NGC 3998
| Galaxy NGC 3998 |
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|---|---|
![NGC 3998 with LEDA 2501974 (ru) [1] SDSS image](https://de.wikipedia.org/wiki/Datei:NGC3998_-_SDSS_DR14.jpg)
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| NGC 3998 with LEDA 2501974 (ru) SDSS image | |
| AladinLite | |
| Constellation | Big Bear |
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Position equinox : J2000.0 , epoch : J2000.0 |
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| Right ascension | 11 h 57 m 56.1333 s |
| declination | + 55 ° 27 ′ 12.922 ″ |
| Appearance | |
| Morphological type | SA (r) 0 ^ / Sy1 / LINER |
| Brightness (visual) | 10.6 mag |
| Brightness (B-band) | 11.6 mag |
| Angular expansion | 2.7 ′ × 2.3 ′ |
| Position angle | 140 ° |
| Surface brightness | 12.5 mag / arcmin² |
| Physical data | |
| Affiliation | UMa cluster NGC 3998 group NGC 3631 group LGG 241 |
| Redshift | 0.003496 ± 0.000017 |
| Radial velocity | 1048 ± 5 km / s |
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Stroke distance v rad / H 0 |
(51 ± 4) · 10 6 ly (15.5 ± 1.1) Mpc |
| history | |
| discovery | Wilhelm Herschel |
| Discovery date | April 14, 1789 |
| Catalog names | |
| NGC 3998 • UGC 6946 • PGC 37642 • CGCG 269-025 • MCG + 09-20-046 • 2MASX J11575616 + 5527128 • GC 2637 • H I 229 • h 1031 • HOLM 310A • NVSS J115756 + 552712 • WISEA J115756.13 + 552713.0 | |
NGC 3998 is a lens-shaped galaxy of the Hubble type S0 with an active galaxy core in the constellation Great Bear in the northern sky . It is estimated to be 51 million light years from the Milky Way and about 40,000 light years in diameter. Together with NGC 3990 , it forms the galaxy pair Holm 310 . It is a member of the Ursa Major Galaxy Cluster and the NGC 3631 group ( LGG 241 ).
In the same area of the sky are u. a. the galaxies NGC 3972 , NGC 3977 , NGC 3982 .
The object was discovered by Wilhelm Herschel on April 14, 1789 .