Astronomers have discovered a hot-Jupiter planet orbiting a red giant star on a circular orbit, a unique system that serve as a perfect laboratory for planet formation and migration theories.
Exoplanet 51 Peg b was the first hot Jupiter planet to be discovered by scientists in 1995, marking a breakthrough in astronomical research, probably one of the least expected discoveries in search for exoplanets. The population of hot Jupiters are rare class of objects, only known to be present around approximately 0.5–1% of sun-like stars.
Warm Jupiters have similar characteristics to Jupiter, gas giants with masses close to or exceeding that of Jupiter however, they orbit much more closely to their parent star, period orbit less than 10 days, or within 0.1 AU, and experience a high surface temperature. The origin of this rare class of objects generally involves early or late migration scenarios where they eventually form a stable orbit, however, the in-situ formation of these systems has also been proposed (warm Jupiters formed locally, rather than migrating down from larger distances.)
The new discovered warm-Jupiter planet, designed as TYC 3667-1280-1 b, orbits an evolved star with a mass roughly twice than the sun, on a circular orbit – a complete orbit take 26 days. Due to its proximity to its host, the planet experience high surface temperature 1350°K (~1100°C) and very strong wind speeds (order of 1-10 km/s).
Until now, it has only been proposed the existence of gas giants orbiting red giants at such relatively short orbital period. Their detection using the actual method would be much more difficult due to their tiny size compared to the stars they orbit.
To detect TYC 3667-1280-1 b, astronomers used a precise radial velocity measurements to collect data over 1920 days with the Hobby-Eberly Telescope and its High-Resolution Spectrograph. Hobby-Eberly Telescope is one of the world’s largest optical telescopes, a 9.2-meter (30-foot) aperture telescope located at the McDonald Observatory — Davis Mountains, West Texas.
TYC 3667-1280-1 planetary system is clearly a unique system given the orbital period of the companion and the stellar mass-an evolved A star entering the red giant branch. The star is the most massive and oldest star found to be hosting a close-in giant planet. The only planetary systems that bear a resemblance to TYC 3667-1280-1b are HIP 67851 b HD 102956 b.
Due to its size, TYC 3667-1280-1b makes a strong case for the study of tidal dissipation, similar to WASP-18b. It is a perfect laboratory for studying inflation processes. Planets like TYC 3667-1280-1 b are extremely rare, one object in the complete sample suggests a frequency of only ∼ 0.1%.
This discovery suggests that worm Jupiters around intermediate-mass stars survive the evolution of their hosts at the beginning of the red giant branch, where TYC 3667- 1280-1 is currently located. In the far future, it is very likely that in the Solar System Jupiter will become a hot Jupiter when the Sun becomes a red giant. So, studying TYC 3667- 1280-1 gives astronomers a glimpse into the future of our Solar System final stages of life.