Science

New clues emerge about runaway star Zeta Ophiuchi’s violent past

Zeta Ophiuchus is on the way.

The star, which is 20 times more massive than our Sun and about 440 light-years from Earth, is hurtling through the galaxy at about 100,000 miles per hour (162,000 km/h). This is rather unusual for stars that usually orbit the center of their galaxy in a fairly calm and orderly manner. A new study has found evidence supporting the leading theory as to why Zeta Ophiuchus went rogue while wandering the Milky Way.

Scientists suspect that Zeta Ophiuchus once belonged to a binary system, but its companion star was destroyed by a supernova over a million years ago. The shockwave from the explosion propelled Zeta Ophiuchi into space, sending him on a journey at high speed. Now, for the first time, astronomers have developed 3D computer models of the shockwave in an attempt to explain the X-ray bubble found around the star.

Related: Enormous Runaway Star Creates Stunning Dust Shockwave

The supernova shock wave theory is not new — scientists arrived at this explanation after analyzing infrared data observed by NASA’s Spitzer Space Telescope, which has since retired from service. This image shows a powerful shock wave that swept material off Zeta Ophiuchus and sent it crashing into the surrounding clouds of gas. Then, in 2016, NASA’s Chandra X-ray image of Zeta Ophiuchi provided another piece of the puzzle: it showed that the gas surrounding the star had been heated to tens of millions of degrees by the shock wave.

A team of astronomers is currently testing 3D computer models of the shock wave that tore Zeta Ophiuchi away from its companion in an attempt to explain how these data came to be, including Spitzer’s infrared data and Chandra X-ray data, as well as data from optical and radio spectra. The team, led by astronomer Samuel Greene of the Dublin Institute for Advanced Study, also created the composite image above, which depicts the violent events unfolding around Zeta Ophiuchus.

The astronomers have just started testing their models, and so far the three simulations they’ve run haven’t quite matched the observed data, especially in the X-ray spectrum.

“All three different computer models predict X-rays that are weaker than what is observed. The X-ray bubble is brightest near the star, while two of the three computer models predict that the X-rays should be brightest near the bow shock. “, the statement says. (will open in a new tab) released by the Chandra program.

As such, they will continue to refine their models, including additional physical elements such as turbulence and particle acceleration, to see if they can replicate the observed data.

A paper describing the development and testing of the team’s models has been accepted for publication in the journal Astronomy & Astrophysics as well as a preprint. (will open in a new tab) available online.

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