Why Do Some Black Holes Appear Pink?

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Discussion Overview

The discussion revolves around the concept of black holes appearing pink, exploring the nature of black holes, their visibility, and the phenomena surrounding them. Participants engage in clarifying the characteristics of black holes, particularly in relation to their accretion disks and the light emitted from surrounding gas.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • Some participants question the notion of black holes being pink and seek clarification on the source of this idea.
  • There is mention of Hawking radiation as a potential point of confusion regarding the visibility of black holes.
  • One participant suggests that the term "pink holes" may stem from a misunderstanding or misinterpretation of popular articles.
  • Another participant explains that while black holes themselves do not emit light, the surrounding material, such as an accretion disk, can emit various forms of electromagnetic radiation, potentially including pink light.
  • The discussion raises the point that the light observed is from gas outside the black hole, which is heated and emits light before crossing the event horizon.

Areas of Agreement / Disagreement

Participants do not reach a consensus on the concept of pink black holes. There are competing views regarding the interpretation of the term "pink" and the nature of light emitted from surrounding materials.

Contextual Notes

The discussion highlights uncertainties regarding the definitions of black holes and the conditions under which they may appear to emit light. There is also a lack of clarity on the sources of information regarding the pink coloration.

haynewp
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Why are some black holes pink? Are pink holes pink on the inside?
 
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Could you give a reference? I never heard of black holes being other than black. Are you talking about Hawking radiation?
 
Originally posted by haynewp
Why are some black holes pink? Are pink holes pink on the inside?

Are you sure you weren't reading a Cosmo article? Black holes get their name from the fact that you can see them. You can see the effects they have on their surroundings. An accretion disk can be found giving off all sorts of EM radiation around an event horizon of a black hole. Where did you get pink from?
 
http://www.chron.com/content/interactive/space/astronomy/news/1999/ds/990507.html
 
Last edited by a moderator:
Welcome to Physics Forums, haynewp! :smile:

Originally posted by haynewp
http://www.chron.com/content/interactive/space/astronomy/news/1999/ds/990507.html

Gotta read your own link. It says..

We're pretty certain that it isn't the black holes themselves that are pink, the pink light is actually coming from gas just outside the black hole," Francis said.

A black hole is a singularity (point). No light escapes that. (Actually, no light escapes from the event horizon around the singularity...which is merely the distance from the singularity where the escape velocity is the speed of light.) So the singularity plus the volume within the event horizon is black. Now stuff falling into that region is being immensely accelerated (due to the extreme gravity). That creates lots of heat which therefore gives off light. Once that shining stuff hits the event horizon, it goes black. So "active" black holes can be imagined as a central black region with a spinning, glowing disk of material around it (stuff spiraling into the hole). An inactive black hole has no such "accretion disk" around it (no nearby matter to eat).

So, the question that remains is, why is the nearby stuff glowing pink?
 
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