4 ms·
I wonder what its velocity is in relation to the sun. Twenty two light years in 70,000 years seems rather fast!
by Santosh83 9y ago
I wonder what its velocity is in relation to the sun. Twenty two light years in 70,000 years seems rather fast!
- jonsen 9y agoThat would be 20/70000 c ~= 300000 km/h ~= 200000 mph
- maze-le 9y agoIt seems to be quite fast, but not exceptionally. Lets do a quick calculation, and neglect all aspects of proper stellar kinematics -- Our sun has traveled quite some distance itself during the 70000 years, I don't properly described that motion itself, so take everything with a grain of salt: Lets call the speed difference of the star with respect to our sun `Δv` Δv = 20 [ly] / 70 000 [y] = 0.000285714 [ly/y] Now, lets convert the unit `ly/y` into a unit that we can relate to, to get a grasp on it: 1ly = 63241.08AU[1]. Δv = 0.000285714 [ly/y] = 18.0688 [AU/y] 18 AU is about the perihelion of Uranus, a bit smaller still. So the star traveled on average, with respect to our sun, about the smallest distance between the Sun and Uranus in 1 year. To put that in perspective: Δv = 18.0688 [AU/y] * 149597900 [km/AU] / 31557600 [s/y] = 85.6550 [km/s] The LSR[2] is about 220 km/s. The Suns deviation from this value is about +14 km/s[3]. So an object with Δv of about 85.6 km/s is quite fast in comparison. But this is still nothing compared to hypervelocity stars, wich can be more than 1000 km/s faster and are exceeding the escape velocity of the galaxy. ------ [1] : 1 AU (Astronomical unit) is the average distance from Earth to Sun. [2] : Local Standard of Rest -- average speed of our stellar neighborhood through the galaxy. [3]: https://arxiv.org/abs/1411.3572 https://arxiv.org/abs/1411.3572