A cosmic amethyst in a dying star

A cosmic amethyst in a dying star

Credit: X-ray: NASA / CXC / UNAM / J. Toalá et al .; Optical: NASA / STScI

On Earth, amethysts can form when gas bubbles in lava cool down under the right conditions. In space, a dying star with a mass comparable to the sun can produce a structure comparable to the pull of these beautiful gems.

As stars like the sun run through their fuel, they shed their outer layers and the core of the star shrinks. Using NASA’s Chandra X-ray Observatory, astronomers have found a bubble of ultra-hot gas in the center of one of these decaying stars, a planetary nebula in our galaxy called IC 4593. About 7,800 light-years away from Earth, IC 4593 is the most distant planetary nebula ever discovered with Chandra.

This new image from IC 4593 has X-rays of Chandra in purple, which evoke similarities to amethysts found in geodes around the world. The bubble detected by Chandra is made of gas heated to over a million degrees. These high temperatures were likely generated by material blowing away from the star’s shrunken core and crashing into gas previously expelled from the star.

This composite image also includes visible light data from the Hubble Space Telescope (pink and green). The pink areas in the Hubble image are the overlapping emission from cooler gas consisting of a combination of nitrogen, oxygen and hydrogen, while the green emission is mainly from nitrogen.

IC 4593 is what astronomers call a “planetary nebula,” a deceptive-sounding name because this class of objects has nothing to do with planets. (The name was given about two centuries ago because they looked like the disk of a planet through a small telescope.) In fact, a planetary nebula is formed after the interior of a star contracts about the mass of the sun and its outer layers. turn off and cool down. In the case of the sun, the outer layers could extend to the orbit of Venus during its red giant phase several billion years in the future.

In addition to the hot gas, this study also finds evidence for a point-like X-ray source in the center of IC 4593. This X-ray emission has higher energies than the bubble of hot gas. The point source could come from the star that discarded its outer layers to form the planetary nebula, or from a possible companion star in this system.

A paper describing these results appears in the April 2020 issue of the Monthly Communications from the Royal Astronomical Society and is available online. The authors are Jesús A. Toalá (Instituto de Radioastronomía y Astrofísica (IRyA) in Michoacan, Mexico); MA Guerrero (Instituto de Astrofísica de Andalucía in Granada, Spain); L. Bianchi (Johns Hopkins University, Baltimore, Maryland); Y.-H. Chu (Institute of Astronomy and Astrophysics, Academia Sinica (ASIAA) in Taipei, Taiwan, Republic of China); and O. De Marco (Macquarie University, in Sydney, Australia).

Stars and Skulls: New ESO image reveals an eerie nebula

More information:
Chandra Observations of the Planetary Nebula IC 4593, arXiv: 2004.04542 [astro-ph.SR] arxiv.org/abs/2004.04542

JA Toalá et al. Chandra observations of the planetary nebula IC 4593, Monthly Communications from the Royal Astronomical Society (2020). DOI: 10.1093 / mnras / staa1024

Quote: A cosmic amethyst in a dying star (2020, November 12) Retrieved November 12, 2020 from https://phys.org/news/2020-11-cosmic-amethyst-dying-star.html

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