Megrez

Megrez, also called Delta Ursae Majoris, is a star in the northern constellation of Ursa Major. It is one of the seven stars that make up the Big Dipper, an famous pattern in the night sky. With an apparent magnitude of +3.3, Megrez is the dimmest star in the Big Dipper.

Measurements using parallax help scientists determine how far away stars are from Earth. For Megrez, these measurements show that it is about 80.5 light-years from the Sun. This means that the light we see from Megrez today actually left the star 80.5 years ago!

Stars like Megrez are important for understanding the universe. By studying their distance, brightness, and other features, astronomers can learn more about how stars form, live, and eventually die. Megrez, as part of the Big Dipper, is also a helpful guide for people who want to explore the night sky.

Stellar properties

Megrez is a bright star that has twice the mass of the Sun and shines about 23 times brighter. It belongs to a special group of stars called A-type stars, which means it creates energy by combining hydrogen atoms in its core.

This star spins very quickly, completing a full rotation in just 3.1 hours. It has a faint disk of dust and particles surrounding it, as well as two dimmer companion stars nearby. Megrez is part of a group of stars called the Ursa Major moving group, which all travel together through space.

Nomenclature

The star Delta Ursae Majoris, also known as Megrez, has a name that comes from Arabic, meaning "the base of the bear's tail." It was also historically called Kaffa, though the origin of that name is unclear. Different cultures had their own names for the star: the Hindus called it Atri, one of the Seven Rishis, and in Chinese it is known as the Fourth Star of the Northern Dipper.

Latinised Bayer designation Arabic Atlas Coeli Antonín Bečvář Hindus Atri Seven Rishis Northern Dipper asterism Chinese name

Namesakes

The United States Navy named a ship after the star Megrez. This ship, called USS Megrez (AK-126), was a Crater class cargo ship. It was one of the many ships in the Navy named after famous stars.