Astronomers Find Evidence of a Strange Type of Star

One has never been spotted for sure in the wild jungle of strange stellar objects out there, but astronomers now think they have finally found a theoretical cosmic curiosity: a Thorne-Zytkow Object, or TZO, hiding in the neighboring Small Magellanic Cloud. With the outward appearance of garden-variety red supergiants, TZOs are actually two stars in one: a binary pair where a super-dense neutron star has been absorbed into its less dense supergiant parter, and from within it operates its exotic elemental forge.

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I don’t understand. Is the neutron star sitting as an entity within the “atmosphere” of the star or has it disintegrated and been absorbed by the star?

Divine Angel said:

I don’t understand. Is the neutron star sitting as an entity within the “atmosphere” of the star or has it disintegrated and been absorbed by the star?

a super-dense neutron star has been absorbed into its less dense supergiant parter,

The problem with pop-sci written pieces is that the sentences aren’t always clear on meaning.

Divine Angel said:

The problem with pop-sci written pieces is that the sentences aren’t always clear on meaning.

Have you read papers with Maths and diagrams?

I get confused with papers and Maths

Im sure Molly and PM2 can help

I try to avoid numbers. Thinking gives me wrinkles.

A Thorne–Żytkow object is formed when a neutron star collides with a star, typically a red giant or supergiant. The colliding objects can simply be wandering stars. This is only likely to occur in extremely crowded globular clusters. Alternatively, the neutron star could form in a binary system. Because no supernova is perfectly symmetric, and because the binding energy of the binary changes with the mass lost in the supernova, the neutron star will be left with some velocity relative to its original orbit. This kick may cause its new orbit to intersect with its companion, or, if its companion is a main-sequence star, be engulfed by its companion when it evolves into a red giant.

Once the neutron star enters the red giant, drag between the neutron star and the outer, diffuse layers of the red giant causes the binary star system’s orbit to decay, and the neutron star and core of the red giant spiral inward toward one another. Depending on their initial separation, this process may take hundreds of years. When the two finally collide, the neutron star and red giant core will merge. If their combined mass exceeds the Tolman-Oppenheimer-Volkoff limit then the two will collapse into a black hole, resulting in a supernova that disperses the outer layers of the star. Otherwise, the two will coalesce into a single neutron star.

Wiki

Thankyou. I’m guessing that this is still largely theoretical?

i guess they’ve seen a signature that fits the theory. but this “one off” needs backup.

Divine Angel said:

I don’t understand. Is the neutron star sitting as an entity within the “atmosphere” of the star or has it disintegrated and been absorbed by the star?

Good question. It’s possible for any object such as a planet or second star to be orbiting for many years inside the atmosphere of a supergiant star, because the density of its atmosphere is so low.

Let me check the technical paper in http://arxiv.org/pdf/1406.0001.pdf
In this case the neutron star has spiralled into the core of the supergiant. Most of the energy comes from conventional thermonuclear reactions, but about 5% from gravitational accretion onto the central core of neutronium.

This chemical signature isn’t typical for a supergiant star that has simply absorbed a white dwarf, because most white dwarfs have cores of only carbon, not heavier elements such as those detected here.