The Gum Nebula ( Gum 12 ) is an emission nebula that extends across 36° in the southern constellations Vela and Puppis . It lies approximately 450 parsecs from the Earth. 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 evolved H II region . It contains the 11,000-year-old Vela Supernova Remnant , along with the Vela Pulsar .
6-521: The Gum Nebula contains about 32 cometary globules . These dense cloud cores are subject to such strong radiation from O-type stars γ Vel and ζ Pup and formerly the progenitor of the Vela Supernova Remnant that the cloud cores evaporate away from the hot stars into comet-like shapes. Like ordinary Bok globules , cometary globules are believed to be associated with star formation. A notable object inside one of these cometary globules
12-402: A mass of about two to 50 solar masses contained within a region about a light year or so across (about 4.5 × 10 m ). They contain molecular hydrogen (H 2 ), carbon oxides and helium , and around 1% (by mass) silicate dust. Bok globules most commonly result in the formation of double - or multiple-star systems. Bok globules were first observed by astronomer Bart Bok in
18-744: Is the Herbig-Haro object HH 46/47 . It is named after its discoverer, the Australian astronomer Colin Stanley Gum (1924–1960). Gum had published his findings in 1955 in a work called A study of diffuse southern H-alpha nebulae (see Gum catalog ). He also published the discovery of the Gum Nebula in 1952 in the journal The Observatory . The observations were made with the Commonwealth Observatory . The Gum nebula
24-868: The 1940s. In an article published in 1947, he and Edith F. Reilly hypothesized that these clouds were "similar to insect's cocoons " that were undergoing gravitational collapse to form new stars, from which stars and star clusters were born. This hypothesis was difficult to verify due to the observational difficulties of establishing what was happening inside a dense dark cloud that obscured all visible light emitted from within it. An analysis of near- infrared observations published in 1990 confirmed that stars were being born inside Bok globules. Further observations have revealed that some Bok globules contain embedded warm sources, some contain Herbig–Haro objects , and some show outflows of molecular gas . Millimeter-wave emission line studies have provided evidence for
30-455: The infall of material onto an accreting protostar . It is now thought that a typical Bok globule contains about 10 solar masses of material in a region about a light-year or so across, and that Bok globules most commonly result in the formation of double- or multiple-star systems. Bok globules are still a subject of intense research. Known to be some of the coldest objects in the natural universe, their structure and density remains somewhat
36-666: Was photographed during Apollo 16 while the command module was in the double umbra of the Sun and Earth, using high-speed Kodak film. The Gum Nebula is explored by the crew of the Starship Titan in the Star Trek novel Orion's Hounds . Bok globule In astronomy , Bok globules are isolated and relatively small dark nebulae containing dense cosmic dust and gas from which star formation may take place. Bok globules are found within H II regions , and typically have
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