Astronomers Detect Three Planetary Companions Around Evolved Stars Using Radial Velocity Measurements
Researchers using the CORALIE spectrograph detected three massive planets orbiting two evolved red giant stars over a 15-18 year observation campaign. The planets—with masses ranging from 0.66 to 2.26 Jupiter masses and orbital periods between 535 and 850 days—populate a sparsely studied region of exoplanet parameter space. This discovery expands understanding of planetary systems around massive stellar hosts and demonstrates improved techniques for detecting planets around pulsating evolved stars.
An international team analyzing long-term radial velocity data from the CORALIE spectrograph identified three planetary signals in the data of three evolved stars: one planet around HD125136 (2.26 Jupiter masses, 850-day orbit) and two planets around HD127195 (0.66 and 0.78 Jupiter masses with 535- and 834-day orbits). A third signal detected around HD220218 was attributed to stellar activity rather than a planetary companion. The researchers employed Bayesian inference analysis and developed an observing strategy specifically designed to mitigate the effects of stellar pulsations in low-luminosity red giants, achieving radial velocity precision below 5 meters per second. These discoveries are significant because they populate a poorly characterized region of exoplanet parameter space—massive planets around evolved stars with long orbital periods—and demonstrate practical methods for improving detection sensitivity around pulsating evolved stars.
What different sources said
- arXiv astro-phCenter
CORALIE radial-velocity search for companions around evolved stars (CASCADES) V. Three planetary companions and achievable precision
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