# Naked Science Forum

## Non Life Sciences => Physics, Astronomy & Cosmology => Topic started by: captcass on 20/04/2021 16:33:07

Title: What is the Galactic Rotation Velocity of Betelguese?
Post by: captcass on 20/04/2021 16:33:07
I am trying to find the Galactic Rotation Velocity for Betelguese. Anybody know where I can find that info?
Title: Re: What is the Galactic Rotation Velocity of Betelguese?
Post by: Halc on 20/04/2021 17:20:38
Like all objects at this radius from the galactic center, we're all travelling as a clump at the same ~230 km/sec relative to the center of mass of the galaxy.
This is assuming a reasonably low eccentricity. Very few objects have one, and any nearby thing that does would have significant motion relative to the neighborhood through which it is passing.

Most stars have some tangential velocity as we cycle above and below the galactic plane, but that component is variable and doesn't contribute significantly to our orbital period (known as the cosmic year).
Title: Re: What is the Galactic Rotation Velocity of Betelguese?
Post by: captcass on 20/04/2021 18:56:53
Thank you, Halc. I know all that. I need more specific than ~. I want to derive it using my formula for galactic rotation velocities. (I show the derivation of that formula in the "What is Space" topic in the New Theories section.) I have derived formulas based on time dilation for both planetary orbits and Galactic rotational velocities. The galactic formula works fine for the Sun at 231 km/s, and after looking at the info for Betelguese and doing some math, I believe it will work there, too. It is the only other star we have enough data on to do that.
Title: Re: What is the Galactic Rotation Velocity of Betelguese?
Post by: evan_au on 20/04/2021 22:20:17
Quote from:
Betelguese ... is the only other star we have enough (Galactic Rotation Velocity) data
Why then did you start this thread with trying to find Galactic Rotation Velocity data for Betelgeuse?

The Gaia spacecraft is measuring the 3D positions and lateral velocities of a billion stars in our galaxy.
- A parallel ground-based project is measuring the radial velocities
- They have produced their first two Data Releases.
- Perhaps most accessible, the Gaia Sky application allows you to explore space in 3D. (It should adapt to your preferred language, and is available for Windows, MAC and several other operating systems)