Hot 'super-Earths' may hide life
- added July 11, 2008
- 0 responses
-
-
-
- rwylie
- added this
-
'Super-Earths': massive, rocky planets up to 15 times the size of ours, were previously dismissed as too harsh for life to exist; largely because many of them are in orbit unbelievably close to their parent stars.
However, at a recent conference organised by Lisa Kaltenegger of the Harvard-Smithsonian Center for Astrophysics in Massachusetts, the consensus was changed significantly.
Kaltenegger herself believes that "there's no reason why the different chemical cycles that are important for life on our planet wouldn't work on super-Earths". And she says that at the conference, "the consensus of attendees was similarly positive – even for those planets once dismissed as being too harsh for life".
One reason that these exo-planets were thought to be so inhospitable to life, was that those ones orbiting very close to their stars experience a strong gravitational pull, which keeps them 'tidally locked', so that they cannot turn, always displaying the same face to the sun: as happens between the Earth and the moon. As a result of this locking, it was assumed that this would create one incredibly hot, and one incredibly cold side: both of which would be far too extreme for life. If an atmosphere, a key element in life, were present, it was also thought that it would quickly become frozen.
New models however suggest that "if a tidally locked super-Earth has an atmosphere at least as dense as Earth's, strong winds could transport heat from its hot side to its cold side." Furthermore, the effect of a global ocean appears to be that heat could be transported away from the hot side, thereby regulating the temperature of the whole planet.
For super-Earth's orbiting around cooler 'Red Giant' stars (which make up 85% of the stars in our Galaxy), the critical distance for temperatures to be offset sufficiently was calculated to be 0.05 AU (where 1AU is the distance from the Earth to the Sun). For comparison, Mercury, the closest planet to the sun in our solar-system, orbits at a distance of 0.38 AU!
These calculations and more, now point to the serious possibility of finding the right conditions for life on a much larger number of planets than has ever been thought.
So what are you astrophysicists waiting for?!
However, at a recent conference organised by Lisa Kaltenegger of the Harvard-Smithsonian Center for Astrophysics in Massachusetts, the consensus was changed significantly.
Kaltenegger herself believes that "there's no reason why the different chemical cycles that are important for life on our planet wouldn't work on super-Earths". And she says that at the conference, "the consensus of attendees was similarly positive – even for those planets once dismissed as being too harsh for life".
One reason that these exo-planets were thought to be so inhospitable to life, was that those ones orbiting very close to their stars experience a strong gravitational pull, which keeps them 'tidally locked', so that they cannot turn, always displaying the same face to the sun: as happens between the Earth and the moon. As a result of this locking, it was assumed that this would create one incredibly hot, and one incredibly cold side: both of which would be far too extreme for life. If an atmosphere, a key element in life, were present, it was also thought that it would quickly become frozen.
New models however suggest that "if a tidally locked super-Earth has an atmosphere at least as dense as Earth's, strong winds could transport heat from its hot side to its cold side." Furthermore, the effect of a global ocean appears to be that heat could be transported away from the hot side, thereby regulating the temperature of the whole planet.
For super-Earth's orbiting around cooler 'Red Giant' stars (which make up 85% of the stars in our Galaxy), the critical distance for temperatures to be offset sufficiently was calculated to be 0.05 AU (where 1AU is the distance from the Earth to the Sun). For comparison, Mercury, the closest planet to the sun in our solar-system, orbits at a distance of 0.38 AU!
These calculations and more, now point to the serious possibility of finding the right conditions for life on a much larger number of planets than has ever been thought.
So what are you astrophysicists waiting for?!
Login/Registration is required to add a response.
