Nanosatellites discover largest star with varying luminosity to date
Astronomers have discovered through nanosatellites in space that the very large star Iota Orionis, visible to the naked eye from Earth, has a repeating short peak in brightness of one percent.
The discovery was made with the Brite Target Explorer, a network of five nanosatellites in space that astronomers use to study the evolution of the brightest stars. The variation in luminosity is due to the fact that Iota Orionis is actually two stars orbiting each other in elliptical orbits over 30 days.
The light from the stars is stable for ninety percent of the time, but periodically the luminosity shows a short dip and then a short peak. Usually the stars are relatively far apart, but periodically they come eight times closer than normal. At that point, the gravitational pull that both stars exert on each other is so great that they are more or less stretched. This phenomenon is the cause of the short peak in luminosity.
It is the first time this effect has been observed on such a large star; Iota Orionis is 35 times as massive as our sun. The star can be seen in the constellation Orion, near the Orion Nebula. The discovery was published in the journal Monthly Notices of the Royal Astronomical Society.
Herbert Pablo, lead researcher at the University of Montreal, says this variation in light intensity is much like an electrocardiogram, which shows the sinus rhythm of the human heart. Such a variation in luminosity is therefore referred to as the ‘heartbeat’ of a star. He also explains that the intense gravity between the stars causes tremors in the stars, allowing the processes in the stars to be investigated. Such tremors are quite rare, especially among stars as large as Iota Orionis.
The research into such large stars is important, according to the astronomers, because as ‘laboratories’ they play a major role in the existence and formation of chemical elements in the universe. The stars could help to better understand a wide range of astrophysical processes. The research also serves to learn more about the evolution of large stars.