Ceres – criovulcanism or sublimation?
Water vapors are present around Ceres. A team of researchers is using satellite data from ESA, Herschel. Ceres is the goal of the U.S. spacecraft Dawn: “These directions are the reason for why Ceres has been chosen as the scientific objective of Dawn. Confirmation by the Herschel team inspires us and strengthens our choice,” said Maria Cristina De Sanctis, PI instrument VIR probe Dawn.
Artistic impression of Ceres
Water vapor around Ceres. This is what a team of researchers has found using satellite data from Herschel.
Astronomers have found that the emission occurs from two sources quite localized, similar to “giant geysers”. The hypothesis put forward to explain the phenomenon; there are two possibilities: either the sublimation of the ice into water vapor (as comets that approach the Sun) or an example of criovulcanism, or eruptions of volatile elements such as water.
At the moment it seems certain that emissions of steam – 6 pounds per second – occurs when Ceres is at perihelion, which would favor the theory of sublimation of ice, and the fact that criovulcanism should result in emission distributed independent of the distance from the Sun.
Ceres is the goal of the U.S. spacecraft Dawn that was launched in 2007 and after visiting the asteroid Vesta – the second largest asteroid in the solar system – should join it in February 2015.
“First of all there is to say that since the early ’90s, thanks to the data EUI (International Ultraviolet Explorer), we had the marginal notes, never confirmed in a definitive manner, the presence of water on Ceres,” says Maria Cristina De Sanctis, PI VIR spectrometer built by INAF – IAPS Rome and aboard the Dawn spacecraft. “These indications are supported by other observational evidence, such as strong spectral signs of the presence of water ice and theoretical models of the interior, which provide the oceans beneath the surface, are the reason that Ceres has been chosen as the scientific objective of Dawn. The confirmation by the Herschel team inspires us and strengthens our choice.”
Hubble Space Telescope images of Ceres helped scientists determine it was unique from other objects in the asteroid belt.
Ceres – discovered in 1801 by the Italian astronomer Giuseppe Piazzi – is in fact a “dwarf planet” with its 960 km in diameter. It is believed that it is composed of a rocky core surrounded by a thick layer of ice, like many comets, in fact, the collision with the celestial bodies – comets and asteroids – rich water would be at the origin of Earth’s oceans.
“When Dawn arrives at Ceres, it will meet at aphelion, or the farthest point in its orbit from the Sun. If, as seems to indicate the observations so far, the activity of the water jets is linked to the position along the orbit, namely that occur when Ceres is located closer to the Sun, we do not expect to see a close up. What we expect is to reconstruct a detailed map of the area and to find out the formation mechanism of these jets of water.”