In the news recently, it has been discovered that the fast burst radio waves are coming from magnetars.

It is doubtful that a habitable planet could form anywhere near one, but such a star would be an unbelievably huge source of energy. Since they do not have the same hazards to space as black holes (their gravity is not really out of the ordinary), it appears that something could peacefully co-exist around one of them. However, apparently they have a tendency to tear atoms apart that get too close.

Also, for Sci-Fi speculation, just exploring the ramifications of quantum physics around such a star would be interesting.

So, if a massively huge generation ship, built in or on say a very large asteroid or 'baby planet', with tens or even hundreds of thousands of humans, happened to wander by, how close could this ship get, without being destroyed, or everyone aboard being killed?

The 'how' of 'how is this generation ship moved' is not within the scope of this question. Just assume that it can be moved around, under control, with relative (pun intended) ease.

  • $\begingroup$ Magnetars are Neutron Stars; their surface escape velocity is a significant fraction of the speed of light and their mass is measured in solar masses. I contest your claim that their gravity is not out of the ordinary. In addition to the gravitational hazards posed by black holes, as a bonus hazard they also emit high-energy thermal radiation from their surface. Neutron stars can have accretion disks and emit massive energy spikes when absorbing something, just like black holes. $\endgroup$
    – mic_e
    Nov 5, 2020 at 17:57
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    $\begingroup$ Why is the generational ship getting close in the first place? If it can move itself easily, it would probably want to get as far away as possible while still getting to its destination. I can think of many ideas for generational ships that cannot move themselves easily, but that is not what your question appears to be about. $\endgroup$ Nov 5, 2020 at 17:58
  • $\begingroup$ @Just'Existing The question is specificallyabout how close it could get. The 'why' or 'how' are seperate questions. $\endgroup$ Nov 5, 2020 at 18:03
  • $\begingroup$ @mic_e But it is not IMPOSSIBLE to escape, as is the case of a blackhole. It is not mandated by the laws of physics that it is a one-way trip. ANd certainly, no generation ship resident would go ON the planet, although the idea of sending uncrewed probes to the planet is within speculation. My question is simple - how close could a ship get to such a star, not why, how, or even when. All of those are a seperate question. $\endgroup$ Nov 5, 2020 at 18:07
  • $\begingroup$ "(their gravity is not really out of the ordinary)". You could say the same with stellar-mass black holes: treat it like any other ordinary mass. If you are close enough for gravity to be "weird" your ship was long since torn to shreds. $\endgroup$ Apr 28 at 6:37

2 Answers 2


Just by reading the "safety sheet" of magnetars makes me shiver:

Like other neutron stars, magnetars are around 20 kilometres (12 mi) in diameter and have a mass about 1.4 solar masses.

A magnetar's magnetic field gives rise to very strong and characteristic bursts of X-rays and gamma rays.

Starquakes triggered on the surface of the magnetar disturb the magnetic field which encompasses it, often leading to extremely powerful gamma ray flare emissions which have been recorded on Earth in 1979, 1998, and 2004

The magnetic field of a magnetar would be lethal even at a distance of 1000 km due to the strong magnetic field distorting the electron clouds of the subject's constituent atoms, rendering the chemistry of life impossible. At a distance of halfway from Earth to the moon, a magnetar could strip information from the magnetic stripes of all credit cards on Earth.

While a magnetic field decays with the cube of the distance, the x and gamma ray bursts follow the usual square of the distance decay, thus they stay lethal way further.

How close could you get to those gamma ray bursts really depends on how good the shielding of the ship are. The lower limit is the 1000 km stated above.

  • $\begingroup$ I am certainly not suggesting that one would get as close to this star as the moon is to the earth, and definitely not within 1000 km. It was more along the lines of orbiting the star, like the earth orbits the sun. Are we talking one astronomical unit, ten, 100? Less than one? It doesn't have to be a goldilocks distance, just a safe distance. I have no issues with shielding being necessary. Exploring the interaction of magnetic ionosphere-type shielding with the magnetic fields of the star are all future possibilities, once a safe distance is determined. I just don't want to be torn apart. $\endgroup$ Nov 5, 2020 at 18:21
  • $\begingroup$ In oter words, is orbiting it like a planet safe from total physical destruction? $\endgroup$ Nov 5, 2020 at 18:25

The magnetic field itself is only a problem at really close ranges. Less than 100000km or so. This is because while intense, the magnetic field reduced as distance cubed, and very rapidly scales down to more conventional levels.

Gravity-wise, the Magnetar behaves exactly like an ordinary neutron star. Intense gravity at the surface of a ridiculously dense 20km-ish sphere, with gravity's normal distance-squared decrement as you get further away.

The problem lies with the ludicrously intense x-ray and gamma-ray events triggered by the rotating magnetic field. These are caused when the rotating magnetif field sweeps through non-empty space around the Magnetar, and when a chunk of debris impacts on the surface. The emissions tend to be somewhat directional, very intense and unpredictable. And intense enough to be detected 160 000 lightyears away!

How close can you get, safely? Several lightyears, due to the danger of directional gamma bursts.

  • $\begingroup$ The gamma bursts are not a concern. First, they are intermitent, second they are not absolutely certainn to occur, and thirdly they can be shielded against (plot twists?). My interest is in the possibility that under such intense magnetic fields, only quantum effects would exist, not relativistic effects. Since we can not presently produce such intense fields, the only way to carry out an experiment would be to visit such a star, and use it as a natural laboratory. $\endgroup$ Nov 10, 2020 at 15:19

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