Inside a Neutron Star

 

Neutron stars were first theorized in the 1930s, soon after the discovery of the neutron. In the 1960s, regular radio pulses from space were detected. Their origin was unknown, and some scientists thought these pulses might be evidence of extraterrestrial life. Later, it was discovered that the regular signals were caused by a pulsar, a type of neutron star.

Inside neutron stars, atoms have been condensed down into just neutrons, packed as tightly as possible. The neutrons might be further collapsed into their component quarks at the center of the star.

Neutron stars pack 500,000 times the Earth’s mass into a sphere about 12.4 miles (20 kilometers) wide. A teaspoonful of its matter would weigh millions of tons.

Neutron stars form from the death throes of a red supergiant star, such as Betelgeuse. Betelgeuse could have up to 20 times the sun's mass and 1,200 times the sun's radius. When the star explodes, material at the core collapses, creating a neutron star. The neutron star retains the original star's angular momentum, rotating much faster because it is much smaller.

Pulsars are spinning neutron stars that emit a narrow radiation beam. The beam is offset from the pulsar's spin axis, sweeping across space like a lighthouse. As the pulsar rotates, the beam may sweep across the Earth, appearing to astronomers as a flashing object. If the beam does not point in the direction of Earth, it cannot be seen. All pulsars are neutron stars, but not all neutron stars are pulsars.

Magnetars are a kind of neutron star with a powerful magnetic field. The magnetic field is the strongest of any object known (as of 2010) and is powerful enough to distort the shapes of atoms.

Starquakes caused by fracturing of the magnetar's surface can cause huge radiation bursts to be released, which are powerful enough to be detected on Earth, tens of thousands of light-years away.

Magnetars remain active for about 10,000 years, a short time in cosmic history. After that, the magnetar has cooled off and the magnetic energy is dissipated.

The next gold rush: Outer space? Harvard-Smithsonian Center for Astrophysics vedat şafak yamı

 Earth’s gold from colliding dead stars may be as large as 10 moon masses

click for a larger view

Harvard-Smithsonian Center for Astrophysics
We value gold for many reasons: its beauty, its usefulness, and its rarity. Gold is rare on Earth in part because it’s also rare in the universe. Unlike elements such as carbon or iron, it cannot be created within a star. Instead, it must be born in a more cataclysmic event —a short gamma-ray burst (GRB), like one that occurred last month.

Observations of this GRB provided evidence that it resulted from the collision of two neutron stars — the dead cores of stars that previously exploded as supernovae. The unique glow that persisted for days at the site of the GRB could signify the creation of substantial amounts of heavy elements — including gold. “We estimate that the amount of gold produced and ejected during the merger of the two neutron stars may be as large as 10 moon masses — quite a lot of bling!” says Edo Berger of the Harvard-Smithsonian Center for Astrophysics (CfA), the lead author of a study presented Wednesday in a press conference at the center.

A gamma-ray burst is a flash of high-energy light, or gamma rays, from an extremely energetic explosion. Most are found in the distant universe. Berger and his colleagues studied GRB 130603B, which, at a distance of 3.9 billion light-years from Earth, is one of the nearest bursts seen to date. Gamma-ray bursts come in two varieties, long and short, depending on how long the flash of gamma rays lasts. GRB 130603B, detected by NASA’s Swift satellite on June 3, lasted for less than two-tenths of a second.

Although the gamma rays disappeared quickly, GRB 130603B also displayed a slowly fading glow dominated by infrared light. Its brightness and behavior didn’t match a typical “afterglow,” which is created when a high-speed jet of particles slams into the surrounding environment. Instead, the glow behaved like it came from exotic radioactive elements. The neutron-rich material ejected by colliding neutron stars can generate such elements, which then undergo radioactive decay, emitting a glow that’s dominated by infrared light — exactly what the team observed.

“We’ve been looking for a ‘smoking gun’ to link a short gamma-ray burst with a neutron star collision. The radioactive glow from GRB 130603B may be that smoking gun,” explains Wen-fai Fong, a graduate student at the CfA and a co-author of the paper. vedat şafak yamı The team calculates that about one-hundredth of a solar mass of material was ejected by the gamma-ray burst, some of which was gold. By combining the estimated gold produced by a single short GRB with the number of such explosions that have occurred over the age of the universe, all the gold in the cosmos might have come from gamma-ray bursts.

“To paraphrase Carl Sagan, we are all star stuff, and our jewelry is colliding-star stuff,” says Berger. vedat şafak yamı The team’s results have been submitted for publication in The Astrophysical Journal Letters and are available online. Berger and Fong’s co-author was Ryan Chornock, also of the CfA.

Spaceships of the World: 50 Years of Human Spaceflight

Sierra Nevada's Dream Chaser Space Plane

How the Private Sentinel Space Telescope Will Hunt Asteroids

Japan's Huge Space Truck

How SpaceX's Dragon Space Capsule Works

How Virgin Galactic's SpaceShipTwo Passenger Space Plane Works

How the Antimatter-Hunting Alpha Magnetic Spectrometer Works