Asymmetrical tidal tails of open star clusters: stars crossing their cluster’s práh† challenge Newtonian gravitation

ABSTRACT After their birth a significant fraction of all stars pass through the tidal threshold (práh) cluster origin into classical tails. The asymmetry between number in leading and trailing tails tests gravitational theory. All five open clusters with tail data (Hyades, Praesepe, Coma Berenices, COIN-Gaia 13, NGC 752) have visibly more within $d_{\rm cl}\approx 50\,{\rm pc}$ centre than tail. Using Jerabkova-compact-convergent-point (CCP) method, extended been mapped out for four nearby 600–2000 Myr old to cl} > pc}$. These are on near-circular Galactocentric orbits, formula estimating orbital eccentricity an being derived. Applying Phantom Ramses code this problem Newtonian gravitation near-symmetrical. In Milgromian dynamics (MOND), reaches observed values 50 < dcl/pc 200 maximal near peri-galacticon, can slightly invert apo-galacticon, Küpper epicyclic overdensities asymmetrically spaced. Clusters circular orbits develop due asymmetrical spill-out, therewith spinning up opposite angular momentum. This positive dynamical feedback suggests demise rapidly as keeps increasing. Future work is necessary better delineate around different ages direct n-body code.