A scientific team co-led by the Institute of Astrophysics of the Canary Islands (IAC) and the Institute of Astrophysics of Andalusia-Higher Council of Scientific Research (IAA-CSIC) has discovered five planets similar to Neptune in a theoretically unpopulated stellar region.
The finding has been published in the journal Astronomy & Astrophysics and the IAC explained this Thursday in a statement that the discovery of new planets around red dwarf stars located, precisely, in that “desert” has been validated through a novel technique.
In this regard, the IAC points out that the distribution of the planets in the more than 5,000 distant solar systems discovered constitutes “a complex puzzle” and details that there is a region known as “the desert of the Neptunes” in which to date there have been very few planets similar to the one mentioned have been recorded, with orbits of between two and four days of period around their star.
This work is the result of Alberto Peláez’s Master’s Thesis (IAC-IAA-CSIC), directed by Emma Esparza and Enric Pallé, and carried out in the IAC Exoplanets group.
The study sought to clarify the planetary nature of thirteen TESS Objects of Interest (TOIs), a NASA mission to search for extrasolar planets.
“These objects could turn out to be both planets and other bodies that imitate them photometrically, such as brown dwarfswhich are considered the link between low-mass stars and large gaseous planets, or binary star systems,” says Alberto Peláez, researcher at the IAC and the IAA-CSIC and the IAC, who heads the work.
The astrophysical center adds that when choosing the most appropriate method for identify the nature of these planetary objects unclassified, the host star – around which they orbit – plays a key role.
In some cases, there are planets that orbit stars whose weakness prevents carrying out studies with the most traditional techniques and this is precisely what happens with the red dwarfsthe host stars on which this investigation focuses.
“M-type stars They are ideal for discovering possible small planets that orbit around it, due to its low temperature and small size, which reduces the contrast between the radii of the star and the planet,” explains Alberto Peláez.
As a result, they have validated five of the TESS exoplanet candidates: TOI-1883b, TOI-2274b, TOI-2768b, TOI-4438b and TOI-5319b.
Additional value is added to this finding, since several of the five validated planets, mainly TOI-2768b, They are located directly in the Neptune Desert.
This region is characterized by the scarcity of planets the size of Neptune, which is four times the Earth’s radius, making the discovery especially unusual.
Various studies indicate that physical phenomena occur in this area that “empty” it of planets with these characteristics, such as the loss of atmospheric mass due to the high energy irradiation from its stara process known as photoevaporation.
This also opens the doors to other future research, since the MuSCAT2 work team, made up of researchers from Spain and Japan, carries out daily monitoring of stars that host possible planets, identified by TESS and other missions, with the aim of objective of continuing to discover and validate new planets.
The IAC adds that planetary findings have shown that the Neptune desert, a concept proposed in 2016 that included planets with orbital periods of between one and four days and radii between two and six times that of the Earth, does not coincide with the current distribution of exoplanets.
With this premise, the study now published proposes a new definition of the Neptune desert, which only covers planets between two and ten times the size of the Earth, and which, in addition, must orbit very close to their star: if they have a small size within this range, they complete an orbit in a single day; if they are larger, it takes about three days.
It also specifies that this work does not have a sufficiently representative sample of validated planets – near or within the Neptune desert – to offer conclusive statistical data.