RCW 74
Coordinates: (305.1°, 0.15°)
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GRS 305.40 +00.20 (Kes 18), often named simply G305, is a major star formation region associated with several HII regions, the star clusters Danks 1 and Danks 2, an estimated 31 O stars and the Wolf-Rayet star WR 48a. It may be one of the most massive star formation regions known in the Milky Way.
Avedisova finds three B-class ionising stars, including the B0.5 Iab supergiant HD 114122 and splits the objects in this direction across several star formation regions including SFR 305.25+0.20 and SFR 305.16-0.03. However, Avedisova's information on this region is largely drawn from research published before the true nature of this region was revealed by the MSX and Spitzer infrared space telescopes and would not include the obscured core ionising clusters, which have not yet been properly analysed.
Dutra identifies the infrared star group [DBS2003] 82 and the infrared star clusters [DBS2003] 83 and [DBS2003] 84 in this direction. Although his notes state "not RCW 74" for the clusters, it is not clear what this means as the 3800 parsec distance estimate he gives places the clusters in the same direction and distance as the larger nebular complex.
You can see the full extent of the RCW 74 region in this spectacular Spitzer infrared image.
Avedisova finds three B-class ionising stars, including the B0.5 Iab supergiant HD 114122 and splits the objects in this direction across several star formation regions including SFR 305.25+0.20 and SFR 305.16-0.03. However, Avedisova's information on this region is largely drawn from research published before the true nature of this region was revealed by the MSX and Spitzer infrared space telescopes and would not include the obscured core ionising clusters, which have not yet been properly analysed.
Dutra identifies the infrared star group [DBS2003] 82 and the infrared star clusters [DBS2003] 83 and [DBS2003] 84 in this direction. Although his notes state "not RCW 74" for the clusters, it is not clear what this means as the 3800 parsec distance estimate he gives places the clusters in the same direction and distance as the larger nebular complex.
You can see the full extent of the RCW 74 region in this spectacular Spitzer infrared image.
"Consideration of the integrated radio flux of the complex implies that a minimum of 31 O7V stars must be present, under the assumption of no photon leakage. Given the age and morphology of the complex and in particular the observation that the central exciting clusters have entirely cleared their natal material, we expect this assumption will be violated, and hence that the true population of massive stars is likely to be significantly larger. If confirmed, the G305 complex represents one of the most massive regions of ongoing triggered star formation currently identified in the galaxy." [1]
This is a major complex with many clusters, HII regions, a WR star and a giant molecular cloud. It appears to be part of a larger structure called the Centaurus Spur. [2]
More details on the Centaurus Spur. [3]
Dutra infrared cluster catalog. [4]
This is a major complex with many clusters, HII regions, a WR star and a giant molecular cloud. It appears to be part of a larger structure called the Centaurus Spur. [2]
More details on the Centaurus Spur. [3]
Dutra infrared cluster catalog. [4]
Notes
1. ^ Clark, J. S. & Porter, J. M. (2004). "Triggered massive star formation in the vicinity of WR 48a", Astronomy and Astrophysics, Vol. 427, 839-847. [2004A&A...427..839C]
2. ^ Danks, A. C., Wamsteker, W., Shaver, P. A., et al. (1984). "A near-infrared study of the region L = 305 deg", Astronomy and Astrophysics, Vol. 132, 301-311. [1984A&A...132..301D]
3. ^ Combi, J. A., Romero, G. E., & Arnal, E. M. (1998). "The spur-like radio feature in Centaurus", Astronomy and Astrophysics, Vol. 333, 298-304. [1998A&A...333..298C]
4. ^ Dutra, C. M., Bica, E., Soares, J., et al. (2003). "New infrared star clusters in the southern Milky Way with 2MASS", Astronomy and Astrophysics, Vol. 400, 533-539. [2003A&A...400..533D]
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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.
According to my correspondence with the Royal Observatory Edinburgh and the Space Telescope Science Institute, I am allowed to use the POSS-II/UKSTU data to create and display images for non-commercial purposes so long as I include this fine print for the SuperCOSMOS data:
Use of these images is courtesy of the UK Schmidt Telescope (copyright in which is owned by the Particle Physics and Astronomy Research Council of the UK and the Anglo-Australian Telescope Board) and the Southern Sky Survey as created by the SuperCOSMOS measuring machine and are reproduced here with permission from the Royal Observatory Edinburgh.
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.
The "Second Epoch Survey" of the southern sky was made by the Anglo-Australian Observatory (AAO) with the UK Schmidt Telescope. Plates from this survey have been digitized and compressed by the ST ScI. The digitized images are copyright ? 1993-5 by the Anglo-Australian Observatory Board, and are distributed herein by agreement.
The "Equatorial Red Atlas" of the southern sky was made with the UK Schmidt Telescope. Plates from this survey have been digitized and compressed by the ST ScI. The digitized images are copyright ? 1992-5, jointly by the UK SERC/PPARC (Particle Physics and Astronomy Research Council, formerly Science and Engineering Research Council) and the Anglo-Australian Telescope Board, and are distributed herein by agreement.
The compressed files of the "Palomar Observatory - Space Telescope Science Institute Digital Sky Survey" of the northern sky, based on scans of the Second Palomar Sky Survey are copyright ? 1993-1995 by the California Institute of Technology and are distributed herein by agreement. The compressed files of the "Palomar Observatory - Space Telescope Science Institute Digital Sky Survey" of the northern sky, based on scans of the Second Palomar Sky Survey are copyright ? 1993-1995 by the California Institute of Technology and are distributed herein by agreement.