Astronomers of Warsaw University in Poland found a likely explanation of mysterious light pulsations from dying stars in the stage of the Red Giant. Scientists submitted their findings in the article published in the Astrophysical Journal Letters magazine. Briefly about the study tells the edition of the Science Alert.
It is known that the red giants are experiencing brightness fluctuations, while cycles can immediately be several. Betelgeuse has one period equal to 185 days, another – 425 days. Both are caused by acoustic waves arising in the depths of the star and make it shrink and expand. However, there are particularly long cycles that cover several years called the long secondary period (Long Secondary Period). They are observed about a third of all red giants and cannot be explained by acoustic waves.
Scientists analyzed the data obtained during optical and infrared observations of 16 thousand red giants with long secondary periods. About 700 stars were selected with a clearly defined infrared glitter curve. When comparing curves in optical and infrared bands, the researchers found that half the stars had a slight decrease in infrared glitter, which accounted for at the time when the brightness of the red giant was at the peak. Moreover, this decrease occurred in opposition to a general decrease in gloss and infrared, and in optical ranges.
Infrared light is usually created by dust surrounding a red giant. She absorbs star light and re-ends it on longer waves. In the event that a companion rotates around the star, it will produce a strong failure on all wavelengths during the passage between the red giant and the observer. However, when the companion hits behind the star, a small drop in brightness in the infrared spectrum will be observed.
The amplitudes of shine curves indicate that the companions are either a very low mass star, or brown dwarfs. If it is brown dwarfs, then they probably were originally exoplanets and throughout their lives were dragging the substance of the outer shell of the Red Giant.