BellaOnline Forums Education Astronomy Smallest Star in the Universe *new article*

No one could possibly say that a star is the smallest one in the whole Universe. But the smallest known star is 2MASS J05233822-1403022, which is a pretty big name for a star that's about the size of Saturn. Could there be even smaller ones as yet unknown?

Smallest Star in the Universe

The smallest stars are red dwarfs. None of them are visible with the unaided eye. The smallest star you can see without binoculars or a telescope - but still only in dark skies - is the binary star 61 Cygni. The second smallest is Epsilon Eridani, which is about 3/4 the size of the Sun. Third smallest is Alpha Centauri B. The Sun itself is the fourth smallest Sun that you can see with your unaided eyes. (But don't stare at it! It could damage your eyes.)

The teeny star so elaborately named 2MASS J05233822-1403022 is dim, and I mean really dim. How dim is that? The faintest star you can see with just your unaided eyes is a million times brighter than the smallest star so far discovered.

How does one see it? Have scientists actually viewed it, or have they done mathematical studies to prove it is there?

The name, 2MASS J05233822-1403022, tells us that the star was discovered in the 2-Micron All Sky Survey. A micron is 1/1000 of a millimeter and 2 microns is the wavelength of the light they detected. It's in the infra-red range. Dim stars and other cool bodies that don't show up - either well or at all - in visible wavelengths may be detected with large infra-red telescopes.

Here is 2MASS J05233822-1403022.

A simply astounding fact about 2MASS J05233822-1403022. Although big stars have short - but brilliant - lives, the smaller the star the longer it will live. This little one should keep on going for 12 trillion years without using up its hydrogen fuel.

Hmmm. The universe is 13.7 billion years old now. So the smallest star so far has a projected lifetime that's about 900 times as long as the Universe has already existed.

Eek! My brain's not up for seriously thinking about that! Time for a cup of tea, I think.

To Korie, who asked. And anyone else who wondered how the smallest-star-so-far was discovered . . . .

In this video, astronomer, author & science communicator Phil Plait explains how it was done.