The CI Tau system, about 500 light-years from Earth, has brought astronomers upside down since 2016. That year, a team of researchers announced the discovery of a planet eleven times more massive than Jupiter orbiting its star. The problem is that it is barely two million years old –in fact, it is so young that it still retains part of the circumstellar disk of gas, ice and dust that characterizes the systems in formation–, while the most widespread hypothesis among experts in Planetary science maintains that worlds like the one that was located take at least ten million years to consolidate.
Baffling? Well, now, another international group of scientists, coordinated by physicists from the Institute of Astronomy, in Cambridge, in the United Kingdom, points out in a new study that around CI Tau there is not only one, but at least four of these giants Of gas. Moreover, they are so far apart that their detection has set a new record in this regard: the planet furthest from the star is a thousand times farther from it than the one closest to it; This is at the same distance as Mercury from the Sun.
Everything in CI Tau seems to collide with current models of planet formation. This is so much the case that those responsible for this work wonder if we are dealing with a unique case or if, on the contrary, its discovery will help to clarify an issue that experts have been debating for a long time: the mechanism by which they are formed. systems containing hot Jupiter-type planets – it is estimated that 1% of stars harbor them – that is, gas giants that orbit very close to their star. Precisely for this reason, the very presence of these objects is intriguing, since, at the very least, it is doubtful that they could have been constituted in situ.
Mystery after mystery
In an essay published in The Astrophysical Journal Letters , the researchers, including Cathie Clarke, an authority on exoplanets from the aforementioned British institution, point out that the data provided by the ALMA observatory, in Chile, made it possible to determine that in the circumstellar disk around CI Tau had distinctive notches that revealed the existence of the three now-discovered worlds. The two furthest away have masses similar to that of Saturn, while that of the new one that follows a more closed orbit resembles that of Jupiter.
“At the moment, it is impossible to know with certainty if CI Tau’s strange planetary architecture is common in systems with hot Jupiter-type worlds. This is due to the fact that the phenomenon that allowed us to locate the three new planets cannot occur in older systems, in which the protoplanetary disk is no longer present, ”says Clarke. Thus, it is not clear how the recently discovered planets have formed, if they have somehow caused the one closest to the star to occupy exactly that place or if it is a normal process in this type of system.
Reference: High resolution millimeter imaging of the CI Tau protoplanetary disc – a massive ensemble of protoplanets from 0.1 – 100 AU. CJ Clarke et al. The Astrophysical Journal Letters (2018) . DOI: 10.3847 / 2041-8213 / aae36b
Image: Amanda Smith – Institute of Astronomy
