The data accumulated by the Kepler space telescope over the years of its successful operation gives literally tons of useful information about our Universe. One of the newest findings based on the analysis of the data acquired from Kepler mission was published yesterday at arXiv.org. The authors also report the discovery of the first seven planet candidate stellar system situated around a star named KOI-351.

The team reports a total of 14 new transiting planet candidates detected by the Kepler space telescope. They also note, that this research is an outstanding example of cooperation between astronomers and public scientists, as more than 250,000 volunteers have participated in the Planet Hunters project.

Until now two other stars with the largest number of confirmed planets (excluding our Sun) were known to contain six planets each: HD 10180 and Kepler-11, and only five exoplanetary systems with five confirmed planets are known. By the way, there are claims stating that HD 10180 could be a nine-planet system, although these statements are highly uncertain from the scientific point of view.

Of course, the crowdsourcing was not the only method for identification of exoplanets. The data has been previously processed with the so-called Transit Planet Search, or TPS algorithm, based on the detection of planet transit (crossing) in front of its parent star’s disk. However, some exoplanet transit signals can be missed despite the effectiveness of this method. Therefore, the paticipants of the Planet Hunters project have checked visually more than 19 million Kepler’s light curves, and this work helped to detect five new planet candidates which should have been detected by the TPS algorithm, but were missed. This volunteer effort amounts to a cumulative total of 180 years of work according to the authors.

The orbital periods of the new exoplanet candidates range from 124 to 904 days. Eight of them also reside in the habitable zone of their host star, which make them an interesting targets for further studies on habitability-related planetary characteristics.

The object of particular interest is a star system with 7 planets – the KOI-351 (where KOI stands for Kepler Object of Interest). The KOI-351 was first described in a scientific paper published in 2012. At that time ‘only’ three orbiting planets were detected by analyzing the data from the Kepler spacecraft obtained during a 16-month period (May 2009 – September 2010). Later, additional planets located in the same star system have been also identified.

The scientists say in the current publication that KOI-351 has many similarities to our own solar system: the sizes of five inner planets range from Earth to mini-Neptune, whereas the outer planets are gas giants. However, this system is very compact if compared with the Solar system: all seven candidate exoplanets reside within a distance of 1 astronomical unit (AU) from their host star.

Additionally, the authors have performed numerical stability tests, which show that the KOI-351 system has remained stable for over 100 million years, which theoretically prove the uniqueness of the exoplanet transit signals. The tests also provide a high probability that KOI-351 is a true seven-planet system.

By Alius Noreika, Source: Technology.org