Unique Teardrop Star Discovered by NASA Satellite

NASA built its Transiting Exoplanet Survey Satellite, or TESS, to search for worlds outside our solar system, but it can also detect bodies that are much bigger than the average planet. Its latest discovery—a teardrop-shaped, pulsating star dubbed HD74423—has roughly 1.7 times the mass of the sun, and it's the first star of its kind studied by scientists, CBS News reports.

An international team of astronomers published their findings about the star captured by TESS in the journal Nature Astronomy [PDF]. HD74423 is remarkable in many ways. Located 1500 light-years from Earth in the Milky Way galaxy, it shares a binary system with a red dwarf. The large star is tidally locked with the smaller one, meaning one side of HD74423 is always being pulled by its partner's gravitational pull in a tight orbit. This has resulted in its warped teardrop shape.

The fact that it's tidally locked also gives the star its unique pulsation pattern. Many stars like our own sun pulsate, which means they rhythmically become brighter and dimmer. When this phenomenon has been observed in the past, the starlight always fluctuates on all sides. Because it's distorted by its neighbor, HD74423 pulsates on only one side—a celestial anomaly. Even the star's composition is noteworthy. Study co-author Simon Murphy of Australia's Sydney Institute for Astronomy said that he first noticed the star because it was poor in metals, something that set it apart from other hot stars like it.

"We've known theoretically that stars like this should exist since the 1980s," study co-author Don Kurtz of Britain's University of Central Lancashire said in a press release. "I've been looking for a star like this for nearly 40 years and now we have finally found one."

HD74423 is just the latest groundbreaking discovery made by NASA's Transiting Exoplanet Survey Satellite. Earlier in 2020, TESS located a potentially habitable, Earth-sized planet 100 light-years away.