NGC 2403

NGC 2403
NGC 2403
	A Hubble Space Telescope (HST), and Subaru image of NGC 2403. NGC 2404 is visible
Observation data (J2000 epoch)
Constellation	Camelopardalis
Right ascension	07h 36m 51.298s
Declination	+65° 36′ 09.662″
Redshift	0.000445
Heliocentric radial velocity	133 ± 0 km/s
Distance	9.65 Mly (2.96 Mpc)
Apparent magnitude (V)	8.9
Characteristics
Type	SAB(s)cd
Size	~90,300 ly (27.69 kpc) (estimated)
Apparent size (V)	21.9′ × 12.3′
Other designations
	Caldwell 7, IRAS 07321+6543, UGC 3918, PGC 21396, CGCG 309-040

NGC 2403 (also known as Caldwell 7) is an intermediate spiral galaxy in the constellation Camelopardalis. It is an outlying member of the M81 Group,^[3] and is approximately 8 million light-years distant. It bears a similarity to M33, containing numerous star-forming H II regions, but being a little bit larger at approximately 90,000 light-years in diameter compared to the 61,100 light-year diameter of M33.^[4] The northern spiral arm connects it to the star forming region NGC 2404.^[3] NGC 2403 can be observed using 10×50 binoculars.^[3] NGC 2404 is 940 light-years in diameter, making it one of the largest known H II regions. This H II region represents striking similarity with NGC 604 in M33, both in size and location in galaxy.

^ ^a ^b ^c ^d ^e ^f ^g ^h ⁱ "NASA/IPAC Extragalactic Database". Results for NGC 2403. Retrieved 2006-11-21.
^ Carlin, Jeffrey L.; Garling, Christopher T.; Peter, Annika H. G.; Crnojević, Denija; Forbes, Duncan A.; Hargis, Jonathan R.; Mutlu-Pakdil, Burçin; Pucha, Ragadeepika; Romanowsky, Aaron J.; Sand, David J.; Spekkens, Kristine; Strader, Jay; Willman, Beth (2019). "Tidal Destruction in a Low-mass Galaxy Environment: The Discovery of Tidal Tails around DDO 44". The Astrophysical Journal. 886 (2): 109. arXiv:1906.08260. Bibcode:2019ApJ...886..109C. doi:10.3847/1538-4357/ab4c32. S2CID 195218404.
^ ^a ^b ^c Kepple, George Robert; Glen W. Sanner (1998). The Night Sky Observer's Guide. Vol. 1. Willmann-Bell, Inc. p. 73. ISBN 978-0-943396-58-3.
^ Ho, Luis C.; Filippenko, Alexei V.; Sargent, Wallace L. W. (October 1997). "A Search for "Dwarf" Seyfert Nuclei. III. Spectroscopic Parameters and Properties of the Host Galaxies". Astrophysical Journal Supplement. 112 (2): 315–390. arXiv:astro-ph/9704107. Bibcode:1997ApJS..112..315H. doi:10.1086/313041. S2CID 17086638.

[ned-1] ^ ^a ^b ^c ^d ^e ^f ^g ^h ⁱ "NASA/IPAC Extragalactic Database". Results for NGC 2403. Retrieved 2006-11-21.

[jeffrey-2] Carlin, Jeffrey L.; Garling, Christopher T.; Peter, Annika H. G.; Crnojević, Denija; Forbes, Duncan A.; Hargis, Jonathan R.; Mutlu-Pakdil, Burçin; Pucha, Ragadeepika; Romanowsky, Aaron J.; Sand, David J.; Spekkens, Kristine; Strader, Jay; Willman, Beth (2019). "Tidal Destruction in a Low-mass Galaxy Environment: The Discovery of Tidal Tails around DDO 44". The Astrophysical Journal. 886 (2): 109. arXiv:1906.08260. Bibcode:2019ApJ...886..109C. doi:10.3847/1538-4357/ab4c32. S2CID 195218404.

[NSOG-3] Kepple, George Robert; Glen W. Sanner (1998). The Night Sky Observer's Guide. Vol. 1. Willmann-Bell, Inc. p. 73. ISBN 978-0-943396-58-3.

[hoetal1997-4] Ho, Luis C.; Filippenko, Alexei V.; Sargent, Wallace L. W. (October 1997). "A Search for "Dwarf" Seyfert Nuclei. III. Spectroscopic Parameters and Properties of the Host Galaxies". Astrophysical Journal Supplement. 112 (2): 315–390. arXiv:astro-ph/9704107. Bibcode:1997ApJS..112..315H. doi:10.1086/313041. S2CID 17086638.

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