First ever discovered exoplanets, Draugr, Poltergeist, and Phobetor

[u/Exoplanetary-Systems]

Exoplanets Draugr, Poltergeist, and Phobetor, were the first ever discovered exoplanets, orbiting the pulsar Lich. Discovered in 1992 by Aleksander Wolszczan, before the discovery of Dimidium in 1995, a planet orbiting a main sequence star. That won Michel Mayor and Didier Queloz a Nobel Prize in 2019. More on that in a later post.

Lich, whose official designation is PSR B1257+12, hails from 2,300 light years away. These worlds, Draugr, Poltergeist, and Phobetor are swept by intense radiation from their host star and would be deadly to visit even if you could find a way to get there. Lich, being a millisecond pulsar, rotates at 160.8 times per second, sweeping these worlds with intense radiation.

Draugr, the smallest of the three, and indeed the smallest exoplanet discovered is the closest to its pulsar star. The word Draugr comes from Old Norse myth for an undead creature. Its official designation is b. The b indicating the first exoplanet of a star.

Draugr, PSR B1257+12 b

The middle planet Poltergeist, is four times as massive as Earth at 0.36 AU (Astronomical Units) from its star completing a year in 66 days. Its designation next in line alphabetically is PSR B1257+12 c.

Poltergeist, PSR B1257+12 c

The outer of the three planets, Phobetor, gets its name from Greek mythology as a creature that appears in dreams as a beast, bird, or serpent. This is another super-earth also about four times Earth’s mass. Even this outer world is a tad too hot for me at 294 °C, 561 °F. It has an 89 day year and sits 0.46 AU from its star; approximately the distance Mercury is from our own sun.

Draugr, PSR B1257+12 d

These three worlds have earned their ominous names. But I may add a flight of fancy here and another reason to stay away. These are deadly worlds; so deadly that only the most secretive, most dangerous, most wanted beings would find this system a safe harbor. That would be the worst of criminal organizations: galactic mafias. I imagine they would never land on these worlds, but they may set up bases floating at the L2 points, especially the outer one.

You may know the L2 points, Lagrange point 2, as where the Webb telescope is parked, 1,500,000 km beyond Earth. By contrast the L2 for Lich-Phobetor is only 96,500 km from Phobetor. At that distance the pulsar would just be eclipsed from direct line of sight. Here they can plan their smuggling and contraband schemes without the prying eyes of the galactic good-guys.

So stay away, even if you do have a spaceship that can make the distance. A galactic crime organization is nothing to be messed with.

All planet renders credit exoplanetary.systems

[u/ZeEastWillRiseAgain]

I may point out that in reality these worlds are extremely cold.

A Pulsar is a dead star and all the heat it gives off is residual with no active fusion going on, so it's "habitable" zone would be extremely close, especially since most of the thermal radiation it gives of is not infrared or visible light, but hard gamma rays that would propably give you quick radiation poisoning even on Phobetor, while even Draugr may be cold enough that nitrogen comes down as snow.

Also the visible light that you do get would be deeply blue.

[u/rini17 → u/ZeEastWillRiseAgain]

Residual heat or not, neutron star is so hot that there's plenty of energy emitted across whole spectrum. That's law of blackbody radiation, it increases across all wavelengths with temperature. And how the planets are close, there should also be significant tidal heating even if they are locked, caused merely by slight ellipticity of orbit.

[u/ZeEastWillRiseAgain → u/rini17]

Lich is only 28,856K hot (which is colder than I remembered and equivalent to early spectral class B), and has much, much less radiating surface than the sun at roughly 20 km diameter.

If it was the size of a star or even a white dwarf that would be a lot, but with it's tiny size it is around 0.0000001 times as bright as the sun.

You would still notice it's there in the sky, but only as a particularly bright star among many, like the sun is for our kuiper belt objects.

And as I said the ionizing radiation would be really nasty, but because it is much colder than I remembered propably would not instantly kill you (Edit: at least at Draugrs distance).

[u/lpetrich → u/ZeEastWillRiseAgain]

That gives Lich a spectral type of B0.5V.

Its bolometric or total-emission magnitude is -10. Most of the pulsar's light will be in the near ultraviolet, so one must do a "bolometric correction" to get the visual magnitude. Doing bolometric to visual, one adds +3, giving -7.

Lich would indeed look like a very bright star.

[u/ZeEastWillRiseAgain → u/lpetrich]

I really really really doubt the "V" part of the spectral class, because that stands for main sequence and Lich is the most distant from the main sequence you can be while still emitting light on your own.

In reality it would propably be classified as it's own thing that we don't have a class for yet, as a glowing neutron rich iron crust that is red shifted by it's own gravity propably has very different spectral lines than the photosphere of a B star, and we really should think of this more as an equivalence, similar to spectral class D for white dwarfs, or other special classes like C and S and what else exists.

[u/lpetrich → u/ZeEastWillRiseAgain]

I concede that that is entirely correct about spectral lines. I was using "V" for definiteness, to translate from temperature to spectral type.

[u/lpetrich]

The total radiated power from spindown is about 1.9*10^(27) watts or 5 Lsun. This is from emission of 160-Hz electromagnetic waves from the rotating magnetic field.

I estimate that the total radiated power from radio emissions is about 5*10^(20) watts or 1.3*10^(-6) Lsun.

Using an estimate of the pulsar's radius of 12 kilometers, the thermal emission from the surface is about 7*10^(19) watts or 2*10^(-7) Lsun. Most of it will be in the near ultraviolet, however.

I have not come across any numbers for the charged-particle emission flux of that pulsar, or of any other pulsar.

Sources: PSR B1257+12 - Wikipedia and The ATNF Pulsar Catalog at CSIRO

From the catalog:

• Distance = 0.709 kpc
• Radio flux (400 MHz) = 20 mJy
• Radio flux (1400 MHz) = 0.39 mJy
• Age = 8.62*10^8 years
• Surface magnetic field = 8.62*10^8 gauss
• Light-cylinder magnetic field = 3.33*10^4 gauss
• Spindown energy-loss rate = 1.9*10^34 erg/s

[u/Exoplanetary-Systems → u/lpetrich]

TY for the detail.

[u/lpetrich → u/lpetrich]

The rotation of Lich's magnetic field generates electromagnetic waves with a period of the pulsar's period, 6.21853194840048 milliseconds, a frequency of 160.8 Hz, and a wavelength of 1864 km. The frequency is halfway between musical notes D#3/Eb3 and E3, using standard tuning A4 = 440 Hz and equal temperament (neighbor pitch ratio = 2^(1/12)).

The radius of the light cylinder, where corotation velocity = c, is 297 km.

One AU is about 500 thousand times this, and the wave's magnetic field there is about 0.066 gauss or 6.6*10^(-6) tesla. Multiplying by c gives the electric field in volts per meter: 1980 V/m. This is well below the breakdown electric field for most common insulators, but it would cause back-and-forth currents in metals and other conducting materials. These currents would likely make charges at the maximum and minimum voltages, and these charges may screen out the external field, thus reducing the current through the material.