Astronomy:NGC 2403

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NGC 2403
A Hubble Space Telescope (HST), and Subaru image of NGC 2403. NGC 2404 is visible
Observation data (J2000 epoch)
ConstellationCamelopardalis
Right ascension 07h 36m 51.298s[1]
Declination+65° 36′ 09.662″[1]
Redshift0.000445[1]
Helio radial velocity133 ± 0 km/s[1]
Distance9.65 Mly (2.96 Mpc)[2]
Apparent magnitude (V)8.9[1]
Characteristics
TypeSAB(s)cd[1]
Size~90,300 ly (27.69 kpc) (estimated)[1]
Apparent size (V)21.9′ × 12.3′[1]
Other designations
Caldwell 7, IRAS 07321+6543, UGC 3918, PGC 21396[1]

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.

Observation history

The galaxy was discovered by German-British astronomer William Herschel on 1 November 1788.[4] Edwin Hubble detected Cepheid variables in NGC 2403 using the Hale Telescope, making it the first galaxy beyond the Local Group within which a Cepheid was discovered.[3] By 1963, 59 variables had been found in NGC 2403, of which 17 were eventually confirmed as Cepheids, with periods between 20 and 87 days. As late as 1950 Hubble was using a distance of just under 2 million light years for the galaxy's distance, but by 1968 the analysis of the Cepheids increased this by almost a factor of five, to within 0.2 magnitudes of the current value.

Characteristics

A Galaxy of Birth and Death

NGC 2403 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.[5] 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.

Supernovae and supernovae imposters

There have been four reported astronomical transients in the galaxy:

  • SN 1954J was first noticed by Gustav Tammann and Allan Sandage as a "bright blue irregular variable" star, which they named V12. They noted it underwent a major outburst on 2/3 November 1954, which attained a magnitude of 16 at its brightest.[6] In 1972, Fritz Zwicky classified this event as a Type V supernova.[7] It was later determined to be a supernova imposter: a highly luminous, very massive eruptive star, surrounded by a dusty nebula, similar to the 1843 Great Eruption of η Carinae in the Milky Way.[8]
  • SN 2002 kg was discovered by LOTOSS (Lick Observatory and Tenagra Observatory Supernova Searches) on 26 October 2002 and initially classified as a Type IIn, or possibly the outburst of a luminous blue variable.[9] On 24 August 2021, it was reclassified as a Gap transient.[10]
  • SN 2004dj (Type II-P, mag. 11.2) was discovered by Kōichi Itagaki on 31 July 2004.[11][12] At the time of its discovery, it was the nearest and brightest supernova observed in the 21st century, and is now listed as the brightest supernova of 2004.[13]
  • AT 2016ccd, initially designated as SNhunt225, is a luminous blue variable, first discovered by Catalina Real-time Transient Survey (CRTS) and Stan Howerton in December 2013. Outbursts from this star have been observed as recently as November 2021.[14][15]

Companions

NGC 2403 has two known companions. One is the relatively massive dwarf galaxy DDO 44. It is currently being disrupted by NGC 2403, as evidenced by a tidal stream extending 82 kly (25 kpc) on both sides of DDO 44. DDO 44 is approaching NGC 2403 at a distance much closer than typical for dwarf galaxy interactions. It currently has a V-band absolute magnitude of −12.9, but its progenitor was even more luminous.[2]

The other known companion is officially named MADCASH J074238+652501-dw, although it is nicknamed MADCASH-1. The name refers to the MADCASH (Magellanic Analog Dwarf Companions and Stellar Halos) project. MADCASH-1 is similar to typical dwarf spheroidal galaxies in the Local Group; it is quite faint, with an absolute V-band magnitude of −7.81, and has only an ancient, metal-poor population of red giant stars.[16]

See also

References

  1. ↑ 1.0 1.1 1.2 1.3 1.4 1.5 1.6 1.7 1.8 "Results for object NGC 2403". NASA and Caltech. https://ned.ipac.caltech.edu/byname?objname=NGC+2403. 
  2. ↑ 2.0 2.1 Carlin, Jeffrey L.; Garling, Christopher T.; Peter, Annika H. G.; Crnojević, Denija; Forbes, Duncan A.; Hargis, Jonathan R.; Mutlu-Pakdil, Burçin; Pucha, Ragadeepika et al. (2019). "Tidal Destruction in a Low-mass Galaxy Environment: The Discovery of Tidal Tails around DDO 44". The Astrophysical Journal 886 (2): 109. doi:10.3847/1538-4357/ab4c32. Bibcode: 2019ApJ...886..109C. 
  3. ↑ 3.0 3.1 3.2 3.3 Kepple, George Robert; Glen W. Sanner (1998). The Night Sky Observer's Guide. 1. Willmann-Bell, Inc.. p. 73. ISBN 978-0-943396-58-3. 
  4. ↑ Seligman, Courtney. "New General Catalogue Objects: NGC 2403". https://cseligman.com/text/atlas/ngc24.htm#2403. 
  5. ↑ 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. doi:10.1086/313041. Bibcode: 1997ApJS..112..315H. 
  6. ↑ Tammann, G. A.; Sandage, Allan (1968). "The Stellar Content and Distance of the Galaxy NGC 2403 IN the M81 Group". The Astrophysical Journal 151: 825. doi:10.1086/149487. Bibcode: 1968ApJ...151..825T. 
  7. ↑ Kowal, C. T.; Sargent, W. L. W.; Searle, L.; Zwicky, F. (1972). "The 1971 Palomar Supernova Search". Publications of the Astronomical Society of the Pacific 84 (502): 844. doi:10.1086/129392. Bibcode: 1972PASP...84..844K. 
  8. ↑ Van Dyk, Schuyler D.; Filippenko, Alexei V.; Chornock, Ryan; Li, Weidong; Challis, Peter M. (2005). "Supernova 1954J (Variable 12) in NGC 2403 Unmasked". Publications of the Astronomical Society of the Pacific 117 (832): 553–562. doi:10.1086/430238. Bibcode: 2005PASP..117..553V. 
  9. ↑ Schwartz, M.; Li, W.; Filippenko, A. V.; Chornock, R. (2003-01-01). "Supernova 2002kg in NGC 2403". International Astronomical Union Circular 8051: 1. Bibcode: 2003IAUC.8051....1S. http://www.cbat.eps.harvard.edu/iauc/08000/08051.html#Item1. 
  10. ↑ "SN 2002 kg". IAU. https://www.wis-tns.org/object/2002kg. 
  11. ↑ Nakano, S.; Itagaki, K.; Bouma, R. J.; Lehky, M.; Hornoch, K. (2004-08-01). "Supernova 2004dj in NGC 2403". International Astronomical Union Circular (8377): 1. Bibcode: 2004IAUC.8377....1N. http://www.cbat.eps.harvard.edu/iauc/08300/08377.html#Item1. 
  12. ↑ "SN 2004dj". IAU. https://www.wis-tns.org/object/2004dj. 
  13. ↑ Bishop, David. "Bright Supernovae - 2004". https://www.rochesterastronomy.org/sn2004/index.html. 
  14. ↑ Bishop, David (9 November 2021). "LBV AT2016ccd in NGC 2403". https://www.rochesterastronomy.org/sn2013/sn2016ccd.html. 
  15. ↑ "AT 2016ccd". IAU. https://www.wis-tns.org/object/2016ccd. 
  16. ↑ Carlin, Jeffrey L.; Mutlu-Pakdil, Burçin; Crnojević, Denija; Garling, Christopher T.; Karunakaran, Ananthan; Peter, Annika H. G.; Tollerud, Erik; Forbes, Duncan A. et al. (2021). "Hubble Space Telescope Observations of Two Faint Dwarf Satellites of Nearby LMC Analogs from MADCASH". The Astrophysical Journal 909 (2): 211. doi:10.3847/1538-4357/abe040. Bibcode: 2021ApJ...909..211C. 

Coordinates: Sky map 07h 36m 51.298s, +65° 36′ 09.662″



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