An international team of astronomers has discovered a unique planetary system consisting of a K-class star (orange), a Jupiter-sized planet and a white dwarf. The discovery is reported in an article published in the arXiv preprint repository.
The TOI-1259 system, discovered by the TESS space telescope, is 385 light-years from Earth. The parent star has a radius of 0.71 times that of the Sun and is 25 percent more massive than it. Exoplanet TOI-1259Ab is about the size of Jupiter, but its mass is 56 percent larger. Its orbital period is 3.48 days at a distance of 0.04 astronomical units (the average distance from the Sun to the Earth).
What makes the TOI-1259 system unusual is the presence of the white dwarf TOI-1259B, which is 1648 astronomical units (AU) distant from the parent star. It has a radius of 0.013 that of the Sun and a mass of about 0.56 that of the Sun. According to astronomers, the age of the system reaches 4.08 billion years.
Astronomers believe that a white dwarf in the past, when it was still a full-fledged star, could influence the formation and evolution of the planet. Then its mass was 1.59 solar masses, and the distance to the star was 900 AU.
