Not all stars are happy with just rotating around the galactic center with all the other stars. Some stars go rogue, ejecting with significant force across the galaxy. These are runaway stars, and we can trace their trajectories to understand the violent events taking place in the universe.
One such star, and one of the most famous, is Zeta Ophiuchi. Located about 440 light-years from Earth in the equatorial constellation of Ophiuchus, it is one of the strangest stars in the sky.
With a velocity of about 30 to 40 kilometers (about 20 to 25 miles) per second, it is not only unusually fast, but it is also a strange kind of star to see through space.
Zeta Ophiuchi is a main-sequence star; That is, still fusing 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 its intense heat.
Such stars have relatively short lives; Zeta Ophiuchi is about halfway through its estimated 8-million-year main sequence lifetime.
This means they are not very common in the Milky Way; But such stars are also born, and spend their lives in such groups, known as confederates.
Yet Zeta Ophiuchi, zooming through space, is all alone, which raised the question of where it came from, and how it came to its current position.
Scientists now believe that Zeta Ophiuchi was kicked into space by a supernova explosion of a binary companion star. A pulsar, also zooming through space, has a path that may have joined with Zeta Ophiuchi about a million years ago.
This suggests that the pulsar was the star that went supernova, causing both stars to fly away.
(NASA/CXC/University of Cambridge/J Sisk-Raines et al.; NSF/NRAO/VLA; PANSTARRS)
Above: a composite optical, infrared and X-ray image of Zeta Ophiuchi.
Because Zeta Ophiuchi is so famous, we know a lot about it. For example, the images show a giant bow shock in the dense cloud through which the star is traveling. This material is created by flying from a star and colliding with gas.
And X-ray emission around the star was detected in Chandra’s observations 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 delves into multi-wavelength data to see whether bow shock dynamics can explain the observed cloudiness, as well as thermal emissions. Is. This includes observations in optical, infrared, radio and X-ray wavelengths.
They simulated and found that their results did not match the observations. The brightest X-radiation in the Chandra data is emitted from a bubble that surrounds the star. In the simulations, the brightest X-rays were at the bow shock itself.
This suggests that something is missing, either in the simulations or in our understanding of the strange star and its environment.
Future simulations will throw more physical processes into the mix or be conducted at higher resolutions to better model turbulence.
In terms of other notably fast stars, the fastest-moving main-sequence star yet discovered is S5-HVS1, which has a velocity of about 1,700 kilometers (about 1,056 miles) per second by interaction with our galaxy’s Sagittarius A*. from across the galaxy. supermassive black hole.
The fastest dead stars are a pair of white dwarfs traveling at 2,200 kilometers (about 1,370 miles) per second, which have been kicked off by a double-explosion supernova.
The fastest star ever identified in our galaxy is S4714, which reaches speeds of 24,000 kilometers (14,900 miles) per second as it orbits Sgr A*.
Team paper has been accepted astronomy and astrophysics, A larger version of Zeta Ophiuchi’s overall optical, X-ray and infrared observations can be found on the Chandra website.
