NGC 1309

NGC 1309
A Hubble Space Telescope (HST) image of NGC 1309. Credit: HST/NASA/ESA.
Observation data (J2000.0 epoch)
Constellation	Eridanus
Right ascension	03h 22m 06.5s [1]
Declination	-15° 24′ 00″ [1]
Redshift	0.007125 (2136 +/- 4 km/sec) [1]
Distance	120 Mly (36 Mpc) [2]
Type	SA(s)bc [1]
Apparent dimensions (V)	2.2 x 2.0 arcmin [1]
Apparent magnitude (V)	12.0 [1]
Other designations
PGC 012626
See also: Galaxy, List of galaxies

NGC 1309 is a spiral galaxy located approximately 120 million light-years away in the constellation Eridanus. It is about 75,000 light-years across; about 3/4s the width of our own galaxy, the Milky Way. Its shape is classified as SA(s)bc, meaning that it has moderately wound spiral arms and no ring. Bright blue areas of star formation can be seen in the spiral arms, while the yellowish central nucleus contains older-population stars. NGC 1309 is one of over 200 members of the Eridanus Group of galaxies.^[3]

Image

The image on the right is a composite of 25 hours of exposures taken by the Hubble Space Telescope (HST) during August and September 2005 using the B (blue: 435 nm), V (visual: 555 nm) and I (infrared: 814 nm) filters. The image is a square capturing 2.9 x 2.9 arcminutes of sky (roughly 100,000 light-years per side).^[3] Note: the smaller galaxies visible in the image are in the distant background; they are not satellites.^[1]

Supernova 2002fk

SN 2002fk was discovered jointly by Reiki Kushida of the Yatsugatake South Base Observatory, Nagano Prefecture, Japan; and Jun-jie Wang and Yu-Lei Qiu of the Beijing Astronomical Observatory on Sept. 17.719 UT.^[4] When it was discovered it was magnitude ~15.0; it was estimated to have reached maximum magnitude of ~13.0 before fading away. It was a Type Ia supernova (i.e., the progenitor star was white dwarf). White dwarfs are older stars that have used up almost all of their main fuel (the lighter elements such as hydrogen and helium). SN 2002fk's spectra showed no indications of hydrogen, helium or carbon; instead ionized calcium, silicon, iron and nickel were found.^[5]

References

1. ^ ^{a b c d e f g} "NASA/IPAC Extragalactic Database". Results for NGC 1309. http://nedwww.ipac.caltech.edu/. Retrieved 8 Dec 2008. 
2. ^ Riess, Adam (Jul 2007). "The Final SHOE; Completing a Rich Cepheid Field in NGC 1309". Hubble Space Telescope Proposal ID #11329 (Cycle 16): 11329. Bibcode 2007hst..prop11329R. 
3. ^ ^{a b} "Hubble Snaps Images of a Pinwheel-Shaped Galaxy". News Release: STScI-2006-07. NASA. http://hubblesite.org/newscenter/archive/releases/2006/07/image/a. Retrieved 8 Dec 2008. 
4. ^ "International Astronomical Union Circular". Supernova 2002fk in NGC 1309. Central Bureau for Astronomical Telegrams. http://www.cfa.harvard.edu/iauc/07900/07973.html#Item2. 
5. ^ Marion, G.H., et al. (Jul 2003). "Near-Infrared Spectra of Type Ia Supernovae". The Astrophysical Journal 591 (1): 316–333. arXiv:astro-ph/0306470. Bibcode 2003ApJ...591..316M. doi:10.1086/375290. 

Coordinates: 03^h 22^m 06.5^s, −15° 24′ 00″