Dynamics of wide binary stars: A case study for testing Newtonian dynamics in the low acceleration regime

Abstract

Extremely wide binary stars represent ideal systems to probe Newtonian dynamics in the low acceleration regimes (<10e-10 m/s/s) typical of the external regions of galaxies. Here we present a study of 60 alleged wide binary stars with projected separation ranging from 0.004 to 1 pc, probing gravitational accelerations well below the limit were dark matter or modified dynamics theories set in. Radial velocities with accuracy ~100 m/s were obtained for each star, in order to constrain their orbital velocity, that, together with proper motion data, can distinguish bound from unbound systems. It was found that about half of the observed pairs do have velocity in the expected range for bound systems, out to the largest separations probed here. In particular, we identified five pairs with projected separation >0.15 pc that are useful for the proposed test. While it would be premature to draw any conclusion about the validity of Newtonian dynamics at these low accelerations, our main result is that very wide binary stars seem to exist in the harsh environment of the solar neighborhood. This could provide a tool to test Newtonian dynamics versus modified dynamics theories in the low acceleration conditions typical of galaxies. In the near future the GAIA satellite will provide data to increase significantly the number of wide pairs that, with the appropriate follow up spectroscopic observations, will allow the implementation of this experiment with unprecedented accuracy.

arXiv commentAccepted for publication on International Journal of Modern Physics D

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Cited by in corpus (11)

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• Asymmetrical tidal tails of open star clusters: stars crossing their cluster's prah challenge Newtonian gravitation
• Internal kinematics of GAIA DR3 wide binaries: anomalous behaviour in the low acceleration regime
• Testing Modified Gravity Theories via Wide Binaries and GAIA
• Challenging a Newtonian prediction through Gaia wide binaries
• The geometric challenge of testing gravity with wide binaries
• A new line on the wide binary test of gravity
• Exact semianalytical calculation of rotation curves with Bekenstein-Milgrom nonrelativistic MOND
• Influence of selection criteria on the interpretation of rotational behaviour of wide-binary star systems