| Abstract from DBPedia | In physical cosmology, a protogalaxy, which could also be called a "primeval galaxy", is a cloud of gas which is forming into a galaxy. It is believed that the rate of star formation during this period of galactic evolution will determine whether a galaxy is a spiral or elliptical galaxy; a slower star formation tends to produce a spiral galaxy. The smaller clumps of gas in a protogalaxy form into stars. The term "protogalaxy" itself is generally accepted to mean "Progenitors of the present day (normal) galaxies, in the early stages of formation." However, the "early stages of formation" is not a clearly defined phrase. It could be defined as: "The first major burst of star formation in a progenitor of a present day elliptical galaxy"; "The peak merging epoch of dark halos of the fragments which assemble to produce an average galaxy today"; "A still gaseous body before any star formation has taken place."; or " an over-dense region of dark matter in the very early universe, destined to become gravitationally bound and to collapse."原始銀河（げんしぎんが、protogalaxy、primordial galaxy、primeval galaxy）は、現代宇宙論において、銀河を形成しつつあるガスの雲である。銀河の進化のこの段階における星形成の速度は、その銀河が渦巻銀河になるか楕円銀河になるかを決定すると考えられており、星形成がゆっくりだと渦巻銀河が形成されやすい傾向があるとされている。原始銀河中のガスの小さな塊が恒星を形成する。「原始銀河」という用語は主にビッグバン理論で使われる。 (Source: http://dbpedia.org/resource/Protogalaxy) |
