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| Supernova remnant | |
|---|---|
 | |
| Observation data:J2000.0epoch | |
| Right ascension | 08h 00m |
| Declination | −43° 00′ |
| Distance | 1470 ly (450 pc) |
| Apparent magnitude (V) | +12 (infrared only) |
| Apparent diameter | 30° |
| Constellation | Vela,Puppis |
| Physical characteristics | |
| Absolute magnitude (V) | 3.73 (infrared) |
| Designations | Gum 12 |
| See also:Lists of nebulae | |
TheGum Nebula (Gum 12) is anemission nebula that extends across 36° in the southernconstellationsVela andPuppis. It lies approximately 450parsecs from the Earth.[1] Hard to distinguish, it was widely believed to be the greatly expanded (and still expanding) remains of a supernova that took place about a million years ago. More recent research suggests it may be an evolvedH II region. It contains the 11,000-year-oldVela Supernova Remnant, along with theVela Pulsar.[2]
It is located between the two bright and massive stars systemNaos (ζ Puppis) andRegor (γ² Velorum), the former is closer to the edge of the cloud facing the Sun , at a distance of about 330 ± 10 parsecs, while the latter, at about336+8
−7 parsecs, is located closer to the center of the cloud. To its southeastern part lies the Vela Nebula , a supernova remnant that lies between the Gum Nebula and the Solar System, along the same line of sight.
The Gum Nebula is one of the largest known nebulae within the Milky Way and constitutes an important scenario for the study of the expansion of bubbles generated by supernova explosions within the environment of the galactic arms, as well as on the interaction between these and the surrounding molecular clouds ; in fact, on the edges of the cloud some limitedstar formation phenomena are active , localized in small clouds (known as cometary globules due to their appearance). Near some of these globules someHH objects are also found , includingHH 47.[3]
The Gum Nebula contains about 32cometary globules.[4] These dense cloud cores are subject to such strong radiation fromO-type starsγ2 Vel andζ Pup and formerly the progenitor of theVela Supernova Remnant that the cloud cores evaporate away from the hot stars into comet-like shapes. Like ordinaryBok globules, cometary globules are believed to be associated with star formation.[5] A notable object inside one of these cometary globules is the Herbig-Haro objectHH 46/47.
The main ionizing sources are theVela OB2 association (includingGamma Velorum cluster and theP Puppis cluster), Zeta Puppis and the OB associationTrumpler 10.[6][7] The star clusterNGC 2547 formed 100 pc more distant than Vela OB2 and is an interloper.[7] The Vela OB2 association is surrounded by the so-called "IRAS Vela Shell", located in the south of the Gum Nebula. The star clusters NGC 2547, Trumpler 10,NGC 2451B,Collinder 135 andCollinder 140 all have similar ages of about 30 Myrs. It is suggested that a few stars exploded insupernovae about 30 Myrs ago in the center of the Gum Nebula andtriggered the formation of stars in the region.[8]
It is named after its discoverer, theAustralian astronomerColin Stanley Gum (1924–1960). Gum had published his findings in 1955 in a work calledA study of diffuse southern H-alpha nebulae (seeGum catalog). He also published the discovery of the Gum Nebula in 1952 in the journalThe Observatory. The observations were made with theCommonwealth Observatory.[9]
The Gum nebula was photographed duringApollo 16 while the command module was in the double umbra of the Sun and Earth, using high-speed Kodak film.[10]
The Gum Nebula is explored by the crew of theStarship Titan in theStar Trek novelOrion's Hounds.[11]
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