An international team of scientists has discovered a neighbouring planetary system
An international team of scientists working from the European Southern Observatory (ESO) in Chile has discovered a neighbouring planetary system that shares many features with our Solar System. The findings, published in the journal Astronomy and Astrophysics, are an outcome of a large-scale survey being conducted with the High Accuracy Radial Velocity Planet Searcher, or HARPS spectrograph.
The astronomers and astrophysicists observed five Neptune-sized planets orbiting the Sun-like star named HD 10180, and uncovered evidence of two smaller planets, called super-Earths. This makes it the most populated known exoplanetary system. In addition, the planets are densely packed but sit in well-ordered orbits, similar to the planets in our own eight-planet system.
The HARPS spectrograph, which is attached to ESO's 3.6-metre telescope, is being used to study around 400 bright stars in our solar neighbourhood. In the present study, the high-precision planet hunter was used to take 190 measurements in the area of the dwarf star HD 10180, located 39 parsecs (127 light-years) away in the direction of the Hydrus constellation.
The team observed tiny back-and-forth motions of the star, indicating complex gravitational attractions from five or more planets. These motions have specific signatures; the 5 strongest correspond to planets measuring between 13 and 25 Earth masses, about the size of Neptune. The orbit periods of these giants range between 6 to 600 Earth days, putting them all at a distance from their sun no farther than Mars is from ours.
Another planet appears to be Saturn-like, and completes its orbit in 2,200 days. The seventh has a mass of around 1.4 times that of the Earth, which would make it the least massive exoplanet ever discovered. This smaller planet is very close to its sun, completing its orbit in 1.18 Earth-days.
Confirming current theoretical models, the researchers also established a relationship between the mass of a planetary system and the mass and chemical content of its host star: very massive planetary systems form around massive and metal-rich stars, while those with very low mass have consistently been found around lower-mass and metal-poor stars.
Future measurement studies should confirm the existence of the near Earth-sized hot planet, the researchers believe. The current findings have demonstrated that the radial velocity technique is well suited to the study of complex, multi-planet systems around nearby solar-type stars, and should be able to detect rocky, icy objects.
Future instruments like VLTESPRESSO are expected to build on HARPS findings and complete a census of these nearby low-mass systems. In addition, transit studies carried out in space observatories are beginning to confirm that, indeed, rocky/icy planets are very common in the Universe.
The results of different studies could proceed in subsequent research in this field, such as the possibility of finding life on other planets that represent extreme conditions. This is the objective of the EUROPLANET RI, funded under the EU's Seventh Framework Programme (FP7), which seeks to understand how to create and prosperous life in the permafrost zones and coping strategies following agencies .