“A candidate is not going to suddenly change once they get into office. Just the opposite, in fact. Because the minute that individual takes that oath, they are under the hottest, harshest light there is. And there is no way to hide who they really are.” -Michelle Obama
The most massive stars in the Universe are true behemoths, rising to hundreds of times the mass of our Sun and burning at temperatures upwards of 30,000 K at their surface. But there are stars out there that are even hotter, despite only being 10% or less as massive: Wolf-Rayet stars. The key to their cosmic success? Blowing off their outer layers of hydrogen.
O-class stars are the hottest main-sequence stars, but by expelling their outer hydrogen layers, as this illustration shows, they can achieve even greater temperatures. The star illustrated here is the first Wolf-Rayet star to be found with a disk. Image credit: NASA, ESA, and G. Bacon (STScI); Science Credit: NASA, ESA, and J. Mauerhan.
By only leaving the dense, massive core of already-fused elements, Wolf-Rayet stars burn helium, carbon, oxygen or even heavier elements at their centers, while the journey to the surface “only” cools the star down to ~200,000 K by time the edge of the photosphere is reached. Elements like carbon, nitrogen, and oxygen may be ionized up to four times when their spectra are viewed.
The Wolf-Rayet star WR 102 is the hottest star known, at 210,000 K. In this infrared composite from WISE and Spitzer, it’s barely visible, as almost all of its energy is in shorter-wavelength light. The blown-off, ionized hydrogen, however, stands out spectacularly. Image credit: Judy Schmidt, based on data from WISE and Spitzer/MIPS1 and IRAC4.
from ScienceBlogs http://ift.tt/2v6RJyI
“A candidate is not going to suddenly change once they get into office. Just the opposite, in fact. Because the minute that individual takes that oath, they are under the hottest, harshest light there is. And there is no way to hide who they really are.” -Michelle Obama
The most massive stars in the Universe are true behemoths, rising to hundreds of times the mass of our Sun and burning at temperatures upwards of 30,000 K at their surface. But there are stars out there that are even hotter, despite only being 10% or less as massive: Wolf-Rayet stars. The key to their cosmic success? Blowing off their outer layers of hydrogen.
O-class stars are the hottest main-sequence stars, but by expelling their outer hydrogen layers, as this illustration shows, they can achieve even greater temperatures. The star illustrated here is the first Wolf-Rayet star to be found with a disk. Image credit: NASA, ESA, and G. Bacon (STScI); Science Credit: NASA, ESA, and J. Mauerhan.
By only leaving the dense, massive core of already-fused elements, Wolf-Rayet stars burn helium, carbon, oxygen or even heavier elements at their centers, while the journey to the surface “only” cools the star down to ~200,000 K by time the edge of the photosphere is reached. Elements like carbon, nitrogen, and oxygen may be ionized up to four times when their spectra are viewed.
The Wolf-Rayet star WR 102 is the hottest star known, at 210,000 K. In this infrared composite from WISE and Spitzer, it’s barely visible, as almost all of its energy is in shorter-wavelength light. The blown-off, ionized hydrogen, however, stands out spectacularly. Image credit: Judy Schmidt, based on data from WISE and Spitzer/MIPS1 and IRAC4.
from ScienceBlogs http://ift.tt/2v6RJyI
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