Physical association of Pismis 6 and Pismis 8

Determine whether Pismis 6 and Pismis 8 constitute a physically associated binary open-cluster system sharing a common age of approximately 1–10 Myr.

Background

Pismis 6 and Pismis 8 have previously been proposed as a binary cluster system on the basis of early classifications as very young clusters. Establishing whether they are genuinely associated would clarify their common formation history and evolutionary status.

The paper reports that the proposed association has not yet been verified, leaving the physical relationship between the two clusters unresolved.

References

Two clusters, Pismis~6 and Pismis~8, have been proposed as a physically associated binary system sharing a common age of order 1--10~Myr \citep{Kopchev_2008}, based on early classifications as young clusters \citep{Vogt_1973, FitzGerald_1979, Forbes_1994, Giorgi_2005}; this putative association remains unconfirmed.

— Honoring Paris Pişmiş' Legacy: Uniform Astrophysical Properties of 14 Understudied Clusters from Gaia DR3  (2609.19486 - Koç et al., 16 Sep 2026) in Section 2.2, “Literature Context for the Selected Clusters”