Cosmic Scale
HR 5171 A
Yellow hypergiant · 12,000 light-years
How big is HR 5171 A?
HR 5171 A is about 1.8 × 10⁹ km across.
See HR 5171 A in 3D, at true scale
HR 5171 A is a rare yellow hypergiant, and rarer still for having a companion star so close that the two touch, sharing an envelope of gas. It is among the largest yellow stars known.
At a glance
| Diameter | 1.8 × 10⁹ km |
|---|---|
| Mass | 7.76 × 10³¹ kg |
| Diameter compared with Earth | 144,000 × Earth |
| Distance | About 12,000 light-years |
| Radius | About 1,300 Suns |
| Brightness | Around 1 million Suns |
| Type | Yellow hypergiant, contact binary |
Good to know
- Its companion orbits inside the hypergiant's own atmosphere, taking about 1,300 days.
- Yellow hypergiants are a brief, unstable stage: only a dozen or so are known in our galaxy.
- It has been slowly cooling and swelling over the last forty years of observation.
- Next smaller: Westerlund 1-26 · 1.7 × 10⁹ km
- Next larger: VY Canis Majoris · 2.0 × 10⁹ km