Flare star

A flare star is a special kind of star that can suddenly become much brighter for a few minutes. These bright flashes happen without warning and can be seen across many types of light, from X-rays to radio waves. Scientists think these flares are caused by magnetic energy building up and then releasing in the star's atmosphere, similar to how the Sun sometimes has solar flares.

The first flare stars were discovered in 1945 by a scientist named A. van Maanen, who noticed bright changes in two stars called WX Ursae Majoris and YZ Canis Minoris. But the most famous flare star is UV Ceti, which was first seen to flare in 1948. Today, stars like this are called UV Ceti type variable stars.

Most flare stars are cool, dim stars known as red dwarfs, but some even smaller objects called brown dwarfs can also flare. Some stars similar to our Sun have been seen to flare too, and scientists think these might be caused by hidden planets close to the star.

Stellar Flare Model

The Sun sometimes has big bursts of light called solar flares, and scientists have studied these a lot. They think that when other stars have sudden brightening called flares, it works in a similar way. Flares happen when magnetic fields in the star's atmosphere twist and snap back into place, releasing a lot of energy.

There are a few steps in a flare. First, the star's atmosphere heats up slowly. Then, a quick burst happens where particles get very energetic and release radiation. After that, the star's light increases rapidly before slowly returning to normal. Sometimes, flares can also happen when two stars close together interact, or when a young star has material swirling around it.

Nearby flare stars

Flare stars are very dim but can be seen from far away—up to 1,000 light years from Earth! In 2014, NASA’s Swift satellite saw a huge burst of energy from a star called DG Canum Venaticorum. This burst was 10,000 times brighter than the biggest solar flare we’ve ever recorded!

Some of our closest stars are flare stars, too. Proxima Centauri, the star nearest to our Sun, sometimes gets brighter because of its magnetic field. Another close star, Wolf 359, is a tiny, dim star that often bursts with energy. Even Barnard's Star, thought to be quiet, was seen to flare in 1998. Young stars like EV Lacertae can have flares thousands of times brighter than the Sun’s.

Record-setting flares

The most powerful flare ever seen in a star was observed in 2005. It came from a binary star system called II Peg. Scientists used a satellite called Swift to study this flare, and they found it released energy in a way similar to flares from our own Sun, including hard X-rays. This discovery helped scientists understand more about how energy works in stars, comparing it to the solar flares we see from the Sun.