Category Astronomy/Space

Neutron star. Credit: NASA

A team of scientists from The Hebrew University of Jerusalem suggests a solution to the Galactic radioactive plutonium puzzle. All the Plutonium used on Earth is artificially produced in nuclear reactors. Still, it turns out that it is also produced in nature. “The origin of heavy elements produced in nature through rapid neutron capture (‘r-process’) by seed nuclei is one of the current nucleosynthesis mysteries,” Dr Hotokezaka, Prof Piran and Prof Paul from the Racah Institute of Physics at the Hebrew University of Jerusalem said in their letter. Plutonium is a radioactive element. Its longest-lived isotope is plutonium-244 with a lifetime of 120 million years.

Detection of plutonium-244 in nature would imply that the element was synthesized in astrophysical ph...

An optical image of the galaxy Messier 51 with the insert showing the location of supernova SN2011dh. Using precise radio imaging techniques, astronomers have determined the size of the shock around this supernovae, and estimated its outward velocity. Credit: Rafael Ferrando, Observatory Pla D’arguines Read more at: http://phys.org/news/2015-12-imaging-supernova-shell.html#jCp

Supernovae, the explosive deaths of massive stars, are among the most momentous events in the cosmos because they disburse into space all of the chemical elements that were produced inside their progenitor stars, including the elements essential for making planets and life. Their bright emission also enables them to be used as probes of the very distant universe...

Calibrator sources have flat radio spectra. Molecules in the intervening gas clouds absorb radio waves at specific frequencies determined by the type of molecules. Credit: R. Ando (The University of Tokyo), ESO/José Francisco Salgado

Astronomers using ALMA have discovered the most tenuous molecular gas ever observed. They detected the absorption of radio waves by gas clouds in front of bright radio sources. This radio shadow revealed the composition and conditions of diffuse gas in the Milky Way galaxy.

To calibrate its systems, ALMA looks at objects emitting strong radio waves (radio ‘bright’ objects). On rare occasions, the signals from distant calibrator sources have specific radio frequencies absorbed out of them by foreground gas...

The Mountainous Shoreline of Sputnik Planum: In this highest-resolution image from NASA’s New Horizons spacecraft, great blocks of Pluto’s water-ice crust appear jammed together in the informally named al-Idrisi mountains. “The mountains bordering Sputnik Planum are absolutely stunning at this resolution,” said New Horizons science team member John Spencer of the Southwest Research Institute. “The new details revealed here, particularly the crumpled ridges in the rubbly material surrounding several of the mountains, reinforce our earlier impression that the mountains are huge ice blocks that have been jostled and tumbled and somehow transported to their present locations.” Credit: NASA/JHUAPL/SwRI

These Pluto images are the best close-ups  that humans may see for decades...