Brown Dwarfs: Failed Stars

I read an article, entitled “Brown Dwarfs: Failed Stars Resembling Planets,” from space.com, that I can connect with our thirteenth conceptual objective, “I can describe how stars form and produce energy in their cores by nuclear fusion.” The article, by Nola Taylor Redd, talks about how brown dwarfs do not quite make it as stars. They start out like main-sequence stars, a cloud of dust and gas collapses in, forming a young protostar in the center. Gravity pushes inward on main sequence stars until hydrogen fusion is started in their core; however, brown dwarfs never reach this hydrogen fusion stage. Before temperature get hot enough to start hydrogen fusion, the close-packed material’s temperature stabilizes and becomes a brown dwarf. Brown dwarfs have a range of 13 to 90 times the mass of Jupiter (around one-tenth the mass of the sun). Just like stars, brown dwarfs are similarly classified by spectral type. Brown dwarfs give off so little light and energy, therefore they can be difficult to locate. They were not seen until the late 1980s; as astronomical instruments continuously grow, brown dwarfs have been detected more often, however it is still challenging. Brown dwarfs were originally named “black dwarfs,” but now that name is used for a white dwarf that has completely radiated all of its heat away. Brown dwarfs have so little mass, therefore it can be easy to confuse them with really big planets. The International Astronomical Union says that any object with enough mass to fuse deuterium to be a brown dwarf, and objects with less than that are considered planets.

I am able to connect this article to our conceptual objective because of class notes, and a lecture tutorial. In class, we did a lecture tutorial called “Star Formation and Lifetimes,” in which I learned that low-mass stars live longer than high-mass stars. With that being said, the article states that brown dwarfs have so little mass, so I can assume that they live long lives. Also, the lecture tutorial gives an example of the beginning of star formation when a cloud of dust and gas begin to collapse inward…

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…The beginning of the article says brown dwarfs start out like main-sequence stars, a cloud of dust and gas collapses in, forming a young protostar in the center. Gravity pushes inward on main sequence stars until hydrogen fusion is started in their core; however, brown dwarfs never reach this hydrogen fusion stage.

All in all, I thought this article was really interesting and a good match for this conceptual objective! I did not even know that brown dwarfs were a thing; I had only ever heard of red dwarf stars and white dwarf stars. Because of this conceptual objective, I was able to read this article and say to myself, “Brown dwarfs probably live long lives considering they have low-mass.” I would recommend anyone reading this post should check out this article!

 

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