Orange stars may have planets having lifeMay 7th, 2009 - 1:46 pm ICT by ANI
London, May 7 (ANI): A new analysis has suggested that the best bet that scientists have in finding life in the Universe may be around stars a little less massive than the sun, called ‘orange dwarfs’.
According to a report in New Scientist, these stars live much longer than sun-like stars, and have safer habitable zones - where liquid water can exist - than those of lighter red dwarf stars.
Stars similar in mass to the sun, categorised as a yellow dwarf, have received the most attention from planet hunters.
Edward Guinan of Villanova University in Pennsylvania, US, leads a team that has been studying how the properties of stars vary with mass.
But, recent research suggests orange dwarfs may provide an even better hunting ground for life-bearing planets.
The team is using observations from a variety of sources, such as archival measurements from the ROSAT X-ray satellite, and more recent measurements from ground-based telescopes.
The results confirm that red dwarf stars, which weigh between 10 and 50 percent as much as the sun, are far more prone to unleashing powerful flares that can deliver deadly radiation to nearby planets.
This activity declines as the red dwarfs age, and scientists have not ruled out red dwarf planets as potential abodes for life, but any such life would certainly face some big challenges.
Orange dwarfs, on the other hand, with masses between 50 and 80 percent that of the sun, have only a little bit more flare activity than sun-like stars.
They would also provide a haven for life for a much longer time - roughly double the 10-billion-year lifetime of a sun-like star.
Moreover, they change very little in brightness compared to sun-like stars.
The odds of intelligent life arising may be better on planets around orange dwarfs than sun-like stars, given the extra time available for it to evolve.
That makes orange dwarfs not only good targets for habitable planet searches, but for the search for extraterrestrial intelligence (SETI) as well, according to Guinan.
“There are old ones around - some are 8 to 9 billion years old, and could have planets that are more evolved,” he told New Scientist.
Orange dwarfs are about three to four times as abundant as sun-like stars, making planet searches easier.
Some planets have already been found around orange dwarfs, though outside the stars’ habitable zones.
But, according to Gregory Laughlin of the University of California, Santa Cruz, it should be possible with current technology to find Earth-mass planets in the habitable zones of nearby orange dwarfs.
“They do seem to be a sweet spot for prospects of actually detecting habitable planets,” he said. (ANI)
Tags: abodes, best bet, deadly radiation, flare activity, guinan, habitable planet, habitable zones, hunting ground, life in the universe, liquid water, nearby planets, new scientist, orange stars, planet hunters, red dwarf stars, red dwarfs, rosat, villanova university, x ray, yellow dwarf