<p>Since planets are known to exist around neutron stars (e.g. see <a href="http://adsabs.harvard.edu/abs/1992Natur.355..145W" rel="noreferrer">Wolcznan &amp; Frail (1992)</a>; and see the list of <a href="https://en.wikipedia.org/wiki/Pulsar_planet#List_of_pulsar_planets" rel="noreferrer">"pulsar planets"</a> - technically, these were the first exoplanets ever discovered), then it is difficult to see any fundamental reason why there should not be examples orbiting black holes. </p>

<p>In fact, since it is probably feasible to form black holes via <a href="https://arxiv.org/abs/1609.01283" rel="noreferrer">direct collapse</a>, without an associated supernova then maybe the hazards for planets are not so severe.</p>

<p>Against this, must be set the fact that black hole progenitors are likely to be more massive than neutron star progenitors and the role of winds and radiation on the formation of planets is still not well established.</p>

<p>Planets orbiting neutron stars are/were found from a timing analysis of pulsar signals. The same phenomenenon is not present for black holes and direct imaging or observing a transit is not remotely feasible at present.</p>

CC BY-SA 3.0
2017-07-07T13:04:23.953Z
Well, nuts. +1 nuts, but nuts. I was about to write up a very similar answer. It might be worthwhile to add that those exoplanets discovered by Wolcznan & Frail were the very first exoplanets to be discovered.
David Hammen
CC BY-SA 3.0
2017-07-11T04:41:00.903Z
And we saw planets orbiting the black hole in "Interstellar" so they have to exist. (Just joking, but they did "science" that movie pretty well. You can even buy a book by Kip Thorne on "The Science of Interstellar".)
Jack R. Woods
CC BY-SA 4.0
2020-12-08T12:22:23.627Z
It just occurred to me that there may also be primordial black holes of pretty arbitrary sizes (in particular, smaller ones than the remains of a massive star). AFAIK it's all pretty speculative; smaller black holes may be hard to observe so there is no good data for principle reasons.If one with the mass of a planet would reverse roles and planet-like orbit a regular star, enough occasional matter may fall in that it becomes visible at times, like its larger cousins, from the resulting radiation.
Peter - Reinstate Monica
CC BY-SA 3.0
2017-07-07T13:02:24.440Z
2017-07-07T15:40:13.457Z
2017-07-07T15:40:13.457Z
ProfRob
<p>I assume such a system would be hard to detect due to a lack of radiation, at least if the vicinity of the black hole does not contain a lot of mass which falls into it over time, thus creating (a lot of) radiation.</p>

<p>Since black hole formation in a supernova explosion is a process which destroys any planetary system around its original star, any planetary system around a black hole must have formed <em>after</em> black hole formation.</p>

<p>A few objections come to mind off-the-cuff: Because black holes have a large mass there is a minimum distance for planetary orbits below which they would disintegrate due to tidal forces. This may interfere with the usual evolution of planets (they clear their orbits and kick out interfering bodies, for example), because their "orbital space volume" becomes too large for them to keep clean, and the orbital period becomes long.</p>

<p>Is anything known or is there any speculation about such systems?</p>

CC BY-SA 3.0
2017-07-07T08:45:19.363Z
Possible duplicate of [Orbiting around a black hole](https://astronomy.stackexchange.com/questions/500/orbiting-around-a-black-hole)
J. Chomel
CC BY-SA 3.0
2017-07-07T12:19:38.967Z
I don't think this is a duplicate. The proposed duplicate asks a general question, whether objects can orbit a black hole. This asks a much more specific question, whether black holes can have planets.
David Hammen
CC BY-SA 3.0
2017-07-07T12:35:15.010Z
You're misunderstanding the meaning of "planet" . All the stars in a galaxy are planets orbiting the central black hole.
Carl Witthoft
CC BY-SA 3.0
2017-07-07T12:57:11.247Z
@CarlWitthoft I think it is safe to say that celestial bodies large enough to maintain nuclear fusion are not planets. I also doubt that they have cleared their galactic orbits or forced other objects in their orbit into resonance. I'm not sure where you see a misunderstanding -- an orbit is not a sufficient condition for a body to be a planet.
Peter - Reinstate Monica
CC BY-SA 3.0
2017-07-07T12:59:18.780Z
@J.Chomel Well, I was not doubting the general physical possibility (as the other OP). I was wondering whether there is theoretical or practical research about it. I'll reword the title.
Peter - Reinstate Monica
CC BY-SA 3.0
2017-07-07T13:04:12.673Z
@PeterA.Schneider the current IAU standards (which neither I nor Phil Plait particularly agree with) only allow Solar objects to be considered.  I see no reason not to use "planet" at the very least as an adjective to distinguish stars in a closed conic section path vs. non-captured stars.
Carl Witthoft
CC BY-SA 3.0
2017-07-07T13:10:13.663Z
@CarlWitthoft - No matter what you definition you want to use for what qualifies as a "planet", stars are not planets.
David Hammen
CC BY-SA 3.0
2017-07-07T18:56:15.943Z
@CarlWitthoft (Almost?) everything orbits something...
Peter - Reinstate Monica
<black-hole><planetary-formation><planetary-systems>
Is there any theoretical or empirical research about planetary systems with a black hole in their center?
Peter - Reinstate Monica
# Is there any theoretical or empirical research about planetary systems with a black hole in their center?

(Asked by: username_0 on 2017-07-07)

I assume such a system would be hard to detect due to a lack of radiation, at least if the vicinity of the black hole does not contain a lot of mass which falls into it over time, thus creating (a lot of) radiation.

Since black hole formation in a supernova explosion is a process which destroys any planetary system around its original star, any planetary system around a black hole must have formed *after* black hole formation.

A few objections come to mind off-the-cuff: Because black holes have a large mass there is a minimum distance for planetary orbits below which they would disintegrate due to tidal forces. This may interfere with the usual evolution of planets (they clear their orbits and kick out interfering bodies, for example), because their "orbital space volume" becomes too large for them to keep clean, and the orbital period becomes long.

Is anything known or is there any speculation about such systems?

**Tags:** black-hole, planetary-formation, planetary-systems
> **Comments:**
> **username_1**: Possible duplicate of [Orbiting around a black hole](https://astronomy.stackexchange.com/questions/500/orbiting-around-a-black-hole)  
> **username_2**: I don't think this is a duplicate. The proposed duplicate asks a general question, whether objects can orbit a black hole. This asks a much more specific question, whether black holes can have planets.  
> **username_3**: You're misunderstanding the meaning of "planet" . All the stars in a galaxy are planets orbiting the central black hole.  
> **username_0**: @CarlWitthoft I think it is safe to say that celestial bodies large enough to maintain nuclear fusion are not planets. I also doubt that they have cleared their galactic orbits or forced other objects in their orbit into resonance. I'm not sure where you see a misunderstanding -- an orbit is not a sufficient condition for a body to be a planet.  
> **username_0**: @J.Chomel Well, I was not doubting the general physical possibility (as the other OP). I was wondering whether there is theoretical or practical research about it. I'll reword the title.  
> **username_3**: @PeterA.Schneider the current IAU standards (which neither I nor Phil Plait particularly agree with) only allow Solar objects to be considered.  I see no reason not to use "planet" at the very least as an adjective to distinguish stars in a closed conic section path vs. non-captured stars.  
> **username_2**: @CarlWitthoft - No matter what you definition you want to use for what qualifies as a "planet", stars are not planets.  
> **username_0**: @CarlWitthoft (Almost?) everything orbits something...  

---

## 1 answers

### Answer by username_4 on 2017-07-07. Score: 11 | Accepted answer

Since planets are known to exist around neutron stars (e.g. see [Wolcznan & Frail (1992)](http://adsabs.harvard.edu/abs/1992Natur.355..145W); and see the list of ["pulsar planets"](https://en.wikipedia.org/wiki/Pulsar_planet#List_of_pulsar_planets) - technically, these were the first exoplanets ever discovered), then it is difficult to see any fundamental reason why there should not be examples orbiting black holes.

In fact, since it is probably feasible to form black holes via [direct collapse](https://arxiv.org/abs/1609.01283), without an associated supernova then maybe the hazards for planets are not so severe.

Against this, must be set the fact that black hole progenitors are likely to be more massive than neutron star progenitors and the role of winds and radiation on the formation of planets is still not well established.

Planets orbiting neutron stars are/were found from a timing analysis of pulsar signals. The same phenomenenon is not present for black holes and direct imaging or observing a transit is not remotely feasible at present.

> **Comments:**
> **username_2**: Well, nuts. +1 nuts, but nuts. I was about to write up a very similar answer. It might be worthwhile to add that those exoplanets discovered by Wolcznan & Frail were the very first exoplanets to be discovered.  
> **username_5**: And we saw planets orbiting the black hole in "Interstellar" so they have to exist. (Just joking, but they did "science" that movie pretty well. You can even buy a book by Kip Thorne on "The Science of Interstellar".)  
> **username_0**: It just occurred to me that there may also be primordial black holes of pretty arbitrary sizes (in particular, smaller ones than the remains of a massive star). AFAIK it's all pretty speculative; smaller black holes may be hard to observe so there is no good data for principle reasons.If one with the mass of a planet would reverse roles and planet-like orbit a regular star, enough occasional matter may fall in that it becomes visible at times, like its larger cousins, from the resulting radiation.  

---

