A new astronomical study indicates that every red dwarf star is host to at least one planet. If that is accurate, that means there could be around 160 billion planets in the Milky Way alone.
The research was led by Mikko Tuomi, from the University of Hertfordshire’s Center for Astrophysics Research. The team analyzed data collected by the European Southern Observatory’s High Accuracy Radial velocity Planet Searcher (HARPS) telescope and the Ultraviolet and Visual Echelle Spectrograph (UVES) to search for planet candidates.
Tuomi said in a statement, “We were looking at the data from UVES alone, and noticed some variability that could not be explained by random noise. By combining those with data from HARPS, we managed to spot this spectacular haul of planet candidates.”
There are several ways to search for planets, one of which is measuring the radial velocity, or the “wobble” of the star due to the gravitational pull of a host planet.
Based on the ESO data, the researchers used Bayes’ Rule, a probability theory that determines the likelihood of that a theory is true based on new evidence. The researchers say their research was attempting to answer the question, “What is the probability that a given star has planets orbiting it based on the available data?”
In the case of red dwarf stars, the researchers determine that it is highly likely that at least one planet is orbiting each of them. Red dwarfs are low-mass stars that are relatively cool, around 5,000 degrees Fahrenheit, compared to the sun and its 27 million-degree Fahrenheit temperature. Red dwarfs are by far the most common type of star, the researchers say, representing three-quarters of all stars in the universe. Previous research using HARP data indicates there could be 160 billion red dwarf stars in the Milky Way galaxy alone. Based on Tuomi's statement, that means there could be 160 billion, or more if one factors in planetary systems, planets in the Milky Way orbiting red dwarfs.
The UVES and HARPS combined data also led to the discovery of eight new planets, as well as the confirmation of two previously discovered planets.
The new planets are located between 15 and 80 light-years from Earth, notes the University of Hertfordshire. All of the planet candidates are within the habitable zone, the orbital area that can support the existence of liquid water on the surface, and are considered Super-Earths. The researchers may have discovered 10 more planets, but the signals were too weak and need to be analyzed further. The research will be published in the Monthly Notices of the Royal Astronomical Society.