Unveiling the Mystery: The Birth of Stars and the Role of Nuclear Fusion

  • Context: Undergrad 
  • Thread starter Thread starter TShock
  • Start date Start date
  • Tags Tags
    Stars
Click For Summary

Discussion Overview

The discussion revolves around the formation of stars, specifically addressing why some stars are larger than others and the role of nuclear fusion in this process. Participants explore concepts related to gravitational collapse, critical mass, and the dynamics of mass accumulation during star formation.

Discussion Character

  • Exploratory
  • Debate/contested
  • Conceptual clarification

Main Points Raised

  • One participant suggests that since the critical mass for nuclear fusion is constant, all stars should be relatively the same size once fusion begins.
  • Another participant challenges this notion, questioning why a star would stop collecting mass after fusion starts.
  • A further reply posits that the ejection of matter from a star, such as the Sun, could prevent additional hydrogen from being collected, drawing parallels to the atmospheres of planets like Mercury and Earth.
  • One participant raises questions about whether the ejection of matter is a universal phenomenon applicable to all stars or specific to Sol-like stars, and whether this occurs immediately upon fusion or if there is a delay.
  • Concerns are expressed regarding the influence of the astrophysical environment on mass accumulation, particularly in relation to the velocity of incoming matter and the presence of currents or flows of material.
  • A participant expresses frustration over the lack of responses to their questions, suggesting a perceived lack of engagement from others.

Areas of Agreement / Disagreement

Participants do not reach a consensus, as there are multiple competing views regarding the mechanisms of mass accumulation and the effects of nuclear fusion on star size.

Contextual Notes

Participants' claims depend on various assumptions about stellar formation processes, the nature of gravitational collapse, and the influence of surrounding astrophysical conditions, which remain unresolved.

TShock
Messages
12
Reaction score
0
Why are some stars larger than others? It is my understanding that hydrogen collapses due to gravity into a sphere and when a critical mass is achieved nuclear fusion occurs. Since the critical mass for this to happen is a constant shouldn't all stars be relatively the same size since a star doesn't collect any more mass once fusion starts?
 
Astronomy news on Phys.org
TShock said:
Since the critical mass for this to happen is a constant shouldn't all stars be relatively the same size since a star doesn't collect any more mass once fusion starts?

I don't think this part is true. Why would a star stop collecting mass just because fusion started?
⚛​
 
CaptainQuasar said:
I don't think this part is true. Why would a star stop collecting mass just because fusion started?
⚛​


The force of matter being ejected by Sol would stop any new hydrogen from being collected. The same reason why Mercury has no atmosphere or what would happen to Earth's atmosphere if Sol turns into a red giant.
 
TShock said:
The force of matter being ejected by Sol would stop any new hydrogen from being collected. The same reason why Mercury has no atmosphere or what would happen to Earth's atmosphere if Sol turns into a red giant.

Hmmm. Well, I'm not an astrophysicist or a physicist of any kind, but my thoughts would be: is this true of all stars or just Sol-like ones? Is it really omnidirectional so that mass can't approach from any direction? And would this be true independent of the astrophysical environment, like would it still happen within a dense dust cloud? And does it really happen immediately as soon as fusion starts, or is there a gap in time between fusion and repellent force, during which the inflow of matter from the astrophysical environment will determine the eventual mass of the star?

It also seems like the velocity of the mass would make a difference. Perhaps if the star forms within a large-scale current or flow of matter the force of that “wind” can inject more mass than in a more tranquil environment.
⚛​
 
well I guess either no one knows or my question was so incredibly stupid no one could be bothered to answer it. Thanks to those that did post replys.
 

Similar threads

Undergrad Why Does Gravity Remain when Star Mass Dissipates?
  • · Replies 10 ·
Replies
10
Views
2K
Undergrad J0524-0336, surprisingly high Li concentration
  • · Replies 2 ·
Replies
2
Views
3K
High School Beware of "truthiness" in astronomy in seemingly reliable websites
  • · Replies 21 ·
Replies
21
Views
3K
Undergrad Star formation and heavy elements
  • · Replies 19 ·
Replies
19
Views
5K
High School What happens to the Core of a main sequence star as additional mass is added?
  • · Replies 42 ·
2
Replies
42
Views
4K
Undergrad The stellar system genesis & supernova cycle
  • · Replies 1 ·
Replies
1
Views
2K
Undergrad Questions about the lifecycle of stars
  • · Replies 77 ·
3
Replies
77
Views
9K
High School What Could Explain the Mysterious Beam of Plasma Seen in the Sky in 2017?
  • · Replies 8 ·
Replies
8
Views
3K
Graduate Does iron really kill fusion in stars?
  • · Replies 5 ·
Replies
5
Views
13K
Undergrad What are the possible states of cold iron balls?
  • · Replies 2 ·
Replies
2
Views
2K