Hello, I'm an expert in astronomy with a keen interest in stellar phenomena. When it comes to the hottest stars known to humanity, we're talking about stars with extremely high surface temperatures that emit a significant amount of their light in the ultraviolet range.

The hottest stars are typically very massive and are often referred to as O-type stars. These stars are extremely rare and short-lived. The **temperature of these stars can exceed 30,000 Kelvin**, which is much hotter than our Sun, which has a surface temperature of about 5,500 Kelvin.

One of the hottest known stars is R136a1, located in the Tarantula Nebula of the Large Magellanic Cloud, a satellite galaxy of the Milky Way. R136a1 is a Wolf-Rayet star, which is a type of star that is losing its outer layers at a high rate. Its **surface temperature is estimated to be around 50,000 Kelvin**.

However, it's important to note that our understanding of the universe is constantly evolving, and new observations and discoveries can lead to revisions in our knowledge about the hottest stars.

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Eta Carinae could be as large as 180 times the radius of the Sun, and its surface temperature is 36,000-40,000 Kelvin. Just for comparison, 40,000 Kelvin is about 72,000 degrees F. So it's the blue hypergiants, like Eta Carinae, which are probably the hottest stars in the Universe.read more >>