The brightest star in the southern sky! A mysterious new celestial body was discovered in the Milky Way for the first time!

The deep and vast starry sky is filled with so many scientific mysteries, and human exploration has never stopped.

By analyzing the survey observation data of the Square Kilometer Array (SKA) low-frequency pilot telescope, Chinese and foreign astronomers discovered for the first time a new celestial body with an extremely strong magnetic field in the Milky Way, about 4,200 light-years away from the solar system.

On January 27, Nature published the collaborative research results of Zhang Xiang, assistant researcher at the Shanghai Astronomical Observatory of the Chinese Academy of Sciences, and Dr. Hurley-Walker of the International Radio Astronomy Research Center at Curtin University in Australia.

MWA discovered long-period transient sources.

The top image is of the transient source, and the bottom is a schematic diagram of the MWA antenna.

Image credit: International Centre for Radio Astronomy Research (ICRAR), Australia

Screenshot of the paper.

Breaking the silence of the “low-frequency radio sky”

The "high-frequency radio sky" (space observed in the high-frequency radio band) is bright with transient celestial bodies such as supernova explosions, gamma-ray bursts, and flares from black hole accretion disks, but the "low-frequency radio sky" is unusually quiet. However, this tranquility is being broken.

In early 2018, Zhang Xiang, Hurley-Walker and others discovered a compact transient source with abnormally slow periodic radiation by analyzing sky survey data from the Murchison Widefield Array (MWA), the SKA low-frequency pilot telescope in Australia.

"The astronomical community didn't know whether such long-period sources existed," Hurley-Walker said. "This time we detected a long-period transient source by accident. Studying such sources will help us fully understand the evolution and death of stars."

Discovering new “windows”

The research team did not find its counterpart in subsequent optical, infrared, and high-energy observations. Dispersion measurements of its radio pulses showed that this transient source is located in the Milky Way, about 4,200 light-years away from the solar system. Polarization measurements showed that the linear polarization degree of this transient source is about 90%.

According to Zhang Xiang, this temporary appearance originated in early 2018. Its burst period is about 18 minutes, which is 9 times longer than the longest known pulsar burst period. Each burst lasts 30-60 seconds, including short-time scale (<0.5 seconds). In more cases, a relatively smooth profile evolving in hours is observed. During the burst, it was one of the 30 brightest radio sources in the southern sky in the 150MHz band.

This discovery is the first time that humans have detected a long-period transient source in the galactic plane of the Milky Way, opening a new window for the search for low-frequency transient sources.

"If we can continue to detect more transient sources with similar characteristics and reveal their physical properties, it will mean that there is a class of long-period stars with ultra-strong magnetic fields in the Milky Way, which will help humans to fully understand the evolution and death of stars ," said Zhang Xiang.

Currently, the team is conducting a systematic search to discover more stars of this type and establish a large sample for statistical research to fill the gap in magnetar research.

Supporting SKA scientists around the world

MWA is the pilot device of the SKA low-frequency telescope, located at the Murchison Radio Astronomy Observatory (MRO) in Western Australia. China's participation in the MWA international cooperation will help cultivate a talent team for scientific data processing and scientific analysis research in my country, and prepare for future SKA1 scientific target research, SKA1 big data and the China SKA Regional Center.

"The difficulty of this study is that the amount of data is extremely large, and multiple supercomputers are involved in the calculation during the data processing." Zhang Xiang said, "The discovery of this transient source is due to the highly sensitive SKA low-frequency pilot radio telescope and the SKA computing cluster customized according to the characteristics of SKA data."

Zhang Xiang said that in the future he will continue to provide computing resources and technical support for the SKA pilot telescope's large-scale sky survey projects, helping SKA scientists around the world to produce more original results.

Related paper information:

https://doi.org/10.1038/s41586-021-04272-x

Comprehensive sources: Xinhuanet, Xinhua Viewpoint, China Science Daily, Shanghai Astronomical Observatory of the Chinese Academy of Sciences, etc.