Nearby Cluster Of Massive Stars Source For Earth’s Cosmic Rays

The majority of the cosmic rays coming at us on Earth from our galaxy originate from nearby clusters of massive stars, according to new observations from the Cosmic Ray Isotope Spectrometer (CRIS), an instrument aboard NASA’s Advanced Composition Explorer (ACE) spacecraft. In the 17 years CRIS has been in space, it detected about 300,000 galactic cosmic-ray nuclei of ordinary iron, but just 15 of the radioactive 60Fe. The distance from the galactic cosmic rays’ point of origin to Earth is limited by the survival of a very rare type of cosmic ray that acts like a miniature clock. [Read More]

Lone White Dwarf Star to blame for Supernova

With data from the Japan-led Suzaku X-ray satellite, astronomers have determined the pre-explosion mass of a white dwarf star that blew up thousands of years ago. The measurement strongly points to the explosion involving only a single white dwarf. This would rule out a well-established alternative scenario involving a pair of merging white dwarfs. According to lead researcher Hiroya Yamaguchi, an astrophysicist at NASA’s Goddard Space Flight Center: Supernova Remnant 3C 397 The researchers analyzed archival observations of a supernova remnant named 3C 397, which is located about 33,000 light-years away in the constellation Aquila. [Read More]

Core-Collapse Supernova Modelled in 3D

One possible outcome when a gigantic star collapses is a core-collapse supernova. Astronomers can tell what is happening on the surface of a star when it explodes in a supernova, but it is lots harder to know what process is going on inside the star at its core. Recently, two Caltech astrophysics demonstrated a three-dimensional model of a swiftly rotating star with a strong magnetic field undergoing the process of collapse and explosion. [Read More]

Gravitational Lensing Galaxy magnifies Type 1A Supernova

In the first example of strong gravitational lensing of a supernova, a galaxy that magnified a background, Type Ia supernova thirty-fold through gravitational lensing has been discovered, astronomers at Kavli IPMU announced. The team has additionally shown how such discoveries of supernovae of Type Ia (SNIa) can be made far more common than was formerly believed possible. SNIa seen through gravitational lenses can be used to make a direct measurement of the universe’s expansion rate, called the Hubble parameter, so this discovery could have a considerable influence on how cosmic expansion is studied in the future. [Read More]