A fast-moving star collides with interstellar gas, causing an amazing arc shock

A fast-moving star collides with interstellar gas, causing an amazing arc shock

A multi-wavelength view of Zeta Oviucci. Credit: X-rays: NASA/CXC/Dublin Inst. Advanced Studies / S. Green et al.; Infrared: NASA / JPL / Spitzer

Zeta Oviucci has an interesting life. It began as a typical star about twenty times the mass of the Sun. She spent her days happily orbiting a large companion star until its companion exploded as a supernova about a million years ago. The explosion ejected Zeta Ophiuchi, so she is now accelerating away through interstellar space. Of course, the supernova also expelled the outer layers of the companion star, so instead of empty space, our gritty star speeds through the remaining gas as well. As they say on Facebook, it’s complicated. And that’s great news for astronomers, as a recent study shows.

Zeta Ophiuchi is famous for beautiful images like the one above. By plowing through interstellar gas, the star would have created hot shock waves that glow in everything from infrared to X-rays. The physics of these shock waves is very complex. It is governed by a set of mathematical equations known as magnetohydrodynamics, which describe the behavior of liquid gases and the magnetic fields around them. Modeling these equations is bad enough, but when you have turbulent motion like shock wavesThings get worse. This is why Zeta Oviucci is so important. Since we have such a great view of the shock wave, we can compare our observations with it computer simulation.

In this latest study, the team created computer models that simulate the shock wave near Zeta Oviucci. Then they compared these models with infrared, visible, and X-rays. Their goal is to define the most accurate simulation so that the models can be further improved. Of their three models, two of them predicted that the brightest region of the X-ray emission should be on the edge of the shock wave closest to the star, and that’s what we observe. But all three models also expected the X-ray emissions to be weaker than we observe, so no model is completely accurate. But these models are hard to do well, and this work is a good start.

A fast-moving star collides with interstellar gas, causing an amazing arc shock

A simulated shock wave from Zeta Oviucci. Credit: Greene et al

The difference in the brightness of the X-rays is likely due to the turbulent motion within the shock wave. The team plans to include some of this turbulent motion in future models. With multiple iterations, they should be able to create simulations that closely model this interstellar shock wave.

Magnetic hydrodynamics is an essential part of many astrophysical processes, starting with Solar flares To form planets, to the powerful black hole drives of quasars. Most of these things Interactions Hidden by distance or dust, so it’s great that Zeta Ophiuchi gives astronomers a shocking view of this complex physics.

Exploding electric wires underwater to understand shock waves

more information:
S. Green et al, Thermal emissions from arc shocks. II. 3D Hydrodynamic Magnetic Models of Zeta Oviucci, Astronomy and astrophysics (2022). DOI: 10.1051 / 0004-6361 / 202243531

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