Castor B
Alpha Geminorum
Scientific overview
Castor B is a main-sequence star in the constellation Gemini (Geminorum), lying about 51.55 light-years from Earth.
Class A. White stars with strong hydrogen lines. Many of the brightest stars in the sky are class A. Such stars have surface temperatures around 7,500–10,000 K and appear white to the eye.
Physical properties
| Spectral type | A m |
| Apparent magnitude | 2.85 |
| Absolute magnitude | 1.86 |
| Luminosity (Sun = 1) | 15.762 |
| Distance | 51.55 ly (15.81 pc) |
Values are real catalogue data; fields without a reliable value are omitted, never estimated.
Evolution
A main-sequence star fuses hydrogen into helium in its core. It will remain on the main sequence for most of its life before evolving into a giant.
Location in the sky
Knowledge connections
- In constellationGemini
Related stars in Gemini
Sources
The primary and reference sources this topic draws on.
- HYG DatabaseHYG Database (Hipparcos + Yale Bright Star + Gliese), by D. Nash / astronexus
Aggregated, openly-licensed star catalogue combining Hipparcos, the Yale Bright Star Catalogue, and the Gliese Catalogue of Nearby Stars.
- HipparcosESA Hipparcos space astrometry mission
High-precision parallax, magnitude, and position for ~118,000 stars.