Astronomy and Space Science News Highlights
The Last Shuttle Launch for Discovery
The space shuttle Discovery safely lifted off from Cape Canaveral, Florida today at 4:53 p.m. EST. It’s on the way to the International Space Station for its 39th flight since the first launch of this orbiter in 1984. The crew members are accompanying a space station module, various spare parts and experiments, and will have the first human-like robot in space as part of the mission.
This is the last mission for space shuttle Discovery, capping a long career of safe access to space. The next launch, of space shuttle Endeavor, is scheduled for April 1. The final shuttle launch should occur in June, when Atlantis is lofted into orbit for a final space station run.
Planet Formation Caught in the Act?
About 330 years ago a massive star exploded and sent a burst of material out through space. That remnant material, called Cassiopeia A by astronomers, is rushing out from what’s left of the star — a highly dense object called a neutron star. Astronomers have been studying this neutron star for years, particularly with the Chandra X-ray Satellite. They’ve found that it is cooling off, which was unexpected. Two new papers by independent research teams show that this cooling is likely caused by a neutron superfluid forming in its central regions, the first direct evidence for this bizarre state of matter in the core of a neutron star.
The inset shows an artist’s impression of the neutron star at the center of Cas A. The different colored layers in the cutout region show the crust (orange), the core (red), where densities are much higher, and the part of the core where the neutrons are thought to be in a superfluid state (inner red ball). The blue rays emanating from the center of the star represent the copious numbers of neutrinos — nearly massless, weakly interacting particles — that are created as the core temperature falls below a critical level and a neutron superfluid is formed, a process that began about 100 years ago as observed from Earth. These neutrinos escape from the star, taking energy with them and causing the star to cool much more rapidly.
This new research has allowed the teams to place the first observational constraints on a range of properties of superfluid material in neutron stars. The critical temperature was constrained to between one half a billion to just under a billion degrees Celsius. A wide region of the neutron star is expected to be forming a neutron superfluid as observed now, and to fully explain the rapid cooling, the protons in the neutron star must have formed a superfluid even earlier after the explosion. Because they are charged particles, the protons also form a superconductor.
Using a model that has been constrained by the Chandra observations, the future behavior of the neutron star has been predicted . The rapid cooling is expected to continue for a few decades and then it should slow down.