Key facts
- Category
- Stars
- Object class
- Yellow supergiant Cepheid star
- Mass
- ~5.1 solar masses
- Host
- Polaris system
- Scale fact
- 64.4 million kmdiameter
- Estimated age
- ~45–67 million years
- Composition
- Hydrogen and helium
- Temperature
- ~6,015 K surface
Polaris Aa
64.4 million kmdiameter
Visual creditscaleofspace.org / CC BY-NC 4.0
Details
Polaris Aa is the yellow supergiant at the heart of the North Star system and the nearest classical Cepheid to Earth. Cepheids are standard candles for measuring cosmic distances, which makes this nearby example an important calibrator.
Polaris Aa is the yellow supergiant at the center of the multiple-star system seen as the North Star. It is a classical Cepheid whose atmosphere expands and contracts on a cycle of about four days, producing a small but measurable change in brightness.
Cepheids link pulsation period to intrinsic luminosity and are used to calibrate astronomical distances. Polaris is especially valuable because it is the nearest classical Cepheid, although measuring its distance, companions and changing pulsation has made it a demanding calibrator rather than a simple one.
Links
- Editorial guides
- Wikipedia
- Polaris Aa on Wikipedia
- Universe journey
- Solar neighborhood
Size neighbors
Objects near Polaris Aa on the scale
Shared physical scale
255million km
Sources
References for Polaris Aa
Measurements and descriptive context are compiled by the Scale of Space team from the references below. If you find an error, please let us know.
- Polaris Aa — Wikipedia
- Visual: scaleofspace.org / CC BY-NC 4.0
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Scale of Space is a scroll-based journey through the universe, placing objects on a single logarithmic scale so you can compare size across an unbroken range.
Guides explain selected parts of that range, while focused views filter the objects by subject.