(ORDO NEWS) — Double and even triple star systems have not been amazed for a long time; planets are also known that are under two or three suns. However, systems that include six stars at once remain very rare. Until recently, only 17 such objects were known, and TIC 168789840 became the 18th. This is reported in a new article by American astronomers, accepted for publication in The Astronomical Journal and available in the open online library arXiv.
TIC 168789840 lies in the constellation Eridani, 1428 light years away. It includes gravitationally bound pairs of stars, two of which (A and C) form the “core” of the system, and the third (B) revolves around them in a distant orbit. The stars of the binary system A go around each other in 1.6 days, the system C – in 1.3 days, and B – in 8.2. In turn, systems A and C themselves revolve around each other in about four Earth years, and system B bypassing them – in 2000 years.
NASA astrophysicist Brian Powell and colleagues discovered TIC 168789840 with the TESS space telescope, noting that such a structure resembles the already known multiple star with six components – Castor (α Gemini). However, the three pairs of TIC 168789840 are even more similar to each other: they all include a larger star with a radius of 1.4-1.7 solar radius and a mass of 1.2-1.3 solar radius, as well as its small companion with a mass of 0.5 -0.7 solar and radius 0.5-0.6 solar.
Binary stars A and C are too close to each other, creating strong gravitational anomalies that it is impossible to imagine that planets could form and survive near them. However, scientists suggest that the relatively distant system B may well have a planet. The authors plan to continue observing TIC 168789840 and possibly discover such a strange distant world.
This work will help to understand exactly how unusual systems are formed, including so many stars at once. It is assumed that they may appear as triple stars, formed together – in a common “cradle”. However, further, passing through the gas and dust cloud, each of the participants in the system acquired a new neighbor, becoming a double one. “This is all amazing,” says Brian Powell. “I wish I had a starship, park it nearby and see everything with my own eyes.”
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