Using radial velocity measurements, astronomers from Japan and China have discovered a new exoplanet orbiting a giant G-type star. The newly discovered alien world is similar in mass to Jupiter, but much hotter than the largest planet in the Solar System. The discovery was reported in a paper published Nov. 12 on the arXiv preprocessing server.

The radial velocity (RV) method for exoplanet detection relies on detecting fluctuations in the velocity of the central star due to the change in gravitational direction from an invisible exoplanet as it orbits the star. Thanks to this technique, more than 600 exoplanets have been discovered today.

Now, a team of astronomers led by Huang-Yui Teng of the Tokyo Institute of Technology in Tokyo, Japan, has reported the discovery of a new giant planet from RV measurements with the High Dispersion Echelle Spectrograph (HIDES) at the Okayama Astrophysical Observatory. (OAO) in Japan. The planet orbits a deeply developed, solar-mass G-type giant star known as HD 167768, located about 353 light-years away.

“For the HD 167768 RV, we were able to detect a strong signal after 20 days, indicating regular changes in the time series,” the researchers explain.

The newly discovered exoplanet, designated HD 167768b, is estimated to have at least 0.85 Jupiter masses. It orbits its host at a distance of about 0.15 AU every 20.65 days. The calculated equilibrium temperature of this planet is 1874 K.

The authors of the article classified HD 167768b as a “hot Jupiter” thanks to its parameters. The planet was found to have one of the shortest orbital periods ever found around deeply evolved stars using radial velocity techniques. The host star HD 167768, estimated to be 5.3 billion years old, belongs to spectral type G8 III, has a solar mass of about 1.08 and is almost 10 times heavier than the Sun. Its effective temperature is 4851 K and its metallicity is -0.75.

Given that HD 167768 is expected to rise to the red giant branch, astronomers predict that its planet will be engulfed in a relatively short time in astronomical terms. By analyzing the evolution of the orbit, they estimate that HD 167768b will be absorbed by an expanding star in about 150 million years. Researchers also suggest that there may be at least two as yet undiscovered planets in the HD 167768 system. This assumption is based on two additional regular variations identified in the RV measurements.

In the residuals periodogram, there are two additional signals for 41 days and 95 days with FAP. [імовірність помилкової тривоги] “just under 0.1 percent, indicating possible additional satellites in the system,” the scientists said.