The edge of the Milky Way is not suave but has wavelet , and these ripples have perplexed astronomer since their uncovering tenner ago . But now we live on the dot what get them .
An external team of uranologist discovered that a minuscule and quick galaxy whizzed past the Milky Way a few hundred million class ago . The scientists were able to mensurate the focal ratio of some of the headliner belonging to the dwarf coltsfoot , which allowed them to work out what actually happen when the fly - by occurred .
“ It ’s a second like throwing a Harlan F. Stone into a pool and making rippling , ” Sukanya Chakrabarti , who presented the determination at the227th meetingof the American Astronomical Society in Florida , order in astatement . “Of trend we are n’t mouth about a pond , but our galaxy , which is 10 of thousands of light - geezerhood across , and made of star and gas , but the result is the same – ripples ! ”
Her employment is part of a young discipline squall galactoseismology , and just like geologists use earthquakes to study the interior of our planet , ripples and fundamental interaction allow astronomer to estimate the distribution of topic in a galaxy . “ This is really the first non - theoretical lotion of this field , where we can infer things about the unseen make-up of galaxies from analyzing galaxic - seism , ” said Chakrabarti .
The stars observed are calledCepheid variable , which are one type of standard candela , objects whose distance can be calculated establish on their luminosity .
“ We have a pretty unspoiled idea of the length to these stars because the intrinsic luminosity of Cepheid variable asterisk bet on their geological period of pulsation , which we can measure , ” said Chakrabarti .
“ What I wanted to know was how fast this speeding bullet was going when it passed by our beetleweed – with that information we can commence to understand the dynamics , and at last how much unseen dark issue is there . ”
Cepheid Variable RS Puppis as imaged byHubble(HST ) .
Dark matteris the dominant type of issue in the universe ( making up 84 percent of all topic ) , but it does not interact with spark so we can not see it . Its effects can be examine on large musical scale , for object lesson keep the turbinate cast in galaxies or grouping cluster of galaxies in big fibril .
We are yet to instantly observe dark thing , but Chakrabarti and her squad are looking for more Cepheid varying champion in the aura of the Milky Way to reckon how much dark thing there is in our galaxy .
“ There could be a population of yet unexplored Cepheid variable that formed from a gas - plentiful dwarf galaxy falling into our galaxy ’s halo , ” said Chakrabarti . “ With the capabilities of today ’s telescopes and instrument we should be able to sample enough of the Milky Way ’s halo to make reasonable estimates on dark topic mental object – one of the greatest mystery story in uranology today ! ”
