Raining hot metal

Raining hot metal

Apr 08, 2019 / By : / Category : 老域名购买

An article appeared yesterday at Space.com that discusses some of the odd things that pass for normal on a brown dwarf, the class of body that resides between "super Jupiter" type planets and stars. The article doesn't appear to be based on new research but it fascinated me, so I thought it was worth a mention. The article focuses on the work of two researchers who have published extensively on brown dwarves, and much of it appears to be based on a paper they published together back in 2002. 老域名出售

There are noticeable differences between Jupiter and the Sun. Of the two, brown dwarves seem to be a bit closer to Jupiter in terms of behavior, as there are observational indications that they have weather and storms driven by convection (on the sun, magnetism is a major driving force). Temperature wise, brown dwarves start out much hotter than Jupiter. Without a star's fusion output, however, they gradually cool over time. This cooling has some bizarre implications: early in their history, brown dwarves have temperatures which are sufficient to not only melt metal, but evaporate it. Once the cooling kicks in, that metal will return to the dwarf's surface in a rain of liquid iron.

Part of this view into the world of brown dwarves is based on theoretical modelling, but direct observation has made some contributions as well. These dim objects are extremely difficult to observe, but inferences regarding their temperatures can be made. The researchers were somewhat surprised to find that older dwarves, which should be the coolest, actually appeared hotter and brighter than young ones. It seems that the clouds of hot metal initially act as an insulator, retaining heat for much longer than might be predicted. As these clouds fall to the surface as rain, more heat is able to radiate from the dwarf, making it appear to get hotter as it ages.

Overall, the article points out that, despite often being labeled "failed stars," brown dwarves are interesting objects with a distinct set of features.

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