A Study of Stellar Spins in 15 Open Clusters

We analyze spectroscopic and photometric data to determine the projected inclinations of stars in 11 open clusters, placing constraints on the spin-axis distributions of six clusters. We combine these results with four additional clusters studied by Healy & McCullough and Healy et al. to perform...

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Bibliographic Details
Published in:The Astrophysical journal 2023-02, Vol.944 (1), p.39
Main Authors: Healy, Brian F., McCullough, P. R., Schlaufman, Kevin C., Kovacs, Geza
Format: Article
Language:English
Subjects:
Alignment
Astrophysics
Clumps
Cluster analysis
Constraints
Inclination
Isotropy
Magnetic fields
Open clusters
Open star clusters
Protostars
Rotation
Star formation
Stars
Stellar rotation
Systematic errors
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Summary:We analyze spectroscopic and photometric data to determine the projected inclinations of stars in 11 open clusters, placing constraints on the spin-axis distributions of six clusters. We combine these results with four additional clusters studied by Healy & McCullough and Healy et al. to perform an ensemble analysis of their spins. We find that eight out of 10 constrained clusters (80%) have spin-axis orientations consistent with isotropy, and we establish a lower limit of four out of 10 (40%) isotropic clusters at 75% confidence, assuming no correlation of spins between clusters. We also identify two clusters whose spin-axis distributions can be better described by a model consisting of an aligned fraction of stars combined with an isotropic distribution. However, the inclination values of these stars may be influenced by systematic error, and the small number of stars modeled as aligned in these two clusters precludes the interpretation that their stellar subsets are physically aligned. Overall, no cluster displays an unambiguous signature of spin alignment, and 97% of the stars in our sample are consistent with isotropic orientations in their respective clusters. Our results offer support for the dominance of turbulence over ordered rotation in clumps and do not suggest the alignment of rotation axes and magnetic fields in protostars.
ISSN:0004-637X
1538-4357
DOI:10.3847/1538-4357/acad7b