Gaia Space Observatory Finds Half a Million New Stars in Milky Way

Subject : Science and Tech

SECTION: Space technology

Gaia space mission:

Launched by: European Space Agency (ESA).
Aim: To create a 3D map of our galaxy.
After observing some 1.8 billion stars, it has created a near complete map of the Milky Way. But they did not have a clear view of parts of the sky that were packed with stars.

Globular cluster:

A globular cluster is a spheroidal conglomeration of stars that is bound together by gravity, with a higher concentration of stars towards their centers.
They are some of the oldest objects in the universe.
Spotting these clusters helped scientists realize that the sun was not at the centre of the spiral Milky Way galaxy.

Recent study:

Scientists have focussed on the Omega Centauri cluster, some 17,090 light years from Earth.
The study revealed half a million new stars in just this one cluster. It also found cosmic objects so heavy they bend light itself.
The majority of the galaxy’s globular clusters are situated near the centre of the Milky Way. Using their locations, they found that the sun (and Earth) was in the open clusters found in one of the galaxy’s spiral arms — the Sagittarius arm.
The data can help us understand how the stars of the Milky Way are distributed and why some parts of the universe have more mass than others.

Why did Gaia choose Omega Centauri?

Omega Centauri is the largest known globular cluster in the Milky Way that can be seen from Earth. It appears to be almost as big as a full Moon when observed from dark, remote areas.
It has a sprawling diameter of 150 light years. It is estimated to be four million times as heavy as the sun and spread across some 10 million stars.

Universe through gravitational lens:

Light tends to get warped when it passes through heavy objects like globular clusters.
These heavy clusters have a greater gravitational pull. So they bend light in a phenomenon called gravitational lensing.
The clusters behave like a giant magnifying glass, or lens, that can amplify the light and cast multiple images of the faraway source onto the sky.
The Omega Centauri cluster’s gravity bend light coming from distant sources called quasars.
- Quasars are remote sources of bright light that could be powered by black holes.

Source: The Wire