Classifying Milky Way planets by what they´re bound to and originate from

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Discussion Overview

The discussion revolves around the classification of planets in the Milky Way based on their binding to stars or star systems, their origins, and their current trajectories. Participants explore various categories of planets, including those bound to specific stars, those that are free-floating, and those that may have originated from other galaxies.

Discussion Character

  • Exploratory
  • Debate/contested
  • Technical explanation

Main Points Raised

  • One participant questions how many planets in the Milky Way can be classified based on their binding and origin, proposing several categories for consideration.
  • Another participant asserts that all detected planets are bound to a host star, while others suggest that none of the proposed categories (2, 3, 4) are currently detected.
  • A different participant challenges the assertion about detection methods, referencing the existence of rogue planets and their classification as free-floating planets, citing various terminology used in astronomical literature.
  • One participant provides numerical estimates for the counts of planets in each proposed category, suggesting specific ranges for free-floating planets.

Areas of Agreement / Disagreement

Participants express disagreement regarding the classification and detection of planets, with some asserting that all detected planets are bound to stars while others argue for the existence of free-floating and rogue planets. The discussion remains unresolved with multiple competing views presented.

Contextual Notes

The discussion highlights limitations in current detection methods and the definitions used for classifying planets, which may affect the understanding of the categories proposed.

snorkack
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TL;DR
Relative numbers of various groups
How many planets now in Milky Way are:
  1. Bound to a particular star or a star system of a few stars?
  2. Not bound to any particular star nor a star system of a few stars but bound to Milky Way and possibly to some star system of many stars?
  3. Not bound to Milky Way, but originating in Milky Way, recently accelerated to unbound and on the way out?
  4. Not bound to Milky Way nor originating here, expelled from another galaxy and currently passing through Milky Way?
 
Astronomy news on Phys.org
Of what we have detected:
1. All of them.
2, 3, 4. None of them.

This is because our detection methods are based on the planet's interaction with its host star.
 
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russ_watters said:
This is because our detection methods are based on the planet's interaction with its host star.
Not true. See https://en.wikipedia.org/wiki/Rogue_planet:
"The two first discovery papers use the names isolated planetary-mass objects (iPMO)[9] and free-floating planets (FFP).[10] Most astronomical papers use one of these terms.[11][12][13] The term rogue planet is more often used for microlensing studies, which also often uses the term FFP.[14][15] A press release intended for the public might use an alternative name. The discovery of at least 70 FFPs in 2021, for example, used the terms rogue planet,[16] starless planet,[17] wandering planet[18] and free-floating planet[19] in different press releases."
 
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