Giant Cosmic ‘Fart’ Makes Wobbling Zombie Star Flash Earth Repeatedly

A giant cosmic “fart” is making a wobbling zombie star repeatedly flash us, groundbreaking observations reveal. The universe has a new kind of burp to explain, and it comes from a star that is mostly dead.

BP Crucis is a binary system about 13,000 light-years from Earth. One side is a blue hypergiant called Wray 977, roughly 60 times larger than the sun. The other side is a neutron star, the collapsed remains of a star that exploded in a supernova, labeled GX 301-2. The neutron star is a pulsar, spinning fast enough to shoot out a wobbling beam of radiation, including X-rays, every 11 minutes.

GX 301-2 stands apart from most pulsars because it produces frequent X-ray flares, which cause its brightness to surge repeatedly rather than flash with regular timing. Scientists have long been uncertain about the cause behind these outbursts. That mystery has now been solved.

The Wind That Feeds the Flare

Massive stars such as Wray 977 release a single massive stream of ionized gas, known as a plume of plasma. This plume moves at roughly 335,000 mph (540,000 km/h). By contrast, stars burning hydrogen release streams of radiation and charged particles called stellar wind, while the sun’s version, the solar wind, triggers auroras near Earth’s poles.

GX 301-2 circles Wray 977 every 41.5 days. It passes through the wind plume when it gets closest to its partner, and that is when the flares happen. The strongest flares occur at closest approach. Researchers had long suspected the wind was the cause, but they lacked proof.

XRISM Captures the Plume

The new study, published Sept. 18 in the journal Science Advances, used the X-ray Imaging and Spectroscopy Mission (XRISM), a space telescope jointly operated by NASA and the Japan Aerospace Exploration Agency. Over a 16-hour observation period, XRISM captured highly detailed X-ray spectra showing “rapidly changing emission and absorption lines.” Those lines revealed how the plume ebbed and flowed around GX 301-2 as it passed through.

“We’ve never before seen clear indications of wind plasma falling onto a compact object,” study first author Roi Rahin, a researcher at the University of Maryland, Baltimore County (UMBC) and NASA’s Goddard Space Flight Center, said in a statement. “We can now test our understanding of these processes in much greater detail.”

According to study co-author Nazma Islam, an astronomer at the Manipal Centre for Natural Sciences in India who was formerly a researcher at UMBC and NASA Goddard, the observations were groundbreaking, and the analysis required particular thoroughness.

What the Burp Does

Once a sufficient amount of wind material builds up on the surface of the neutron star, the stellar corpse erupts in a violent blast. That sudden burst is what observers on Earth see as the bright flash. The researchers plan to employ XRISM to examine upcoming flaring episodes, so they can gain a clearer understanding of the connection between GX 301-2 and Wray 977’s windy stream.

The statement came from Brian Williams, XRISM project scientist at NASA Goddard, who said “The BP Crucis system is an ideal laboratory for studying wind-fed pulsar accretion,”. XRISM is “an ideal instrument for advancing our understanding of the processes involved.”.

This system functions as a natural laboratory for observing wind falling onto compact objects. Researchers have now obtained the first direct spectral proof of wind falling onto a compact object, which opens the door to studying similar systems in the future.

The comparison is simple:

Researchers say these findings represent the very first detection of such stellar material mixing with a neutron star, or with any other object of the same kind.

See the video the story is built around at Live Science.

astronomy · neutron star · pulsar · stellar wind · X-ray flare