Milky Way galaxy ‘wobbles’

October 23, 2013 03:16 pm | Updated November 16, 2021 09:01 pm IST - Berlin

An artist rendering shows the different types of planets in our Milky Way galaxy detected by NASA’s Kepler. File photo

An artist rendering shows the different types of planets in our Milky Way galaxy detected by NASA’s Kepler. File photo

Astronomers have discovered that besides being permanently in motion, our Milky Way galaxy also makes small wobbling or squishing movements.

Being a barred spiral galaxy, Milky Way rotates around the Galactic centre. In addition to the regular Galactic rotation, scientists found the Milky Way moving perpendicular to the Galactic plane.

The galaxy makes small wobbling or squishing movements.

It acts like a Galactic mosh pit or a huge flag fluttering in the wind, north to south, from the Galactic plane with forces coming from multiple directions, creating a chaotic wave pattern, researchers said.

However, the source of the forces is still not understood. Possible causes include spiral arms stirring things up or ripples caused by the passage of a smaller galaxy through our own.

An international team of astronomers, including Mary Williams from the Leibniz Institute for Astrophysics Potsdam (AIP) in Germany, detected and examined this phenomenon with the RAdial Velocity Experiment (RAVE), a survey of almost half a million stars around the Sun.

In the study, RAVE stars were used to examine the kinematics (velocities) of stars in a large, 3D region around the Sun — the region surveys 6,500 light years above and below the Sun’s position as well as inwards and outwards from the Galactic centre, reaching a quarter of the way to the centre.

Using a special class of stars, red clump stars, which all have about the same brightness, mean distances to the stars could be determined.

This was important as then the velocities measured with RAVE, combined with other survey data, could be used to determine the full 3D velocities (up-down, in-out and rotational).

The RAVE red clump giants gave an unprecedented number of stars with which it is possible to study 3D velocities in a large region around the Sun.

The 3D movement patterns obtained showed highly complex structures. Researchers then concentrated on differences between the north and south of the Galactic plane.

From these velocities it was seen that our Galaxy has a lot more going on than previously thought. The velocities going upwards and downwards show that there is a wave-like behaviour, with stars sloshing in and out.

The study was published in Monthly Notices of the Royal Astronomical Society (MNRAS).

0 / 0
Sign in to unlock member-only benefits!
  • Access 10 free stories every month
  • Save stories to read later
  • Access to comment on every story
  • Sign-up/manage your newsletter subscriptions with a single click
  • Get notified by email for early access to discounts & offers on our products
Sign in

Comments

Comments have to be in English, and in full sentences. They cannot be abusive or personal. Please abide by our community guidelines for posting your comments.

We have migrated to a new commenting platform. If you are already a registered user of The Hindu and logged in, you may continue to engage with our articles. If you do not have an account please register and login to post comments. Users can access their older comments by logging into their accounts on Vuukle.