Swift J1818.0-1617 is located about 22,000 light-years away in the constellation Sagittarius.
Swift J1818.0-1617, discovered in 2020, rotates with a rotation period of 1.36 seconds and is thought to be the fastest rotating magnetar yet discovered.
The star is located on the opposite side of the Milky Way galaxy's bulge, 22,000 light-years away, making it relatively close to Earth.
In fact, it's so close that we can use parallax to pinpoint its 3D location within the galaxy.
The lifespan of magnetars is currently unknown, but astronomers estimate that Swift J1818.0-1617 is only a few hundred years old.
“A magnetar's bright X-ray emission requires a mechanism of extremely high-energy outflow. Only the rapid decay of its powerful magnetic field can explain the force behind these spectral features,” said Dr. Hao Ding, an astronomer at the National Astronomical Observatory of Japan, and his colleagues.
“But again, this is an extreme process: for normal stars on the main sequence, bright blue stars burn through their fuel much faster than yellow stars, and therefore have very short lifetimes.”
“In the case of magnetars, although the physics are different, their lifetimes are also thought to be shorter than those of pulsars.”
“Magnetars are too young to continue releasing energy at this rate for long periods of time,” the researchers added.
“Moreover, magnetars can also exhibit radiation in the lower end of the electromagnetic spectrum, i.e. at radio wavelengths.”
“In these cases, the most likely energy source is synchrotron radiation produced by the magnetar's rapid rotation.”
“In synchrotron radiation, the plasma surrounding the neutron star itself is so tightly attached to the surface of the star that it rotates at very close to the speed of light and produces radiation at radio wavelengths.”
Astronomers NSF's Very Long Baseline Array (VLBA) was conducted over a three-year period to collect data on the position and velocity of Swift J1818.0-1617.
“The VLBA provided excellent angular resolution to measure this extremely small disparity, and the spatial resolution is unmatched,” said Dr Ding.
Swift J1818.0-1617's parallax is the smallest of any neutron star, and its so-called transverse velocity is the smallest of any magnetar (a new lower limit).
“Velocity in astronomy can be most simply described as having two components: direction and velocity,” the researchers explained.
“Radial velocity tells us how fast we're moving along the line of sight. In this case, radial velocity means the speed along the radius of the galaxy.”
“For magnetars like Swift J1818.0-1617, which are located on the opposite side of the central bulge, there is too much other material in the way to accurately measure the radial velocity.”
“Transverse velocity, sometimes called proper velocity, describes motion perpendicular to the galactic plane and is more easily identifiable.”
Astronomers are trying to understand the common (and different) formation processes between regular neutron stars, pulsars and magnetars, and hope to use precise measurements of the transverse velocities to analyse the conditions under which stars evolve along one of these three paths.
“This study adds weight to the theory that magnetars are unlikely to form under the same conditions as young pulsars, and suggests that magnetars are born from a more unconventional formation process,” Dr Ding said.
“We need to know how fast magnetars were moving when they were first born. The mechanism by which magnetars form is still a mystery, and we want to find out.”
Source: www.sci.news
