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Press Trust of IndiaApril 22, 2020 2:19:55 PM IST
Scientists have discovered a system of six planets: one “super-Earth” and five “mini-Neptunes” that show exceptionally regular spacing, suggesting how the system was formed.
Planets rotating star HD 158259 in the constellation Draco were found using the SOPHIE spectrograph installed at the Observatory of Haute Provence in southern France, according to the study published in the journal. Astronomy and astrophysics.
“The discovery of this exceptional system has been possible thanks to the acquisition of a large number of measurements, as well as a dramatic improvement of the instrument and our signal processing techniques,” said Francois Bouchy, professor at the University of Geneva. (UNIGE) in Switzerland.
SOPHIE observations showed that the planet closest to HD 158259 and the five outer planets have masses two and six times that of Earth, respectively, the researchers said.
The Kepler-11 artist impression is a sun-like star around which six planets orbit. Representative image. Image credit: NASA
The system has been found to be compact, in the sense that the distance from the planet most external to its star is 2.6 times less than the distance between Mercury and the Sun, they said.
NASA’s TESS space telescope observed a decrease in the star’s brightness as the innermost planet traveled between the observer and the star.
“TESS measurements strongly support the detection of the planet and allow us to estimate its radius, which provides valuable information about the planet’s internal structure,” said Isabelle Boisse, a researcher at the Marseille Astrophysics Laboratory in France, and co-author of the study. .
The researchers noted that hundreds of multi-planet systems are known, but only a dozen contain six or more planets.
The presence of six planets in orbit HD 158259 makes this system remarkable, but it’s not its most interesting feature: what makes it exceptional is its regularity, they said.
The period ratio of either of the two subsequent planets is close to 3: 2. This means that as the first planet, closest to the star, completes three orbits, the second completes approximately two.
As this second planet completes three orbits, the third planet completes about two, and so on.
This situation is best understood in the general “resonances” framework, which plays a key role in the architecture of planetary systems.
Several planets are said to be in resonance when they periodically meet in the same configuration, after completing a potentially different number of orbits, the researchers explained.
“This is comparable to several musicians playing different rhythms, but hitting at the beginning of each bar at the same time,” said Nathan C Hara, UNIGE researcher and first author of the study.
Planets can also be close to resonance, but not exactly within. This is the case for HD planets 158259, the researchers said.
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