In a new study accepted for publication in the Astronomical Journal (arXiv.org), astronomers show that a previously known red dwarf star called LP 876-10 is part of the Fomalhaut system.
Fomalhaut, the 18th brightest star visible in night sky, is located in the constellation Piscis Austrinus about 25 light-years from Earth. The star is twice as massive as the Sun and 20 times brighter.
The name Fomalhaut derives from the Arabic name for this star – Fum al Hut, meaning ‘the Fish’s Mouth.’
Fomalhaut has been featured in science fiction novels by writers Isaac Asimov, Stanislaw Lem, Philip K. Dick, and Frank Herbert.
Despite being a well-studied system, it was only recently confirmed that Fomalhaut was a binary star – two stars (Fomalhaut A and B) that orbit each other – although it had been first suggested in the 1890s.
In the new study, lead author Dr Eric Mamajek of the University of Rochester and his colleagues have found the triple nature of Fomalhaut through a bit of detective work.
“I noticed this third star a couple of years ago when I was plotting the motions of stars in the vicinity of Fomalhaut for another study,” Dr Mamajek said.
“However I needed to collect more data and gather a team of co-authors with different observations to test whether the star’s properties are consistent with being a third member of the Fomalhaut system.”
By carefully analyzing astrometric and spectroscopic measurements, the astronomers were able to measure the distance and speed of the third star. They concluded that a star known as LP 876-10 is part of the Fomalhaut system, making it Fomalhaut C.
Image Credit: Eric E. Mamajek et al/David Hardy