Unresolved Binaries in the Intermediate Mass Range in the Pleiades Star Cluster. (arXiv:2201.05146v1 [astro-ph.SR])
<a href="http://arxiv.org/find/astro-ph/1/au:+Malofeeva_A/0/1/0/all/0/1">A. Malofeeva</a> (UrFU), <a href="http://arxiv.org/find/astro-ph/1/au:+Seleznev_A/0/1/0/all/0/1">A. Seleznev</a> (UrFU), <a href="http://arxiv.org/find/astro-ph/1/au:+Carraro_G/0/1/0/all/0/1">G. Carraro</a> (UniPD)

The identification of binary stars of different mass ratios in resolved
stellar populations is a challenging task. We show how the photometric diagram
constructed with the pseudo-colors (H-W2)-W1 vs W2-(BP-K) can be employed to
estimate the binary and multiple star ratios and the distribution of their
component mass ratio $q$ effectively. As an application, we investigate the
Pleiades star cluster in the range of primary component mass between 0.5 and
1.8 $M_{odot}$. The binary star ratio is found to be between 0.54$pm$0.11 and
0.70$pm$0.14. On the other hand, the ratio of systems with multiplicity more
than 2 is between 0.10$pm$0.00 and 0.14$pm$0.01. The distribution of the
component mass ratio $q$ has been approximated by a power law with the exponent
between -0.53$pm$0.10 and -0.63$pm$0.22. Below 0.5 $M_{odot}$, we expect a
large number of brown dwarfs among secondary components.

The identification of binary stars of different mass ratios in resolved
stellar populations is a challenging task. We show how the photometric diagram
constructed with the pseudo-colors (H-W2)-W1 vs W2-(BP-K) can be employed to
estimate the binary and multiple star ratios and the distribution of their
component mass ratio $q$ effectively. As an application, we investigate the
Pleiades star cluster in the range of primary component mass between 0.5 and
1.8 $M_{odot}$. The binary star ratio is found to be between 0.54$pm$0.11 and
0.70$pm$0.14. On the other hand, the ratio of systems with multiplicity more
than 2 is between 0.10$pm$0.00 and 0.14$pm$0.01. The distribution of the
component mass ratio $q$ has been approximated by a power law with the exponent
between -0.53$pm$0.10 and -0.63$pm$0.22. Below 0.5 $M_{odot}$, we expect a
large number of brown dwarfs among secondary components.

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