We dive back into one of the earliest studies of the outer solar system that helped us understand how four gas giants playing a chaotic game of catch could have knocked Pluto into its topsy-turvy orbit.
ALMA has taken a brand-new image of Fomalhaut’s famous debris disk. What can we learn from it?
Cepheids’ pulsing brightness variations happen because the star’s temperature and radius is changing, and they occupy a unique niche of stellar evolution. We can learn a lot about what is physically happening inside stars during this tumultuous time through close observations. Or rather, we could learn a lot about what happens inside Cepheid variable stars, if only we knew their masses.
Instead of happily orbiting in circles with constant velocity, the two stars spend most of their time far apart, and a few harrowing hours racing past each other. Or, to put it another way: hours and hours of boredom punctuated by moments of sheer terror. This is a heartbeat star.
Close encounters with a passing star can excite a planet into an eccentric or inclined orbit. But a circumstellar disk can damp a planet’s eccentricity and inclination. Who wins? Find out when the authors of this paper model a stellar flyby with two circumstellar disks!
For planets too old for plate tectonics, a companion planet could drive tidal heating to keep conditions primed for life.