What Is the Estimated Number of Homeless Planets in Our Galaxy?

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In summary, there is a claim that there are roughly 100,000 times more planets than stars in our galaxy, with a significant percentage being nomad or unbound planets. However, the evidence for this is based on a small sample size and further observations are needed to confirm these numbers.
  • #1
JonDE
Number of "homeless" planets

So I stumbled upon this article and wanted to get others opinions of it. The short and long of it is it is claiming that there are roughly 100,000 X as many planets wandering about our galaxy (not attached to a star) as there are stars in our galaxy. Seems a little high to me.
Further can anyone make an estimation on how much mass this would be (percentage wise) of our galaxy? The article has some information that would be helpful.
http://www.voanews.com/english/news...Be-Awash-with-Homeless-Planets-140350363.html

p.s. I was exagerating when I said a little.
 
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  • #2


I think if this were true there would be better/more stories and at least one picture of this discovery.
"Strigari also says there is a slight chance that two nomad planets could collide, flinging bacterial debris into other solar systems."

I've learned (correct me if I'm wrong) that when galaxies collide that there's not even a slight(not a unit of measurement either) chance of 2 stars colliding. Also, I think it is playing a lot of the "life out there" hype.
 
  • #3


That number seems really high, and the one I'm familiar with is ~2x freely floating planets as bound planets (and the number of bound planets is ~ the number of stars).

See: http://arxiv.org/abs/1105.3544v1

These microlensing studies have a very small population of detections (only 11!), from which they infer a population of hundreds of millions of planets, so I'm somewhat skeptical of the results (but their statistical analysis appears to be sound).
 
  • #4


Nabeshin said:
That number seems really high, and the one I'm familiar with is ~2x freely floating planets as bound planets (and the number of bound planets is ~ the number of stars).

See: http://arxiv.org/abs/1105.3544v1

These microlensing studies have a very small population of detections (only 11!), from which they infer a population of hundreds of millions of planets, so I'm somewhat skeptical of the results (but their statistical analysis appears to be sound).

Just a minor correction. The arxiv link you gave says there are twice as many Jupiter size planets as stars (actually the same thing my article said).
From your link
"Here, we report the discovery of a population of unbound or distant Jupiter-mass objects, which are almost twice (1.8_{-0.8}^{+1.7}) as common as main-sequence stars"

So it leaves open how many smaller planets could be out there. I am skeptical that there are 50,000 X as many smaller planets as Jupiter sized planets, unless someone has a link to that.
Also it does seem to be a very small sample size as you said.
 
  • #5


First, a correction. Strigari et al aren't claiming to have proven the numbers, merely giving an upper bound based on current observational data and the mass of the Galaxy that's not bound up in stars. The 100,000/1 ratio is based on extrapolating the mass-function of brown dwarfs down to Pluto-mass objects. And, surprisingly, the observational limits are consistent with the high figure. In true scientific spirit, the researchers suggest ways of making the numbers harder based on piggy-back observations - using data from other large-scale observational studies.
 

What is the definition of a "homeless" planet?

A "homeless" planet is a planet that does not orbit around a star or have a stable orbit within a planetary system. These planets may have been ejected from their original planetary system or have never been part of one to begin with.

How many homeless planets are estimated to exist in our galaxy?

While the exact number is unknown, it is estimated that there could be millions of homeless planets in our galaxy alone. This number is based on observations of planetary systems and simulations of planet formation.

Can homeless planets sustain life?

It is unlikely that life can exist on a homeless planet. These planets do not receive any energy from a star, making it difficult for them to maintain a stable temperature. Additionally, without a stable orbit, they may not have the necessary conditions for life to develop.

What methods are used to detect homeless planets?

One method is through direct imaging, using telescopes to capture images of planets floating freely in space. Another method is through studying the effects of gravitational lensing, which occurs when a planet passes in front of a distant star, causing a distortion in light. Scientists also use simulations and computer models to predict the presence of homeless planets.

What can the study of homeless planets tell us about the formation of planetary systems?

The existence of homeless planets provides valuable insights into the formation and evolution of planetary systems. It suggests that the traditional model of planets forming in a stable orbit around a star may not always be the case. By studying these planets, scientists can better understand the mechanisms of planet formation and the factors that contribute to the diversity of planetary systems in our universe.

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