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New astro-ph.* submissions cross listed on cs.LG, cs.AI, stat.*, physics.data-an staritng 202607302000 and ending 202608052000

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The Bimodal Mass Ratio Distribution of the Hyades

Authors: Henri M. J. Boffin
Comments: Submitted to RevMexAA
Primary Category: astro-ph.SR
All Categories: astro-ph.SR, astro-ph.GA, astro-ph.IM, physics.data-an

The distribution of stellar mass ratios, q, in binary systems provides critical insights into the dynamical history and star-formation processes of open clusters. Here, I re-evaluate the recently published mass ratio distribution (MRD) of a sample of spectroscopic binaries in the Hyades cluster, which was based on stellar positions in colour-magnitude diagrams. I demonstrate that the mass ratios derived in that work are statistically inconsistent with a random distribution of orbital inclinations. Furthermore, several systems yielded non-physical results. By applying a Richardson-Lucy deconvolution to the spectroscopic mass functions and assuming a random distribution of inclinations, I re-derive the MRD for this sample, showing that it is statistically different from a uniform distribution. I further find a significant dependence on the primary mass: systems with lower-mass primaries exhibit a peak near q~1, whereas more massive primaries show a distribution heavily skewed toward low mass ratios (q~0.15). These findings highlight the potential pitfalls of photometric mass ratio derivations and underscore the need for further verification with future data releases such as Gaia DR4.