The Gum Catalog

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Gum 41

Coordinates: (294.2°, -2.3°)
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RCW 61 forms the feet of the Running Chicken nebula complex.

According to Avedisova, RCW 61 is ionised by three O9 giant stars: HD 100099 (O9 III), CD -62 535 (O9 II) and HD 100444 (O9 II), as well as three B-class stars. (SIMBAD reports that CD -62 535 and HD 100444 are the same star.)

She places RCW 60, RCW 61, RCW 62, Gum 39, Gum 40, Gum 41, Gum 42, and IC 2944 in star formation region SFR 293.64-1.41 with 51 components, including 7 masers and 18 infrared sources. Humphreys says that the hot stars in this direction form the Cru OB1 association at an average distance of 2510 parsecs.

Gum 42

Coordinates: (294.8°, -1.5°)
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The large bright nebula IC 2944 (RCW 62 / Gum 42) corresponds to the "body" of the Running Chicken nebula complex, which is ionised by the Cru OB1 association.

According to Avedisova, the nebula is ionised by the O6 III giant HD 101190, the O6 V star HD 101436 and the O9 IV subgiant HD 101223 as well as the B0.5 Iab supergiant HD 101545. (SIMBAD gives a much cooler B6Ib/II class for HD 101436.)

A 2013 study finds that the X-ray sources in this direction are concentrated around the O8 V star HD 101205 suggesting that this star may also be associated with the nebula.

Avedisova places RCW 60, RCW 61, RCW 62, Gum 39, Gum 40, Gum 41, Gum 42, and IC 2944 in star formation region SFR 293.64-1.41 with 51 components, including 7 masers and 18 infrared sources. Humphreys says that the hot stars in this direction form the Cru OB1 association at an average distance of 2510 parsecs.

Dutra and colleagues say that RCW 62 contains the infrared group [DBS2003] 69, although curiously they give a distance of only 1700 parsecs.

You can see the spectacular MSX 8μm infrared view here.

Some astronomers misleadingly call this the Lambda Centaurus nebula. Lambda Centaurus is the bright star in the upper right of the image, however, it is a foreground star at a distance of only 63 pc.

Gum 43

Coordinates: (301.0°, 1.2°)
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Avedisova places RCW 65 in star formation region SFR 300.90+1.23 with three masers, the infrared HII region [WHR97] 12320-6122 and the star cluster Ruprecht 105.

The infrared cluster [DBS2003] 77 is embedded in RCW 65. The nebula appears to be next to or part of a much larger nebula visible in infrared as can be seen in this MSX image.

The RCW catalog identifies RCW 65 with Gum 43.

RCW 66 and RCW 67 appear to have a similar distance and direction as RCW 65.

Gum 44

Coordinates: (301.1°, 0.9°)
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Avedisova places RCW 66, RCW 67, and Gum 44 together in the star formation region SFR 301.05+0.89 along with the infrared HII region [GSL2002] 30 and the two optical nebula Bran 391a and Bran 391b. (SIMBAD identifies RCW 66 and Bran 391b.)

Dutra et,al conclude that RCW 66 includes the infrared cluster [DBS2003] 78.

RCW 66 and RCW 67 are prominent at radio frequencies and are located next to a nebula prominent in infrared.

RCW 66 and RCW 67 appear to have a similar distance and direction as RCW 65.

Gum 45

Coordinates: (302.2°, 0.3°)
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Although once believed to be an HII region, RCW 69 is now established to be the bipolar planetary nebula PN G302.1+00.3.

Gum 46

Coordinates: (302.9°, 1.3°)
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RCW 71 is ionised by the O9.5V star CP -60 4312 according to Avedisova (also known as HD 311999) and contains the infrared cluster [DBS2003] 80.

A 2005 study notes that the nebula is surrounded by an emission ring, which can be seen in this MSX infrared image.

Gum 47

Coordinates: (307.2°, -3.5°)
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This is the planetary nebula NGC 5189 = Gum 47 = IC 4274 with the central star KN Mus.

Gum 48a

Coordinates: (306.19°, 0.18°)
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This HII region surrounds and is ionised by the young cluster Stock 16, which is part of the Cen OB1 association and contains the reflection nebula complex VdBH 60a, VdBH 60b, VdBH 60c and VdBH 60d. The region is probably physically connected to the huge and diffuse m Cen nebula.

Kharchenko lists 9 ionising members of Stock 16, including the O stars HD 115455 (O8) and DM -61 3587 (O 9.5 V) as well as 7 B-class stars. She gives a distance of 1640 parsecs and an age of 6 million years.

Dutra places the infrared star group [DBS2003] 86 in VdBH 60b at 2400 parsecs and the infrared star group [DBS2003]85 in VdBH 60d at 2100 parsecs.

Avedisova places this nebula in star formation region SFR 306.20+0.18, along with the emission star IRAS 13168-6208 and the dark cloud Dcld 306.2+0.1.

Although the little documented m Cen HII region is named after the prominent G6 II giant m Cen near its core, it is of course ionised by several much hotter OB stars. Avedisova calls this huge diffuse nebula Ge 136 and lists HD 116796 (O9 V) as the main ionising star, along with two B2 class stars. SIMBAD gives an O9 II class for HD 116796 but curiously appears to be missing the surrounding nebula all together.

You can view a larger image of RCW 75 here and the full extent of the nebulosity (including the huge diffuse m Cen nebula) in this SuperCOSMOS hydrogen-alpha image. You can also see RCW 75 at the edge of the far larger (and twice as distant) RCW 74 nebular complex in this Spitzer infrared image.

Gum 48b

Coordinates: (307.9°, 0.2°)
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This is a ring nebula around the Wolf-Rayet star WR 55.

Gum 48c

Coordinates: (308.7°, 0.6°)
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This 1.7 million year old nebula forms a ring around a central ionising star. A 2002 paper identifies the ionising star, which is visible in both hydrogen-alpha and infrared, as either a late O-class star or Wolf-Rayet star but does not cite a catalog identifier.

A magnificent infrared image of this nebula can be found here and a different version (with more infrared frequencies visible) can be found on this Spitzer image.

Gum 48d

Coordinates: (309.3°, -0.5°)
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Gum 48d (RCW 80) is an HII region ionised by the B0 IP supergiant HR 5171B, which has as a companion the highly variable G8 Ia supergiant HR 5171A.

Avedisova also lists the B2 Ia supergiant HD 119646 as an ionising star.

SIMBAD follows several sources in identifying RCW 80 with the supernova remnant SNR 309.2-00.6. However, the nebula and the radio peak within the supernova remnant seem to have different locations as can be seen in this Parkes radio image. A 2009 paper states clearly that the HII region and the supernova remnant are two distinct and likely unrelated objects.

RCW 80 can be seen in visual light on this Wikipedia page and in infrared in this Spitzer image.

Gum 49

Coordinates: (327.6°, -0.8°)
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According to a 2006 paper, the Coffee Bean nebula is 310 thousand years old and is ionised by the O9.5 IV subgiant LSS 3423 = CPD-54 6791. A follow-up 2007 paper identified two dense cores in the small molecular cloud associated with RCW 98, one of which contains 3 young stellar objects.

You can view a good image of the Coffee Bean nebula in visible light on this astrophotography site.

Gum 50

Coordinates: (328.57°, -0.53°)
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According to a 1975 paper, RCW 99 is an extended HII region with low density and 102 solar masses of gas and dust.

Avedisova lists 5 ionising stars, including the hot O5 III giant LSS 3443, the O9.5 II giant CP -53 6950 and 3 B-class supergiants. She places the nebula in star formation region SFR 328.60-0.51 along with the star cluster Trumpler 23.

The Georgelins give an O7 III class for LSS 3443 and SIMBAD lists it as a B-class star. A 2006 paper gives an age of 700 milion years and a distance of 2200 parsecs for Trumpler 23, raising some doubts as to whether this cluster can really be associated with RCW 99.

Dutra says that the infrared cluster [DBS2003] 98 is deeply embedded in RCW 99.

RCW 99 is an intensely bright infrared source as can be seen in this Spitzer image.

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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.