55 Cancri- the Diamond Planet
55 Cancri, also cataloged Rho1 Cancri or abbreviated 55 Cnc, is a binary star approximately 41 light-years away from Earth in the constellation of Cancer. The system consists of a G-type star and a smaller red dwarf, separated by over 1,000 AU (one thousand times the distance from the Earth to the Sun).
Astronomers have detected sudden and wild changes of temperatures of 55 Cancri. It’s the first time that the atmospheric variability is observed on a rocky planet outside the Solar System. They call it “diamond planet” and is one of the densest exoplanets ever discovered so far. 55 Cancri e, from the name of its parent star, is an extrasolar planet “hot” and rocky. For years now that this exoplanet, discovered in 2004, astronomers are interested for its particular structure. According to a study of the 2012-55 Cancers and would be composed for the most part by iron, carbon and silicon carbide: at least one third of the planet would be done just carbon in the form of diamond. This theory, however, could soon be wiped out. In the course of two years, for the first time, a group of researchers at the University of Cambridge has indeed analyzed in detail the atmosphere of a rocky exoplanet outside Solar System focusing on the extreme variability of temperatures. In this period of observation it was detected three major changes of 55 Cancri e.
Credit: NASA/JPL–Caltech/R. Hurt
The wild atmosphere of 55 Cancri e is still a mystery to the researchers, who, however, have already advanced some hypotheses: according to experts, in fact, one possible solution could be the intense volcanic activity on the planet’s surface. Analyses were made by NASA’s Spitzer orbiting telescope (located in space from 4,270 days), through which it was possible to observe the thermal emission from the rocky planet orbiting very close around a Sun-like star (55 Cancri A) in the constellation of Cancer. Around the star four other planets orbit 55 Cancri e it is so close to 55Cancri A so that a year lasts just 18 hours. What has been discovered is remarkable, and scary: the warmer side (that is always exposed to the nearby Star because it is in synchronous rotation) temperatures range between 1000 ° and 2700 ° Celsius. Well, not really what we would call a habitable planet.
As we said, 55 Cancri e is a super-Earth, meaning a rocky exoplanet, about twice the size and eight times the mass of Earth, and is the super-Earth closer to us, so also among the best Candidates for the detailed observations of the surface and atmospheric conditions of rocky exoplanets. “It’s the first time we see such drastic changes in the light emitted by an exoplanet, mainly because it is a super-Earth,” noted Nikku Madhusudhan, the Institute of Astronomy at Cambridge and co-author of the study published in Monthly Notices of the Royal Astronomical Society. The research and studies so far have focused more on gaseous exoplanets, (like Jupiter and Neptune), because larger and visible. Study the rocky super-Earths is not so simple, at least with the tools currently available. He added: “No trace of thermal emission or surface activity had ever been detected on other super-Earth before today.”
Credit: U. Texas, NSF, NASA
At the origin of this phenomenon could be enormous plumes of gas and dust that sometimes cover the surface, in some areas partially molten. The plumes could be caused, in fact, by the intense volcanic activity, far more dramatic than that observed on Io, one of Jupiter’s moons and the most geologically active body in the solar system (with more than 400 active volcanoes). Brice-Olivier Demory, first author of the study, explained: “We have seen a change of 300% on the signal from this planet and it is the first time we’ve seen such a huge level of variability in an extrasolar planet.”
Madhusudhan then underlined: “When we identified the planet for the first time, the measurements corroborate the model of the abundance of carbon. But now we have discovered that these data are changing over time. The planet may be carbon-rich, but now we are not so sure, because previous studies have also suggested that it could be a water world. The current variability is something that we have never seen anywhere else. ”
The possibility of peeking – especially in the future with the new telescopes – in the atmospheres of rocky super-Earths scrutinizing the conditions of their surfaces marks an important step towards finding habitable planets outside the solar system, although it is clear that 55 Cancri can to be removed from our list of habitable zone.