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Aleksander Wolszczan of Pennsylvania State University found three planets circling a pulsar called PSR B1257+12.Two of the planets were the size of Earth.The pulsar observed by Spitzer, named 4U 0142+61 spotted a warm glowing disk formed from debris, The disk has a orbit of about 1 million miles and contains 10 Earth mass materials. Deepto Chakrabarty of the Massachusetts Institute of Technology, principal investigator states "Pulsars emit a tremendous amount of high energy radiation".

In a pulsar star system, could human life thrive on a planet with high energy radiation? If answering the question, please provide the latest references to date that are relevant with your statement.

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Only five pulsar planets have been confirmed or have garnered enough evidence to make a strong case for their existence. None of them are like the terrestrial planets in the Solar System insofar as the way they formed and their orbital movements.

  • PSR B1620-26 b. This planet is in a circumbinary orbit around a pulsar and a white dwarf, with a semi-major axis of ~23 AU. It is theorized that it formed around a Sun-like star, which became a binary star system after encountering a neutron star (another partner must have been ejected from the system, as is the case with triple-star encounters). The Sun-like star promptly became a white dwarf, and the planet's orbit would have widened after the encounter with the neutron star, which is a pulsar.

    Basically, this planet did not form around the pulsar. The system was captured so to speak, and so neither the Sun-like star/white dwarf or planet would have been affected by the supernova. Additionally, the planet is fairly far away from the two stars in the system, meaning that effects from the pulsar are even less negligible.

    The point of this is that life on this planet is possible - especially given the planet's old age - but it would be hard for it to survive. If life formed before the encounter with the original binary system, it would have been disrupted a bit by the orbital changes, reducing the amount of starlight it received. Today, it would receive little light, as the white dwarf has a low luminosity. There wouldn't be enough energy to sustain life - as is the case for most pulsar planets.

    Also, as Rob Jeffries pointed out, this planet is a gas giant, not a terrestrial planet, meaning that human-like life could not develop on it and any arriving humans bent on colonization would not be able to live on it normally.

  • The planets of PSR B1257+12. Three planets orbit this pulsar, at distances of about 0.19, 0.36, and 0.48 AU - fairly close to the pulsar and within range of a decent amount of harmful radiation, relative to PSR B1629-26 b. The major reason that these planets are not a good place for life is that they are thought to have formed after the supernova that led to the evolution of the star to a pulsar, from remnants of debris from the supernova. The star itself is quite young - ~3 billion years - and the supernova would have happened relatively soon thereafter. The planets themselves are less than 1 billion years old, meaning that life has not had time to develop.

    My issue with the age of the planets isn't based on the short time period for life to develop so much as on the idea that conditions might be hellish, comparable to those experienced in the Hadean eon. Geologically, these planets would have had different starts than Earth did, and they most likely would not have encountered the problems of the Late Heavy Bombardment, but life might not have a good chance at starting at all for another 500 million years.

  • PSR J1719-1438 b. This planet is unusual because it is thought to be the remnant of the companion star - severely damaged by the supernova. It is also composed of exotic materials, for a planet - crystallized carbon. The conditions here are not conducive to life.

Looking at this list we see three distinct types of pulsar planets emerge:

  • Captured planets
  • Newly formed planets
  • Former companion stars

The latter two are not good places for life, in part because they may not be composed or compounds life can use. The first group may be the best chance, as their formation could have been relatively normal. The problem lies in the fact that they might have been rogue planets, floating along without good sources of energy from stars.

All of this isn't even taking into account the radiation from the pulsar itself. The only escape is to have an orbit far from the pulsar, as with PSR B1620-26b, but then there's no outside source of energy. The best chance would be to have the planet in a circumbinary orbit around the pulsar and a companion star, as in this planet's case. At least then there would be some helpful light.

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    $\begingroup$ Slight snag with the first system you consider (and which I didn't) - it's a gas giant. I'm deleting my answer since I hadn't appreciated that these were millisecond pulsars. However, I don't think you can rule something out on the basis that it is a billion years old. Who knows, the pulsar radiation could accelerate mutation rates and evolution. $\endgroup$ – Rob Jeffries Jan 23 '16 at 18:19
  • $\begingroup$ @RobJeffries I completely forgot to consider that it's a gas giant. I'll make a note of that. My rationale ruling out the planets on the basis of age was more the supposition that early conditions would not have been conducive to anything but extremophilic life. While the Earth clearly isn't necessarily indicative of an average planet, many terrestrial planets would have gone through inhospitable conditions like those in the Hadean eon. That would leave maybe 500 million years for life to start - and while I hadn't considered that radiation could have helped life, I assumed it would have hurt. $\endgroup$ – HDE 226868 Jan 23 '16 at 18:25

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