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Despite the harsh radiation released by pulsars, exoplanets orbiting them may be "habitable" if their atmospheres are thick enough:
The most exciting exoplanet finds are those that orbit within their host star's habitable zone, an area at just the right distance from the star to allow for liquid surface water and thus, potentially life. The paper's authors, two astronomers at Leiden Observatory in the Netherlands, suggest that pulsars have their own habitable zones — surprising, given the harsh X-rays and other radiation that such stars emit.
But, if a planet is big enough — some one to 10 times Earth's mass — and it has an atmosphere at least 1 million times as thick as Earth's, then it might just cut it as habitable even around a pulsar. The idea is that the enormous atmosphere would act as a shield for the planet's surface, absorbing the deadly radiation while still allowing for enough heat to melt water. And a bigger world, preferably with a decent magnetic field, is necessary to hold on to that atmosphere over long enough time scales.
It doesn't sound like complex life would make the cut.
Neutron star planets: Atmospheric processes and irradiation (open, DOI: 10.1051/0004-6361/201731102) (DX)
Of the roughly 3000 neutron stars known, only a handful have sub-stellar companions. The most famous of these are the low-mass planets around the millisecond pulsar B1257+12. New evidence indicates that observational biases could still hide a wide variety of planetary systems around most neutron stars. We consider the environment and physical processes relevant to neutron star planets, in particular the effect of X-ray irradiation and the relativistic pulsar wind on the planetary atmosphere. We discuss the survival time of planet atmospheres and the planetary surface conditions around different classes of neutron stars, and define a neutron star habitable zone based on the presence of liquid water and retention of an atmosphere. Depending on as-yet poorly constrained aspects of the pulsar wind, both Super-Earths around B1257+12 could lie within its habitable zone.
(Score: 0) by Anonymous Coward on Thursday December 28 2017, @11:27PM (3 children)
The pressure in the Marianas Trench is about 1000 times sea level air pressure. We need a thousand times more pressure than that to get to a million. That's not an atmosphere, it's practically a solid object.
Wouldn't a Europa-type situation be far more plausible, though? Miles of ice or rock makes for far better radiation protection than an absurdly thick atmosphere.
(Score: 2) by takyon on Thursday December 28 2017, @11:37PM
Habitable zone is defined by surface liquid water.
Including places like Europa is a little too optimistic right now. Because we could say that places [wikipedia.org] like Ceres, Europa, Ganymede, Callisto, Enceladus, Dione, Rhea, Titan, Titania, Oberon, Triton, Orcus, Pluto, Makemake, 2007 OR10, Eris, and Sedna could all have microbes in a subsurface oceans. Some might have better prospects than others (more internal heat, tidal heating from a large planet like Jupiter, Saturn... or Planet Nine), but these are all plausible places for microbial life to be found. Yet I don't think we want to include Pluto and Makemake in the "habitable zone" even if they were found to have life forms.
[SIG] 10/28/2017: Soylent Upgrade v14 [soylentnews.org]
(Score: 0) by Anonymous Coward on Friday December 29 2017, @02:48AM
"Thicker" is one of those words that happens when journalists who don't understand the science try to translate it for people who they expect to have even less understanding than they do.
It appears that they mean "more massive" rather than "higher pressure". A million times more mass would roughly equal the mass of the Earth, and they also talk about the planet itself having a mass of up to ten times Earth. At that point you have a planet that is more like Neptune than Earth. The conditions at the bottom of the atmosphere would not be hospitable to life. Neptune has a water layer, which is about 2000 degrees C, and is kept liquid only by extreme pressure. Solar energy doesn't enter into it - it's still hot from planetary formation.
Maybe someday, a planet like this will cool down enough to support life in its interior, but at that point it doesn't make any difference what kind of star it's near.
(Score: 1) by pdfernhout on Friday December 29 2017, @03:56AM
So maybe indeed just solid rock instead of an atmosphere? http://www.techtimes.com/articles/31394/20150208/scientists-determine-that-life-possibly-exists-deep-beneath-earths-surface.htm [techtimes.com]
"The key factor here, though, is that these microbes sustained extreme heat underground with temperatures up to 250 degrees Fahrenheit, the hottest temperature we believe life can withstand. However, high pressure underground probably stabilized the microbe's DNA, so it survived there. ... "Underground environments would potentially be favorable locations for extraterrestrial life because they are more shielded from harmful surface conditions like cosmic radiation and insulated from extreme surface temperatures," said Stoddard. "It's definitely something we should keep in mind as we explore other planets.""
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