Archive

Archive for April 14, 2014

Beauty From Chaos


Copyright ESA/DLR/FU Berlin

Copyright ESA/DLR/FU Berlin

Beautiful streamlined islands and narrow gorges were carved by fast-flowing water pounding through a small, plateau region near the southeastern margin of the vast Vallis Marineris canyon system.

Images captured on 7 December 2013 by ESA’s Mars Express show the central portion of Osuga Valles, which has a total length of 164 km. It is some 170 km south of Eos Chaos, which lies in the far eastern section of Valles Marineris.

Osuga Valles is an outflow channel that emanates from a region of chaotic terrain at the edge of Eos Chaos to the west (top in the main images). Such landscape is dominated by randomly oriented and heavily eroded blocks of terrain. Another example is seen at the bottom of this scene, filling the 2.5 km-deep depression into which Osuga Valles empties.

Link To Full Story

Advertisements

Faraway Moon Or Faint Star? Possible Exomoon Found


Titan, Europa, Io and Phobos are just a few members of our solar system’s pantheon of moons. Are there are other moons out there, orbiting planets beyond our sun?

NASA-funded researchers have spotted the first signs of an “exomoon,” and though they say it’s impossible to confirm its presence, the finding is a tantalizing first step toward locating others. The discovery was made by watching a chance encounter of objects in our galaxy, which can be witnessed only once.

“We won’t have a chance to observe the exomoon candidate again,” said David Bennett of the University of Notre Dame, Ind., lead author of a new paper on the findings appearing in the Astrophysical Journal. “But we can expect more unexpected finds like this.”

The international study is led by the joint Japan-New Zealand-American Microlensing Observations in Astrophysics (MOA) and the Probing Lensing Anomalies NETwork (PLANET) programs, using telescopes in New Zealand and Tasmania. Their technique, called gravitational microlensing, takes advantage of chance alignments between stars. When a foreground star passes between us and a more distant star, the closer star can act like a magnifying glass to focus and brighten the light of the more distant one. These brightening events usually last about a month.

Link To Full Story

Supernova Cleans Up Its Surroundings


Credit: X-ray: NASA/CXC/Morehead State Univ / T.Pannuti et al.; Optical: DSS; Infrared: NASA/JPL-Caltech; Radio: NRAO/VLA / Argentinian Institute of Radioastronomy / G.Dubner

Credit: X-ray: NASA/CXC/Morehead State Univ / T.Pannuti et al.; Optical: DSS; Infrared: NASA/JPL-Caltech; Radio: NRAO/VLA / Argentinian Institute of Radioastronomy / G.Dubner

Supernovas are the spectacular ends to the lives of many massive stars. These explosions, which occur on average twice a century in the Milky Way, can produce enormous amounts of energy and be as bright as an entire galaxy. These events are also important because the remains of the shattered star are hurled into space. As this debris field – called a supernova remnant – expands, it carries the material it encounters along with it.

Astronomers have identified a supernova remnant that has several unusual properties. First, they found that this supernova remnant – known as G352.7-0.1 (or, G352 for short) – has swept up a remarkable amount of material, equivalent to about 45 times the mass of the Sun.

Another atypical trait of G352 is that it has a very different shape in radio data compared to that in X-rays. Most of the radio emission is shaped like an ellipse, contrasting with the X-ray emission that fills in the center of the radio ellipse.

A recent study suggests that, surprisingly, the X-ray emission in G352 is dominated by the hotter (about 30 million degrees Celsius) debris from the explosion, rather than cooler (about 2 million degrees) emission from surrounding material that has been swept up by the expanding shock wave. This is curious because astronomers estimate that G352 exploded about 2,200 years ago, and supernova remnants of this age usually produce X-rays that are dominated by swept-up material. Scientists are still trying to come up with an explanation for this behavior.

Link To Full Story

NASA’s Hubble Extends Stellar Tape Measure 10 Times Farther Into Space


Using NASA’s Hubble Space Telescope, astronomers now can precisely measure the distance of stars up to 10,000 light-years away — 10 times farther than previously possible.

Astronomers have developed yet another novel way to use the 24-year-old space telescope by employing a technique called spatial scanning, which dramatically improves Hubble’s accuracy for making angular measurements. The technique, when applied to the age-old method for gauging distances called astronomical parallax, extends Hubble’s tape measure 10 times farther into space.

“This new capability is expected to yield new insight into the nature of dark energy, a mysterious component of space that is pushing the universe apart at an ever-faster rate,” said Noble laureate Adam Riess of the Space Telescope Science Institute (STScI) in Baltimore, Md.

Parallax, a trigonometric technique, is the most reliable method for making astronomical distance measurements, and a practice long employed by land surveyors here on Earth. The diameter of Earth’s orbit is the base of a triangle and the star is the apex where the triangle’s sides meet. The lengths of the sides are calculated by accurately measuring the three angles of the resulting triangle.

Link To Full Story
Link To Another Story

Smallest Speed Jump Of Pulsar Caused By Billions Of Superfluid Vortices


Artist’s impression of a pulsar. Credit: NASA

Artist’s impression of a pulsar. Credit: NASA

A team of astronomers, including Danai Antonopoulou and Anna Watts from the University of Amsterdam, has discovered that sudden speed jumps in the rotational velocity of pulsars have a minimum size, and that they are caused not by the unpinning and displacement of just one sub-surface superfluid vortex, but by billions. This result is important to our understanding of the behavior of matter under extreme conditions, and has been published this week in the journal Monthly Notices of the Royal Astronomical Society.

Pulsars are rotating neutron stars – remnants of massive stars that end their lives in supernova explosions. They act like cosmic lighthouses whose beams sweep through the Universe. Their rotational velocity decreases in time, but can suddenly increase in rare events called glitches. These glitches are caused by the unpinning and displacement of vortices that connect the crust with the mixture of particles containing superfluid neutrons beneath the crust.
The team of astronomers discovered that the glitches of the Crab Pulsar always involve a decrease in the rotational period of at least 0.055 nanoseconds. The Crab Pulsar was one of the first pulsars to be discovered and has been observed almost daily with the 42-ft Telescope at the Jodrell Bank Observatory over the last 29 years. The huge amount of data makes this object the best choice to study glitches.

Link To Full Story