The star outside your spaceship's windshield is a spectacular sight. HR 5171 A is a fireball 1,300 times larger than the Earth's sun. It's so big that if it were in our sun's position, it would swallow up Earth beneath its 10,000°F surface. To look at it from your spaceship, you have to wear special goggles--this star is almost a million times brighter than our sun.
As you watch HR 5171A burn, you notice something strange. An object is peeking over the horizon, growing larger and larger. It's another sun--a smaller one that orbits the giant HR 5171 A. This small sun (though it's still about 350 times larger than Earth's sun) is snuggled up so close to its sister sun that they're touching.
Even though it's tiny compared to the giant HR 5171 …show more content…
This makes it the largest yellow star known. It is also in the top ten of the largest stars known — 50% larger than the famous red supergiant Betelgeuse — and about one million times brighter than the Sun. Despite its great distance of nearly 12 000 light-years from Earth, the object can just about be seen with the naked eye [4] by the keen-sighted. HR 5171 A has been found to be getting bigger over the last 40 years, cooling as it grows, and its evolution has now been caught in action. Only a few stars are caught in this very brief phase, where they undergo a dramatic change in temperature as they rapidly evolve. Chesneau concludes “The companion we have found is very significant as it can have an influence on the fate of HR 5171 A, for example, stripping off its outer layers and modifying its evolution.” By analysing data on the star’s varying brightness, using observations from other observatories, the astronomers confirmed the object to be an eclipsing binary system where the smaller component passes in front and behind the larger one as it orbits. In this case HR 5171 A is orbited by its companion star every 1300 days. The smaller companion is only slightly hotter than HR 5171 A’s surface temperature of 5000 degrees
As you watch HR 5171A burn, you notice something strange. An object is peeking over the horizon, growing larger and larger. It's another sun--a smaller one that orbits the giant HR 5171 A. This small sun (though it's still about 350 times larger than Earth's sun) is snuggled up so close to its sister sun that they're touching.
Even though it's tiny compared to the giant HR 5171 …show more content…
This makes it the largest yellow star known. It is also in the top ten of the largest stars known — 50% larger than the famous red supergiant Betelgeuse — and about one million times brighter than the Sun. Despite its great distance of nearly 12 000 light-years from Earth, the object can just about be seen with the naked eye [4] by the keen-sighted. HR 5171 A has been found to be getting bigger over the last 40 years, cooling as it grows, and its evolution has now been caught in action. Only a few stars are caught in this very brief phase, where they undergo a dramatic change in temperature as they rapidly evolve. Chesneau concludes “The companion we have found is very significant as it can have an influence on the fate of HR 5171 A, for example, stripping off its outer layers and modifying its evolution.” By analysing data on the star’s varying brightness, using observations from other observatories, the astronomers confirmed the object to be an eclipsing binary system where the smaller component passes in front and behind the larger one as it orbits. In this case HR 5171 A is orbited by its companion star every 1300 days. The smaller companion is only slightly hotter than HR 5171 A’s surface temperature of 5000 degrees