The researchers from the Sloan Digital Sky survey have reported most detailed look at the warp of our home galaxy
Usually, one think of spiral galaxies as a flat disc rotating around its centre but about 60-70% of the spiral galaxies including our home galaxy Milky Way have discs with a slight warp or twist.
Not much was known about the warp or twist in our home galaxy because of position of the solar system within the Milky Way
The researchers of the Sloan Digital Sky Survey (SDSS), a consortium of several research organisations dedicated to creation of most detailed 3-dimensional maps of the Universe, after carefully studying the positions and motions of stars all over the Milky Way have traced out the warp. They have reported findings that the Milky Way’s disc is warped and the wrap travels around the galaxy once every 440 million years.
The analysis showed that the twist or the warp is caused by the ripple or the wave travelling through the Milky Way causing individual stars to move up and down. The twist or the warp is continuing gravitational ripple passing through the galaxy caused most likely due to interaction with the satellite galaxy about 3 billion years ago.
Interestingly, our home galaxy Milky Way is expected to collide with the Andromeda galaxy in about 4 billion years from now when both the galaxies will merge with each other.
The Sloan Digital Sky Survey 2021. Press release – The Milky Way does the Wave. Published 15 January 2021. Available online at https://www.sdss.org/press-releases/the-milky-way-does-the-wave/