Zeta Persei (ζ Persei) is a multiple-star system in the constellation Perseus. Backyard astronomers can enjoy this tight pair of stars on autumn and winter nights.
There are several things that make Zeta Persei an interesting star. For one, it’s a huge, supergiant star with a blue-white colored hue. Astronomers estimate this blowtorch sphere to be 26 times the radius of our sun and 13-16 times the mass. What’s more, it’s an incredible beacon of light with a luminosity 47,000 times the Sun! 1
Also, the star has several companion stars, some just optical doubles. However, its most notable companion is the close B star at a magnitude of 9.2 at 12.9 arcseconds away. Backyard astronomers enjoying a clear, crisp night with good seeing should be able to spot the nearby star with most scopes. According to Jim Kaler, this faint companion “orbits at least 3900 Astronomical Units away, and takes at least 50,000 years to make a full circuit.” 2
Zeta Persei will eventually find its fate as a supernova.
My Observations
| Date | November 14, 2022 |
| Time | 9:20 p.m. |
| Location | Seattle, WA |
| Magnification | 169x |
| Scope | Meade 8″ SCT |
| Eyepiece | 12mm |
| Seeing | Good |
| Transparency | Good |
I decided to wait a little longer tonight in the near-freezing cold (36 degrees) to watch Persei rise above the eastern Douglas Fir trees. I’m glad I did, as this region around Zeta Persei is attractive. In addition to enjoying the close double star, I find the nearby set of deep blue stars to be really pretty. There are several other faint stars in the 12mm field, but I’m sure which ones are considered real companions. I’ll have to research more.
Key Stats
| Constellation | Perseus |
| Best Viewing | Autumn |
| Visual Magnitude | +2.9 | +9.2 |
| Absolute Visual Magnitude | -3.93 |
| Distance from Earth | 750 ly |
| Separation | 12.9″ | 2970 AU |
| Orbital Period | Unknown |
| Milky Way Location | Orion Spur |
| My Viewing Grade | B |
Sources and Notes
Banner adapted from an illustration created by Pablo Budassi. The illustration is licensed under the Creative Commons Attribution-Share Alike 4.0 International license. Full details here.
1 “Zeta Persei.” Wikipedia, Wikimedia Foundation, 27 Mar. 2022, https://en.wikipedia.org/wiki/Zeta_Persei.
2 Kaler, Jim. Zeta Per, http://stars.astro.illinois.edu/sow/zetaper.html.
AKA: ζ Per, ζ Persei, Atik, ZETA PER, SAO 56799, STF 464, 44 Per
The Garden Astronomer 