This Runaway Star Penetrates Space at More Than 160,000 Kilometers Per Hour

Not all stars enjoy just wandering around, orbiting the galactic center with all the other stars. Some stars go rogue, crossing the Milky Way with significant force. It is a runaway star, and we can trace its trajectory to understand the violent events that could occur in the Universe.

One such star, and one of the more famous ones, is Zeta Ophiuchi. Located about 440 light-years from Earth in the equatorial constellation Ophiuchus, it is also one of the strangest stars in the sky.

Not only is it incredibly fast, at about 30 to 40 kilometers (roughly 20 to 25 miles) per second, but it’s a strange type of star to see roaring in space.

Zeta Ophiuchi is the main sequence star; that is, one that still combines hydrogen into helium in its core. And it’s a hot, massive O-type star: about 20 times the mass of the Sun, glowing blue with intense heat.

Such stars also have relatively short lives; Zeta Ophiuchi is about half way past the main sequence’s projected age of 8 million years.

That means they are not very common in the Milky Way; but such stars also tend to be born, and spend their lifetimes, in groups known as associations.

But Zeta Ophiuchi, gliding through space, is alone, which raises questions about where he came from, and how he got into his current predicament.

Scientists now believe that Zeta Ophiuchi was kicked across space by a supernova explosion from a binary companion star. A pulsar, also gliding through space, has a path that would have intersected the path of Zeta Ophiuchi about a million years ago.

This indicates that the pulsar is a star that becomes a supernova, sending both stars flying.

(NASA/CXC/Univ. of Cambridge/J. Sisk-Reynés et al.; NSF/NRAO/VLA; PanSTARRS)

Above: Zeta Ophiuchi optical, infrared, and X-ray composite image.

Since Zeta Ophiuchi is very famous, we know very little about him. For example, the image shows a colossal arc shock in the thick cloud through which the star travels. It is created by material blowing from the star and colliding with the gas.

And X-ray emission around the star was detected in observations from Chandra in 2016 – thermal emission, created by shock-induced heating.

A new study led by computational astrophysicist Samuel Green of the Dublin Institute for Advanced Studies in Ireland has investigated multi-wavelength data to see if arc shock dynamics can explain the observed cloud, as well as thermal emissions. That includes observations across optical, infrared, radio, and X-ray wavelengths.

They performed simulations and found that their results did not match the observations. The brightest X radiation in the Chandra data is emitted from the bubble surrounding the star. In the simulation, the brightest X-rays are in the arc of the shock itself.

This suggests that something is missing either in our simulations or our understanding of the strange star and its environment.

Future simulations will incorporate more physical processes into the mix or will be performed at higher resolutions to better model the turbulence involved.

In terms of other very fast stars, the fastest escape main sequence star ever found is S5-HVS1, hurtling through the galaxy at about 1,700 kilometers (roughly 1,056 miles) per second through interactions with Sagittarius A*, our galaxy. supermassive black hole.

The fastest dead star is a pair of white dwarfs moving at a speed of 2,200 kilometers (about 1,370 miles) per second, kicked up by a double-detonation supernova.

The fastest star identified to date in our galaxy is S4714, which reaches speeds of 24,000 kilometers (14,900 miles) per second while orbiting Sgr A*

Team paper has been accepted at Astronomy & Astrophysics. A large version of the Zeta Ophiuchi composite optical, X-ray and infrared observations can be found on Chandra’s website.

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