Archive

Archive for July, 2013

ALMA Sheds Light On Mystery Of Missing Massive Galaxies


Three-dimensional view of ALMA observations. Credit: ALMA (ESO / NAOJ / NRAO) / Erik Rosolowsky

Three-dimensional view of ALMA observations. Credit: ALMA (ESO / NAOJ / NRAO) / Erik Rosolowsky

Galaxies — systems like our own Milky Way that contain up to hundreds of billions of stars — are the basic building blocks of the cosmos. One ambitious goal of contemporary astronomy is to understand the ways in which galaxies grow and evolve, a key question being star formation: what determines the number of new stars that will form in a galaxy?

The Sculptor Galaxy, also known as NGC 253, is a spiral galaxy located in the southern constellation of Sculptor. At a distance of around 11.5 million light-years from our Solar System it is one of our closer intergalactic neighbours, and one of the closest starburst galaxies visible from the southern hemisphere. Using the Atacama Large Millimeter/submillimeter Array (ALMA) astronomers have discovered billowing columns of cold, dense gas fleeing from the centre of the galactic disc.

“With ALMA’s superb resolution and sensitivity, we can clearly see for the first time massive concentrations of cold gas being jettisoned by expanding shells of intense pressure created by young stars,” said Alberto Bolatto of the University of Maryland, USA lead author of the paper. “The amount of gas we measure gives us very good evidence that some growing galaxies spew out more gas than they take in. We may be seeing a present-day example of a very common occurrence in the early Universe.”

Full Story: http://www.eso.org/public/news/eso1334/
Also: http://www.nrao.edu/pr/2013/starburst-bust/
Also: http://www.mpia.de/Public/menu_q2.php?Aktuelles/PR/2013/PR_2013_06/PR_2013_06_en.html

Starburst Wind Keeps Galaxies ‘Thin’


Unlike humans, galaxies don’t have an obesity problem. In fact there are far fewer galaxies at the most massive end of the galactic scale than expected and scientists have long sought to explain why. A new, UMD-led study published in the journal Nature suggests that one answer lies in a kind of feast and fast sequence through which large galaxies can keep their mass down.

Galaxies become more massive by ‘consuming’ vast clouds of gas and turning them into new stars. The new study shows in unprecedented detail how a burst of star formation in a galaxy can blow most of the remaining star-building gas out to the edge of the galaxy, resulting in a long period of starvation during which few new stars are produced.

“For the first time, we can clearly see massive concentrations of cold molecular gas being jettisoned by expanding shells of intense pressure created by young stars,” says lead author Alberto Bolatto of the University of Maryland. “The amount of gas we measure gives us very convincing evidence that some growing galaxies blow out more gas than they take in, slowing star formation down to a crawl.”

Full Story: http://umdrightnow.umd.edu/news/starburst-wind-keeps-galaxies-%E2%80%98thin%E2%80%99

Solar System’s Youth Gives Clues To Planet Search


Disk isotopes modeling results. Image courtesy of Alan Boss

Disk isotopes modeling results. Image courtesy of Alan Boss

Comets and meteorites contain clues to our solar system’s earliest days. But some of the findings are puzzle pieces that don’t seem to fit well together. A new set of theoretical models from Carnegie’s Alan Boss shows how an outburst event in the Sun’s formative years could explain some of this disparate evidence. His work could have implications for the hunt for habitable planets outside of our solar system. It is published by The Astrophysical Journal.

One way to study the solar system’s formative period is to look for samples of small crystalline particles that were formed at high temperatures but now exist in icy comets. Another is to analyze the traces of isotopes—versions of elements with the same number of protons, but a different number of neutrons—found in primitive meteorites. These isotopes decay and turn into different, so-called daughter, elements. The initial abundances of these isotopes tell researchers where the isotopes may have come from, and can give clues as to how they traveled around the early solar system.

Stars are surrounded by disks of rotating gas during the early stages of their lives. Observations of young stars that still have these gas disks demonstrate that sun-like stars undergo periodic bursts, lasting about 100 years each, during which mass is transferred from the disk to the young star.

Full Story: https://carnegiescience.edu/news/solar_system%E2%80%99s_youth_gives_clues_planet_search

Ancient Snowfall Likely Carved Martian Valleys


Credit: Image from NASA

Credit: Image from NASA

Valley networks branching across the Martian surface leave little doubt that water once flowed on the Red Planet. But where that ancient water came from — whether it bubbled up from underground or fell as rain or snow — is still debated by scientists. A new study by researchers at Brown University puts a new check mark in the precipitation column.

The study finds that water-carved valleys at four different locations on Mars appear to have been caused by runoff from orographic precipitation — snow or rain that falls when moist prevailing winds are pushed upward by mountain ridges. The new findings are the most detailed evidence yet of an orographic effect on ancient Mars and could shed new light on the planet’s early climate and atmosphere.

Full Story: http://news.brown.edu/pressreleases/2013/07/snow

NASA’s Spitzer Observes Gas Emission From Comet ISON


Image credit: NASA/JPL-Caltech/JHUAPL/UCF

Image credit: NASA/JPL-Caltech/JHUAPL/UCF

Astronomers using NASA’s Spitzer Space Telescope have observed what most likely are strong carbon dioxide emissions from Comet ISON ahead of its anticipated pass through the inner solar system later this year.

Images captured June 13 with Spitzer’s Infrared Array Camera indicate carbon dioxide is slowly and steadily “fizzing” away from the so-called “soda-pop comet,” along with dust, in a tail about 186,400 miles (300,000 kilometers) long.

“We estimate ISON is emitting about 2.2 million pounds (1 million kilograms) of what is most likely carbon dioxide gas and about 120 million pounds (54.4 million kilograms) of dust every day,” said Carey Lisse, leader of NASA’s Comet ISON Observation Campaign and a senior research scientist at the Johns Hopkins University Applied Physics Laboratory in Laurel, Md. “Previous observations made by NASA’s Hubble Space Telescope and the Swift Gamma-Ray Burst Mission and Deep Impact spacecraft gave us only upper limits for any gas emission from ISON. Thanks to Spitzer, we now know for sure the comet’s distant activity has been powered by gas.”

Full Story: http://www.jpl.nasa.gov/news/news.php?release=2013-231

Team Led By University Of Leicester Sets New Record For Cosmic X-Ray Sightings


Scientists led by the University of Leicester have set a new record for cosmic X-ray sources ever sighted – creating an unprecedented cosmic X-ray catalogue that will provide a valuable resource allowing astronomers to explore the extreme Universe.

The XMM-Newton Survey Science Centre, led by a team from the University of Leicester’s Department of Physics and Astronomy, used the University’s ‘ALICE’ supercomputer to help them produce a new X-ray catalogue, dubbed “3XMM”.

This new catalogue contains over half a million X-ray source detections, representing a 50% increase over previous catalogues and is the largest catalogue of X-ray sources ever produced. This vast inventory is also home to some of the rarest and most extreme phenomena in the Universe, such as tidal disruption events – when a black hole swallows another star, producing prodigious outbursts of X-ray emission.

Full Story: http://www2.le.ac.uk/offices/press/press-releases/2013/july/team-led-by-university-of-leicester-sets-new-record-for-cosmic-x-ray-sightings

Pawsey Powerhouse Supercomputer Crunches Pre-SKA Data Torrent


High-performance computing specialists from Perth’s International Centre for Radio Astronomy Research (ICRAR) today became the first users of one of Australia’s leading supercomputing facilities – the Pawsey Centre – ahead of its official opening later this year.

The recent launch of the Murchison Widefield Array (MWA) – a radio telescope based in Western Australia’s Mid West – marked the start of an impressive flow of astronomical data that will be stored in the iVEC-managed Pawsey Centre in Kensington for later use by researchers around the world.

“We now have more than 400 megabytes per second of MWA data streaming along the National Broadband Network from the desert 800km away,” said Professor Andreas Wicenec, from The University of Western Australia node of ICRAR.

“To store the Big Data the MWA produces, you’d need almost three 1TB hard drives every two hours,” said Prof Wicenec. “The technical challenge isn’t just in saving the observations but how you then distribute them to astronomers from the MWA team in far-flung places so they can start using it.”

Full Story: http://www.icrar.org/news/news_items/pawsey-powerhouse-supercomputer-crunches-pre-ska-big-data

UK Researchers Make New Discovery About Neutrinos, Bringing Us One Step Closer To Perhaps Solving One Of The Biggest Mysteries In Fundamental Physics


International research including the UK and Japan has confirmed that subatomic particles called neutrinos have a new form of identity-shifting property. Announced today (19 July 2013) these results could one day help scientists explain why the universe contains matter but very little antimatter.

Dr Alfons Weber, Professor of Physics at STFC and the University of Oxford is one of many scientists in the UK working on T2K – he designed the electronics for the experiment. He explains: “The UK particle physics community was one of the driving forces behind this experiment. We not only provided part of the detector that characterises the beam, but also designed the target that produces the neutrinos in the first place. The long years of hard work have now come to fruition.

“Our findings now open the possibility to study this process for neutrinos and their antimatter partners, the anti-neutrinos. A difference in the rate of electron or anti-electron neutrino being produced may lead us to understand why there is so much more matter than antimatter in the universe. The neutrino may be the very reason we are here.”

Full Story: http://www.stfc.ac.uk/2802.aspx

Two Suns Are Probably Better Than One, Or Not?


An International Collaboration of FACom researchers and Astronomers of the University of Texas (El Paso) and New Mexico State University, have discovered a physical mechanism that could make binary stars more hospitable to habitable planets than single stars. The discovery could imply a modification in the estimations of the number of planets potentially harboring life in the Galaxy and in the future selection of targets for the search of life elsewhere.

Habitability is the term astronomers use for referring to the general condition a planet must fulfill in order to be suitable for life. It has been customary to think that habitability is determined mainly by the amount of light a planet receives from its host star. If the planet receives too much light it is too hot and water will be boiling in its atmosphere (if it has one!). On the other hand, if the planet is too far and light from the star shines weakly, the surface is too cold and water becomes frozen. In the middle between these extremes lies the so called “radiative habitable zone” also nicknamed the “Goldilocks Zone”.

But planets in the Goldilocks Zone need to meet other conditions to be considered actually habitable. One of the most important is having a dense and wet atmosphere where heat could be trapped and water could condensate at the surface. But preseving an atmosphere is a real challenge for a young planet.

Full Story: http://urania.udea.edu.co/sitios/facom/press.php?

Snow Falling around Infant Solar System: Icy Region Gives Planet And Comet Formation A Boost


ALMA image of CO snow line. Credit: Karin Oberg, Harvard/University of Virginia

ALMA image of CO snow line. Credit: Karin Oberg, Harvard/University of Virginia

The sight of a snowfall can thrill children, but the first-ever snow line seen around a distant star gives astronomers an even greater thrill because of what it reveals about the formation of planets and our Solar System’s history.

Astronomers using the new Atacama Large Millimeter/submillimeter Array (ALMA) telescope have taken the first-ever image of a snow line in an infant solar system. This frosty landmark is thought to play an essential role in the formation and chemical make-up of planets around a young star.

On Earth, snow lines typically form at high elevations where falling temperatures turn atmospheric moisture to snow. In much the same way, snow lines are thought to form around young stars in the distant, colder reaches of the disks from which solar systems form. Depending on the distance from the star, however, other more exotic molecules can freeze and turn to snow.

“ALMA has given us the first real picture of a snow line around a young star, which is extremely exciting because of what it tells us about the very early period in the history of our own Solar System,” said Chunhua “Charlie” Qi, a researcher with the Harvard-Smithsonian Center for Astrophysics in Cambridge, Mass., who led the international research team with Karin Oberg, a researcher with Harvard University and the University of Virginia in Charlottesville.

Full Story:  http://www.nrao.edu/pr/2013/snowline/
Also: http://www.eso.org/public/news/eso1333/