Hot ice in UNIVERSE
Exactly the opposite of what common sense might suggest the best chances of find Earth-like planets with life and maybe there would be peering around the cooler stars. These are the results of a study published on Astrobiology.
Notice to hunters of extra solar planets: if you are looking to find new worlds where life forms, do not bet on exoplanet around stars with high surface temperatures, but rather focus on those with colder days. The suggestion, seemingly contradictory to what common sense would tell us, derived from the results of a study published in the journal Astrobiology and guided by Aomawa Shields, doctoral student at the University of Washington. Gliese 436 B is a Neptune sized ice world, yet orbits its star at a very toasty 4.3 million miles. It is literally an ice cube on fire.
It seems logical fact that the temperature of the terrestrial planets or rocky in general depends on the amount of light they receive. In particular, for equal light received, the planets should be more temperate than orbiting around the hottest stars that emit a greater amount of ultraviolet and visible radiation, compared to the planets around more ‘warm’ stars that produce radiation of lower energy, especially in the infrared range and the near infrared.
The result of the study decidedly limelight this scenario , indicating how planets orbiting cool stars may actually be much warmer and less icy than those orbiting around stars with higher surface temperatures, even though they receive the same total amount of light. The reason for this anomalous behavior is to be sought in the properties of the ice, which absorbs more efficiently the radiation of longer wavelengths and therefore the near-infrared light emitted mainly from cooler stars. Around this kind of stars, planets are heated mainly thanks to their ice that absorbs heat. And if there were to be around them also an atmosphere composed of greenhouse gases, this phenomenon it would be reinforced. So for researchers, it would be rare to find completely icy planets around stars of this type.
Source: www.kepler.nasa.gov; Credit given to Lynette Cook
The work, however, indicates that the intensity of the phenomenon tends to decrease between the planets that are located on the fringes of the end of habitability, or the area around a star where liquid water can be found. Moving away from the star in fact, planets tend to have thicker atmospheres, rich in carbon dioxide and other greenhouse gases that block the radiation at high altitude, thereby nullifying the absorption of energy by the ice on their surface.
Shields for astronomers hunting for life outside the solar system should therefore focus on the study of planets orbiting around the hottest stars. But this does not have to leave the investigation of the coldest planets. “The last event in which our Earth was totally iced is associated with the explosion of multicellular life on our planet,” said the young researcher. “If someone had been observing our Earth at that time, would not have thought – mistakenly – that there were traces of life. So we should never eliminate this class of objects in our investigations. Even if there might be life, it would be much more difficult to detect. “