Capella: The Golden Four-Star System of Auriga

When winter settles over the Northern Hemisphere, Capella shines golden-yellow high above in the constellation Auriga. The star, also known as Alpha Aurigae, is the sixth brightest star in the night sky. Capella’s name draws from rich historical lore, originating from the Latin word for “little nanny goat.” In traditional star charts, the Charioteer is often depicted holding a goat and her kids on his shoulder. Capella marks the heart of the mother goat.

A Brilliant Quartet

While it looks like a single star to the naked eye, Capella actually consists of four stars paired into two distinct sets: a dominant pair of bright, massive yellow giants, and a faint pair of small red dwarfs orbiting much further out.

The main light we see comes from a tight pair of evolved giant stars, known as Capella Aa and Capella Ab. They lie roughly 43 light-years from Earth, and these two stars orbit each other every 104 days. The two behemoths are only separated by a distance only slightly less than the span between Earth and the Sun!

Capella Aa is a yellow giant star (spectral type G8 III) that has expanded to roughly 12 times the diameter of our Sun and radiates about 79 times more luminous energy. Its partner, Capella Ab, is a slightly smaller, hotter yellow giant (spectral type G1 III) that is roughly 9 times the size of our Sun and shines with 78 times the Sun’s luminosity.

These two are a spectroscopic binary, so we cannot visually resolve them as two separate stars with a standard backyard telescope; they are just too close together.

Hunting the Red Dwarf Companions

For backyard astronomers seeking a good observational challenge, the outer red dwarf pair offers a tough test of optics and patience. Located roughly 10,000 astronomical units away from the primary pair, these two dim, cool stars require a telescope to spot.

Positioned about 720 arcseconds away from Capella’s main glare, Capella H shines at a modest magnitude 10.2 and can be readily spotted in most amateur telescopes.

However, its companion, Capella L, is a ghost by comparison at magnitude 13.7. Separated from H by a mere 3.6 arcseconds, splitting this dim duo requires dark skies, stable atmospheric seeing, and a larger aperture. You’ll typically need an 8-inch or greater telescope at high magnification to coax the feeble point of Capella L out from its partner’s shadow.

A Winter Jewel

Whether you are simply enjoying its warm golden glow through a pair of binoculars or pushing your telescope to its absolute limits to split its elusive red dwarf companions, Capella is a winter sky treasure. Next time you look up at the Charioteer, take a moment to appreciate what’s more than meets the eye.

My Observations

It’s hard to believe this is my first time seeing Capella through the telescope since starting this site in 2020. It’s a beautiful star in the telescope among a nice starfield of brighter stars. I know there are companion optical partners to this multiple-star system, but I’m unsure of which ones are considered partners.

Key Stats

Constellation	Auriga
Best Viewing	Winter
Visual Magnitude	0.08 (combined system)
Absolute Visual Magnitude	-0.48
Distance from Earth	42.9 light-years
Milky Way Location	Orion Spur
My Viewing Grade	A
Designations	Alhajoth, Hokulei, α Aurigae, 13 Aurigae, GC 6427, HD 34029, HIP 24608, HR 1708, SAO 40186

Sources and Notes

Kaler, J. B. (1998, November 13). Capella (Alpha Aurigae). University of Illinois. Retrieved June 5, 2026, from http://stars.astro.illinois.edu/sow/capella.html

SkyLive. (n.d.). Capella – α Aurigae (alpha Aurigae) – Star in Auriga. Retrieved June 5, 2026, from https://theskylive.com/sky/stars/capella-alpha-aurigae-star

Sketch and photos by Wayne McGraw.