Astronomers Document the Rise and Fall of a Rarely Observed Stellar Dance

January 14, 2021 | James Urton | UW News

A team led by Dr. James Davenport, research assistant professor of astronomy at the UW and associate director of the UW’s DIRAC Institute, analyzed more than 125 years of observations of HS Hydra – from astro-photographic plates in the late 1800s to 2019 observations by TESS – and showed how this system has changed dramatically over the course of just a few generations. The two stars began to eclipse in small amounts starting around a century ago, increasing to almost full eclipses by the 1960s. The degree of eclipsing then plummeted over the course of just a half century, and will cease around February 2021.

The sun is the only star in our system. But many of the points of light in our night sky are not as lonely. By some estimates, more than three-quarters of all stars exist as binaries — with one companion — or in even more complex relationships. Stars in close quarters can have dramatic impacts on their neighbors. They can strip material from one another, merge or twist each other’s movements through the cosmos.

And sometimes those changes unfold over the course of a few generations.

That is what a team of astronomers from the University of Washington, Western Washington University and the University of California, Irvine discovered when they analyzed more than 125 years of astronomical observations of a nearby stellar binary called HS Hydrae. This system is what’s known as an eclipsing binary: From Earth, the two stars appear to pass over one another — or eclipse one another — as they orbit a shared center of gravity. The eclipses cause the amount of light emitted by the binary to dim periodically.

Continue reading this article by James Urton in the UW press release here.