| NGC 891 | |
|---|---|
 NGC 891 | |
| Observation data (J2000epoch) | |
| Constellation | Andromeda |
| Right ascension | 02h 22m 33.4s[1] |
| Declination | +42° 20′ 57″[1] |
| Redshift | 528 ± 4 km/s[1] |
| Distance | 27.3 ± 1.8Mly (8.4 ± 0.5Mpc)[2] |
| Apparent magnitude (V) | 10.8[1] |
| Characteristics | |
| Type | SA(s)b?[1] |
| Size | 130,700ly (40.09kpc) (estimated)[1] |
| Apparent size (V) | 13′.5 × 2′.5[1] |
| Other designations | |
| UGC 1831,PGC 9031,[1]Caldwell 23 | |
NGC 891 (also known asCaldwell 23, theSilver Sliver Galaxy, and theOuter Limits Galaxy) is an edge-onunbarred spiral galaxy about 30millionlight-years away in theconstellationAndromeda. It was discovered byWilliam Herschel on October 6, 1784.[3] The galaxy is a member of theNGC 1023 group ofgalaxies in theLocal Supercluster. It has anH II nucleus.[4]
The object is visible in small to moderate sizetelescopes as a faint elongated smear of light with adust lane visible in largerapertures.
In 1999, theHubble Space Telescope imaged NGC 891 ininfrared.
In 2005, due to its attractiveness and scientific interest, NGC 891 was selected to be thefirst light image of theLarge Binocular Telescope.[5][6]In 2012, it was again used as a first light image of theLowell Discovery Telescope with the Large Monolithic Imager.[7]
Supernova SN 1986J was discovered on August 21, 1986 at apparent magnitude 14.[8]
NGC 891 looks as theMilky Way would look like when viewed edge-on (some astronomers have even noted how similar to NGC 891 our galaxy looks as seen from theSouthern Hemisphere[9]) and, in fact, both galaxies are considered very similar in terms of luminosity and size;[10] studies of the dynamics of its molecularhydrogen have also proven the likely presence of a centralbar.[11]Despite this, recent high-resolution images of its dusty disk show unusual filamentary patterns. These patterns are extending into thehalo of the galaxy, away from itsgalactic disk. Scientists presume that supernova explosions caused this interstellar dust to be thrown out of the galactic disk toward the halo.[12]
It may also be possible that the light pressure from surrounding stars causes this phenomenon.[13]
The galaxy is a member of a small group of galaxies, sometimes called theNGC 1023 Group. Other galaxies in this group are the NGCs925,949,959,1003,1023, and1058, and the UGCs1807,1865 (DDO 19),2014 (DDO 22),2023 (DDO 25),2034 (DDO 24), and2259.[14] Its outskirts are populated by multiple low-surface brightness, coherent, and vast substructures, like giant streams that loop around the parent galaxy up to distances of approximately 50 kpc. The bulge and the disk are surrounded by a flat and thick cocoon-like stellar structure. These have vertical and radial distances of up to 15 kpc and 40 kpc, respectively,[15] and are interpreted as the remnant of asatellite galaxy disrupted and in the process of being absorbed by NGC 891.[16]
NGC 891 appears alongsideM67, theSombrero Galaxy(M104), thePinwheel Galaxy(M101),NGC 5128,NGC 1300,M81, and theAndromeda Galaxy in the end credits of theOuter Limits TV series, which is why it is occasionally called theOuter Limits Galaxy.[17][18][19][20]
The soundtrack of the 1974 filmDark Star byJohn Carpenter features amuzak-style instrumental piece called "When Twilight Falls on NGC 891".[21]
The first solo album byEdgar Froese,Aqua, also released in 1974, contained a track called "NGC 891". Side 2 of the album, which included this track, was unusual in having been a rare example of a commercially issued piece of music recorded using theartificial head system.
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