Astronomers spot a neutron star devouring matter from a nearby star
What does it take to capture a neutron star devouring matter from a nearby star?
A team of researchers from eleven countries and ten telescopes, according to a press release by the University of Southampton, the institution that led this effort.
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The end result is a mesmerizing image and a never-before-captured space phenomenon.
A hungry neutron star
The team made of researchers from eleven nations studied the recent eruption of the X-ray binary known as Swift J1858. They used a variety of telescopes, including NASA’s Hubble Space Telescope (HST), the European Space Agency’s XMM-Newton satellite, the European Southern Observatory Organisation’s Very Large Telescope (VLT) and the Spanish Gran Telescopio Canarias (GTC).
“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,” co-author Dr. Hernández Santisteban from the University of St Andrews said.
How did this neutron star manage to consume so much matter from another star? It was all because of its strong gravitational pull that allows it to gobble up gas from other stars.
Cosmic cookie monsters
But things are not that simple. These neutron stars don't just devour all the gas they pull toward them. Instead, they send it flying into space at high speeds. Co-author Nathalie Degenaar, from the University of Amsterdam, described them as "stellar cannibals" that are "messy eaters" and "cosmic cookie monsters.”
Although these descriptions make the new discovery seem fun and playful it is still a significant breakthrough in astrophysics.
“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," said lead author Dr. Noel Castro Segura, of the University of Southampton.
The study was published in the journal Nature.
All disc-accreting astrophysical objects produce powerful disc winds. In compact binaries containing neutron stars or black holes, accretion often takes place during violent outbursts. The main disc wind signatures during these eruptions are blue-shifted X-ray absorption lines, which are preferentially seen in disc-dominated ‘soft states’. By contrast, optical wind-formed lines have recently been detected in ‘hard states’, when a hot corona dominates the luminosity. The relationship between these signatures is unknown, and no erupting system has as yet revealed wind-formed lines between the X-ray and optical bands, despite the many strong resonance transitions in this ultraviolet (UV) region. Here we report that the transient neutron star binary Swift J1858.6-0814 exhibits wind-formed, blue-shifted absorption lines associated with C IV, N V and He II in time-resolved UV spectroscopy during a luminous hard state, which we interpret as a warm, moderately ionized outflow component in this state. Simultaneously observed optical lines also display transient blue-shifted absorption. Decomposing the UV data into constant and variable components, the blue-shifted absorption is associated with the former. This implies that the outflow is not associated with the luminous flares in the data. The joint presence of UV and optical wind features reveals a multi-phase and/or spatially stratified evaporative outflow from the outer disc. This type of persistent mass loss across all accretion states has been predicted by radiation–hydrodynamic simulations and helps to explain the shorter-than-expected duration of outbursts7
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