Nu Eridani

Lore & Background

Nu Eridani is a B-type subgiant star with a stellar classification of B1.5 IV. In 1926, Robert H. Baker announced his discovery that the brightness of Nu Eridani is variable. It is a hybrid pulsator variable, lying as it does on the overlapping instability strips for Beta Cephei variables and slowly pulsating B-type stars. The star shows at least fourteen pulsation frequencies, with nine that also display radial velocity variations. It has about nine times the mass of the Sun and six times the Sun's radius. Nu Eridani shines with 7,943 times the solar luminosity from its outer atmosphere at an effective temperature of 22,000 K. If the star were 10 pc from the Sun, it would be the brightest star in the night sky with an apparent magnitude of −2.84, outshining Sirius at magnitude −1.46.

Reader's Guide

Nu Eridani's significance lies in its classification as a hybrid pulsator variable, bridging two types of stellar variability: Beta Cephei variables and slowly pulsating B-type stars. Its discovery of variability in 1926 by Robert H. Baker marked an early recognition of such behavior in a B-type subgiant. The star's at least fourteen detected pulsation frequencies, nine of which also show radial velocity variations, make it a valuable object for studying stellar oscillations and interior structure. Its high luminosity—7,943 times that of the Sun—and effective temperature of 22,000 K place it among the more massive and hotter stars in the night sky. The fact that it would be the brightest star if placed at 10 parsecs underscores its intrinsic brilliance. Nu Eridani also appears in the same field as the galaxies NGC 1618, NGC 1622, and NGC 1625, providing a visual context for observers. Its legacy includes serving as a benchmark for understanding hybrid pulsation in B-type stars and the overlapping instability strips that govern such behavior.

Did You Know?

• Nu Eridani would be the brightest star in the night sky if placed 10 parsecs away, with an apparent magnitude of −2.84.
• It is a hybrid pulsator variable, lying on overlapping instability strips for Beta Cephei and slowly pulsating B-type stars.
• The star shows at least fourteen pulsation frequencies, nine of which also display radial velocity variations.