The research, spearheaded by Professor Kyu-Hyun Chae of Sejong University, Seoul, scrutinized the orbital dynamics of approximately 26,500 wide binary stars situated within a 650 light years range. Prof. Chae had expert assistance from Kareem El-Badry, formerly at Harvard and currently faculty at Caltech, in accessing and utilizing the Gaia database.
One of the study's distinctive qualities was its focus on deducing gravitational accelerations of binary stars based on their separation or orbital period. This was achieved through a Monte Carlo deprojection, converting observed two-dimensional motions into three-dimensional space dynamics.
Commenting on the methodology, Prof. Chae remarked, "Gravity can be directly and efficiently tested by calculating accelerations. My previous engagements with galactic rotation curves influenced this approach." He further noted similarities between wide binaries and galactic disks, with the major difference being the former's elongated orbits in contrast to the nearly circular orbits of the latter.
A surprising outcome of this research was the realization that, under certain conditions, observed star accelerations began deviating from what Newton's and Einstein's laws would predict. Specifically, for accelerations less than approximately 0.1 nanometer per second squared, the observed acceleration exceeded the Newton-Einstein prediction by a significant 30 to 40 percent.
This observation has intriguing parallels with a theoretical proposition made four decades ago by physicist Mordehai Milgrom, of the Weizmann Institute in Israel. Milgrom's framework, termed as modified Newtonian dynamics (MOND) or Milgromian dynamics, posits such a deviation in gravitational behavior under specific circumstances.
Adding further weight to this, the exact boost in acceleration was found to be consistent with a MOND-type gravity theory named AQUAL, originally conceived by Milgrom and physicist Jacob Bekenstein. Importantly, this alignment depends on a unique external field effect from the Milky Way galaxy, a cornerstone of MOND-type modified gravity.
Prof. Chae commented on the implications, asserting that potential systemic errors were rigorously examined and the results appeared to be genuine. He anticipates that the results will undergo further scrutiny and refinement as more data becomes available.
Interestingly, while boosted accelerations in galactic rotation curves might be attributed to dark matter, according to Newton-Einstein standard gravity, this isn't the case for wide binary dynamics. Such dynamics evidently challenge the standard gravity framework, aligning more with the MOND perspective.
Historical analogies are hard to ignore. Just as anomalies in Mercury's orbits in the 19th century precipitated the birth of Einstein's general relativity, the anomalies now observed in wide binaries might necessitate an evolution or replacement of current gravitational theories.
Adding to the discourse, Pavel Kroupa, professor at both Bonn University and Charles University in Prague, conveyed agreement with the study's conclusions, emphasizing the significant implications for astrophysics.
Xavier Hernandez, who originally proposed testing gravity using wide binary stars, appreciated the robustness of Chae's work and felt it qualified as a true discovery. Similarly, Mordehai Milgrom lauded Chae's meticulous analysis but called for further independent validations.
In challenging longstanding beliefs about dark matter and gravity, this research indeed heralds what might be the onset of a paradigm shift in astrophysics.Research Report:Breakdown of the Newton-Einstein Standard Gravity at Low Acceleration in Internal Dynamics of Wide Binary Stars
Related Links
Sejong University
Stellar Chemistry, The Universe And All Within It
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