NGC 638 is a barred spiral galaxy located in the constellation of Pisces. Its velocity speed to the cosmic microwave background is 2,864± 21 km/s, which corresponds to a Hubble's law of 42.2 ± 3.0 Mpc (∼138 million light-year).[1] NGC 638 was discovered by American astronomer Lewis A. Swift in 1886.

NGC 638
The barred spiral galaxy NGC 638
Observation data (J2000 epoch)
ConstellationPisces
Right ascension01h 39m 37.8s
Declination07° 14′ 14″
Redshift+0.010547± 0.000007
Heliocentric radial velocity3,162 km/s
Distance42.24 ± 2.97 Mpc (∼138 million light-year)
Apparent magnitude (V)13.8
Apparent magnitude (B)14.5
Surface brightness12.81 mag/am
Characteristics
TypeBarred spiral galaxy
Size47,200 ly (24.48 kpc)
Apparent size (V)0.8' x 0.5'
Other designations
PGC 6145, Mrk 1003, CGCG 412-11

Only Professor Seligman classifies this galaxy as a barred spiral, and the SDSS survey image proves him right.[original research?]

NGC 638 has a broad Hydrogen line. NGC 638 is a galaxy whose nucleus shines in the ultraviolet domain. It is listed in the Markarian catalogue under the code Mrk 1003 (MK 1003).[2]

To date, two non-redshift measurements give a distance of 55.330 0 ± 1.273 Mpc (∼180 million light-year),[3] which is outside the Hubble distance values. Note that the NASA/IPAC database calculates the diameter of a galaxy using the average value of independent measurements, when available, and that consequently the diameter of NGC 638 could be about 11.1 kpc (∼36,200 light-year) if the Hubble's law were used to calculate it.

Location of NGC 638

NGC 645 Group

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NGC 638 is part of the NGC 645 group which includes at least five galaxies. The other three galaxies in this group are NGC 632, UGC 1137 and UGC 1172.[4]

See also

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Related article

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References

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  1. ^ "By Name | NASA/IPAC Extragalactic Database". ned.ipac.caltech.edu. Retrieved 2024-07-23.
  2. ^ "NGC 638". astrovalleyfield.ca. Retrieved 2024-07-23.
  3. ^ "NED Query Results for NGC 638". ned.ipac.caltech.edu. Retrieved 2024-07-23.
  4. ^ Garcia, A. M. (1993-07-01). "General study of group membership. II. Determination of nearby groups". Astronomy and Astrophysics Supplement Series. 100: 47–90. Bibcode:1993A&AS..100...47G. ISSN 0365-0138.
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  •   Media related to NGC 638 at Wikimedia Commons