Determining stable orbits for other stars

In summary, your friend is disputing the universality of the law of gravity, citing the Roche Limit as evidence.
  • #1
aau
2
0
Howdy,
first post, good to be here. I'm sure it will be a learning experience.

My question concerns planetary formation and planet orbits for other stars, specifically the star Vega. I'm having a "disagreement" with someone who claims that Vega's mass, diameter, and density prevents the formation of planets close to the star. I'm having trouble getting this person to define "close", nevertheless I maintain we don't know nearly enough about the physics of planet formation to know this for sure. He also says replace the sun with Vega and Mercury and Venus would not have stable orbits. When I asked the reason he cited the universal law of gravitation and calculated the force of Vega's gravity at Mercury's distance. I find this unconvincing. He also stated force of gravity depends on diameter and density as well as mass, which I dispute. So can anyone clue me in as to what I'm missing here? Thanks!
 
Astronomy news on Phys.org
  • #2
Maybe your friend is talking about the Roche Limit ? If a smaller body orbits too close to a massive body it will suffer tidal stresses and be broken up?
 
  • #3
I could calculate the Roche Limit for Vega if I knew its density and the density of protoplanets in the circumstellar disk. I'm sure the density of Vega is less than the sun's density of 1.41, and I suspect the density of condensed material close to the star must be similar to iron or rocky asteroids, so around 3-5. Plugging in some guesstimates i get a Roche Limit of around 3 million kilometers, pretty close to the star. This would seem to strengthen my case. I suspect this distance is actually too close to the star's feeding zone, however, so no planet could form as it would be starved for material. Still this is a start. Thanks.
 
  • #4
You really don't need to know Vega's density, only it's mass and use the formula:

[tex]
R_{Roche}= 1.52 \sqrt[3]{\frac{M}{\rho}}[/tex]

Where

[tex]M[/tex] is the mass of Vega
and

[tex]\rho[/tex] is the density of the protoplanet.
 
  • #5
Welcome to Physics Forums, aau!
 

1. How do scientists determine stable orbits for other stars?

Scientists use various methods and techniques to determine stable orbits for other stars. One common method is to observe the motion of the star and its surrounding planets using telescopes and other advanced instruments. By analyzing the data collected, scientists can calculate the orbital parameters and determine if the orbit is stable.

2. What factors influence the stability of orbits for other stars?

The stability of orbits for other stars can be influenced by several factors, such as the mass and composition of the star and its surrounding planets, the distance between the star and its planets, and the presence of other celestial bodies that may affect the gravitational pull.

3. Why is it important to determine stable orbits for other stars?

Determining stable orbits for other stars is crucial in understanding the potential for life on other planets. If a planet has a stable orbit, it may have the right conditions to support life. Additionally, studying stable orbits can also provide insights into the formation and evolution of planetary systems.

4. Can scientists predict the stability of orbits for other stars in the long term?

While scientists can make predictions based on current data, it is challenging to accurately predict the stability of orbits for other stars in the long term. Small changes in the system can significantly impact the stability of orbits over time, making long-term predictions difficult.

5. How do scientists use computer simulations to determine stable orbits for other stars?

Computer simulations are an essential tool in determining stable orbits for other stars. Scientists can input data such as the mass and position of the star and its planets into the simulation, and the software will calculate the orbital parameters and predict the stability of the orbits. These simulations allow scientists to test different scenarios and make predictions about the long-term stability of orbits for other stars.

Similar threads

  • Astronomy and Astrophysics
Replies
8
Views
2K
  • Astronomy and Astrophysics
Replies
19
Views
3K
  • Astronomy and Astrophysics
Replies
6
Views
2K
  • Astronomy and Astrophysics
Replies
12
Views
2K
  • Sci-Fi Writing and World Building
Replies
21
Views
855
Replies
17
Views
2K
  • Astronomy and Astrophysics
Replies
12
Views
3K
  • Astronomy and Astrophysics
Replies
2
Views
1K
  • Astronomy and Astrophysics
Replies
23
Views
3K
  • Astronomy and Astrophysics
Replies
18
Views
3K
Back
Top