Jeff Benensohn, Don Q. Lamb (University of Chicago), Ronald E. Taam (Northwestern University)

The majority of stars in our Milky Way Galaxy exist in binary or multiple systems. These systems consist of two or more stars that are bound gravitationally to one another. Our Solar System is an example of a gravitationally-bound system, the Sun being massive enough to attract the nearby planets. However, if we consider a binary star system, a logical question to ask is what happens when these two stars evolve? In many cases, one star evolves faster than the other, causing material from the evolving star to expand outward. This material is pulled in by the companion. For massive stars, the stellar remnant left behind will be a black hole or a neutron star. Simultaneously, the companion star is evolving and matter is eventually thrown back onto the stellar remnant. This material is heated to extreme temperatures as it arrives at the super-dense black hole or neutron star, causing it to glow in X-ray wavelengths. Astronomers call these systems X-ray binaries.

The simulation

This animation depicts an X-ray binary system consisting of a neutron star and a supergiant star. The neutron star is very dense, about 10 kilometers (6 miles) in diameter with the mass of 1.5 Suns. The supergiant companion star is about 7 times larger and 15 times more massive than our Sun. The neutron star has a massive gravitational pull, causing the winds from the companion star to be violently pulled into the neutron star. The result is a swirling mess of material in the stellar system, demonstrating the harsh environment produced by the strong gravitational force from the neutron star.

Eve Klein