| NGC 7674 | |
|---|---|
.jpg) NGC 7674 by theHubble Space Telescope | |
| Observation data (J2000epoch) | |
| Constellation | Pegasus |
| Right ascension | 23h 27m 56.7s[1] |
| Declination | +08° 46′ 45″[1] |
| Redshift | 0.028924 ± 0.000030[1] |
| Heliocentric radial velocity | 8,671 ± 9km/s[1] |
| Distance | 380Mly (117Mpc)[1] |
| Apparent magnitude (V) | 13.1[2] |
| Characteristics | |
| Type | SA(r)bc pec[1] |
| Apparent size (V) | 1.1′ × 1.0′[1] |
| Notable features | Seyfert galaxy |
| Other designations | |
| Arp 182,UGC 12608,MCG +01-59-080,Mrk 533,PGC 71504,CGCG 406-112,VV 343a[1] | |
NGC 7674 is aspiral galaxy located in the constellationPegasus. It is located at a distance of about 350 millionlight years from Earth, which, given its apparent dimensions, means that NGC 7674 is about 125,000 light years across. It was discovered byJohn Herschel on August 16, 1830.[3]
The galaxy is seen nearly face-on, at an inclination of 31 degrees. The centralbar-shaped structure, measuring 15×5 arcseconds is made up of stars. The galaxy has twospiral arms that become broader as the distance increases. One arm vanishes at the point it overlaps with the nearby galaxy NGC 7674A. The shape of NGC 7674, including the long narrow streamers emanating northeast and northwest of the galaxy can be accounted for bytidal interactions with its companions. There is no dwarf galaxy seen inside the streamers.[4] It is featured in Arp'sAtlas of Peculiar Galaxies as number 182, in the category"galaxies with narrow filaments".[5]
NGC 7674 has a powerfulactive nucleus of the kind known as atype 2 Seyfert that is perhaps fed by gas drawn into the center through theinteractions with the companions.[5] In 1975, observations of excess ultraviolet emission led to designation as Markarian 533 inMarkarian's catalog.[6] Later, usingspectropolarimetry, emission characteristic of a hidden broad-line region (BLR), visible only in the polarized fluxspectrum was detected, implying that the nucleus of NGC 7674 is an obscured type 1 Seyfert, hidden by a dust torus.[7] In the center of NGC 7674 lies asupermassive black hole whose mass is estimated to be nearly3.63×107 M☉ based on stellarvelocity dispersion.[8] When observed inradio waves, NGC 7674 features tworadio jets with an S-shape, 0.7 kpc long. The reason for this shape may be a change in the black hole spin axis due to aminor merger, the presence of a binary black hole or due to interactions with the interstellar medium.[9] Two radio sources with characteristics similar to accreting supermassive black holes have been observed in the centre of NGC 7674, at a projected separation of 0.35 parsec.[10]
NGC 7674 falls into the family ofluminous infrared galaxies, with its infrared luminosity being 1011.54L☉.[11] The luminous infrared galaxies are characterised by intense star forming activity. The totalstar formation rate in NGC 7674 is estimated to be 54M☉ per year, and the star formation rate at the nucleus is 4.3M☉ per year.[9]
Twosupernovae have been observed in NGC 7674, SN 2011ee (type Ic, mag 18.6) and SN 2011hb (type Ia, mag 18.8).[12]
NGC 7674 is the brightest and largest member of the isolatedHickson 96 compactgroup of galaxies, consisting of four galaxies. NGC 7674 forms a pair with its smaller companion NGC 7674A, which lies 34 arcseconds to the north.NGC 7675, anelliptical galaxy, lies 2.2 arcminutes to the east.[4][13]
