Combining radial velocity and astrometry reveals new cold giant planets around 5 stars

Star system: HIP 39330 | Distance from the Sun: 119 light years

Long-period giant planets, or cold Jupiters, play a key role in shaping planetary systems, but they are difficult to detect because they orbit far from their stars. Traditional methods like radial velocity and transit surveys have limited sensitivity at these distances. By combining long-term radial velocity data with precise astrometry from the Hipparcos and Gaia missions, astronomers can now better detect and measure these distant worlds.

In this study, researchers extended the Chile-Hertfordshire ExoPlanet Survey (CHEPS) by analyzing up to 16 years of radial velocity data together with absolute astrometry for five target stars. Their improved analysis framework allowed them to confirm two previously known planets and discover five new ones, including a warm Jupiter and four Jupiter analogues with orbital periods ranging from about 7 to 14 years. Adding astrometry to the analysis significantly reduced uncertainties in the planets’ masses and orbits, and increased the confidence in their detection. This approach demonstrates that combining these two techniques is a powerful way to find and characterize cold giant planets, turning minimum mass estimates into true masses.

Key findings
- Five new cold giant planets were discovered using combined radial velocity and astrometry
- The new planets include a warm Jupiter and four Jupiter analogues with long orbital periods
- Astrometry reduced uncertainties in planet mass and period by factors of 3 to 10
- The method increases detection confidence and allows measurement of true planet masses
- This synergy provides a robust pathway for discovering and characterizing cold giant planets

Scientific study

Cold giant discoveries from a joint radial-velocity and astrometry framework (external link)