Ask A Scientist© Astronomy Archive

Question:  If the sun is a medium sized star, then what is the size
and name of the largest size star and the smallest?
Thank you
Daniel Pinkawa

Answer:  One of the largest (in physical size) stars is the red supergiant
Betelgeuse in the constellation Orion. It has a diameter 500 to perhaps 750
times that of the Sun. One of the most massive stars is the variable star called 
Eta Carinae, with a mass of about 200 solar masses. The Guiness Book of World Re cords lists a white
dwarf named L362-81 as the smallest star in size; its diameter is estimated to
be only about 3500 miles, or about the same size as the planet Mercury. The star 
with the smallest mass (again, according to Guiness) is designated RG 0058.8-280 7; its mass is only
0.014 solar mass (it is also the faintest known star).
Rcwinther