Caltech IPAC announces new executive director, Tom Greene
Business Announcement
In honor of Global Astronomy Month, we’re exploring the science of space. Learn how astronomy connects us through curiosity, discovery, and a shared wonder for what lies beyond.
Updates every hour. Last Updated: 29-Jul-2025 00:11 ET (29-Jul-2025 04:11 GMT/UTC)
Astrophysicist Kyu-Hyun Chae at Sejong University (Seoul, South Korea) has developed a new method of measuring gravity with all three components of the velocities (3D velocities) of wide binary stars, as a major improvement over existing statistical methods relying on sky-projected 2D velocities. The new method based on the Bayes theorem derives directly the probability distribution of a gravity parameter (a parameter that measures the extent to which the data departs from standard gravitational dynamics) through the Markov Chain Monte Carlo simulation of the relative 3D velocity between the stars in a binary. When the method is applied to a sample of about 300 highest-quality wide binaries selected from European Space Agency's Gaia Data Release 3, the results indicate a 4.2σ discrepancy with standard gravity at acceleration lower than about 1 nanometer per second squared. Much improved results are expected in the near future with upcoming data of precise velocities of stars in the line-of-sight (radial) direction.
MIT scientists may have solved the mystery of why the moon shows ancient signs of magnetism although it has no magnetic field today. An impact, such as from a large asteroid, could have generated a cloud of ionized particles that briefly enveloped the moon and amplified its weak magnetic field.