Sent: 2/6/2013 6:51:23 P.M. Eastern Standard Time
Subj: The Daily Galaxy: News from Planet Earth & Beyond
_The Daily Galaxy: News from Planet Earth & Beyond_
_Strange 'Ist-of-Its-Kind' Galaxy --"Reveals Clues to Evolution of the
Posted: 06 Feb 2013 08:33 AM PST
A unique galaxy, dubbed Speca by its discoverers, holds clues to the
evolution of galaxies billions of years ago. The galaxy has a combination of
characteristics never seen before, giving astronomers a tantalizing peek at
processes they believe played key roles in the growth of galaxies and
_clusters of galaxies_ (http://en.wikipedia.org/wiki/Galaxy_groups_and_clusters)
early in the history of the Universe.
The galaxy is only the second spiral, as opposed to elliptical, galaxy
known to produce large, powerful jets of subatomic particles moving at nearly
the speed of light. It also is one of only two galaxies to show that such
activity occurred in three separate episodes.
Giant jets of superfast particles are powered by supermassive black holes
at the cores of galaxies. Both elliptical and spiral galaxies harbor such
black holes, but only Speca and one other spiral galaxy have been seen to
produce large jets. The jets pour outward from the poles of rapidly-rotating
disks of material orbiting the black hole. The on-and-off jet episodes have
been seen in a dozen ellipticals, but only one other elliptical shows
evidence, like Speca, for three such distinct episodes.
"This is probably the most exotic galaxy with a black hole ever seen. It
has the potential to teach us new lessons about how galaxies and clusters of
galaxies formed and developed into what we see today," said Ananda Hota,
of the Academia Sinica Institute of Astronomy and Astrophysics, in Taiwan.
The scientists believe that Speca, about 1.7 billion light-years from
Earth, and the 60-some other galaxies in a cluster with it are providing a look
at what young galaxies and clusters may have been like when the Universe
was much younger. In the young Universe, galaxies in such clusters would
have been gathering up additional material, colliding with each other,
undergoing bursts of star formation, and interacting with primordial material
falling into the cluster from outside.
"Speca is showing evidence for many of these phenomena," Ananda said,
adding that "We hope to find many more galaxies like it with future
observations, and to learn more about the processes and an environment that were much
more common when the Universe was a fraction of its current age."
Speca (an acronym for Spiral-host Episodic radio galaxy tracing _Cluster_
Accretion) first came to
Ananda's attention in an image that combined data from the visible-light _Sloan
Digital Sky Survey_ (http://en.wikipedia.org/wiki/Sloan_Digital_Sky_Survey)
and the FIRST survey done with the _National Science Foundation's_
_Very Large Array_
(Very%20Large%20Array)&t=h) (VLA) radio telescope. Followup observations with the
Lulin optical telescope in Taiwan and ultraviolet data from NASA's GALEX
satellite confirmed that the giant lobes of radio emission, usually seen coming
from elliptical galaxies, were coming from a spiral galaxy with ongoing
Ananda's team also examined the galaxy in images from the _NRAO VLA Sky
(NVSS), then made
new observations with the _Giant Meterwave Radio Telescope (GMRT)_
667,74.0497416667 (Giant%20Metrewave%20Radio%20Telescope)&t=h) in India,
which observes at longer wavelengths than the VLA and is the premier
telescope for observing at those long wavelengths.
With this impressive variety of data from across the electromagnetic
spectrum, the researchers unraveled the galaxy's complex and fascinating
The radio images from the VLA FIRST survey had shown one pair of
radio-emitting lobes. The VLA's NVSS images showed another, distinct pair of lobes
farther from the galaxy. The GMRT images confirmed this second pair, but
showed another, smaller pair close to the galaxy, presumably produced by the
most-recently ejected jet particles.
"By using these multiple sets of data, we found clear evidence for three
distinct epochs of jet activity," Ananda explained.
The biggest surprise -- the low-frequency nature of the oldest, outermost
lobes -- gave a valuable clue about the galaxy's -- and the cluster's --
environment. The outermost radio-emitting lobes are old enough that their
particles should have lost most of their energy and ceased to produce radio
"We think these old, relic lobes have been 're-lighted' by shock waves
from rapidly-moving material falling into the cluster of galaxies as the
cluster continues to accrete matter," said Ananda.
"All these phenomena combined in one galaxy make Speca and its neighbors a
valuable laboratory for studying how galaxies and clusters evolved
billions of years ago," Ananda said.
"The ongoing low-frequency TIFR GMRT Sky Survey will find many more relic
radio lobes of past black hole activity and energetic phenomena in clusters
of galaxies like those we found in Speca," said Sandeep K. Sirothia of
India's _National Centre for Radio Astrophysics_
(National%20Centre%20for%20Radio%20Astrophysics)&t=h) , _Tata Institute of Fundamental Research_
Composite image of Speca below : Optical SDSS image of the galaxies in
yellow,low resolution radio image from NVSS in blue, high resolution radio
image from GMRT in red.
More information: Original Research Paper: NGC 3801 caught in the act: A
post-merger starforming early-type galaxy with AGN-jet feedback.
The Daily Galaxy via _nrao.edu_ (http://www.nrao.edu/)
_Black Holes of the Universe
Growing Faster than Previously Thought_
) _Outburst from Enormous Black Hole 11-Billion Years Ago Swept Past Earth
in 2011 --"Brighter than All the Stars in Milky Way"_
Awed by Colossal Galaxy Outburst 10-Times Brighter than Largest Supernova_
Spiral Galaxy in the Universe Confirmed --FiveTimes Size of the Milky Way_
_Jupiter's Dissolving Core Sheds Light on Alien Planets_
Posted: 06 Feb 2013 08:23 AM PST
In March of 2012, scientists unlocked evidence that _Jupiter's_
core has been dissolving, and the implications
reach far outside of our solar system. This new data may help to explain a
puzzling discovery of a strange exo-planet. The planet, _CoRoT_
-20b, was announced in February, and its discoverers
searched for a suitable explanation for its unusual density. Using
conventional models, the astronomers calculated that the core would have to make up
over half of the planet. For comparison, Jupiter's core only represents
about between 3-15 percent of the planet’s total mass.
"It's a really important piece of the puzzle of trying to figure out
what's going on inside giant planets," said Jonathan Fortney, a planetary
scientist at the _University of California Santa Cruz_
(University%20of%20California,%20Santa%20Cruz)&t=h) who was not affiliated with the research.
Conventional planetary formation theory has modeled Jupiter as a set of
neat layers with a gassy outer envelope surrounding a rocky core consisting
of heavier elements. But increasing evidence has indicated that the insides
of gas giants like Jupiter are a messy mixture of elements without strictly
This new research on a melting _Jovian_
core bolsters a mixing model of gas giant planets and would provide
another avenue for heavier elements to flow throughout the planet.
"People have been working on the assumption that these planets are layered
because it's easier to work on this assumption," said _Hugh Wilson_
planetary scientist at the _University of California Berkeley_
(University%20of%20California,%20Berkeley)&t=h) and a coauthor of the new research
appearing in _Physical Review Letters_ (http://prl.aps.org/)
. Although scientists
had previously toyed with the idea of melting cores in large planets,
nobody sat down and did the necessary calculations, said Wilson.
Scientists have to rely on calculations of Jupiter's core environment
because the conditions there are far too extreme to recreate on Earth. Wilson
and his UC-Berkeley colleague Burkhard Militzer used a computer program to
simulate temperatures exceeding 7,000 degrees Celsius and pressures reaching
40 million times the air pressure found on Earth at sea level.
Those conditions are thought to be underestimates of the actual conditions
inside Jupiter’s core. Nonetheless, the authors found that magnesium oxide
-- an important compound likely found in Jupiter's core -- would liquefy
and begin drifting into Jupiter's fluid upper envelope under these
relatively tame conditions.
Researchers believe that similarly-sized gas giant exoplanets -- planets
found outside of our solar system -- probably have similar internal
structures to Jupiter. Consequently, scientists were baffled earlier this year when
they found a planet with approximately the same volume as Jupiter yet four
to five times more mass.
CoRoT-20b's core presented a huge problem for traditional assumptions
surrounding planet formation. "It's much easier to explain the composition of
this planet under a model where you have a mixed interior," said Wilson.
Even the team that discovered the planet noted that a mixing model could
allow for a more palatable planet density. Wilson's simulations not only add
credence to the mixing model of giant planets but also suggest that this
specific exoplanet's core is probably melting just like Jupiter's.This
melting may help explain why the exoplanet's heavy elements are likely stirred
up and distributed throughout its volume, said Wilson.
Santa Cruz's Fortney agrees that most of the exoplanet's heavy elements
likely reside in the outer envelope. Nonetheless, he expects other factors
played a larger role in how the planet's interior became mixed: "It's more of
a planet formation issue."
Several other events, such as two gas giants colliding together, might
explain the ultra-high density of this new planet, Wilson admits. Certain
processes may also limit the effectiveness of the melting and mixing process.
Liquefied parts of a gas giant's core may have trouble reaching the outer
envelope due to double diffusive convection -- a process commonly found in
Earth's oceans. When salty water accumulates at the bottom of the ocean,
its density keeps it from mixing thoroughly with the upper layers. In a
similar fashion, the heavy elements in Jupiter's core may have trouble gaining
enough energy to move upward and outward.
Scientists don't know how much this hindrance will affect potential mixing
inside Jupiter, and many other questions remain to be answered about the
"The next question is, 'How efficient is this process?'" said Fortney.
Researchers will have more tools to answer this question once NASA's _Juno
Jupiter in 2016. With the spacecraft's instruments carefully analyzing
Jupiter's composition, Wilson believes that there will be signatures of mixing
and core erosion.
The Daily Galaxy via _Inside Science News Service_
Image courtesy of NASA/JPL
_"Did Life First
Appear on Alien Worlds 12-13 Billion Years Ago?" --Ask Leading
_Fifteen New Planets
Discovered in Habitable Zones --"Earth-sized Moons Prime Candidates"_
Known Alien Planets - Born at Dawn of Universe 8-Billion Years Earlier than
Found to Occur Beyond Our Solar System --Could Provide Clues to Alien Planets_
_"No Jupiter, No Advanced Life? " ('2012 Most
_Super-Earths are more like mini-Neptunes_
_Astrophotos: Jupiter and the Moon Conjunction_
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