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Universe Simulator
20 years 10 months ago #8156
by Jim
Replied by Jim on topic Reply from
LB, I see I misused the term velocity in my haste. The correct term is speed not velocity of course, so you are right. Please subtitute the term speed where I used velocity in the above post. Sorry about that-you got me on that in the past.
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20 years 10 months ago #8346
by Rudolf
Replied by Rudolf on topic Reply from Rudolf Henning
To what extend have star velocities been mapped at different distances from our galaxy center?
I'm looking for some 'real' numbers to also include in my 'simulator' which is taking shape slowly.
I'm looking for some 'real' numbers to also include in my 'simulator' which is taking shape slowly.
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- Larry Burford
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20 years 10 months ago #8449
by Larry Burford
Replied by Larry Burford on topic Reply from Larry Burford
In the dim past I read about a rule of thumb based on the observation that Earth's orbital speed is near the average for all of the planets orbiting Sol and Sol's orbital speed is near the average for stars in the Milkey Way.. It goes something like this:
Each step up and down the scale ladder sees a speed change of about one order of magnitude.
So Sol should orbit the center of our galaxy at about 300 km/sec, and the Milky Way should orbit the local cluster at about 3000 km/sec. As luck would have it, the Moon orbits Earth at about 3 km/sec.
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Obviously the numbers depend on how far something is from the center of its orbit etc., so they are very inexact. But you need a range of values so that shouldn't be a problem.
I suppose you could get the orbital speeds for Mercury and Neptune or Pluto and use a similar rule of thumb to add predictions for minimum and maximum values for other scales to this average value.
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I'm still wondering if we know for sure that stars orbit (as in a closed repeating ellipse) the center of their galaxy, or if they spiral outward. After all, we've never actually seen a galaxy rotate. And accurate distance measurements are only available out to about 1000 ly. And (if you believe SR) time is a function of distance as well as speed.
LB
Each step up and down the scale ladder sees a speed change of about one order of magnitude.
So Sol should orbit the center of our galaxy at about 300 km/sec, and the Milky Way should orbit the local cluster at about 3000 km/sec. As luck would have it, the Moon orbits Earth at about 3 km/sec.
===
Obviously the numbers depend on how far something is from the center of its orbit etc., so they are very inexact. But you need a range of values so that shouldn't be a problem.
I suppose you could get the orbital speeds for Mercury and Neptune or Pluto and use a similar rule of thumb to add predictions for minimum and maximum values for other scales to this average value.
===
I'm still wondering if we know for sure that stars orbit (as in a closed repeating ellipse) the center of their galaxy, or if they spiral outward. After all, we've never actually seen a galaxy rotate. And accurate distance measurements are only available out to about 1000 ly. And (if you believe SR) time is a function of distance as well as speed.
LB
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20 years 10 months ago #8349
by Rudolf
Replied by Rudolf on topic Reply from Rudolf Henning
I also won't be supprise if the stars of the milkyway is actually spiralling out instead of orbiting. The distribution of stars are so irradic that the idea of cumulative attraction towards the galaxy center over a long period of time is hard to believe.
Rudolf
Rudolf
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