IC 4593 (also known as the White-Eyed Pea Nebula) is a planetary nebula in the constellation Hercules.[2] It was first discovered in 1907 by astronomer Williamina Fleming.[5] The nebula is approximately 0.96 light-years across.[6] At the center of the nebula is a hot white dwarf that's known as HD 145649, which is an O-type star with a spectral type of O7f.[7] The temperature of the white dwarf is approximately 30,000 to 40,000 K.[8][9]
A study published in 2020 found that there are bubbles of extremely hot gas in its inner cavities, with the gas heating to over a million degrees. They were formed because of stellar winds colliding with previously expelled gas.[10]
Characteristics
IC 4593 is homogeneous and amorphous, with little to no clustering when compared to other planetary nebulae.[9][11]
The star is surrounded by an asymmetrical inner core about 10 arcseconds across. The core has a faint but fast gas flow, reaching speeds of over 100 kilometers per second. The star has a dense ring-like structure around it. There are bright, low-ionized knots that extend out of the core and into the inner halo. The knots can be best seen in nitrogen emission lines. The inner halo is partially enclosed by a shell, creating a visible arc shape or bulge near the northwest part of the halo.[12][13]
The outer halo is irregluar and unaligned with the inner halo.[12] The halo is faint and fragmented.[14]
↑O'Connor, J. A.; Meaburn, J.; López, J. A.; Redman, M. P. (January 17, 2000). "Kinematics of the Asymmetrical Planetary Nebula IC 4593". Asymmetrical Planetary Nebulae II: From Origins to Microstructures. 199: 405 – via ui.adsabs.harvard.edu.
This page is based on this Wikipedia article Text is available under the CC BY-SA 4.0 license; additional terms may apply. Images, videos and audio are available under their respective licenses.
