Article · Wikipedia archive · Last revised Jun 14, 2026

NGC 1931

NGC 1931 is a reflection and emission nebula and around a young star cluster in the constellation Auriga. The nebula shares similarities to the Orion Nebula as it is a mixed emission-reflection nebula that also contains a small Trapezium of hot young stars. At around 2 million years of age, most of the ongoing star formation in the star cluster is hidden away in the nebula. It is believed that the main ionizing source for the dusty molecular cloud is a single, hot B-type star. The distance from Earth is estimated at 7500 light years.

Last revised
Jun 14, 2026
Read time
≈ 2 min
Length
400 w
Citations
11
Source
Wikipedia ↗
NGC 1931
Reflection nebula
emission nebula
NGC 1931
Observation data: J2000.0 epoch
Right ascension5h 31m 1
Declination+34° 15′1
Distance~7500 ly
Apparent magnitude (V)10.11
Apparent dimensions (V)7′
ConstellationAuriga

NGC 1931 is a reflection and emission nebula and around a young star cluster in the constellation Auriga. The nebula shares similarities to the Orion Nebula as it is a mixed emission-reflection nebula that also contains a small Trapezium of hot young stars.2 At around 2 million years of age,3 most of the ongoing star formation in the star cluster is hidden away in the nebula.4 It is believed that the main ionizing source for the dusty molecular cloud is a single, hot B-type star.3 The distance from Earth is estimated at 7500 light years.4

History

The German-born English astronomer William Herschel discovered the small reflection nebula in 1793 and noted seeing a few stars in the middle.5 IC 417 is a nearby nebula discovered in 1892. In 1931, Swedish astronomer Per Collinder included it in his catalog of open star clusters as the "nebulous cluster" Collinder 68.6 American astronomer Stewart Sharpless cataloged the emission component, which lies outside the center, as Sh 2-237 in 1959.7

References

References

  1. "NGC 1931". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2008-11-16.
  2. Ambartsumian, V. A. (1954-01-01). "Multiple Systems of Trapezium type". Communications of the Byurakan Astrophysical Observatory. 15: 3–40. Bibcode:1954CoBAO..15....3A.
  3. Lim, Beomdu; Sung, Hwankyung; Bessell, Michael S.; Kim, Jinyoung S.; Hur, Hyeonoh; Park, Byeong-Gon (2015-04-01). "The Sejong Open Cluster Survey (SOS). IV. the Young Open Clusters NGC 1624 and NGC 1931". The Astronomical Journal. 149 (4): 127. arXiv:1502.00105. Bibcode:2015AJ....149..127L. doi:10.1088/0004-6256/149/4/127. hdl:1885/14284. ISSN 0004-6256.
  4. Dewangan, L. K.; Ojha, D. K.; Zinchenko, I.; Janardhan, P.; Luna, A. (2017-01-01). "Multiwavelength Study of the Star Formation in the S237 H II Region". The Astrophysical Journal. 834 (1): 22. arXiv:1610.08428. Bibcode:2017ApJ...834...22D. doi:10.3847/1538-4357/834/1/22. ISSN 0004-637X.
  5. Herschel, William (1802). "Catalogue of 500 New Nebulae, Nebulous Stars, Planetary Nebulae, and Clusters of Stars; With Remarks on the Construction of the Heavens". Philosophical Transactions of the Royal Society of London. 92: 477–528. ISSN 0261-0523. JSTOR 107131.
  6. Collinder, Per (1931-01-01). "On Structural Properties of Open Galactic Clusters and their Spatial Distribution. Catalog of Open Galactic Clusters". Annals of the Observatory of Lund. 2: B1–B46. Bibcode:1931AnLun...2....1C.
  7. Sharpless, Stewart (1959-12-01). "A Catalogue of H II Regions". The Astrophysical Journal Supplement Series. 4: 257. Bibcode:1959ApJS....4..257S. doi:10.1086/190049. ISSN 0067-0049.
External links