The European Southern Observatory (ESO) telescope has captured images of the yellow star mayor discovered so far, and one of the 10 largest stars known. The new star, named HR 5171, has a diameter 1300 times greater than the Sun and a million times brighter, although it is 12,000 light years from Earth.
In New Scientist they give an interesting data to understand the giant size of this star. If you were in the center of our Solar System, you would gobble all the planets between Mercury and Jupiter (to the Earth and Mars included, of course). This star is in fact not alone, its second component is so close that it is in contact with the larger star.
The yellow giants are very rare, since their larger size makes them very unstable, and of short life in astronomical terms. The discovery of the true nature of HR 5171 has been possible thanks to a technique called interferometry, which combines the light of recovery by multiple individual telescopes, recreating a giant telescope of more than 140 meters.
In the case of HR 5171, the comparison with the observations of the last 60 years indicates that the star is growing and cooling. The smaller star orbits around the main one, making a full revolution every 1,300 days. Its temperature is also somewhat higher than that of the surface of its huge companion, which is about 5,000 degrees. Both emit abundant material that forms a cloud around them. The discovery of HR 5171 is a unique opportunity to study the rapid evolution of these unstable stars. [via ESO]
Scientists are not entirely clear that it is the largest star in the Universe, but there are two main options to take into account the colossal size.
The dimensions of the Universe are so enormous that we really have not even been able to conceive the size of this one. The earth itself is already big to our eyes, and next to the sun is ridiculously small. But in fact, not even the Sun itself is a particularly large star, it is a medium-sized star. Imagine then, if the Sun is a medium-sized star, like the largest star in the Universe ...