Scientists discover a pulsating star that only gets brighter in one hemisphere

Researchers at Penn State have announced they have discovered a new type of pulsating star with a brightness that oscillates periodically but only over one of its hemispheres. Pulsating stars typically have brightness that oscillates periodically across its entire surface. The team says that the stars located in a binary star system, and its unusual single-sided pulse is because of the gravitational pull of its close companion star distorting the oscillations.The team says that the clue that led to the discovery of the unusual star came from citizen scientists. Rhythmic pulsations in the stellar surface of a star happens in both young and old examples and vary with some having long pulsations and others having short ones. The cause of the brightness of the pulsations also varies. However, one common the stars of always had, until now, is that the oscillations were always visible on all sides of the star.

The initial discovery of the odd behavior of the star was discovered by citizen scientists going through the TESS data. When the amateur astronomers discovered the bizarre behavior, they alerted their professional astronomer colleagues. The team says that the two companion stars in the binary system are so close together that they orbit each other every two days.

The very close proximity of the stars causes them to be distorted into a teardrop-shaped by the gravitational pull of their companion. The team later found the strength of the pulsations depended very much on the angle at which the star was observed. Scientists say the teardrop shape causes observers on Earth see different cross-sections of the star at different times.

That shape was how the team can discover that the pulses are only found on one side of the star. Interestingly, the idea that the pulsations of a star could be impacted by close companion was theorized in the 1940s, while the notion that tidal forces can move the axis of pulsation was theorized over 30 years ago. Proof for those theories was missing until now.