Researches of Brazil’s ON discover that exoplanet Ross 128b can harbour life

Artistic representation of planet Ross 128 b, with its host star on the background. Credit: ESO / M. Kornmesser

The exoplanet Ross 128b has the capacity to harbor life. A team of researchers from Brazil’s Observatório Nacional has led a coordinated investigation to determine the physio-chemical characteristics of the Ross 128 extrasolar system, and noted that this solar system has many similitudes with the Sun and the Earth. 

The team conducted a detailed studied of the star’s properties to better understand the exoplanet Ross 128b, discovered in 2017 by scientists led by Institute of Palaeontology and Astrophysics of Grenoble, in France. Ross 128b has a mass equivalent to that of our planet, and it lies in the habitable zone of its host star, having an average surface temperature of 21ºC. also, this planet is very close to Earth, only 10 light years (a light year is equivalent to 9.46 billon kilometres). 

“We have produced a detailed studied of the physio-chemical characteristics for the Ross 128 star in order to infer the characteristics of the Ross 128b exoplanet and that way get to know it better. For that, we used models of planetary formation and we verified that the exoplanet must be composed with materials very similar to those on Earth, however, with a core a little bit bigger”, explains Diogo Souto, lead investigator. The exoplanet Ross 128b, has a minimum mass of 30% bigger than the Earth, while it has a radius 10% bigger than our planet. The ratio between the mass and the radius for this planets makes it a rocky planet, like the Earth. 

Amongst the characterises similar to the Earth for Ross128b, the team concluded that the radiation Ross128b receives from its host star is similar to that received by the Earth from the Sun. the star Ross128b has a temperature of de 2,958 ° C, almost half that of our Sun (5499 ° C); having a radius a fifth of the Sun. Ross 128b lies at a distance of 6 million kilometres of its host star, whilst the Earth lies at approximately 150 million kilometres from the Sun. 

Habitable zone relative to the size of a star. Credit: Wikipedia

“Never before has an investigation of a cool star like Ross 128 been so detailed. It is difficult to studied cool stars like these ones because the optical spectrum of this objects presents strong molecular bands which makes its analysis difficult. Employing infrared spectroscopy, these bands are fainter and so it is possible to study its atomic molecules to extract information which helps characterised the star”, explains Katia Cunha, investigator of the coordination of the Astronomy and Astrophysics of the ON. 

“This investigation has as a novelty the technique developed for the detailed chemical study for this type of stas, chich populates the universe and concentrates exoplanets which could be the target of future investigations”, reassures Diogo Souto. The investigation employs data from the Sloan Digital Sky Survey (SDSS), where the National Observatory of Brazil participates. The star Ross 128 a low temperature star, classified as an M-type dwarf star, these constitutes between 65 to 75% of the stars of our Galaxy, so it is very important to know more about them. 

“One of the differences between stars is the abundance of its chemical elements, the chemical composition of the star Ross 128, is somehow, similar to that of the Sun. In this investigation, we have been able to study the signature of eight elements: carbon, oxygen, magnesium, aluminium, potassium, calcium, titanium and iron. The proportions between some of these elements such Fe / Mg, Ca / Mg y Al / Mg are similar with what we observe in the Sun and on the Earth, and, according to our analysis, they are similar to the exoplanet Ross 128b. With this, we have hints that the composition and formation of Ross 128b would be similar to that of the Earth. We also verified that there was no indication of a strong magnetic field in Ross 128, which could hindrance its habitability”, explains the investigator. 

The investigation was published on June 13 in the Astrophysical Journal Letters and can be access at:    

http://iopscience.iop.org/article/10.3847/2041-8213/aac896/pdf y https://arxiv.org/pdf/1805.11633.pdf

Sources: National Observatory of Brazil, Wikipedia, Carnegie Institution for Science,