Aug 1, 2015 05:15 PM
https://www.newscientist.com/article/dn2...to-thrive/
EXCERPT: [...] Life is most likely to evolve in giant elliptical galaxies whereas dwarf galaxies are thought to be the least hospitable – with the spiral Milky Way falling somewhere in between.
[...] two studies have zoomed out even further in an attempt to identify the most habitable types of galaxies.
One approach, led by Pratika Dayal [...] proposes that [...] a low rate of star formation to cut down on the number of supernovae ['ticking timebombs']. That’s because supernovae’s violent explosions – which occur when massive stars die after only a few million years – may lead to mass extinctions on nearby worlds.
[....] “If the Milky Way is capable of hosting one habitable planet, giant elliptical galaxies would host as many as 10,000 habitable planets,” Dayal says, based on the observed supernova rate in our galaxy.
The worst places to find life in the universe might be small, irregular galaxies with lots of newborn stars. Here, regular supernova blasts could sterilise the whole galaxy.
[...] It’s not just supernovae we need to consider. Gamma ray bursts – rarer, deadlier cousins of supernova explosions – put similar constraints on life, says Li Ye at the University of Nevada in Las Vegas [...]
Earth is thought to have experienced only one gamma ray burst in the last 500 million years, possibly resulting in the Ordovician mass extinction that terrorised trilobites about 440 million years ago. But an Earth-like planet in an active dwarf galaxy might need to weather 100 gamma ray bursts during the same timeframe....
EXCERPT: [...] Life is most likely to evolve in giant elliptical galaxies whereas dwarf galaxies are thought to be the least hospitable – with the spiral Milky Way falling somewhere in between.
[...] two studies have zoomed out even further in an attempt to identify the most habitable types of galaxies.
One approach, led by Pratika Dayal [...] proposes that [...] a low rate of star formation to cut down on the number of supernovae ['ticking timebombs']. That’s because supernovae’s violent explosions – which occur when massive stars die after only a few million years – may lead to mass extinctions on nearby worlds.
[....] “If the Milky Way is capable of hosting one habitable planet, giant elliptical galaxies would host as many as 10,000 habitable planets,” Dayal says, based on the observed supernova rate in our galaxy.
The worst places to find life in the universe might be small, irregular galaxies with lots of newborn stars. Here, regular supernova blasts could sterilise the whole galaxy.
[...] It’s not just supernovae we need to consider. Gamma ray bursts – rarer, deadlier cousins of supernova explosions – put similar constraints on life, says Li Ye at the University of Nevada in Las Vegas [...]
Earth is thought to have experienced only one gamma ray burst in the last 500 million years, possibly resulting in the Ordovician mass extinction that terrorised trilobites about 440 million years ago. But an Earth-like planet in an active dwarf galaxy might need to weather 100 gamma ray bursts during the same timeframe....