HD 184010 Exoplanet System

Compact trio of gas giants orbiting an ageing orange star // HD 184010 is a real exoplanet system located almost exactly 200 light-years away in the constellation Vulpecula. It consists of an evolved K-type star and three Saturn-mass gas giants. The host star, HD 184010, is younger than the Sun at approximately 2. 76 billion years old, but has a higher mass of about 1. 35 solar masses. Its spectral classification (K0 III–IV) indicates an orange-hued subgiant transitioning onto the red giant branch. The star is no longer fusing hydrogen in its core and is instead powered by hydrogen shell burning. As a result, it has expanded to about 4. 86 solar radii. Despite a cooler effective temperature of ~4971 K (4698 °C), its much larger surface area makes it roughly 13 times more luminous than the Sun. Three gas giants with intermediate-length orbits were discovered around HD 184010 in 2022. From innermost to outermost, they are HD 184010 b, c and d. The trio possess minimum masses of 0. 31, 0. 30 and 0. 45 Jupiter masses, respectively, though their true masses may be somewhat larger because the inclination of their orbits is unknown. They orbit their host every 286. 6, 484. 3, and 836. 4 days, with average orbital distances of 0. 940, 1. 334, and 1. 920 AU. These are fairly close separations for such big gas giants, so their orbits must be near-circular for the system to remain stable. Indeed, simulations have shown that the planets must have eccentricities below 0. 1, else one or more will be ejected within 1 billion years. As HD 184010 continues ascending the red giant branch over the next several hundred million years, its luminosity and radius will increase substantially. The innermost planet may eventually be engulfed if the star expands sufficiently. The outer two giants are expected to survive longer, though their orbits may gradually migrate outward as the star loses mass near the end of its life. During this stage of stellar evolution, the system’s habitable zone has been pushe