What does this number measure?
A very cool red supergiant in the NGC 7419 cluster. The disc shown represents its diameter, twice the adopted radius of 2061 nominal solar radii (1 nominal solar radius = 695 700 km). The value is a dated estimate, not an established size record. The radius is inferred from a model at 3 000 K and a luminosity of 310 000 solar luminosities, Humphreys et al. (2020). Temperature and dust make this size highly model-dependent; other studies give a much smaller star.
Compare the stated dimensions
The comparison uses the number in each fact sheet: altitude, height, diameter, length or distance, depending on the reference. Two values in metres do not necessarily describe the same property.
Source and limitations
Radius inferred from a model at 3 000 K and a luminosity of 310 000 solar luminosities, Humphreys et al. (2020). Temperature and dust make this size highly model-dependent; other studies find a much smaller star.
MY Cephei: artistic illustration of a stellar photosphere. A shared generic pattern for comparing diameters; neither a photograph nor a reconstruction of this star. The value and its uncertainties are given in the object information.