Donor Star Breathes Life Into Zombie Companion

Phys dot org ^ | March 5, 2018 | European Space Agency

[SunkenCiv]

Stars the mass of our Sun, and up to eight times more massive, evolve into red giants towards the end of their lives. Their outer layers puff up and expand millions of kilometres, their dusty, gassy shells blown away from the central star in relatively slow winds up to few hundreds of km/s.

Even larger stars, up to 25–30 times more massive than the Sun, race through their fuel and explode in a supernova, sometimes leaving behind a spinning stellar corpse with a strong magnetic field, known as a neutron star. This tiny core packs the mass of nearly one and half Suns into a sphere only 10 km across, making them some of the densest celestial objects known.

It is not uncommon to find stars paired together, but the new system of a neutron star and red giant is a particularly rare breed known as a 'symbiotic X-ray binary', with no more than 10 known...

The pairing is certainly peculiar. ESA's XMM-Newton and NASA's NuSTAR space telescopes showed that the neutron star spins almost every two hours – very slow compared with other neutron stars, which can spin up to many times per second. Then, the first measurement of the magnetic field of such a neutron star revealed it to be surprisingly strong.

A strong magnetic field typically points to a young neutron star – the magnetic field is thought to fade over time – while a red giant is much older, making it a bizarre couple to have grown up together.

With a young neutron star and an old red giant, at some point the winds travelling from the puffed-up giant will begin to rain on to the smaller star, slowing its spin and emitting X-rays.

[SunkenCiv]

Stellar evolution. Credit: European Space Agency

[SunkenCiv]

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[Telepathic Intruder]

• 0.08 - 0.4 solar mass
  Red dwarf stars leaving a hypothetical helium white dwarf remnant after a few trillion years
• 0.4 - 8 solar mass
  Medium-sized stars leaving a carbon/oxygen white dwarf after a few billion years
• 8 - 10.5 solar mass
  Large stars leaving a oxygen/neon/magnesium white dwarf after a few 100 million years
• over 10.5 solar mass
  Giant stars leaving a neutron star/black hole after a few million years

Most star systems are multiple ones, unlike our own. Combinations are interesting.

[glock rocks]

bkmk

[WayneS]

Stars the mass of our Sun, and up to eight times more massive, evolve into red giants towards the end of their lives. Their outer layers puff up and expand millions of kilometres, their dusty, gassy shells blown away from the central star in relatively slow winds up to few hundreds of km/s.

That's all well and good but everybody knows anything that happens to our sun is the result of human activity on earth - it's settled science...

[BraveMan]

A more in-depth reference of the observed phenomenon can be found here (if this article isn't geeky enough).

IGR J17329-2731: The birth of a symbiotic X-ray binary

[SunkenCiv]

Thanks!