are taking shape in this protostellar cocoon is gusting a powerful wind of very energetic particles. 

The inset shows an illustration of the wind blown by this newborn star. 

When the energetic particles hit the surrounding material, they may collide with atoms that are present in the star's environment, break them apart and produce new elements. 

Our Sun likely gusted a similar wind of particles in its early days; this could explain the origin of a puzzling isotope of beryllium, whose traces are found in meteorites. 

Credit: Herschel image: ESA/Herschel/Ph. André, D. Polychroni, A. Roy, V. Könyves, N. Schneider for the Gould Belt survey Key Programme; inset and layout: ESA/ATG medialab

The most abundant molecule in star-forming clouds, hydrogen, can be broken apart by cosmic rays, energetic particles that permeate the entire Galaxy.

The hydrogen ions then combine with other elements that are present – albeit only in trace amounts – in these clouds: carbon and oxygen, or nitrogen.

Normally, the nitrogen compound is also quickly destroyed, yielding more hydrogen for the carbon and oxygen compound. As a result, the latter is far more abundant in all known stellar nurseries.

Strangely enough, though, this was not the case for OMC2 FIR4, suggesting that an additional wind of energetic particles is destroying both chemical species, keeping their abundances more similar.

Astronomers think that a similarly violent wind of particles also gusted through the early Solar System, and this discovery might finally point to an explanation for the origin of a particular chemical element seen in meteorites.

Meteorites are the remains of interplanetary debris that survived the trip through our planet's atmosphere.

These cosmic messengers are one of the few tools we have to directly probe the elements in our Solar System.

"Some elements detected in meteorites reveal that, long ago, these rocks contained a form of beryllium: this is quite puzzling, as we can't quite understand how it got there," explains Dr Dominik.

Isotope Beryllium-10 formation
The formation of the isotope Beryllium-10 in the Universe is an intricate puzzle of its own.

Astronomers know that it is not produced in the interior of stars, like some other elements, nor in the supernova explosion that happens at the end of a massive star's life.

The majority of beryllium-10 was formed in collisions of very energetic particles with heavier elements like oxygen, but since this isotope decays very quickly into other elements, it must have been produced just before it was incorporated in the rocks that would later appear on Earth as meteorites.

To trigger these reactions and produce an amount of beryllium matching that recorded in meteorites, our own Sun must have blown a violent wind in its youth.

These new observations of OMC2 FIR4 give a very strong hint that it is possible for a young star to do this.

"Observing star-forming regions with Herschel not only provides us with a view on what happens beyond our cosmic neighbourhood, but it's also a crucial way to piece together the past of our own Sun and Solar System," says Göran Pilbratt, ESA's Herschel project scientist.

More information: "Herschel finds evidence for stellar wind particles in a protostellar envelope: is this what happened to the young Sun?" by C. Ceccarelli et al. is published in The Astrophysical Journal Letters, July 2014. iopscience.iop.org/2041-8205/790/1/L1/article

NASA MSL: Apparent Mystery of Mars 'doughnut' rock solved

NASA image shows before-and-after of the same patch of ground in front of NASA's Mars Exploration Rover Opportunity 13 days apart documenting the arrival of a bright rock onto the scene, on January 22, 2014

NASA scientists were finally able to explain the origin of the mysterious rock shaped like a jelly doughnut that appeared near the rover Opportunity in early January.

The small, round object suddenly popped up in pictures taken 12 days apart by the US space agency's decade-old Opportunity rover.

On December 26, 2013, it was not there. On January 8, it was. But what is it?

The explanation is somewhat prosaic: the 1.5 inches (four centimeters) wide, white-rimmed, red-centered rock, dubbed Pinnacle Island, is a piece of a larger rock that was broken and moved by Opportunity's wheel in early January.

"Once we moved Opportunity a short distance, after inspecting Pinnacle Island, we could see directly uphill an overturned rock that has the same unusual appearance," said Opportunity Deputy Principal Investigator Ray Arvidson of Washington University in St. Louis on Friday.

"We drove over it. We can see the track. That's where Pinnacle Island came from."

However, the rock is unusual and scientifically significant.

A close examination with Opportunity's spectrometer showed "high levels of elements such as manganese and sulphur, suggesting these water-soluble ingredients were concentrated in the rock by the action of water," NASA said.

This image taken by the panoramic camera on Opportunity shows the rover's Moessbauer spectrometer (circular device in center).

"This may have happened just beneath the surface relatively recently," Arvidson said, "or it may have happened deeper below ground longer ago and then, by serendipity, erosion stripped away material above it and made it accessible to our wheels."

Opportunity is one of two Mars Exploration Rovers. Its companion, Spirit, stopped communicating with Earth in 2010.

Both have lived long beyond their planned 90-day missions and have made important discoveries about water on Mars and environments that might have supported microbial life in the distant past.

Massive neutrinos solve a cosmological conundrum

UK Scientists have solved a major problem with the current standard model of cosmology identified by combining results from the Planck spacecraft and measurements of gravitational lensing in order to deduce the mass of ghostly sub-atomic particles called neutrinos.

The UK team, from the universities of Manchester and Nottingham, used observations of the Big Bang and the curvature of space-time to accurately measure the mass of these elementary particles for the first time.

Planck spacecraft

The recent Planck spacecraft observations of the Cosmic Microwave Background (CMB) - the fading glow of the Big Bang - highlighted a discrepancy between these cosmological results and the predictions from other types of observations.

The CMB is the oldest light in the Universe, and its study has allowed scientists to accurately measure cosmological parameters, such as the amount of matter in the Universe and its age.

But an inconsistency arises when large-scale structures of the Universe, such as the distribution of galaxies, are observed.

Professor Richard Battye, from the University of Manchester's School of Physics and Astronomy, said: "We observe fewer galaxy clusters than we would expect from the Planck results and there is a weaker signal from gravitational lensing of galaxies than the CMB would suggest.

"A possible way of resolving this discrepancy is for neutrinos to have mass. The effect of these massive neutrinos would be to suppress the growth of dense structures that lead to the formation of clusters of galaxies."

Cosmic Microwave Background (CMB)

Neutrinos interact very weakly with matter and so are extremely hard to study.

They were originally thought to be massless but particle physics experiments have shown that neutrinos do indeed have mass and that there are several types, known as flavours by particle physicists.

The sum of the masses of these different types has previously been suggested to lie above 0.06 eV (much less than a billionth of the mass of a proton).

Adam Moss

In this paper, Professor Battye and co-author Dr Adam Moss, from the University of Nottingham, have combined the data from Planck with gravitational lensing observations in which images of galaxies are warped by the curvature of space-time.

They conclude that the current discrepancies can be resolved if massive neutrinos are included in the standard cosmological model.

They estimate that the sum of masses of neutrinos is 0.320 +/- 0.081 eV (assuming active neutrinos with three flavours).

Dr Moss said: "If this result is borne out by further analysis, it not only adds significantly to our understanding of the sub-atomic world studied by particle physicists, but it would also be an important extension to the standard model of cosmology which has been developed over the last decade."

More Information: 'Evidence for Massive Neutrinos from Cosmic Microwave Background and Lensing Observations' DOI:10.1103/PhysRevLett.112.051303

Hubble: Astronomers Solve Mystery of Universe's Massive Galactic Burnouts

From telescope observations, astronomers have pieced together how massive elliptical galaxies grow over 13 billion years. 

Credit: NASA, ESA, S. Toft (Niels Bohr Institute), and A. Feild (STScl)

Using data from the Hubble Space Telescope and other observatories, astronomers are learning why some massive galaxies hit their peak young and quit making stars when the universe was less than a quarter of its current age.

Scientists have been puzzled by compact, elliptical-shaped galaxies that seem to have burned out when the universe was 3 billion years old.

For comparison, our Milky Way galaxy is 12 billion years old and still making stars.

These burnouts are sometimes nicknamed "red and dead" galaxies because of their reddish color, compared to the blue hues of star-making galaxies, according to NASA.

Strangely, these dead galaxies are just as massive as today's large spiral galaxies, but with stars squeezed into an area three times smaller.

"This means that the density of stars was 10 times greater," Sune Toft, an astrophysics and cosmology professor at the Niels Bohr Institute in Copenhagen, explained in a statement.

Sune Toft

"Furthermore, the galaxies were already dead, so they were no longer forming new stars. It was a great mystery."

These burnouts appear to have started out as intense starburst galaxies in the very early universe, quickly gobbling up all the gas around them before fading, Toft and colleagues found.

To piece together a life history of the "red and dead" galaxies, the scientists looked at infrared data from space-based telescopes and ground-based telescopes, as well as two Hubble surveys;

• the Cosmic Assembly Near-Infrared Deep Extragalactic Legacy Survey (CANDLES), which probes distant objects to help astronomers understand how galaxies, black holes and supernovas formed in the early universe and,
• 3D-HST, a near-infrared spectroscopic survey.

The burnouts shared characteristics with dust-shrouded galaxies that were rife with violent starburst activity and 1 billion to 2 billion years older, the scientists found.

These live-fast-die-young galaxies seem to quickly use up available gas for star formation and burn out.

Through merging, they eventually grow into giant elliptical galaxies in our local universe.

"We at last show how these compact galaxies can form, how it happened, and when it happened," Toft said.

"This basically is the missing piece in the understanding of how the most massive galaxies formed, and how they evolved into the giant ellipticals of today."

More Information: 'Submillimeter Galaxies as Progenitors of Compact Quiescent Galaxies' Astrophysical Journal; S. Toft et al. 2014 ApJ 782 68. doi:10.1088/0004-637X/782/2/68

Jansky Very Large Array (VLA): Solving a 30-year-old problem in massive star formation

This false-colour Very Large Array image of the ionized gas in the star forming region Sgr B2 Main was used to detect small but significant changes in brightness of several of the sources. 

The spots and filaments in this image are regions of ionized gas around massive stars. 

The changes in brightness detected support a model that could solve a 30-year-old question in high mass star formation. 

Credit: NRAO /Agnes Scott College

An international group of astrophysicists has found evidence strongly supporting a solution to a long-standing puzzle about the birth of some of the most massive stars in the universe.

Young massive stars, which have more than 10 times the mass of the Sun, shine brightly in the ultraviolet, heating the gas around them, and it has long been a mystery why the hot gas doesn't explode outwards.

Now, observations made by a team of researchers using the Jansky Very Large Array (VLA), a radio astronomy observatory in New Mexico, have confirmed predications that as the gas cloud collapses, it forms dense filamentary structures that absorb the star's ultraviolet radiation when it passes through them. As a result, the surrounding heated nebula flickers like a candle.

The findings were published recently in The Astrophysical Journal Letters.

"Massive stars dominate the lives of their host galaxies through their ionizing radiation and supernova explosions," said Mordecai-Mark Mac Low, a curator in the American Museum of Natural History's Department of Astrophysics and an author on the paper.

"All the elements heavier than iron were formed in the supernova explosions occurring at the ends of their lives, so without them, life on Earth would be very different."

Observations of the massive star forming region Sgr B2 were made with the Karl G. Jansky Very Large Array (VLA) in 1989 and 2012. 

The VLA has been operational since 1980 and received a major upgrade that was completed in 2011. 

Credit: NRAO/AUI

Stars form when huge clouds of gas collapse. Once the density and temperature are high enough, hydrogen fuses into helium, and the star starts shining.

The most massive stars, though, begin to shine while the clouds are still collapsing.

Their ultraviolet light ionizes the surrounding gas, forming a nebula with a temperature of 10,000 degrees Celsius. Simple models suggest that at this stage, the gas around massive stars will quickly expand.

But observations from the VLA radio observatory show something different: a large number of regions of ionized hydrogen (so-called HII regions) that are very small.

"In the old theoretical model, a high-mass star forms and the HII region lights up and begins to expand."

Chris De Pree

"Everything was neat and tidy," said lead author Chris De Pree, a professor of astronomy and director of the Bradley Observatory at Agnes Scott College.

"But the group of theorists I am working with were running numerical models that showed accretion was continuing during star formation, and that material was continuing to fall in toward the star after the HII region had formed."

More information: arxiv.org/abs/1312.7768

Supervolcano eruption mystery solved

Supervolcanoes like Yellowstone can explode without an earthquake or other external trigger, experts have found.

The sheer volume of liquid magma is enough to cause a catastrophic super-eruption, according to an experiment at the European Synchrotron Radiation Facility (ESRF) in Grenoble.

Simulating the intense heat and pressure inside these "sleeping giants" could help predict a future disaster.

The study by a Swiss team from ETH Zurich appears in Nature Geoscience.

Lead author Wim Malfait, of ETH Zurich said: "We knew the clock was ticking but we didn't know how fast: what would it take to trigger a super-eruption?

"Now we know you don't need any extra factor - a supervolcano can erupt due to its enormous size alone.

"Once you get enough melt, you can start an eruption just like that."

There are about 20 known supervolcanoes on Earth - including Lake Toba in Indonesia, Lake Taupo in New Zealand, and the somewhat smaller Phlegraean Fields near Naples, Italy.

Super-eruptions occur rarely - only once every 100,000 years on average. But when they do occur, they have a devastating impact on Earth's climate and ecology.

When a supervolcano erupted 600,000 years ago in Wyoming, in what today is Yellowstone National Park, it ejected more than 1,000 cubic km of ash and lava into the atmosphere - enough to bury a large city to a depth of a few kilometres.

Lake Toba in Sumatra was formed during the eruption of a supervolcano 74,000 years ago

This ejection was 100 times bigger than Mount Pinatubo in the Philippines in 1992 and dwarfs even historic eruptions like Krakatoa (1883).

"This is something that, as a species, we will eventually have to deal with. It will happen in future," said Dr Malfait.

"You could compare it to an asteroid impact - the risk at any given time is small, but when it happens the consequences will be catastrophic."

Being able to predict such a catastrophe is obviously critical. But the trigger has remained elusive - because the process is different from conventional volcanoes like Pinatubo and Mount St Helens.

One possible mechanism was thought to be the overpressure in the magma chamber generated by differences between the less dense molten magma and more dense rock surrounding it.

"The effect is comparable to holding a football under water. When you release it, the air-filled ball is forced upwards by the denser water around it," said Wim Malfait, of ETH Zurich.

But whether this buoyancy effect alone was enough was not known. It could be that an an additional trigger - such as a sudden injection of magma, an infusion of water vapour, or an earthquake - was required.

More Information: dx.doi.org/10.1038/ngeo2042

Scientists solve a decades-old mystery in the Earth's upper atmosphere

The top panel shows electron fluxes before (left) and after (right) a geomagnetic storm. 

The injection of low-energy plasma sheet electrons into the inner magnetosphere (1) causes chorus wave excitation in the low-density region outside the cold plasmasphere (2). 

Local energy diffusion associated with wave scattering leads to the development of strongly enhanced phase space density just outside the plasmapause (3). 

Subsequently, radial diffusion can redistribute the accelerated electrons inwards or outwards from the developing peak (4). 

Credit: Jacob Bortnik/UCLA

New research published in the journal Nature resolves decades of scientific controversy over the origin of the extremely energetic particles known as ultra-relativistic electrons in the Earth's near-space environment and is likely to influence our understanding of planetary magnetospheres throughout the universe.

Discovering the processes that control the formation and ultimate loss of these electrons in the Van Allen radiation belts—the rings of highly charged particles that encircle the Earth at a range of about 1,000 to 50,000 kilometers above the planet's surface—is a primary science objective of the recently launched NASA Van Allen Probes mission.

Understanding these mechanisms has important practical applications, because the enormous amounts of radiation trapped within the belts can pose a significant hazard to satellites and spacecraft, as well astronauts performing activities outside a craft.

Ultra-relativistic electrons in the Earth's outer radiation belt can exhibit pronounced variability in response to activity on the sun and changes in the solar wind, but the dominant physical mechanism responsible for radiation-belt electron acceleration has remained unresolved for decades.

Two primary candidates for this acceleration have been "inward radial diffusive transport" and "local stochastic acceleration" by very low-frequency plasma waves.

In research published Dec. 19 in Nature, lead author Richard Thorne, a distinguished professor of atmospheric and oceanic sciences in the UCLA College of Letters and Science, and his colleagues report on high-resolution satellite measurements of high-energy electrons during a geomagnetic storm on Oct. 9, 2012, which they have numerically modeled using a newly developed data-driven global wave model.

Their analysis reveals that scattering by intense, natural very low–frequency radio waves known as "chorus" in the Earth's upper atmosphere is primarily responsible for the observed relativistic electron build-up.

The local wave-acceleration process is a "universal physical process" and should also be effective in the magnetospheres of Jupiter, Saturn and other magnetized plasma environments in the cosmos, Thorne said.

He thinks the new results from the detailed analysis of Earth will influence future modeling of other planetary magnetospheres.

More information: Paper: dx.doi.org/10.1038/nature12889