#Wolf-Rayet star

NASA's James Webb Space Telescope's mid-infrared image shows four coiled shells of dust around a pair of Wolf-Rayet stars known as Apep for the first time.

Image Credit: Image: NASA, ESA, CSA, STScI; Science: Yinuo Han (Caltech), Ryan White (Macquarie University); Image Processing: Alyssa Pagan (STScI)

The luminous, hot star Wolf-Rayet 124 (WR 124) is prominent at the center of the James Webb Space Telescope’s composite image combining near-infrared and mid-infrared wavelengths of light. The star displays the characteristic diffraction spikes of Webb’s Near-Infrared Camera (NIRCam), caused by the physical structure of the telescope itself. NIRCam effectively balances the brightness of the star with the fainter gas and dust surrounding it, while Webb’s Mid-Infrared Instrument (MIRI) reveals the nebula’s structure. Background stars and background galaxies populate the field of view and peek through the nebula of gas and dust that has been ejected from the aging massive star to span 10 light-years across space. A history of the star’s past episodes of mass can be read in the nebula’s structure. Rather than smooth shells, the nebula is formed from random, asymmetric ejections. Bright clumps of gas and dust appear like tadpoles swimming toward the star, with tails streaming out behind them, blown back by the stellar wind. This image combines various filters from both Webb imaging instruments, with the color red assigned to wavelengths of 4.44, 4.7, 12.8, and 18 microns (F444W, F470N, F1280W, F1800W), green to 2.1, 3.35, and 11.3 microns (F210M, F335M, F1130W), and blue to 0.9, 1.5, and 7.7 microns (F090W, F150W, F770W).

Image Credit: NASA, ESA, CSA, STScI, Webb ERO Production Team

This image from NASA's James Webb Space Telescope reveals at least 17 concentric dust rings emanating from a pair of stars orbiting one another. Located just over 5,000 light-years from Earth, the system is known as Wolf-Rayet 140 because one of the stars is a Wolf-Rayet star. The other is an O-type star, one of the most massive star types known. Each ring was created when the two stars came close together and their stellar winds (streams of gas they blow into space) collided, compressing the gas and forming dust. A ring is produced once per orbit, every 7.93 years. A Wolf-Rayet star is an O-type star born with at least 25 times more mass than our Sun that is nearing the end of its life, when it will likely collapse directly to black hole, or explode as a supernova. These delays between periods of dust production create the unique ring pattern. Some Wolf-Rayet binaries in which the stars are close enough together and have circular orbits produce dust continuously, often forming a pinwheel pattern. WR 140's rings are also referred to as shells because they are not perfectly circular and are thicker and wider than they appear in the image. The rings appear brighter in some areas but are almost invisible in others, rather than forming a perfect "bullseye" pattern. That's because production of dust is variable as the stars get close to one another, and because Webb views the system at an angle and is not looking directly at the orbital plane of the stars. One of the densest regions of dust production creates the bright feature appearing at 2 o'clock. The image was taken by the Mid-Infrared Instrument (MIRI), now managed by the agency's Goddard Space Flight Center. MIRI was developed through a 50-50 partnership between NASA and ESA (European Space Agency).

Image Credit: NASA, ESA, CSA, STScI, JPL-Caltech