| NGC 638 | |
|---|---|
 The barred spiral galaxy NGC 638 | |
| Observation data (J2000epoch) | |
| Constellation | Pisces |
| Right ascension | 01h 39m 37.8s |
| Declination | 07° 14′ 14″ |
| Redshift | +0.010547± 0.000007 |
| Heliocentric radial velocity | 3,162km/s |
| Distance | 42.24 ± 2.97 Mpc (~138 millionlight-year) |
| Apparent magnitude (V) | 13.8 |
| Apparent magnitude (B) | 14.5 |
| Surface brightness | 12.81 mag/am |
| Characteristics | |
| Type | Barred spiral galaxy |
| Size | 47,200ly (24.48kpc) |
| Apparent size (V) | 0.8' x 0.5' |
| Other designations | |
| PGC 6145,Mrk 1003,CGCG 412-11 | |
NGC 638 is a barredspiral galaxy located in the constellation ofPisces. Its velocity speed to thecosmic microwave background is 2,864± 21 km/s, which corresponds to aHubble's law of 42.2 ± 3.0Mpc (~138 millionlight-year).[1] NGC 638 was discovered by American astronomerLewis A. Swift in 1886.
NGC 638 has a broadHydrogen line. NGC 638 is a galaxy whose nucleus shines in the ultraviolet domain. It is listed in theMarkarian catalogue under the code Mrk 1003 (MK 1003).[2]
To date, two non-redshift measurements give a distance of 55.330 0 ± 1.273Mpc (~180 millionlight-year),[3] which is outside theHubble distance values. Note that theNASA/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 11.1kpc (~36,200light-year) if theHubble's law were used to calculate it.
NGC 638 is part of theNGC 645 group which includes at least five galaxies. The other three galaxies in this group are NGC 632,UGC 1137 andUGC 1172.[4]
Media related toNGC 638 at Wikimedia Commons | Thisspiral galaxy article is astub. You can help Wikipedia byexpanding it. |