Eskimo Nebula Explained

The Eskimo Nebula (NGC 2392), also known as the Clown-faced Nebula, Lion Nebula,^[1] or Caldwell 39, is a bipolar^[2] double-shell^[3] planetary nebula (PN). It was discovered by astronomer William Herschel in 1787. The formation resembles a person's head surrounded by a parka hood. It is surrounded by gas that composed the outer layers of a Sun-like star. The visible inner filaments are ejected by a strong wind of particles from the central star. The outer disk contains unusual, light-year-long filaments.

NGC 2392 lies about 6500 light-years away, and is visible with a small telescope in the constellation of Gemini.

At the center of NGC 2392, there is an O-type star with a spectral type of O(H)6f.^[4]

Historic data

The nebula was discovered by William Herschel on January 17, 1787, in Slough, England. He described it as "A star 9th magnitude with a pretty bright middle, nebulosity equally dispersed all around. A very remarkable phenomenon."^[5] NGC 2392 WH IV-45 is included in the Astronomical League's Herschel 400 observing program.

Location

NGC 2392 is located just east of δ Geminorum, just south the ecliptic.

Naming controversy

On 11 August 2020, the IAU Working Group on Star Names (WGSN), NASA/IPAC Extragalactic Database (NED), and SIMBAD Astronomical Database (CDS) discontinued use of three nicknames that were perceived as offensive - "Eskimo Nebula", "Clown Face Nebula", and "Clownface Nebula" - and strongly recommended the nebula be referred to by its NGC designation in further publications.^[6]

See also

• List of planetary nebulae
• New General Catalogue

Notes

1. Radius = distance × sin(angular size / 2) = ≥2900 ly * sin(48 / 2) = ≥0.34 ly
2. 10.1 apparent magnitude - 5 * (log₁₀(≥880 pc distance) - 1) = ≤0.4 absolute magnitude

External links

• • APOD (2003-12-07) – NGC 2392
• Eskimo Nebula Lowell Observatory
• The Structure & Evolution of the Eskimo Planetary Nebula University of Maryland Astronomy Department
• A Kinematic Determination of the Structure of the Double Ring Planetary Nebula NGC 2392, the Eskimo Astrophysical Journal v.362, p. 226 October 1990
• A Cat's Eye view of the Eskimo from Saturn Maria-Teresa Garc ́ıa-D ́ıaz, Jose-Alberto L ́opez, Wofgang Steffen, Michael G. Richer and Hortensia Riesgo, 2011

Notes and References

1. Deep-Sky Companions: The Caldwell Objects, 2nd Edition, Stephen James O'Meara, 2016, p.181
2. O'dell, C. R. . 4 . Balick, B. . Hajian, A. R. . Henney, W. J. . Burkert, A. . Knots in Planetary Nebulae . Winds, Bubbles, and Explosions: a conference to honor John Dyson, Pátzcuaro, Michoacán, México, September 9–13, 2002 . S. J. Arthur & W. J. Henney . Revista Mexicana de Astronomía y Astrofísica (Serie de Conferencias) . 2003 . 15 . 29–33 . 2003RMxAC..15...29O . 2007-01-04 . 2018-05-01 . https://web.archive.org/web/20180501131545/http://www.astroscu.unam.mx/~rmaa/ . dead .
3. Guerrero, M. A. . Chu, Y.-H. . Gruendl, R. A. . Meixner, M. . XMM-Newton detection of hot gas in the Eskimo Nebula: Shocked stellar wind or collimated outflows? . . 2005 . 430 . 3 . L69–L72 . 2005A&A...430L..69G . 10.1051/0004-6361:200400131. astro-ph/0412540 . 6518963 .
4. 10.1051/0004-6361/202141916. Planetary nebulae in Gaia EDR3: Central star identification, properties, and binarity. 2021. González-Santamaría. I.. Manteiga. M.. Manchado. A.. Ulla. A.. Dafonte. C.. López Varela. P.. Astronomy & Astrophysics. 656. A51. 2109.12114. 2021A&A...656A..51G. 237940344.
5. The Scientific Papers of Sir William Herschel by J. L. E. Dreyer, Royal Society, London 1912
6. News: Talbert . Tricia . NASA to Reexamine Nicknames for Cosmic Objects . 11 August 2020 . . 11 August 2020.