NGTS-10b: The shortest period hot Jupiter yet discovered

Astronomers from the University of Warwick have observed an exoplanet orbiting a star in just over 18 hours, the shortest orbital period ever observed for a planet of its type. It means that a single year for this hot Jupiter – a gas giant similar in size and composition to Jupiter in our own solar system – passes in less than a day of Earth time.

The discovery is detailed in a new paper published today (20 February) for the Monthly Notices of the Royal Astronomical Society and the scientists believe that it may help to solve a mystery of whether or not such planets are in the process of spiralling towards their suns to their destruction.

Abstract : We report the discovery of a new ultra-short period transiting hot Jupiter from the Next Generation Transit Survey (NGTS). NGTS-10b has a mass and radius of 2.162^{+0.092−0.107} M_J and 1.205 ^ {+0.117−0.083} R_J and orbits its host star with a period of 0.7668944 ± 0.0000003 days, making it the shortest period hot Jupiter yet discovered. The host is a 10.4 ± 2.5 Gyr old K5V star (Teff = 4400 ± 100 K) of Solar metallicity ([Fe/H] = −0.02 ± 0.12 dex) showing moderate signs of stellar activity. NGTS-10b joinsa short list of ultra-short period Jupiters that are prime candidates for the study ofstar-planet tidal interactions. NGTS-10b orbits its host at just 1.46 ± 0.18 Roche radii, and we calculate a median remaining inspiral time of 38 Myr and a potentially measurable orbital period decay of 7 seconds over the coming decade, assuming a stellar tidal quality factor Q′s=2×10^7.