Astronomers spot rare sight of astral winds blowing across neutron star

By Mark Waghorn via SWNS

Astronomers have glimpsed mighty winds blowing across a neutron star - the densest object in the universe.

The collapsed sun is ripping up its companion in a binary system on the other side of the Milky Way.

It provides a unique look at the properties and behavior of these mysterious entities.

Lead author Dr. Noel Castro Segura, of Southampton University, said: "Eruptions like this are rare, and each of them is unique.

"Normally they are heavily obscured by interstellar dust, which makes observing them really difficult.

"Swift J1858 was special because even though it is located on the other side of our galaxy, the obscuration was small enough to allow for a full multiwavelength study."

The phenomenon was spotted using space and ground-based telescopes including Hubble and the Very Large Telescope in Chile.

Blasts of hot, warm and cold winds were detected as the star consumed matter in process known as accretion.

It occurred during a violent eruption when the systems brightened dramatically.

At the same time, some of the material that spirals in was propelled back into space in the form of winds and jets.

The study in Nature showed a simultaneous persistent warm and cold wind at ultraviolet and optical wavelengths, respectively.

It is the first time winds from such a system have been seen across different bands of the electromagnetic spectrum.

Co-author Dr. Hernandez Santisteban, of St Andrews University, said: "Only one other system - the black hole X-ray binary, V404 Cyg - has shown similar properties.

"However, our attempt to perform the same experiment on that system was unsuccessful, because the eruption ended before we could get the ground-based and space-based telescopes to observe it simultaneously,”

Swift J1858 displays extreme variability across the electromagnetic spectrum - which presented a rare opportunity.

Dr. Segura said: "All the astronomers in the field were incredibly excited, to the point that we combined our efforts to cover the full spectrum, from radio to X-ray using state-of-art observatories on Earth and in space."

To make something as dense as a neutron star, the whole of humanity would need to be crammed into a space the size of a sugar cube.

Just a teaspoonful of this material would weigh over a trillion kilograms.

Co-author Dr. Nathalie Degenaar, of Amsterdam University, said: "Neutron stars have an immensely strong gravitational pull that allows them to gobble up gas from other stars.

"The stellar cannibals are, however, messy eaters and much of the gas that neutron stars pull towards them is not consumed, but flung into space at high speed.

"This behavior has a large impact both on the neutron star itself, and on its immediate surroundings.

"In this paper, we report on a new discovery that provides key information about the messy eating patterns of these cosmic cookie monsters."

Neutron stars are the collapsed, burnt-out cores of dead stars. They are only about 12 miles across.

Dr. Santisteban said: "This time we had cosmic luck on our side, as we were able to co-ordinate ten telescopes and point them towards the J1858, all while it was fully active.

"This allows us to obtain much more information since we can use different techniques at different wavelengths."

Neutron stars are very hot, perhaps a million degrees, highly radioactive, and have incredibly intense magnetic fields.

Dr. Degenaar said: "Designing such an ambitious observing campaign – built around the best telescopes on Earth and in space – was a huge challenge.

"So, it is incredibly exciting that all this work has paid off and allowed us to make a key discovery that would not have been possible otherwise."

As well as discovering the different types of winds, the team were able to study the temporal evolution of the gas that flows out.

They found the warm wind was not affected by the strong variations in the brightness of the system.

The absence of such a response had previously been an unconfirmed theoretical prediction based on sophisticated simulations.

Dr. Segura said: "In this research, we combined the unique capabilities of Hubble with the best ground-based telescope to obtain a complete picture of the dynamics of the gas in the system, from the near-infrared to ultraviolet wavelengths.

"This allowed us to unveil for first time the true nature of these powerful outflows."

The dense objects, in particular their cores, are key to our understanding of the universe's heavy elements.

Dr. Segura said: "The new insights provided by our results are key to understanding how these objects interact with their environment.

"By shedding energy and matter into the galaxy, they contribute to the formation of new generations of stars, and to the evolution of the galaxy itself."