| NGC 1365 | |
|---|---|
 NGC 1365 imaged by theCerro Tololo Inter-American Observatory | |
| Observation data (J2000epoch) | |
| Constellation | Fornax |
| Right ascension | 03h 33m 36.4s[1] |
| Declination | −36° 08′ 25″[1] |
| Redshift | 0.005457±0.000003[1] |
| Heliocentric radial velocity | 1,636±1 km/s[1] |
| Distance | 74 Mly (22.69 Mpc)h−1 0.6774 (Light-travel) |
| Group orcluster | Fornax Cluster |
| Apparent magnitude (V) | 10.3[1] |
| Characteristics | |
| Type | (R')SBb(s)b[1] |
| Size | 201,700 to 306,800 ly (61.85 to 94.08 kpc) (diameter;2MASS K-band total andD25.5 B-band isophotes)[1] |
| Apparent size (V) | 11.2′ × 6.2′[1] |
| Other designations | |
| Great Barred Spiral Galaxy, ESO 358-G 017,NGC 1365,UGC 5887,LEDA 13179,MCG -06-08-026,PGC 13179[1],VV 825 | |
NGC 1365, also known as theFornax Propeller Galaxy[2] or theGreat Barred Spiral Galaxy,[3] is a double-barred spiral galaxy about 56 millionlight-years away[4] in theconstellationFornax. It was discovered by Scottish astronomerJames Dunlop on 2 September 1826.[5]
NGC 1365 is a large barred spiral galaxy in theFornax Cluster. Within the larger long bar stretching across the center of the galaxy appears to be a smaller bar that comprises the core, with an apparent size of about 50″ × 40″.[6] This second bar is more prominent in infrared images of the central region of the galaxy, and likely arises from a combination of dynamical instabilities of stellar orbits in the region, along with gravity,density waves, and the overall rotation of the disc. The inner bar structure likely rotates as a whole more rapidly than the larger long bar, creating the diagonal shape seen in images.
The spiral arms extend in a wide curve north and south from the ends of the east–west bar and form an almostring like Z-shaped halo.[6] Astronomers think NGC 1365's prominent bar plays a crucial role in the galaxy's evolution, drawing gas and dust into a star-forming maelstrom and ultimately feeding material into the central black hole.[7]
NGC 1365, including its two outer spiral arms, spreads over around 300,000 light-years. Different parts of the galaxy take different times to make a full rotation around the core of the galaxy, with the outer parts of the bar completing one circuit in about 350 million years. NGC 1365 and other galaxies of its type have come to more prominence in recent years with new observations indicating that the Milky Way could also be a barred spiral galaxy. Such galaxies are quite common — two thirds of spiral galaxies are barred according to recent estimates, and studying others can help astronomers understand our own galactic home.[8]
Foursupernovae have been observed in NGC 1365:
The centralsupermassive black hole in theactive nucleus, which has a mass of about 2 millionsolar masses or half the mass of the Milky Way's central black holeSagittarius A*, rotates at close to the speed of light. These observations, announced in February 2013, were made using the X-ray telescope satelliteNuSTAR.[19][20]
As seen fromearth, the location of NGC 1365 is one and a half degrees eastward of STAR 2 (Philip S. Harrington's STAR 2) which is a telescopic asterism in the shape of a triangle, composed of the stars Chi 1-2-3 Fornacis (χ 1-2-3 Fornacis).
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