Key facts
- Category
- Stars
- Object class
- Extreme red supergiant candidate
- Temperature
- ~3,200 K surface
- Scale fact
- ~2.99 billion kmdiameter
- Composition
- Hydrogen and helium
Stephenson 2-18
~2.99 billion kmdiameter
Visual creditscaleofspace.org / CC BY-NC 4.0
Details
Stephenson 2-18 is a very cool, luminous red supergiant candidate in the direction of the Stephenson 2 stellar association. It has been given one of the largest published stellar size estimates, but its exact diameter remains uncertain because the star is distant, dust-affected, and difficult to separate cleanly from its surrounding region.
Stephenson 2-18, also cataloged as Stephenson 2 DFK 1, is a cool red-supergiant candidate in the direction of the Stephenson 2 association. The often quoted diameter near three billion kilometers is inferred from luminosity and temperature rather than measured as a crisp disk.
Its distance, membership in the association and surrounding dust remain uncertain, and each affects the derived radius. It is therefore one of the largest published stellar candidates, not a secure holder of a “largest known star” record.
Links
- Editorial guides
- Universe journey
- Solar neighborhood
- Preset views
- Wikipedia
- Stephenson 2-18 on Wikipedia
Size neighbors
Objects near Stephenson 2-18 on the scale
On the logarithmic size axis, Stephenson 2-18 falls between VY Canis Majoris and Solar System. Compared below with other objects in Stars.
Shared physical scale
2.29billion km
Sources
References for Stephenson 2-18
Measurements and descriptive context are compiled by the Scale of Space team from the references below. If you find an error, write to hello@scaleofspace.org.
- Stephenson 2-18 on Wikipedia
- Visual: scaleofspace.org / CC BY-NC 4.0
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About
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.