2021年4月27日 · I don't get the difference between the two terms named "Eccentricity" and "Ellipticity", especially, in astronomy. I understand eccentricity as a measure of the curvature of a orbit but what is ellipticity?

2016年2月15日 · What is the best approach to determine the ellipticity of galaxies in the SDSS DR12. I have read this page. Are those really good methods? Do flux-weighted second moments (as given in the stokes

2024年2月10日 · I understand that ellipticity is a very important concept in weak gravitational lensing because it describes the shape properties of the transformed galaxy. Shear, on the other hand, also describes the shape properties of the transformed galaxy.

2016年2月17日 · What methods exist to calculate the ellipticity of galaxies and what are their drawbacks? I have asked this question about ellipticity in the SDSS but I want to know about general methods for cases where I have just an image of a galaxy.

2019年8月18日 · The ellipticity cannot be greater than 1, for any kind of galaxy. (Or equal to 1, really, as that would require an infinitely thin disk.)

2021年4月8日 · The inclinations of spiral galaxies can be coarsely derived from the ellipticity of apertures used for photometry, assuming that the image of a spiral galaxy is the projection of a disk with the shape of an oblate spheroid.

2013年12月23日 · Why do planets rotate around a star in a specific elliptical orbit with the star at one of it's foci? Why isn't the orbit a circle?

2022年6月3日 · I have been struggling for a few days with this. I know just my distance from gravity origin, gravity source mass and my actual velocity vector on the orbit. Can I calculate whole trajectory with t...

2020年11月16日 · As a planet, Saturn has the highest flattening (ellipticity) which is 0.09796. So, it makes Saturn with the largest equatorial bulge as a planet and as such Saturn is the flattest planet. However, I have encountered this statement from here: Earth's Moon is even less elliptical, with a flattening of less than 1/825, while Jupiter is visibly oblate at about 1/15 and …

2023年3月10日 · SAO DS9 is a powerful software tool for viewing and analyzing astronomical images, and there are many other parameters you can determine for galaxies using DS9. Here are some additional parameters you may be interested in: Surface brightness: You can use DS9 to measure the surface brightness of a galaxy, which can provide information about its …