## Which star has the largest radius?

The largest known star in the universe is UY Scuti, a hypergiant with a radius around 1,700 times larger than the sun.

## Where are the most massive stars on the HR diagram?

The giant branch and supergiant stars lie above the main sequence, and white dwarfs are found below it. There are 3 main regions (or evolutionary stages) of the HR diagram: The main sequence stretching from the upper left (hot, luminous stars) to the bottom right (cool, faint stars) dominates the HR diagram.

## Where are the hottest stars on the HR diagram?

A plot of the nearest stars on the HR diagram is shown below: Most stars in the solar neighborhood are fainter and cooler than the Sun. There are also a handful of stars which are red and very bright (called red supergiants) and a few stars that are hot, but very faint (called white dwarfs).

## How do you find the radius of a star?

A star is well approximated by a SPHERICAL blackbody (surface area = 4 pi R^2), so the formula which gives the total luminosity of a star is the following: Thus, if we know the luminosity L* of a star (found from its intensity and its distance) and if we know the temperature T* of a star, we can compute its radius R*.

## Which star has the smallest radius?

The smallest known star right now is OGLE-TR-122b, a red dwarf star that’s part of a binary stellar system. This red dwarf the smallest star to ever have its radius accurately measured; 0.12 solar radii. This works out to be 167,000 km.

## What color are the hottest stars?

blue

## What is the radius of a star?

The surface area of a star is directly related to the square of its radius (assuming a spherical star). (5.67 x 10-8 Wm-2K-4), and T is the star’s surface temperature in Kelvin. The temperature of a star is related to its b-v magnitude.

Photo in the article by “Wikipedia” `https://en.wikipedia.org/wiki/Mu_Cephei`