New model de­tails Rosette Ne­bula and its mys­te­ri­ous hol­low heart

Iran Daily - - Science & Technology -

The size of the empty cav­ity at the cen­ter the Rosette Ne­bula — a hol­low heart — has long puz­zled astronomers. But sci­en­tists now have some an­swers thanks to a new sur­vey of the in­ter­stel­lar cloud.

Ne­bula mod­els sug­gest Rosette’s cen­tral cav­ity should be larger than it is based on the size of its cen­tral stars. But new anal­y­sis sug­gested the dis­crep­ancy is the prod­uct of a mis­un­der­stand­ing of Rosette’s shape, UPI wrote.

The Rosette Ne­bula, or Cald­well 49, is found 5,000 light-years from Earth in the Milky Way. It’s named for its rose-like shape.

Christo­pher Ware­ing, an astronomer at Leeds Uni­ver­sity, said, “The mas­sive stars that make up the Rosette Ne­bula’s cen­tral clus­ter are a few mil­lions of years old and half­way through their life­cy­cle.

“For the length of time their stel­lar winds would have been flow­ing, you would ex­pect a cen­tral cav­ity up to ten times big­ger.”

Stel­lar winds and ra­di­a­tion from a ne­bula’s stel­lar in­hab­i­tant im­pact its size and struc­ture, in­clud­ing the size and shape of its cen­tral cav­ity.

Pre­vi­ous sur­veys of Rosette sug­gested the ne­bula was a thick, donut-like shape, but the lat­est anal­y­sis proved the ne­bula is ac­tu­ally rel­a­tively thin — more a disk than a donut.

When astronomers re­pro­grammed their model of Rosette to ac­count for its thin, disk-like shape, they min­i­mized the dis­crep­ancy.

Ware­ing said, “We sim­u­lated the stel­lar wind feed­back and for­ma­tion of the ne­bula in var­i­ous molec­u­lar cloud mod­els in­clud­ing a clumpy sphere, a thick fil­a­men­tary disc and a thin disc, all cre­ated from the same low den­sity ini­tial atomic cloud.

“It was the thin disc that re­pro­duced the phys­i­cal ap­pear­ance — cav­ity size, shape and mag­netic field align­ment — of the ne­bula, at an age com­pat­i­ble with the cen­tral stars and their wind strengths.”

The ac­cu­racy of the new model was im­proved by fresh data from the Gaia sur­vey, which in­cluded ob­ser­va­tion of sev­eral stars in the ne­bula.

Astronomers de­scribed their im­proved model in the jour­nal Monthly No­tices of the Royal As­tro­nom­i­cal So­ci­ety.

Sci­en­tists cred­ited im­prov­ing tech­nol­ogy for the ef­fi­ciency with which the new re­search was con­ducted.

Astronomer Martin Cal­laghan said, “The fact that the Rosette Ne­bula sim­u­la­tions would have taken more than five decades to com­plete on a stan­dard desk­top com­puter is one of the key rea­sons we pro­vide pow­er­ful su­per­com­put­ing re­search tools.

“These tools en­abled the sim­u­la­tions of the Rosette Ne­bula to be done in a mat­ter of a few weeks.”


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