Space News & Blog Articles

Magnetars are some of the most fascinating astronomical objects. One teaspoon of the stuff they are made out of would weigh almost one billion tons, and they have magnetic fields that are hundreds of millions of times more powerful than any magnetic that exists today on Earth. But we don’t know much about how they form. A new paper points to one possible source – mergers of neutron stars.

Neutron stars themselves are equally fascinating in their own right. In fact, magnetars are generally considered to be a specific form of neutron star, with the main difference being the strength of that magnetic field. There are thought to be about a billion neutron stars in the Milky Way, and some of them happen to come in binary pairs.

When they are gravitationally bound to one another, the stars enter a final dance of death, typically resulting in either a black hole or, potentially, one or both of them transforming into a magnetar. That process can take hundreds of millions of years to build up to a certain point when the actual explosion (or collapse) happens. But when it does, it’s spectacular, and a team of researchers thinks they found that that happened only a few weeks before they spotted it.

More accurately, it happened around 228 million years ago, which is how far away the galaxy it happened in is. However, the light from this spectacular event reached the sensors at Pan-STARRs only a few weeks before it started observing that patch of the sky. And what makes this magnetar stand out from all the others scientists have found is how fast it is spinning.

Typically, neutron stars rotate thousands of times per minute, making their period on the order of milliseconds. But the magnetars scientists have found are distinct in that their rotational time is much slower, typically only once every two to ten seconds. But GRB130310A, as the new magnetar is now known, has a rotational period of 80 milliseconds, putting it closer to the order of neutron stars than the typical magnetar.

When white dwarfs go wild, their planets suffer through the resulting chaos. The evidence shows up later in and around the dying star’s atmosphere after it gobbles up planetary and cometary debris. That’s the conclusion a team of UCLA astronomers came to after studying the nearby white dwarf G238-44 in great detail. They found a case of cosmic cannibalism at this dying star, which lies about 86 light-years from Earth.

If that star were in the place of our Sun, it would ingest the remains of planets, asteroids, and comets out to the Kuiper Belt. That expansive buffet makes this stellar cannibalism act one of the most widespread ever seen.

“We have never seen both of these kinds of objects accreting onto a white dwarf at the same time,” said lead researcher Ted Johnson, a physics and astronomy graduate of UCLA. “By studying these white dwarfs, we hope to gain a better understanding of planetary systems that are still intact.”

An artist’s view of a white dwarf siphoning off debris from shattered worlds in its planetary system. Courtesy NASA/ESA, Joseph Olmstead (STScI)

Finding Evidence of Chaos at a Dying Star

Johnson was part of a team from UCLA, UC San Diego, and the University of Kiel in Germany working to study chemical elements detected in and around the white dwarf atmosphere. They used data from NASA’s retired Far Ultraviolet Spectroscopic Explorer, the Keck Observatory’s High-Resolution Echelle Spectrometer in Hawaii, and the Hubble Space Telescope’s Cosmic Origins Spectrograph and Space Telescope Imaging Spectrograph. The team found and measured the presence of nitrogen, oxygen, magnesium, silicon, and iron, as well as other elements.