Brahmand NewsPrevious Article
Brahmand NewsNext Article
Headlines
  • DefExpo 2020:-DefExpo 2020 themed as "Digital Transformation of Defence" will be held from 5 to 8 February 2020, for the first time at Vrindavan Yojna, Sector 15, Lucknow, Uttar Pradesh....
  • Indo Defence 2020 Expo & Forum :-The Indo Defence Expo 2020 Expo & Forum will be held at Jakarta International Expo Kemayoran, Indonesia, from 4 to 7 November 2020. ...
  • Arms sales of top Indian defence firms drop by 6.9 per cent: SIPRI report:-The combined sales of three public sector Indian defence companies that figure among the world's 100 top arms suppliers dropped by 6.9 per cent to stand at USD 5.9 billion in 2018 despite a rise in the global weapons sales, according to a new report published by a leading Swedish think tank....
  • Eurosatory 2020:-Eurosatory – an international exhibition dedicated to land and airland Defence and Security- will be held from 08 to 12 June 2020 in Paris. ...

Astronomers find 11 runaway galaxies

Line Spacing+- AFont Size+- Print This Article

WASHINGTON (PTI): Astronomers have spotted 11 runaway galaxies that have been flung out of their birthplaces to wander the void of intergalactic space.

An object is a runaway if it's moving faster than escape velocity, which means it will depart its home never to return.

In the case of a runaway star, that speed is more than 500 km per second. A runaway galaxy has to race even faster, travelling at up to 3,000 km per second.

"These galaxies are facing a lonely future, exiled from the galaxy clusters they used to live in," said astronomer Igor Chilingarian at the Harvard-Smithsonian Center for Astrophysics and Moscow State University.

Chilingarian and his co-author, Ivan Zolotukhin of the L'Institut de Recherche en Astrophysique et Planetologie in Toulouse and Moscow State University, initially set out to identify new members of a class of galaxies called compact ellipticals.

These tiny blobs of stars are bigger than star clusters but smaller than a typical galaxy, spanning only a few hundred light-years. In comparison, the Milky Way is 100,000 light-years across. Compact ellipticals also weigh 1,000 times less than a galaxy like our Milky Way.

Prior to this study, only about 30 compact elliptical galaxies were known, all of them residing in galaxy clusters.

To locate new examples Chilingarian and Zolotukhin sorted through public archives of data from the Sloan Digital Sky Survey and the GALEX satellite.

Their search identified almost 200 previously unknown compact ellipticals. Of those, 11 were completely isolated and found far from any large galaxy or galaxy cluster.

"The first compact ellipticals were all found in clusters because that's where people were looking. We broadened our search, and found the unexpected," said Zolotukhin.

These isolated compact galaxies were unexpected because theorists thought they originated from larger galaxies that had been stripped of most of their stars through interactions with an even bigger galaxy. So, the compact galaxies should all be found near big galaxies.

Not only were the newfound compact ellipticals isolated, but also they were moving faster than their brethren in clusters.

"We asked ourselves, what else could explain them? The answer was a classic three-body interaction," said Chilingarian.

A hypervelocity star can be created if a binary star system wanders close to the black hole at the centre of our galaxy. One star gets captured while the other is thrown away at tremendous speed.

Similarly, a compact elliptical could be paired with the big galaxy that stripped it of its stars. Then a third galaxy blunders into the dance and flings the compact elliptical away. As punishment, the intruder gets accreted by the remaining big galaxy.

Tags:

Astronomer  Galaxy  Star  Space  
Line Spacing+- AFont Size+- Print Article

Other Related News

US makes history with first all-female spacewalk

US astronauts Christina Koch and Jessica Meir have become the first all-female pairing to carry out a spacewalk, following a spacesuit flub earlier this year that caused the historic mission to be aborted.

Upcoming Defence Exhibitions

BRAHMOS Missile Systems

Headlines

Brahmand World Defence Update 2019

Image Gallery