Top best answers to the question «What is the largest known star in the universe»
- The largest known star in the universe is UY Scuti, a hypergiant with a radius around 1,700 times larger than the sun. And it's not alone in dwarfing Earth's dominant star. The largest of all In 1860, German astronomers at the Bonn Observatory first cataloged UY Scuti, naming it BD -12 5055.
- the largest known star in the universe is vy canis majoris, but there may be bigger ones out there. the most massive (in weight) star known is R136a1, a blue hypergiant star …at an estimated 265 solar masses, also holding the record as the most luminous, shining at 8,700,000 times the luminosity of the sun.
- WOH G64 was once thought to measure a whopping 3,000 times the width of the sun…
- Westerlund 1-26,which measures more than 1,500 times the width of the sun,according to NASA .
- NML Cygni is measured at 1,639 times the width of the sun,according to a 2012 paper in the journal Astronomy and Astrophysics .
4 other answers
With that said, so far, the winner of largest star in the known universe probably goes to UY Scuti — a massive red supergiant located in our own Milky Way galaxy in the constellation Scutum and...
Used to be described as the largest known star based on a radius of 1,800–2,100 R ☉. Older estimates gave the radius of VY CMa as above 3,000 R ☉ ,  or as little as 600 R ☉ .  Matsuura et al. 2013 estimates 2,069 R ☉ based on a luminosity of 237,000 L ☉ and an assumed effective temperature of 2,800 K.  
This red hypergiant is among the largest known stars in our galaxy. It has an estimated radius between 1,800 and 2,100 times that of the Sun. At this size, if placed in our solar system, it would reach nearly to the orbit of Saturn.
Surpassing UY Scuti, St2-18 is now considered to be the largest star in the known universe.