Using a century - old technique to probe the borders of our galaxy , a squad of Australian astronomers has estimate the amount of glum affair in the Milky Way . Intriguingly , according to their young calculations , there could be half as much of this poorly interpret heart in our extragalactic nebula as once thought . Their work has been print inThe Astrophysical Journal .
Dark topic is an tough substance ; it doesn’tabsorb , reflect or utter light , meaning it ’s invisible to both our oculus and the instrument we use to detect normal topic . Because it does n’t interact with the electromagnetic force play , we only make love it subsist because it maintain gravitational effect on visible thing . Although we ca n’t see it , physicist have calculated that it makes up around25%of the universe . The stuff of our bodies , stars , dust and satellite , or “ normal ” matter , make up a mere 4 % . The eternal rest is something even more strange- dark-skinned energy .
Although dark thing is very difficult to study , investigator are able to measure out its mass using a method acting pioneer in the early 19thCentury by a British stargazer calledJames Jeans . This technique , which was develop long before scientists even knew dark matter existed , involves measuring the speed that star are travelling throughout our galaxy . While stargazer have been doing this for some time , they had never used it to examine the very edge of the Milky Way , which is what they did in this latest study .
By peering this far out , some 5 million billion km from Earth , they were able to hold measurements that admit them to count on the mass of dreary affair in our galaxy . Although it was found to be a pretty huge human body , some 800,000,000,000 times the batch of our sun ( 8 x 1011solar masses ) , this is around one-half of the previous estimates .
The squad ’s raw measurement has also helped them solve a trouble that has been “ a spikelet in the cosmological side for almost 15 year , ” according to study atomic number 27 - authorProfessor Geraint Lewis .
As explained by lead generator Dr. Prajwal Kafle , the wide accept idea of galaxy formation and evolution – the Lambda Cold Dark Matter theory– presage that there should be legion prominent orbiter coltsfoot around the Milky Way . However , when their fresh measure is utilise , the theory presage that there should only be three . And that is precisely what we observe : the Large Magellanic Cloud , the Small Magellanic Cloud and the Sagittarius Dwarf Galaxy .
[ ViaInternational Centre for Radio Astronomy Research , siliconrepublicandThe Astrophysical Journal ]
