Seagull Nebula (IC 2177)

Canis Majoris OB1 association
Canis Majoris OB1 association: Various parts identified. The Seagull Nebula is the most prominent one. Section from DSS [147]


On 10 January 1785 William Herschel sweeped his 18.7 inch reflecting telescope through the constellation Monoceros and found three «coarsely scattered clusters of stars»: VIII 32 (NGC 2335), VIII 33 (NGC 2343) and VIII 34 (NGC 2353).

Few nights later on 31 January 1785 William Herschel came again across the same region and found an object, which he classified as IV 25 (class IV = planetary nebulae, stars with burs, with milky chevelure, with short rays, remarkable shapes, etc). He noted: «A pcst. (pretty cometic? star) with very faint and very small much chevelure of an irregular figure.» [463] His Sohn John cataloged that object in 1833 as h 428, not being sure whether it was the same as IV 25. He described it with: «A double star whose large star is in centre of a very faint nebula which involves the small star also.» [466] In his «General Catalogue» the object got the designation GC 1487 and the description: «pretty bright double star involved in small, very faint nebula.» [467] In 1888 Dreyer added this discovery as NGC 2327 to his «New General Catalogue». [313]

In 1898 the British astronomer Isaac Roberts took a picture of that region using the 20" reflector at his observatory «Starfield» in Crowborough Hill, Sussex, UK. He wrote: «Nebula in Monoceros in which the star 7.3 mag BD -10°1848 is involved together with several other faint stars. The nebula is irregularly round, bright, with a wide nebulous band across it in s. f. to n. p. direction. The nebula is about 13 minutes of arc in diameter.» [554] This sighting was then added as IC 2177 by Dreyer in 1910 to his «Second Index Catalogue». [315]

In 1955 Colin S. Gum from the Commonwealth Observatory in Canberra did a survey of H-II regions and identified parts of the nebula, which are known as Gum 1, Gum 2 and Gum 3. [555] Stewart Sharpless «Catalogue of H II Regions» published in 1959 lists Sh 2-292, Sh 2-295, Sh 2-296, Sh 2-297. [310] In the early 1960ies Beverly Lynd identified numerous dark (LDN 1657, LDN 1658) and bright nebulae (LBN 1027, LBN 1033, LBN 1035, LBN 1039) in this region. [270, 473]

Seagull Nebula
Seagull Nebula: Image taken with VLT in Chile. © ESO [558]

Physical Properties

This is an interstellar cloud of dust, molecules, hydrogen, helium and other ionised gases where new stars are being born. The whole nebula is also known under the designation Canis Majoris OB1 association (CMa OB1).

The main components of the Seagull are three large clouds of gas, the most distinctive being Sharpless 2-296, which forms the «wings». IC 2177 or SH 2-292 forms the «head of the seagull». The hydrogen glows brightly red due to the energetic radiation from embedded very hot young star HD 53367 (BD -10°1848) and becomes a HII region. HD 53367 is a Be type star with 20 times the mass of our Sun. It has a companion with 5 solar masses in a highly elliptical orbit. Light from the hot blue-white stars is also scattered off the tiny dust particles in the nebula to create a contrasting blue haze.

Dark lanes of dust interrupt the glowing clouds. These are parts of much denser material that hide some of the luminous gas behind them. Nebulae like this one have densities of a few hundred atoms per cubic centimetre, compared to the density of the surrounding nebula of about 1 atom per cubic centimetre.

The entire nebula is located about 3700 light-years away from earth and spans over 100 light-years across. [556, 557, 558]

Revised+Historic NGC/IC, Version 22/9, © Dr. Wolfgang Steinicke [277]
NameRADecTypebMagvMagDimDreyer DescriptionIdentification, Remarks
NGC 232707 04 07.2-11 18 51RN1 × 1pB ** inv in S, vF, nebCED 89B
NGC 233507 06 49.4-10 01 43OCL (III3m)7.27Cl, L, lCOCL 562
NGC 234307 08 06.7-10 37 00OCL (III3p)6.76Cl, cL, P, lCOCL 565
NGC 235307 14 30.3-10 15 57OCL (II2p)7.118Cl, L, lC, one vB *OCL 567
IC 217707 04 25.3-10 27 13EN20 × 20pB, eL, iR, v difLBN 1027, vdB 93, Sh2-292, Be star

Finder Chart

The nebula IC 2177 is located between the constellations Monoceros and Canis Maior. The best season for observation is from October until March.

Chart Seagull Nebula (IC 2177)
Seagull Nebula (IC 2177) in constellation Canis Maior. Chart created using SkySafari 6 Pro and STScI Digitized Sky Survey. [149, 160]

More Objects Nearby (±15°)


147Aladin Lite; (2020-12-23)
149SkySafari 6 Pro, Simulation Curriculum;
160The STScI Digitized Sky Survey;
270«Catalogue of Bright Nebulae» Lynds, Beverly T.; Astrophysical Journal Supplement, vol. 12, p.163 (1965); DOI:10.1086/190123
277«Historische Deep-Sky Kataloge» von Dr. Wolfgang Steinicke; (2021-02-17)
310«A Catalogue of H II Regions» Stewart Sharpless, US Naval Observatory, 1959; DOI:10.1086/190049; Bibcode:1959ApJS....4..257S
313«A New General Catalogue of Nebulae and Clusters of Stars, being the Catalogue of the late Sir John F.W. Herschel, Bart., revised, corrected, and enlarged» Dreyer, J. L. E. (1888); Memoirs of the Royal Astronomical Society. 49: 1–237; Bibcode:1888MmRAS..49....1D
315«Second Index Catalogue of Nebulae and Clusters of Stars; containing objects found in the years 1895 to 1907, with Notes and Corrections to the New General Catalogue and to the Index Catalogue for 1888–94» Dreyer, J. L. E. (1910); Memoirs of the Royal Astronomical Society. 59: 105–198; Bibcode:1910MmRAS..59..105D
463«Catalogue of one thousand new nebulae and clusters of stars» William Herschel, Philosophical Transactions of the Royal Society of London, 1 January 1786; DOI:10.1098/rstl.1786.0027
466«Observations of nebulæ and clusters of stars, made at Slough, with a twenty-feet reflector, between the years 1825 and 1833» John Frederick William Herschel, Philosophical Transactions of the Royal Society of London, 1 January 1833, Pages: 359-505; DOI:10.1098/rstl.1833.0021
467«Catalogue of nebulae and clusters of stars» John Frederick William Herschel, Philosophical Transactions of the Royal Society of London, 1 January 1864; DOI:10.1098/rstl.1864.0001
473«Catalogue of Dark Nebulae» Lynds, Beverly T.; Astrophysical Journal Supplement, vol. 7, p.1 (1962); DOI:10.1086/190072; Bibcode:1962ApJS....7....1L
554«Nebulae which are not recorded in the Catalogues» Roberts, I.; Astronomische Nachrichten, volume 147, p.87, August 1898; DOI:10.1002/asna.18981470406; Bibcode:1898AN....147...87R
555«A Survey of Southern HII Regions» Gum, Colin S.; Memoirs of the Royal Astronomical Society, Vol. 67, p.155, 1955; Bibcode:1955MmRAS..67..155G
556eso1237 — Photo Release: The Rich Colours of a Cosmic Seagull; 26 September 2012; Richard Hook, ESO, La Silla, Paranal, E-ELT & Survey Telescopes Public Information Officer, Garching bei München, Germany; (2022-10-12)
557eso1306 — Photo Release: The Wings of the Seagull Nebula; 6 February 2013; Richard Hook, ESO, La Silla, Paranal, E-ELT & Survey Telescopes Press Officer, Garching bei München, Germany; (2022-10-12)
558eso1913 — Photo Release: «Anatomy of a Cosmic Seagull, ESO’s VST captures a celestial gull in flight» 7 August 2019; Mariya Lyubenova, ESO Head of Media Relations Team, Garching bei München, Germany; (2022-10-12)