Sigma Draconis

Sigma Draconis is a single star in the northern constellation of Draco. Known by the proper name Alsafi, it shines with an apparent visual magnitude of 4.7, making it just visible to the naked eye on a clear night. This quiet celestial object is located about 18.8 light years from the Sun, a relatively close neighbor in our cosmic neighborhood. As one of the closer stars visible without a telescope, Sigma Draconis has been studied by astronomers for centuries.

The star’s name "Alsafi" has ancient roots, tracing back to Arabic astronomy. Over time, it was given the latinised name σ Draconis, often shortened to Sig Dra or σ Dra, following the Bayer designation system used to label stars in each constellation. Measurements using parallax — the apparent shift in a star’s position as Earth orbits the Sun — have helped scientists determine its distance from us. Currently, Sigma Draconis is moving away from the Sun at a radial velocity of 26.6 kilometers per second, a gentle drift through space that adds to our understanding of the star’s journey.

Name

σ Draconis (Latinised to Sigma Draconis) is the star's Bayer designation, established in 1603 as part of the Uranometria, a star catalogue produced by German celestial cartographer Johann Bayer.

It has the traditional name Alsafi, which comes from the Arabic word Athāfi. In 2016, a group called the Working Group on Star Names decided to make the name Alsafi the official name for this star. In Chinese, it is called 天廚二, meaning "the Second Star of Celestial Kitchen."

Properties

Sigma Draconis is a small, ordinary star that can be seen with the naked eye. It is a little cooler and less bright than our Sun, and it rotates slowly. Scientists have measured its size and found it to be slightly smaller than the Sun.

This star moves quickly across the sky and follows a path that takes it farther from the center of our Milky Way galaxy than the Sun does. So far, no large planets or disks of dust have been found around Sigma Draconis.

Search for planets

Scientists have looked for planets around Sigma Draconis using special tools at the Keck Observatory and the Lick Observatory. From 2004 to 2013, they found hints that a planet about the size of Uranus might orbit the star every 308 days, but they need more proof before announcing a discovery.

In 2017, another study using the same tools did not find a planet, suggesting the changes they saw might be due to the star’s magnetic activity instead. A more recent study in 2025 found variations every 409.7 days, which they also think is caused by the star’s activity.