When is the best time to observe Gorgonea Tertia?

Gorgonea Tertia is best observed from October through December, with peak visibility during November when it transits around midnight in the Northern Hemisphere.

Where is Gorgonea Tertia located in the sky?

Gorgonea Tertia lies in the constellation Perseus at right ascension 03h 05m and declination +38° 50′.

What telescope do I need to follow Gorgonea Tertia?

To follow Gorgonea Tertia through its full brightness cycle (magnitude 3.3 to 4.0) you need the naked eye under a dark sky — the star fades out of smaller apertures near minimum light.

Gorgonea Tertia — Variable Star in Perseus

HIP 14354; Rho Persei; 25 Persei

Observable Variable Star Excellent (67/100)

Range: 3.13 - 3.77, Period: 54.7d, Type: SRB

Magnitude 3.3–4.0^m VariableStar Perseus (Per) Visible

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About Gorgonea Tertia

Description

Gorgonea Tertia, Rho Persei, is a red supergiant of spectral class M4+ IIIa about 297 light-years away — one of the closer M-type giants to Earth. It is a semiregular variable, pulsating between magnitudes 3.3 and 4.0 over a primary period of about 50 days, with longer secondary modulations of 600 to 900 days. The star has about 150 solar radii and a luminosity of 240 Suns.

Observing Tips

Gorgonea Tertia is one of the sky's finest deep-orange stars. Its brightness changes by almost a full magnitude — easy for the naked eye to follow over a few weeks against the steady comparison star Algol nearby. Rho Per is very close to Algol and makes an excellent paired observation. Best observed September through February.

History

The name refers to the "Third Gorgon" — one of three mythical Gorgon sisters whose severed head (Medusa) Perseus carries. Algol is the "Demon's Head" (the Gorgon Medusa), and Rho Per represents one of her two immortal sisters. The three Gorgons are sometimes collectively traced in the southwestern part of Perseus. The IAU adopted the name in 2016.

Fun Facts

Gorgonea Tertia's deep orange color is a striking contrast with the nearby blue-white Algol — a visual reminder that the two stars represent radically different stages of stellar evolution, despite their proximity on the sky. Rho Per will likely end its life as a planetary nebula.