NGC 247

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Galaxy
NGC 247
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NGC 247 recorded with the Wide Field Imager at the 2.2 meter telescope of the MPG / ESO in the La Silla Observatory
NGC 247 recorded with the Wide Field Imager at the 2.2 meter telescope of the MPG / ESO in the La Silla Observatory
AladinLite
Constellation whale
Position
equinox :  J2000.0 , epoch : J2000.0
Right ascension 00 h 47 m 08.55 s
declination -20 ° 45 ′ 37.4 ″
Appearance
Morphological type SAB (s) d / HII  
Brightness  (visual) 8.9 likes
Brightness  (B-band) 9.6 likes
Angular expansion 19.9 ′ × 5.5 ′
Position angle 172 °
Inclination 75 °
Surface brightness 13.8 mag / arcmin²
Physical data
Affiliation Sculptor group  
Redshift 0.000520 ± 0.000007  
Radial velocity 156 ± 2 km / s  
Stroke distance
v rad  / H 0 		(8 ± 1)  x  10 6  ly
(2.36 ± 0.17)  Mpc 
Dimensions approx. 1.8 · 10 10 M ☉
diameter approx. 50,000 ly
history
discovery Wilhelm Herschel
Discovery date October 20, 1784
Catalog names
NGC  247 • UGCA  11 • PGC  2758 • ESO  540-022 • MCG  -04-03-005 • IRAS  00446-2101 • KUG  0044-210 • 2MASX  J00470855-2045374 • GC  132 • H  V 20 • h  57 • HIPASS J0047- 20 • LDCE 26 NED005

NGC 247 is a faint bar spiral galaxy of the Hubble type SBcd with extensive star formation areas in the constellation Whale south of the ecliptic . It is estimated to be 8 million light years from the Milky Way and about 50,000 light years in diameter . The galaxy belongs to the Sculptor group that is adjacent to our local group .

One difficulty in determining the range of NGC 247 is that from Earth we see the galaxy from the side. The distance of galaxies is determined by the apparent brightness of variable stars, the Cepheids . The side view weakens the light from interstellar dust and the stars appear to be further away. Measurements of the Araucaria project in the infrared range from 2009 showed that the extinction had been somewhat underestimated in previous studies and led to a distance estimate that was 7% lower.

The object was discovered on October 20, 1784 by the German-British astronomer Wilhelm Herschel .

Web links

Commons : NGC 247  - collection of images, videos, and audio files

Individual evidence

  1. ↑ a b c d e NASA / IPAC EXTRAGALACTIC DATABASE
  2. ↑ a b c d e f SEDS : NGC 247
  3. ^ W. Gieren et al .: The Araucaria Project . The Distance to the Sculptor Galaxy NGC 247 from Near-Infrared Photometry of Cepheid Variables. May 16, 2009, arxiv : 0905.2699 .
  4. ↑ Seligman