JWST finds neutron star in remnant of SN1987a, last naked-eye supernova

The 1987a supernova left behind a neutron star and the JWST has finally found it, giving astronomers the best chance to investigate the early days of this astronomical phenomenon. While older supernova remnants in our own galaxy provide much better opportunities to study matter in its most extreme form, this helps build a picture of the explosion for which we have the most detailed data.

Supernovae formed by the death of giant stars produce neutron stars or black holes, depending on the mass and composition of their precursor. In 1987, for the first time, we had archival images of the progenitor star before the explosion, and the estimated mass indicated that a neutron star was more likely. The length of the neutrino burst that accompanied the explosion – and transformed our knowledge of these cryptic particles – also favored a neutron star.

Astronomers have been searching for this historic object ever since, but have found only indirect evidence in the form of a pulsar wind nebula, which some neutron stars create. The JWST has changed that, according to newly published research.

The gas and dust clouds thrown off by SN 1987a have been a popular target for southern sky telescopes since the event. JWST joined shortly after operations began, revealing the keyhole and rings at infrared wavelengths. Crescent-shaped structures not previously seen were also found, along with clues that raised hopes of discovering the neutron star itself.

Now a team, including Professor Mike Barlow of University College London, has detected emission lines of highly ionized argon and sulfur in those observations. Although the radiation from these gases does not come from the object itself, it indicates that they are illuminated by a source of X-rays and ultraviolet light. Neutron stars have two processes that allow them to produce this kind of high-energy radiation, but black holes have none.

“This radiation could be emitted from the million-degree surface of the hot neutron star, but also from a pulsar wind nebula that could have been created as the neutron star spins rapidly, dragging charged particles around it,” Barlow said in a statement. . Responsible regulation will be a priority in the future.

Finding the neutron stars in supernova remnants can be challenging; Before they die, the stars that go supernova often shed enormous amounts of material that can hide what’s happening in the core. In the case of 1987a, this is further complicated by an equatorial ring, thought to be made up of material thrown out 20,000 years ago when the star that became 1987a swallowed a companion.

Some of the ejected particles from the 1987a precursor collided with the equatorial ring at such a high speed that it created X-rays. Previous observations had picked up radiation from X-ray illuminated argon, but could not determine whether these came from the suspected collisions with the neutron star or from collisions with the equatorial ring.

The excellent resolution of the JWST has changed this, revealing a component whose distribution and blueshift show that it emanates from the center of the remnant. It is also significant that only argon and sulfur were detected in this way. Both are produced by the fusion of oxygen and silicon and are therefore found in the inner core of supernova ejecta, as they are produced very late in the pre-supernova process. From our perspective, if we want these gases to be illuminated by something behind them, the source must be at the heart of the remnant.

The amount of blue shift in the emission lines indicates that the neutron star has experienced a ‘natal kick’. This is a common phenomenon with black holes and neutron stars, keeping them in motion compared to the average of the surrounding material.

The study was published in the journal Science.

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