The Gum Catalog

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Gum 31

Coordinates: (286.22°, -0.17°)
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Also called IC 2599. Gum 31 is ionised by the star cluster NGC 3324. Gum also associates this nebula with the B-class HD 92206. SIMBAD gives a hotter O6.5V class for this multiple star. Avedisova lists this as an ionising star along with the O6 V HD 92209. Avedisova may be mistaken about HD 92209, however, as SIMBAD gives a K2 III class for this star.

Gum 32

Coordinates: (287.2°, 0.4°)
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The RCW catalog describes RCW 52 as a "Bright knot in η Carina nebula separated from main region by absorption".

This ring nebula is ionised by the O8 V star LSS 1887. Avedisova adds two additional B-class ionising stars. It is viewed next to the vast clouds of the Eta Carinae nebula (RCW 53) and may be nearby if the Avedisova estimate is correct or much further away if the Cameron Reed estimate from 1993 is correct.

Avedisova places RCW 52 together with the Eta Carinae nebula (RCW 53) and Gum 31, Gum 32, and Gum 33 in the massive and complex star formation region SFR 287.28-0.88 with 143 components.

You can view a good image of this nebula here.

Gum 33

Coordinates: (287.61°, -0.85°)
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The Carina nebula, NGC 3372, is ionised by star clusters belonging to the massive Car OB1 association, which includes some of the brightest known stars in the Milky Way: 20 O-stars, 4 ionising B-stars the Wolf-Rayet star WR 25 and the massive and very strange variable star Eta Carinae.

The Car OB1 member HD 93129A is perhaps the brightest known star in the Milky Way and has been put into its own O2 class.

Kharchenko identifies about a dozen ionising clusters in this direction. Nine of these have distance estimates ranging from about 2000 to 3000 parsecs: Trumpler 14, Trumpler 15, Trumpler 16, Bochum 10, Collinder 228, NGC 3324, NGC 3293, Loden 153 and [KPR2005] 62. Distances are controversial, however, even for such a well-studied region. For example, a 2004 paper argues that Trumpler 16 is a background object at 4000 parsecs.

The Hubble space telescope has produced a huge panorama of the Carina nebula.

Gum 34a

Coordinates: (289.08°, 0.09°)
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Gum 34a and 34b both lie in a similar direction to RCW 54b and are filaments making up part of a shell surrounding NGC 3503 and the Car OB2 association.

Gum 34a is a knot of nebulosity below and to the right of NGC 3503 in galactic coordinates.

Gum 34b

Coordinates: (289.6°, 0.51°)
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Gum 34a and 34b both lie in a similar direction to RCW 54b and are filaments making up part of a shell surrounding the Car OB2 association.

Gum 34b marks the forked structure above the ring surrounding NGC 3503.

Gum 35

Coordinates: (289.90°, -1.26°)
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This HII region is associated with the giant molecular cloud [GCB88] 13 and according to Avedisova is ionised by the Wolf-Rayet star WR 35.

Dutra et.al report the infrared cluster [DBS2003] 57 in this direction.

You can see a detailed colour image in this direction here.

Gum 36

Coordinates: (290.42°, 1.68°)
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Also called Bran 347, the HII region Gum 36 (RCW 54d) is ionised by the B0 V class star HD 97471.

Gum 37

Coordinates: (290.61°, 0.33°)
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Gum 37, also called RCW 54c, is associated with the star cluster NGC 3572.

You can see a good colour image of this region here.

Gum 38a

Coordinates: (291.284°, -0.712°)
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The giant HII region NGC 3576 is ionised by a large star cluster visible in the infrared and at least 10 times brighter than the Orion nebula. Curiously for such a prominent HII region, no very hot O-stars have yet been identified in the central cluster. A 2002 paper finds the brightest star to be the B1 V FBDC 48. (Although the paper says that the data might allow for this to be a late (cool) O-star as well.)

Avedisova identifies 4 nearby stars that may help to ionise the nebula, including three B-class stars and the O7.5 III giant HD 97319 (SIMBAD gives an O9.5 Ib class for this star). She places NGC 3576 in the star formation region SFR 291.30-0.69 with 23 components, including 3 masers and the smaller HII regions NGC 3576 IRS 1 and NGC 3581.

You can see a good visual image of NGC 3576 here and see the MSX 8μ infrared false-colour image here.

Gum 38b

Coordinates: (291.61°, -0.528°)
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NGC 3603 is one of the brightest HII regions known in the galaxy, with several sources stating that it is the brightest currently known. It is ionised by an extremely dense starburst cluster. A 2004 study identified 14 O-stars (7 ultrahot class O3) and 3 Wolf-Rayet stars in the cluster core, which includes the massive multiple star system NGC 3603YC.

You can see a very good Hubble image of the star cluster at the heart of this nebula and the region in MSX 8μ infrared. You can also see a striking image of RCW 57b together with the much closer RCW57a (NGC 3576) here.

Gum 39

Coordinates: (293.59°, -1.26°)
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This bright nebula is centred around the O6 V HD 99897 and corresponds to the "head" of the Running Chicken nebula complex.

Gum associates Gum 39 with HD 99897 but gives a B5 class, too cool to ionise the nebula. Cameron Reed, the Georgelins and SIMBAD all give a much hotter O6 class, making it likely that this is the main ionising star.

Gum 40

Coordinates: (293.70°, -1.60°)
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There are several knots of nebulosity in this direction, which correspond to the "wattles" of the Running Chicken nebula complex, below the "head", Gum 39 (RCW 60a).

Gum associates Gum 40 with the nebula IC 2872 and the star HD 99898. He gives a B8 class for this star, too cool to ionise the nebula. However, Cameron Reed gives a B2/5 III class and SIMBAD (following the Georgelins) gives a much hotter O9 V, making it more likely that this is the ionising star.

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Colin Gum, working at Australia's Mount Stromlo observatory in 1951, completed the first major survey of HII regions visible in the southern hemisphere. He published his nebula catalog in 1955. Although Gum's catalog was largely superceded by the RCW catalog published in 1960, many HII regions are still referenced by their Gum numbers even today, so these pages provide an easy reference with cross references to the RCW and Sharpless catalogs.

Most of the images used to illustrate the Gum catalog were created using the SuperCOSMOS Sky Survey, with red = hydrogen-alpha, blue = UKST Blue and green = UKST Infrared. Because green represents infrared, the images are not quite the same as would be seen at purely visual frequencies. Green in these images usually reveals warm dust or red giant stars.

These images were 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.