Abt al-Joza is one of the largest stars that can be seen in the sky with the naked eye, with a radius of a thousand times that of the sun. The brightness of this star, which is located at a distance of 642 light years from Earth, shows that it should emit almost 100,000 times more light than the Sun.
Over the past five years, Abt al-Juza has become the focus of astronomers’ attention due to its unexpected dimming. This dimming occurred in late 2019 and the star returned to normal again in the first half of 2020. It is generally accepted that this decrease in light occurred due to a cloud of dust in an event known as “great light drop”.
The light curve of Gemini indicates a long secondary period (LSP) of approximately 2,100 days. This is not unusual for stars in the red giant branch of the Hertzsprung-Russell diagram and can range from a few hundred to thousands of days. Although the mechanism of LSP remains unknown, it certainly seems that the duration of LSP in this region is several tens of times slower than the radial oscillation of stars.
