Astronomy:IC 4593

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IC 4593
Nebula
Image of IC 4593
Observation data: J2000.0 epoch
ClassO7f[3]
Right ascension 16h 11m 44.5s[1]
Declination+12° 04′ 17″[2]
Distance7,900[4] ly
Apparent magnitude (V)10.7[1]
Apparent dimensions (V)0.22 × 0.22[1]
ConstellationHercules[1]
See also: Lists of nebulae

IC 4593 (also known as the White-Eyed Pea Nebula) is a planetary nebula in the constellation Hercules.[1] 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]

References

  1. ↑ 1.0 1.1 1.2 1.3 1.4 "IC 4593 - Planetary Nebula in Hercules | TheSkyLive". https://theskylive.com/sky/deepsky/ic4593-object. 
  2. ↑ "By Name | NASA/IPAC Extragalactic Database". https://ned.ipac.caltech.edu/byname?objname=IC+4593&hconst=67.8&omegam=0.308&omegav=0.692&wmap=4&corr_z=1. 
  3. ↑ Anandarao, B. G.; Banerjee, D. P. K. (August 19, 1988). "High resolution observations of the planetary nebulae NGC 6153 and IC 4593.". Astronomy and Astrophysics 202: 215–218. https://ui.adsabs.harvard.edu/abs/1988A%26A...202..215A/abstract. Retrieved January 19, 2026. 
  4. ↑ "IC 4593 - NASA Science". September 11, 2007. https://science.nasa.gov/asset/hubble/ic-4593/. 
  5. ↑ "Index Catalog Objects: IC 4550 - 4599". https://cseligman.com/text/atlas/ic45a.htm#ic4593. 
  6. ↑ "Chandra :: Photo Album :: IC 4593 :: November 12, 2020". https://chandra.cfa.harvard.edu/photo/2020/ic4593/. 
  7. ↑ "Who's who?". https://wwwmpa.mpa-garching.mpg.de/RKcat/whoswho.html. 
  8. ↑ "IC4593 Planetary Nebula (HST WFPC2) Unilabs Experiments". https://unilabs.altervista.org/astronomy-gallery/planetary-nebulae-gallery/ic4593-hst/. 
  9. ↑ 9.0 9.1 Czyzak, S. J.; Buerger, E. G.; Aller, L. H. (June 16, 1975). "Spectrophotometric studies of gaseous nebulae. XXIV. The amorphous low-excitation planetary IC 4593.". The Astrophysical Journal 198: 431. doi:10.1086/153618. Bibcode: 1975ApJ...198..431C. https://ui.adsabs.harvard.edu/abs/1975ApJ...198..431C/abstract. Retrieved January 16, 2026. 
  10. ↑ A, Toalá, J; A, Guerrero, M; L, Bianchi; Y-H, Chu; O, De Marco (May 21, 2020). "Chandra observations of the planetary nebula IC 4593". Monthly Notices of the Royal Astronomical Society 494 (3): 3784–3789. doi:10.1093/mnras/staa1024. https://academic.oup.com/mnras/article/494/3/3784/5823138. Retrieved January 15, 2026. 
  11. ↑ Buerger, E. G. (March 24, 1973). "Abundances and ionization distribution in planetary nebulae.". The Astrophysical Journal 180: 817. doi:10.1086/152009. https://ui.adsabs.harvard.edu/abs/1973ApJ...180..817B/abstract. Retrieved January 31, 2026. 
  12. ↑ 12.0 12.1 O'Connor, J. A.; Meaburn, J.; López, J. A.; Redman, M. P. (June 17, 1999). "Kinematics of the strange knots and halo of the planetary nebula IC 4593". Astronomy and Astrophysics 346: 237–242. https://ui.adsabs.harvard.edu/abs/1999A%26A...346..237O/abstract. Retrieved January 17, 2026. 
  13. ↑ 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. https://ui.adsabs.harvard.edu/abs/2000ASPC..199..405O/abstract. Retrieved January 17, 2026. 
  14. ↑ Dgani, Ruth; Soker, Noam (March 24, 1998). "Instabilities in Moving Planetary Nebulae". The Astrophysical Journal 495 (1): 337–345. doi:10.1086/305257. https://ui.adsabs.harvard.edu/abs/1998ApJ...495..337D/abstract. Retrieved January 31, 2026. 



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