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Astronomy and Space Science News Highlights

The Last Shuttle Launch for Discovery

Launch! Courtesy NASA TV.

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?

This artist’s impression shows the disc around the young star T Cha. Using ESO’s Very Large Telescope this disc has been found to be in two parts, a narrow ring close to the star and the remainder of the disc material much further out. A companion object, seen in the foreground, has been detected in the gap in the disc that may be either a brown dwarf or a large planet. The inner dust disc is lost in the glare of the star on this picture. Credit: ESO/L. Calçada

Astronomers using the Very Large Telescope in Chile, part of the European Southern Observatory, have been studying a disk of material around a very young star called T Chamaeleontis (or T Cha, for short), a faint star in the southern constellation of Chamaeleon. The disk may be in the process of forming a planetary system, and hidden inside that disk is a very small object that appears to be clearing out an orbital path through the dust and gas. T Cha lies about 350 light-years from the Earth and is only about seven million years old. Until this study, no forming planets have been found in a disk like this one (referred to as a “transitional disk”, while planets have been found in older more mature disks.This is the first such detection of an object much smaller than a star within a gap in the planet-forming dust disk around a young star. Now, astronomers must figure out what the object is. The evidence suggests that the companion object cannot be a normal star, but it could be either a brown dwarf surrounded. The evidence is also tantalizing that it could be a recently formed planet. If so, then, astronomers have caught the process of planetary formation very early in the act.

How Kleopatra Got Its Moons

The process of planetary formation also includes such actions as the capture of smaller objects by larger ones. Mars got its two moons that way, as did many of the planets in the outer solar system. Asteroids, too, capture moons — as evidenced by the discovery of the existence of two tiny objects orbiting the asteroid Kleopatra. This week, a team of French and American astronomers reported the discovery and also confirmed earlier reports that the asteroid is shaped like a dog bone.

The team’s detailed study of the asteroid using small telescopes as well as the large Keck II telescope in Hawaii allowed it to determine the precise orbits of the twin moons and calculate the density of Kleopatra, showing that the asteroid is probably a big pile of rock and metal rubble. Read more about this discovery and the followup research here.

Strange States of Matter at the Heart of a Neutron Star

This composite image shows a beautiful X-ray and optical view of Cassiopeia A (Cas A), a supernova remnant located in our Galaxy about 11,000 light years away. These are the remains of a massive star that exploded about 330 years ago, as measured in Earth's time frame. X-rays from Chandra are shown in red, green and blue along with optical data from Hubble in gold. Courtesy Chandra X-ray Satellite.

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.

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August 2015
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