IC 10

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IC 10
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The dwarf galaxy IC 10, superimposed images from the Hubble Space Telescope and (in the X-ray range) from the Chandra Space Telescope
The dwarf galaxy IC 10, superimposed images from the Hubble Space Telescope and (in the X-ray range ) from the Chandra Space Telescope
Constellation Cassiopeia
equinoxJ2000.0 , epoch : J2000.0
Right ascension 00 h 20 m 17.3 s
declination + 59 ° 18 ′ 14 ″
Morphological type dIrr IV / BCD  
Brightness  (visual) 11.2 mag
Brightness  (B-band) 11.8 mag
Angular expansion 6.4 ′ × 5.3 ′
Position angle 135 °
Surface brightness 14.9 mag / arcmin²
Physical data
Affiliation Local group ,
Andromeda subgroup  
Redshift −0.001161 ± 0.000003  
Radial velocity −384 ± 1 km / s  
distance 2.2  ·  10 6  years  
discovery Lewis A. Swift
Discovery date October 8, 1887
Catalog names
IC  10 • UGC  192 • PGC  1305 • MCG  + 10-1-1 • IRAS  00177 + 5900 •

IC 10 is an irregular dwarf galaxy in the constellation Cassiopeia . The galaxy is part of the Local Group , which also includes our home galaxy, the Milky Way . The "IC" in the name stands for the index catalog , an astronomical catalog of galactic nebulae, star clusters and galaxies published at the end of the 19th / beginning of the 20th century. IC 10 is a very young galaxy with highly active star formation , and the closest starburst galaxy to Earth .

History of discovery and location

IC 10 was discovered on October 8, 1887 by the American astronomer Lewis A. Swift , and identified as an extragalactic object in 1935. Since the galaxy is only around three degrees away from the galactic plane , optical observations are difficult, and it took decades before this object could be precisely located: Edwin Hubble already suspected that it could be a galaxy in the Local Group , which also our home galaxy, the Milky Way, belongs to. Concrete evidence for this could not be obtained until 1962 , in the form of measurements of the object's radial velocity , which Hubble's assumption confirmed. Subsequent optical observations of the H-II regions of the galaxy confirmed the comparatively short distance of this galaxy from our own.

It was not until 1996 that membership of the local group was finally established. In the course of eleven years of observations, a number of variable stars had been detected in the galaxy, including so-called Cepheids , in which the period of changes in brightness changes the absolute brightness and so, in comparison with the observed apparent brightness , the Distance lets close. In addition, it turned out that IC 10 is a companion galaxy to the Andromeda Galaxy .


The question of the type and number of star types present in this galaxy has been the subject of research since the 1980s . Compared to other galaxies, a comparatively large number of new stars are forming in IC 10. In addition, this galaxy contains an unexpectedly large number of Wolf-Rayet stars ; massive stars in the late phase of stellar evolution . IC 10 is thus the closest starburst galaxy to earth .

Observations of the non- ionized hydrogen in the galaxy ( HI regions ) indicate that IC 10 is still emerging: The galaxy is still drawing gas from the surrounding regions ( accretion ); In the galaxy's interior, the stellar wind has created cavities of active, massive stars, at the outer limits of which stars of the next generation are formed. The galaxy is apparently in a star formation phase that started only a few tens of millions of years ago. Another sign of the galaxy's young age is the lack of traces of supernova explosions.

Web links

Commons : IC 10  - collection of pictures, videos and audio files

Individual evidence

  2. a b c d e f SEDS : IC 10
  3. ^ NU Mayall: An Extra-Galactic Object 3 ° from the Plane of the Galaxy. In: Publications of the Astronomical Society of the Pacific , Vol. 47, No. 280, 1935, pp. 317-318. bibcode : 1935PASP ... 47..317M
  4. ^ E. Hubble: In the Realm of the Nebulae. Yale University Press, New Haven 1936.
  5. ^ G. de Vaucouleurs and H. Ables: Integrated Magnitudes and Color Indices of IC 10. In: Publications of the Astronomical Society of the Pacific , Vol. 77, No. 457, 1965, pp. 272-282. bibcode : 1965PASP ... 77..272D
  6. ^ A. Saha, A., John G. Hoessel, John Krist and G. Edward Danielson: Variable Stars in the Dwarf Galaxy IC 10 . In: Astronomical Journal , Vol. 111, 1996, pp. 197f. bibcode : 1996AJ .... 111..197S
  7. ^ DA Hunter and JS Gallagher, III: Star-forming properties and histories of dwarf irregular galaxies - Down but not out. In: Astrophysical Journal Supplement Series , Vol. 58, 1985, pp. 533-560. bibcode : 1985ApJS ... 58..533H
  8. ^ Philip Massey, Taft E. Armandroff and Peter S. Conti: IC 10 - A 'poor cousin' rich in Wolf-Rayet stars. In: Astronomical Journal , Vol. 103, April 1992, pp. 1159-1165 and 1421, bibcode : 1992AJ .... 103.1159M ; Philip Massey and Shadrian Holmes: Wolf-Rayet Stars in IC 10: Probing the Nearest Starburst . In: Astrophysical Journal Letters , Vol. 580, 2002, pp. L35-L38. doi : 10.1086 / 345405
  9. Eric M. Wilcots and Bryan W. Miller: The Kinematics and Distribution of HI in IC 10 . In: Astronomical Journal , Vol. 116, No. 5, 1998, pp. 2363-2394. bibcode : 1998AJ .... 116.2363W

Attention: The sorting key “IC 0010” overwrites the previously used key “IC0010”.