Coldest star found


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Astronomers have found a star that's only as hot as a cup of coffee, making it a candidate for the coldest star known. That is, assuming it's a star.

While a cup of coffee may sound hot ? the newly discovered object is about 200 degrees Fahrenheit (100 degrees Celsius) ? our sun is about 10,000 degrees F (5,500 degrees C). So, by comparison, it really is quite cold.

The object is considered a brown dwarf, a cosmic misfit that's cold enough to blur the lines between small cold stars and big hot planets. Astronomers consider brown dwarfs failed stars because they lack the mass and gravity to trigger the nuclear reactions that make stars shine brightly.

The newly discovered brown dwarf, identified as CFBDSIR 1458+10B, is the dimmer member of a binary brown dwarf system located about 75 light-years from Earth.

"In terms of its physical properties, it is really much closer to typical gas planets that are being found by radial velocity surveys than most brown dwarfs we know about," Michael Liu of the University of Hawaii's Institute for Astronomy said.

Astronomers expect the brown dwarf to exhibit the properties of a gas giant planet, such as the presence of water clouds in its atmosphere.

"We think as we accumulate more data on its different colors and its spectra we should be able to learn more about its atmosphere, and that will be very unique," Liu added. For example, the color of hotter brown dwarfs is largely shaped by the presence of sodium and potassium atoms in the atmosphere.

At cooler temperatures, according to theory, the sodium and potassium will lock themselves into molecules such as potassium chloride and be removed from the atmosphere. Liu and colleagues have asked for time on the Hubble Space Telescope to observe the system in optical wavelengths.

"The optical colors of this object should be very different than any previously known brown dwarf," Liu said.

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That's interesting. I never knew a star could be so cold and yet be considered a star.

It probably isn't. It is either a small brown dwarf or a large gas giant. Either way, it isn't rightly considered a star.

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It probably isn't. It is either a small brown dwarf or a large gas giant. Either way, it isn't rightly considered a star.

Brown Dwarfs are odd things, way to massive to be planets but not massive enough to support hydrogen fusion. With that being said, they're definitely not "mainline sequence stars" but it is pretty safe to be they're more star than planet.

wikipedia brown dwarfs:

"Currently, the International Astronomical Union considers an object with a mass above the limiting mass for thermonuclear fusion of deuterium (currently calculated to be 13 Jupiter masses for objects of solar metallicity) to be a brown dwarf, whereas an object under that mass (and orbiting a star or stellar remnant) is considered a planet"

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