Gum 11
Also called
RCW 20Coordinates: (254.5°, 0.0°)
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This is the HII region NGC 2579, which is ionised by three O-class stars. A 1998 paper argues that it is associated with RCW 19. However, a more recent 2007 paper gives a much greater distance for NGC 2579, placing it in the Norma arm.
According to a 2007 paper, NGC 2579 has a distance of 7600 +/- 900 pc and is ionised by three O-class stars: DENIS-P J082052.8-361258 / VdBH 13a B (O5 V), DENIS-P J082054.8-361258 / VdBH 13b A (O6.5 V) and DENIS-P J082055.0-361306 / VdBH 13b B (O8 V). [1]
The same paper states that Gum 11 = NGC 2579 is an HII region and is *not* RCW 20 - they are completely different objects. The paper gives no reason for making this distinction and it is an odd statement to make because the RCW catalog itself identifies RCW 20 with both Gum 11 and NGC 2579 and clearly identifies a nebula with the same extent and location. As Gum's coordinates are not completely accurate, the fact that the location he gives is slightly different is no evidence for distinguishing these objects.
Moffat, Fitzgerald and Jackson (1979) identified 7 possible ionising stars in the direction of RCW 20. They give only spectral types for 3 B-class stars. [2]
This is in the same location as the reflection nebula NGC 2579 (Gum 11).[3]
RCW 19/20 have a joint distance of 3400 pc.[4]
The same paper states that Gum 11 = NGC 2579 is an HII region and is *not* RCW 20 - they are completely different objects. The paper gives no reason for making this distinction and it is an odd statement to make because the RCW catalog itself identifies RCW 20 with both Gum 11 and NGC 2579 and clearly identifies a nebula with the same extent and location. As Gum's coordinates are not completely accurate, the fact that the location he gives is slightly different is no evidence for distinguishing these objects.
Moffat, Fitzgerald and Jackson (1979) identified 7 possible ionising stars in the direction of RCW 20. They give only spectral types for 3 B-class stars. [2]
This is in the same location as the reflection nebula NGC 2579 (Gum 11).[3]
RCW 19/20 have a joint distance of 3400 pc.[4]
Notes
1. ^ Copetti, M. V. F., Oliveira, V. A., Riffel, R., et al. (2007). "A study of the neglected Galactic H ii region NGC 2579 and its companion ESO 370-9", Astronomy and Astrophysics, Vol. 472, 847-854. [2007A&A...472..847C]
2. ^ Moffat, A. F. J., Jackson, P. D., & Fitzgerald, M. P. (1979). "The rotation and structure of the galaxy beyond the solar circle. I - Photometry and spectroscopy of 276 stars in 45 H II regions and other young stellar groups toward the galactic anticentre", Astronomy and Astrophysics Supplement Series, Vol. 38, 197-225. [1979A&AS...38..197M]
3. ^ Bhatt, H. C., Jain, S. K., & Sagar, R. (1998). "The Puppis OB III association: polarization measurements", Astronomy and Astrophysics, Vol. 331, 737-741. [1998A&A...331..737B]
4. ^ Neckel, Th. & Staude, H. J. (1995). "IRAS 08159-3543: Optical Detection of the Dusty, Neutral Bipolar Wind of a Luminous Young Stellar Object", The Astrophysical Journal, Vol. 448, 832. [1995ApJ...448..832N]
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Most of the sources used to create these nebula descriptions are listed in the
notes section for each description. In some cases,
for example the Avedisova, Humphreys and Reed catalogs, the source is used extensively and is not listed in the
individual nebula descriptions. See this catalog overview
for more information on the catalogs and the general sources used
to create these descriptions and this introduction to HII regions
on the general history of this area of astronomy.
This image was created using the POSS-II/UKSTU data of the Digitized Sky Survey and SuperCOSMOS using the process described here.
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and this acknowledgement taken from the DSS site:
The Digitized Sky Surveys were produced at the Space Telescope Science Institute under U.S. Government grant NAG W-2166. The images of these surveys are based on photographic data obtained using the Oschin Schmidt Telescope on Palomar Mountain and the UK Schmidt Telescope. The plates were processed into the present compressed digital form with the permission of these institutions.
The Second Palomar Observatory Sky Survey (POSS-II) was made by the California Institute of Technology with funds from the National Science Foundation, the National Geographic Society, the Sloan Foundation, the Samuel Oschin Foundation, and the Eastman Kodak Corporation.
The UK Schmidt Telescope was operated by the Royal Observatory Edinburgh, with funding from the UK Science and Engineering Research Council (later the UK Particle Physics and Astronomy Research Council), until 1988 June, and thereafter by the Anglo-Australian Observatory. The blue plates of the southern Sky Atlas and its Equatorial Extension (together known as the SERC-J), as well as the Equatorial Red (ER), and the Second Epoch [red] Survey (SES) were all taken with the UK Schmidt.
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