15 Arietis

Lore & Background

15 Arietis is a short-period semiregular variable star, cataloged as AV Arietis. The General Catalogue of Variable Stars lists a period of 5.032 days, but long-term photometry reveals that the strongest pulsation period is 18.1 days with an amplitude of 0.028 magnitudes, while a secondary period of 21.9 days has an amplitude of 0.030 magnitudes. The star's measured angular diameter, combined with its estimated distance, yields a physical size of about 67 times the radius of the Sun.

Reader's Guide

As a semiregular variable of type M3 III, 15 Arietis contributes to the understanding of pulsation behavior in evolved red giants. Its multiple periods—5.032 days from the General Catalogue of Variable Stars, and the stronger 18.1-day and 21.9-day cycles from long-term photometry—illustrate the complexity of stellar oscillations in such stars. The star's brightness, reduced by interstellar extinction, and its distance of roughly 560 light-years place it among the more distant naked-eye variables. Its designation as both a Flamsteed and variable star links historical cataloging with modern variability studies, and its single-star nature avoids complications from binarity. The star's legacy lies in its role as a test case for red giant pulsation models and for photometric monitoring programs that refine period and amplitude measurements.

Did You Know?

• 15 Arietis is also known by the variable star designation AV Arietis.
• The star has a radius about 67 times that of the Sun.
• Interstellar extinction reduces its apparent brightness by 0.33 magnitude.