MYSTERIOUS MOLECULES IN SPACE

Researchers at Harvard-Smithsonian Center for Astrophysics finger silicon-capped hydrocarbons as possible source of mysterious “diffuse interstellar bands” 

From the FMS Global News Desk of Jeanne Hambleton Released: 29-Jul-2014
Source Newsroom: American Institute of Physics (AIP) Journal of Chemical Physics

 

Newswise — WASHINGTON D.C., July 29, 2014 – Over the vast, empty reaches of interstellar space, countless small molecules tumble quietly though the cold vacuum. Forged in the fusion furnaces of ancient stars and ejected into space when those stars exploded, these lonely molecules account for a significant amount of all the carbon, hydrogen, silicon and other atoms in the universe.

In fact, some 20 percent of all the carbon in the universe is thought to exist as some form of interstellar molecule.

Many astronomers hypothesize that these interstellar molecules are also responsible for an observed phenomenon on Earth known as the “diffuse interstellar bands,” spectrographic proof that something out there in the universe is absorbing certain distinct colors of light from stars before it reaches the Earth.

But since we do not know the exact chemical composition and atomic arrangements of these mysterious molecules, it remains unproven whether they are, in fact, responsible for the diffuse interstellar bands.

Now in a paper appearing this week in The Journal of Chemical Physics, from AIP Publishing, a group of scientists led by researchers at the Harvard-Smithsonian Center for Astrophysics in Cambridge, Mass. has offered a tantalizing new possibility: these mysterious molecules may be silicon-capped hydrocarbons like SiC3H, SiC4H and SiC5H, and they present data and theoretical arguments to back that hypothesis.

At the same time, the group cautions that history has shown that while many possibilities have been proposed as the source of diffuse interstellar bands, none has been proven definitively.

“There have been a number of explanations over the years, and they cover the gamut,” said Michael McCarthy a senior physicist at the Harvard-Smithsonian Center for Astrophysics who led the study.

Molecules in Space and How We Know They Are There

Astronomers have long known that interstellar molecules containing carbon atoms exist and that by their nature they will absorb light shining on them from stars and other luminous bodies. Because of this, a number of scientists have previously proposed that some type of interstellar molecules are the source of diffuse interstellar bands — the hundreds of dark absorption lines seen in color spectrograms taken from Earth.

In showing nothing, these dark bands reveal everything. The missing colors correspond to photons of given wavelengths that were absorbed as they travelled through the vast reaches of space before reaching us. More than that, if these photons were filtered by falling on space-based molecules, the wavelengths reveal the exact energies it took to excite the electronic structures of those absorbing molecules in a defined way.

Armed with that information, scientists here on Earth should be able to use spectroscopy to identify those interstellar molecules — by demonstrating which molecules in the laboratory have the same absorptive “fingerprints.” But despite decades of effort, the identity of the molecules that account for the diffuse interstellar bands remains a mystery. Nobody has been able to reproduce the exact same absorption spectra in laboratories here on Earth.

“Not a single one has been definitively assigned to a specific molecule,” said Neil Reilly, a former postdoctoral fellow at Harvard-Smithsonian Center for Astrophysics and a co-author of the new paper.

Now Reilly, McCarthy and their colleagues are pointing to an unusual set of molecules — silicon-terminated carbon chain radicals — as a possible source of these mysterious bands.

As they report in their new paper, the team first created silicon-containing carbon chains SiC3H, SiC4H and SiC5H in the laboratory using a jet-cooled silane-acetylene discharge. They then analyzed their spectra and carried out theoretical calculations to predict that longer chains in this family might account for some portion of the diffuse interstellar bands.

However, McCarthy cautioned that the work has not yet revealed the smoking gun source of the diffuse interstellar bands. In order to prove that these larger silicon capped hydrocarbon molecules are such a source, more work needs to be done in the laboratory to define the exact types of transitions these molecules undergo, and these would have to be directly related to astronomical observations. But the study provides a tantalizing possibility for finding the elusive source of some of the mystery absorption bands — and it reveals more of the rich molecular diversity of space.

“The interstellar medium is a fascinating environment,” McCarthy said. “Many of the things that are quite abundant there are really unknown on Earth.”

The article, “Optical Spectra of the Silicon-Terminated Carbon Chain Radicals SiCnH (n=3,4,5),” is authored by D. L. Kokkin, N. J. Reilly, R. C. Fortenberry, T. D. Crawford and M. C. McCarthy. It will be published in The Journal of Chemical Physics on July 29, 2014. After that date, it can be accessed at: http://scitation.aip.org/content/aip/journal/jcp/141/4/10.1063/1.4883521

Authors of the paper are affiliated with Harvard University, Arizona State University, Virginia Tech, the University of Louisville and Georgia Southern University.

ABOUT THE JOURNAL
The Journal of Chemical Physics publishes concise and definitive reports of significant research in the methods and applications of chemical physics. See: http://jcp.aip.org

 

Young Binary Star System May Form Planets with Weird and Wild Orbits

From the FMS Global News Desk of Jeanne Hambleton Embargo expired: 30-Jul-2014
Source Newsroom: National Radio Astronomy Observatory – Nature, July 31, 2014

 

Newswise — Unlike our solitary Sun, most stars form in binary pairs — two stars that orbit a common center of mass. Though remarkably plentiful, binaries pose a number of questions, including how and where planets form in such complex environments.

While surveying a series of binary stars with the Atacama Large Millimeter/submillimeter Array (ALMA), astronomers uncovered a striking pair of wildly misaligned planet-forming disks in the young binary star system HK Tau. These results provide the clearest picture ever of protoplanetary disks around a double star and could reveal important details about the birth and eventual orbit of planets in a multiple star system.

“ALMA has given us an unprecedented view of a main star and its binary companion sporting mutually misaligned protoplanetary disks,” said Eric Jensen, an astronomer at Swarthmore College in Pennsylvania. “In fact, we may be seeing the formation of a solar system that may never settle down.”

The two stars in this system, which is located approximately 450 light-years from Earth in the constellation Taurus, are less than 5 million years old and separated by about 58 billion kilometers, or 13 times the distance of Neptune from the Sun.

This system’s companion star, dubbed HK Tau B, appears fainter to astronomers on Earth because its disk of dust and gas blocks out much of the starlight. The disk itself, however, can be easily observed by the starlight that it scatters at optical and near-infrared wavelengths.

The disk around the main star, HK Tau A, is tilted in such a way that the light from its host star shines through unobscured, making it difficult for astronomers to see the disk optically. This is not a problem for ALMA, however, which can readily detect the millimeter-wavelength light emitted by the dust and gas that comprise the disk.

With its unprecedented resolution and sensitivity, ALMA was able to fully resolve the rotation of HK Tau A’s disk for the first time. This clearer picture enabled the astronomers to calculate that the disks were misaligned – meaning they were out of sync with the orbit of their host stars — by as much as 60 degrees or more.

“This clear misalignment has given us a remarkable look at a young binary star system,” said Rachel Akeson of the NASA Exoplanet Science Institute at the California Institute of Technology in Pasadena, California. “Though there have been hints before that this type of misaligned system exists, this is the cleanest and most striking example.”

Stars and planets form out of vast clouds of dust and gas. As material in these clouds contracts under gravity, it begins to rotate until most of the dust and gas falls into a flattened protoplanetary disk swirling around a growing central protostar. Despite forming from a flat, regular disk, planets can end up in highly eccentric orbits, and may be misaligned with the star’s equator. One theory for how planets can migrate to these unusual orbits is that a binary companion star can influence them — but only if its orbit is initially misaligned with the planets.

“Our results demonstrate that the necessary conditions exist to modify planetary orbits and that these conditions are present at the time of planet formation, apparently due to the binary formation process,” noted Jensen. “We can’t rule other theories out, but we can certainly rule in that a second star will do the job.”

Since ALMA can see the otherwise invisible dust and gas of protoplanetary disks, it allowed for never-before-seen views of this young binary system. “Because we’re seeing this in the early stages of formation with the protoplanetary disks still in place, we can see better how things are oriented,” noted Akeson. “You can simply see gas better than you can see planets.”

Looking forward, the researchers want to determine if this type of system is typical or not. They note that this is a remarkable individual case, but additional surveys are needed to determine if this sort of arrangement is common throughout our Galaxy.

The results will appear in the journal Nature on July 31, 2014.

The National Radio Astronomy Observatory is a facility of the National Science Foundation, operated under cooperative agreement by Associated Universities, Inc.

The Atacama Large Millimeter/submillimeter Array (ALMA), an international astronomy facility, is a partnership of Europe, North America and East Asia in cooperation with the Republic of Chile. ALMA is funded in Europe by the European Southern Observatory (ESO), in North America by the U.S. National Science Foundation (NSF) in cooperation with the National Research Council of Canada (NRC) and the National Science Council of Taiwan (NSC) and in East Asia by the National Institutes of Natural Sciences (NINS) of Japan in cooperation with the Academia Sinica (AS) in Taiwan. ALMA construction and operations are led on behalf of Europe by ESO, on behalf of North America by the National Radio Astronomy Observatory (NRAO), which is managed by Associated Universities, Inc. (AUI) and on behalf of East Asia by the National Astronomical Observatory of Japan (NAOJ). The Joint ALMA Observatory (JAO) provides the unified leadership and management of the construction, commissioning and operation of ALMA.

 

Huge Waves Measured for First Time in Arctic Ocean

From the FMS Global News Desk of Jeanne Hambleton  Released: 29-Jul-2014
Source Newsroom: University of Washington

http://www.newswise.com/articles/view/621297/?sc=swhn

 

Huge Waves Measured for First Time in Arctic Ocean

From the FMS Global News Desk of Jeanne HambletonReleased: 29-Jul-2014
Source Newsroom: University of Washington

Newswise — As the climate warms and sea ice retreats, the North is changing. An ice-covered expanse now has a season of increasingly open water which is predicted to extend across the whole Arctic Ocean before the middle of this century. Storms thus have the potential to create Arctic swell – huge waves that could add a new and unpredictable element to the region.

A University of Washington researcher made the first study of waves in the middle of the Arctic Ocean, and detected house-sized waves during a September 2012 storm. The results were recently published in Geophysical Research Letters.

“As the Arctic is melting, it is a pretty simple prediction that the additional open water should make waves,” said lead author Jim Thomson, an oceanographer with the UW Applied Physics Laboratory.

His data show that winds in mid-September 2012 created waves of 5 meters (16 feet) high during the peak of the storm. The research also traces the sources of those big waves: high winds, which have always howled through the Arctic, combined with the new reality of open water in summer.

Arctic ice used to retreat less than 100 miles from the shore. In 2012, it retreated more than 1,000 miles. Wind blowing across an expanse of water for a long time creates whitecaps, then small waves, which then slowly consolidate into big swells that carry huge amounts of energy in a single punch.

The size of the waves increases with the fetch, or travel distance over open water. So more open water means bigger waves. As waves grow bigger they also catch more wind, driving them faster and with more energy.

Shipping and oil companies have been eyeing the opportunity of an ice-free season in the Arctic Ocean. The emergence of big waves in the Arctic could be bad news for operating in newly ice-free Northern waters.

“Almost all of the casualties and losses at sea are because of stormy conditions, and breaking waves are often the culprit,” Thomson said.

It also could be a new feedback loop leading to more open water as bigger waves break up the remaining summer ice floes.

“The melting has been going on for decades. What we’re talking about with the waves is potentially a new process, a mechanical process, in which the waves can push and pull and crash to break up the ice,” Thomson said.

Waves breaking on the shore could also affect the coastlines, where melting permafrost is already making shores more vulnerable to erosion.

The observations were made as part of a bigger project by a sensor anchored to the seafloor and sitting 50 meters (more than 150 feet) below the surface in the middle of the Beaufort Sea, about 350 miles off Alaska’s north slope and at the middle of the ice-free summer water.

It measured wave height from mid-August until late October 2012. Satellites can give a rough estimate of wave heights, but they do not give precise numbers for storm events. They also do not do well for the sloppy, partially ice-covered waters that are common in the Arctic in summer.
Warming temperatures and bigger waves could act together on summer ice floes,

Thomson said: “At this point, we do not really know relative importance of these processes in future scenarios.”
Establishing that relationship could help to predict what will happen to the sea ice in the future and help forecast how long the ice-free channel will remain open each year.
The recent paper recorded waves at just one place. This summer Thomson is part of an international group led by the UW that is putting dozens of sensors in the Arctic Ocean to better understand the physics of the sea-ice retreat.
“There are several competing theories for what happens when the waves approach and get in to the ice,” Thomson said. “A big part of what we are doing with this program is evaluating those models.”
He will be out on Alaska’s northern coast from late July until mid-August deploying sensors to track waves. He hopes to learn how wave heights are affected by the weather, ice conditions and amount of open water.
“It’s going to be a quantum leap in terms of the number of observations, the level of detail and the level of precision” for measuring Arctic Ocean waves, Thomson said.
The other author is W. Erick Rogers at the Naval Research Laboratory. The research was funded by the U.S. Office of Naval Research.

Back tomorrow. Enjoy Jeanne


					
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About jeanne hambleton

Journalist-wordsmith, former reporter, columnist, film critic, editor, Town Clerk and then fibromite and eventer with 5 conferences done and dusted. Interested in all health and well being issues, passionate about research to find a cure and cause for fibromyalgia. Member LinkedIn. Worked for 4 years with FMA UK as Regional Coordinator for SW and SE,and Chair for FMS SAS the Sussex and Surrey FM umbrella charity and Chair Folly Pogs Fibromyalgia Research UK - finding funding for our "cause for a cure" and President and co ordinator of National FM Conferences. Just finished last national annual Fibromyalgia Conference Weekend. This was another success with speakers from the States . Next year's conference in Chichester Park Hotel, West Sussex, will be April 24/27 2015 and bookings are coming in from those who raved about the event every year. I am very busy but happy to produce articles for publication. News Editor of FMS Global News on line but a bit behind due to conference. A workaholic beyond redemption! The future - who knows? Open to offers with payment. Versatile and looking for a regular paid column - you call the tune and I will play the pipes.
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