Painting a family portrait of the yellow super- and hypergiants in the Milky Way

I. Constraining the distances and luminosities

¹ Tartu Observatory, University of Tartu, Observatooriumi 1, Tõravere 61602, Estonia
² European Southern Observatory, Alonso de Córdova 3107, Vitacura, Casilla 19001 Santiago de Chile, Chile

^★ Corresponding author: This email address is being protected from spambots. You need JavaScript enabled to view it.

Received: 11 December 2025
Accepted: 2 February 2026

Abstract

Context. The distances to evolved massive stars in the Milky Way are poorly constrained by Gaia parallaxes because these stars are bright and variable. This makes it difficult to determine their fundamental stellar parameters, such as radius or luminosity, and infer their evolutionary states.

Aims. We aim to improve the distance estimates of yellow hypergiants (YHGs) and yellow supergiants (YSGs) by identifying possible cluster and association memberships. Using these distances, we derived updated luminosities and revised their positions in the Hertzsprung-Russell diagram.

Methods. We compiled a sample of 35 luminous yellow massive stars (YHGs and the most luminous YSGs) from the literature. We used Gaia DR3 astrometry to identify possible membership in clusters and OB associations. We derived distances by combining the parallaxes of nearby co-moving stars. We independently validated these distances by comparing the stellar radial velocities to the Galactic H I kinematic map. We combined angular diameters and effective temperature values from the literature with the new distances to estimate the luminosities.

Results. We improved the distance estimates for 28 of the 35 stars through association with co-moving stellar groups. For an additional 6 stars, we provided distance estimates based on the H I kinematic map. For one star, the distance remains unclear. Most YSGs are members of young stellar populations, while the environments of the YHGs are more diverse, and the origin populations for some of them remain unclear. We derived updated luminosities for a subset of 20 stars. Most YHGs have luminosities above log L/L_⊙ = 5.4, while YSGs occupy a wider range of luminosities, and the luminosities of the most luminous YSGs are similar to those of YHGs.