12 Ophiuchi
A young BY Draconis variable with two overlapping starspot cycles.
12 Ophiuchi, also designated V2133 Ophiuchi, is a variable star located 32.3 light-years away in the constellation Ophiuchus. It is notable as a BY Draconis variable, with variability driven by magnetic activity on its chromosphere, including starspots, combined with its rotation. The star was among the top 100 target stars for NASA's canceled Terrestrial Planet Finder mission.
- Distance
- 32.3 light-years
- Constellation
- Ophiuchus
- Variable star designation
- V2133 Ophiuchi
- Variability type
- BY Draconis variable
- Rotation period cycles
- 4.0 and 17.4 years
- Space velocity
- 30 km/s relative to the Solar System
- Surface gravity
- Somewhat higher than the Sun's
Lore & Background
12 Ophiuchi is categorized as a BY Draconis variable, with its variability attributed to large-scale magnetic activity on the chromosphere in the form of starspots. The rotational period moves these active regions into and out of the line of sight, resulting in low-amplitude luminosity changes. The star also displays rapid variation in luminosity, possibly due to changes in the starspots themselves. Measurements of its long-term variability reveal two overlapping cycles of starspot activity, with periods of 4.0 and 17.4 years, in contrast to the Sun's single 11-year cycle. No companions have yet been detected in orbit around this star, and it remains uncertain whether it possesses a dust ring. Its high rotation period and active chromosphere indicate it is a relatively young star.
Reader's Guide
12 Ophiuchi's significance lies in its role as a nearby laboratory for studying stellar magnetic activity and starspot cycles. Its two overlapping activity cycles, with periods of 4.0 and 17.4 years, offer a contrast to the Sun's single cycle, providing insight into how different stars generate and modulate magnetic fields. The star's inclusion among the top 100 targets for NASA's canceled Terrestrial Planet Finder mission underscores its perceived value for exoplanet and circumstellar disk studies, though no companions or dust rings have been confirmed. Its near-solar abundance of heavy elements and somewhat higher surface gravity further make it a useful comparison object for solar physics. The rapid luminosity variations attributed to starspot changes highlight the dynamic nature of its chromosphere. As a young star with a high space velocity of 30 km/s relative to the Solar System, 12 Ophiuchi represents an active phase of stellar evolution that can inform models of stellar rotation and magnetic activity over time.
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