Astrophysicists lately stumbled upon a little star entitled 2MASS J0523-1403 situated just 40 light years away. It's not only the smallest star discovered up to now; it might also characterize the tiniest possible star. By observing stars for instance this, researchers are starting to be able to response the question: where do stars finish and brown dwarfs initiate? Stars are red-hot balls of gas held together by gravity that are powered by the merging of hydrogen atoms to helium in their centers. Stars come in a range of sizes; the smallest stars, recognized as red dwarfs, can hold as little as 10% of the mass of our Sun, while the biggest stars, known as hypergiants, can be over 100 times as huge as the Sun. But just how small can an entity be and still be called as a star? This question has puzzled astrophysicists for years. All that was earlier acknowledged is that objects below this edge don’t have enough mass to start the fusion of hydrogen in their centers. These objects are recognized as brown dwarfs.
Image Credit: NASA/JPL-Caltech/UCB
Brown dwarfs are mysterious objects that are supposed to be the disappeared connection among gas giants and low-mass stars, for example, red dwarfs. They’re usually about the size of Jupiter, but they don’t have enough mass to turn into a star. Unlike stars, brown dwarfs have no interior energy source.
There is another odd variance among brown dwarfs and stars; they have reverse relations between mass and size. The further material you add to a star, in the form of hydrogen, the larger the radius of the star. I.e. stars growth in size as mass rises. Brown dwarfs, instead, really shrink in size with increasing mass because of something called electron degeneracy pressure.
So by what means do we find the boundary that dictates whether an object is a star or a brown dwarf? Astrophysicists perused the skies and found objects that were believed to lie around the stellar/brown dwarf border. They then measured the luminosity, temperatures and radii of all of these objects and plotted them. Temperature is reliant on on mass but it’s easier to measure. They discovered that as temperature reduces, so did radius; this is the projected tendency for stellar objects. Though, they found that afterward temperatures of around 2100K (1826oC) there was a disruption till radius jumps to increase with decreasing temperature; this is the tendency that would be projected for brown dwarfs. Thanks to this data, researchers can now locate the exact temperature, luminosity and radius at which the main sequence ends. The main sequence is a relationship among luminosity and temperature that is followed by stars during the mainstream of their lives. 2MASS J0523-1403 is situated around this boundary, but toward the stellar side. This star essentially has a temperature of 2074K, which is the lowermost labeled temperature up to now for a main sequence star. It’s also the tiniest and the least massive; if it had a smaller amount of mass then it would be a brown dwarf. This star has, hence, been acknowledged as a illustrative of the smallest possible star. Though, it is theoretically probable that a star with a marginally smaller mass than 2MASS J0523-1403 could occur, but we haven’t discovered it yet.
Researchers consider that info such as this might help us in our hunt for life on other planets.
Brown dwarfs cool much faster than stars, so their nearby planets are possibly not very habitable. Hence knowing the temperatures of objects around the star/brown dwarf edge will support astrophysicists in their hunt for candidates that could support habitable planets.
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