HD 3605: An Orange Binary in Sculptor

For those of us in the Northern Hemisphere, autumn is a great time to wander through the southern reaches of the sky and appreciate the stars of Sculptor. One of its most familiar treasures is the Silver Coin Galaxy, which I recently photographed. Nearby, you will find HD 3605, a binary star worth a stop.

The primary star shines at magnitude 6.58. It is a K-type giant that has exhausted its core hydrogen and now glows with a soft orange light. Its companion star is much fainter, with a magnitude of 9.7. Though that makes it a challenge for smaller telescopes, the generous separation of 47 arcseconds gives observers a good chance at spotting both stars. According to Stelle Doppie, this distant pair lies roughly 894 light-years from us and was discovered in 1830.

My Observations

Even with the sky glow rising from Tampa to the southwest of my home, I am always grateful that the double stars in this part of the sky still shine through well. HD 3605 is no exception. At the eyepiece, the primary immediately catches my attention with its warm orange color and steady presence.

Its companion, sitting close by at about 47 arcseconds, appears white and much fainter, but still distinct once I settle into the view. There is also another magnitude 9 star a bit farther out from the pair that I can just make out. After some research, though, it seems this extra point of light is only a line-of-sight visitor and not physically connected to the binary.

Key Stats

Constellation	Sculptor
Best Viewing	Autumn
Visual Magnitude	+6.58 | +9.73
Separation	47.19″
Position Angle	95.1°
Distance	893.69 light years
Milky Way Location	Orion Spur
My Viewing Grade	B
Designations	HD 3605, SAO 166443, HIP 3056

Sources and Notes

Stelledoppie. (n.d.). ID 2598 — HD 3605 / SAO 166443. Retrieved November 21, 2025, from https://www.stelledoppie.it/index2.php?iddoppia=2598

Sketch by Wayne McGraw