Binary stars with strange orbits have been found by the Kepler space telescope.
They’re called “heartbeat stars”, but not because they expand and contract. In fact, they’re double star systems in which one star has a highly elongated orbit similar to that of a comet. As this star swings close to its companion, gravity pulls the latter into a non-spherical shape, changing its light output. A plot of the brightness of such systems shows a regular intensity variation, reminiscent of an electrocardiogram. Studying such strange stellar partners, as SETI Institute scientist Susan Mullally does, will tell us more about how binary stars – the most common type of star systems in the universe – get along with one another. The big mystery: Why don’t such systems eventually settle down into more circular orbits?
Read the Press release at http://www.jpl.nasa.gov/news/news.php?release=2016-277