ALMA Discovers Large “Hot” Cocoon Around A Small Baby Star
A large hot molecular cloud around a very young star was discovered by ALMA. This hot cloud is about ten times larger than those found around typical solar-mass baby stars, which indicates that the star formation process has more diversity than ever thought. This result was published in the Astrophysical Journal Letters on September 20th, 2013.
Stars are formed in very cold (-260 degrees Celsius) gas and dust clouds. Infrared Dark Clouds (IRDC) are dense regions of such clouds, and thought that in which clusters of stars are formed. Since most of stars are born as members of star clusters, investigating IRDCs has a crucial role in comprehensive understanding the star formation process.
A baby star is surrounded by the natal gas and dust cloud, and the cloud is warmed up from its center. Temperature of the central part of some, but not all, of such clouds reaches as high as -160 degrees Celsius. Astronomers call those clouds as “hot core” – it may not be hot on the Earth, but is hot enough for a cosmic cloud. Inside hot cores, various molecules, originally trapped in the ice mantle around dust particles, are sublimated. Organic molecules such as methanol (CH3OH), ethyl cyanide (CH3CH2CN), and methyl formate (HCOOCH3) are abundant in hot cores.