3-million-mile-high tsunamis crash down on "heartbreak" star
From strange stars to weird worlds and other odd objects that defy explanation, the cosmos constantly surprises us. Now astronomers have discovered a “heartbreak” star system where tidal waves, three times taller than the Sun, rise and crash on the surface of a giant star thanks to the motions of a smaller companion star.
The star system in question is known as MACHO 80.7443.1718, and it belongs to a group known as “heartbeat” stars after their tendency to pulsate in a steady rhythm. However, this is the most extreme known example, with its brightness swinging by about 20% each time – 200 times more than most. As such, it’s been nicknamed a “heartbreak star” instead.
For the new study, scientists at the Harvard & Smithsonian Center for Astrophysics investigated why this system pulses so wildly. The team created a computer model of both stars in the system and simulated their interactions as they orbit each other.
The primary star is absolutely huge, measuring 24 times wider than the Sun and 35 times more massive. As the smaller star whizzes close by, every 33 days or so, its gravitational pull kicks up stellar material on the bigger star into waves that swell and crest, before finally breaking like waves on an Earthly beach. These tides are a tad bigger than anything around here though – they can get to about 2.7 million miles (4.3 million km) tall, or as high as three Suns stacked on top of each other.
“Each crash of the star's towering tidal waves releases enough energy to disintegrate our entire planet several hundred times over,” says Morgan MacLeod, co-author of the study. “These are really big waves.”
That’s not the only effect. This monthly gravitational dance stretches the bigger star into a kind of egg shape, while flicking stellar material off into a spinning atmosphere. These factors are what create the drastic swings in brightness as seen from Earth.
MACHO 80.7443.1718 is one of about 20 known heartbeat star systems that shows abnormally large brightness fluctuations, so more observations could reveal other heartbreakers out there.
“This heartbreak star could just be the first of a growing class of astronomical objects,” said MacLeod. “We're already planning a search for more heartbreak stars, looking for the glowing atmospheres flung off by their breaking waves.”
The research was published in the journal Nature Astronomy.