Hubble cap­tures far­thest star ever seen

The blue su­per­giant Icarus is spied more than 9 bil­lion light years from Earth in an as­ton­ish­ing dis­cov­ery

All About Space - - Launch Pad -

“This is the first time we’re see­ing a mag­ni­fied, in­di­vid­ual star"

As­tronomers us­ing NASA's Hubble Space Te­le­scope have de­tected the most dis­tant star ever viewed. The enor­mous blue star, which has been nick­named Icarus, is as much as a mil­lion-times more lu­mi­nous and twice as hot as our Sun. It is lo­cated in a very dis­tant spi­ral galaxy and it is so far away that its light would have taken a stag­ger­ing 9 bil­lion years to reach Earth.

Ac­cord­ing to the team lead­ing the dis­cov­ery, the blue su­per­giant ap­pears to us as it did when the uni­verse was about 30 per cent of its cur­rent age, and it is more than 100-times fur­ther away than the next in­di­vid­ual star to have been stud­ied. “This is the first time we’re see­ing a mag­ni­fied, in­di­vid­ual star,” says study leader Pa­trick Kelly, a former Univer­sity of Cal­i­for­nia at Berke­ley post­doc who now works at the Univer­sity of Min­nesota,

Twin Cities.

The find came as the team was mon­i­tor­ing a su­per­nova in the spi­ral galaxy, and was made pos­si­ble thanks to grav­i­ta­tional lens­ing, a quirk of na­ture that acts to am­plify the star's fee­ble glow. Grav­ity from a mas­sive fore­ground clus­ter of gal­ax­ies called MACS J1149+2223 acts as a nat­u­ral lens, bend­ing and am­pli­fy­ing light. Sit­u­ated 5 mil­lion light years from Earth, the clus­ter sits be­tween our planet and Icarus, and it al­lowed for a bet­ter – al­beit fleet­ing – view. In­deed, it was only tem­po­rar­ily mag­ni­fied to 2,000times its true bright­ness. Usu­ally it is ‘only’ mag­ni­fied by 600-times.

The team was able to rule out the source of light as be­ing the su­per­nova they were mon­i­tor­ing. “The source isn’t get­ting hot­ter; it’s not ex­plod­ing. The light is just be­ing mag­ni­fied,” said Kelly. “And that’s what you ex­pect from grav­i­ta­tional lens­ing.” Kelly has also used Icarus to test a the­ory of dark mat­ter and to in­ves­ti­gate the com­po­si­tion of a fore­ground galaxy clus­ter. A state­ment says the team probed what is floating around in the fore­ground clus­ter and ap­peared to rule out the the­ory that dark mat­ter is made up mostly of a large number of pri­mor­dial black holes formed in the birth of the uni­verse. If that was the case, they say, then light fluc­tu­a­tions from the back­ground star would have looked dif­fer­ent.

Kelly also says that more stars like Icarus are ex­pected to be found when the more sen­si­tive James Webb Space Te­le­scope is launched. The joint col­lab­o­ra­tion be­tween NASA, ESA and the Cana­dian Space Agency is set to be launched in May 2020.

This com­pos­ite shows the lo­ca­tion of the most

dis­tant known star, de­tected us­ing Hubble

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