Mighty Dons Of Science News

Artist'sren­der­ing of what HD 131488's in­ner plan­e­tary sys­tem might look like as two large rocky bod­ies col­lide. In­set il­lus­trates the lo­ca­tion of HD 131488's dust belts (top) and com­pa­ra­ble re­gions to our own So­lar Sys­tem (bot­tom). HD 131488's hot in­ner dust belt has si­m­i­lar sep­a­ra­tions from its host star as the ter­res­tri­al plan­et zone around our Sun while the star's cool dust belt has si­m­i­lar sep­a­ra­tions from its host star as the Kuiper Belt re­gion in our So­lar Sys­tem. Al­so shown for our So­lar Sys­tem are the or­bits of Ju­pi­ter, Sat­urn, Ura­nus, and Nep­tune.</font> (Cour­te­sy Gem­i­ni Ob­serv­a­to­ry)

A far-off so­lar sys­tem seems to be form­ing from a strange dust whose make­up is un­like that of our and oth­er so­lar sys­tems, as­tro­no­mers say.

The researchers at the Univers­ity of Cal­i­for­nia Los An­ge­les found ev­i­dence for the forma­t­ion of young, rocky plan­ets from dust cir­cling a star some 500 light-years away. A light-year is the dis­tance light trav­els in a year

“Un­til now, warm dust found around oth­er stars has been very si­m­i­lar in com­po­si­tion to as­ter­oi­dal or com­et­ary ma­te­ri­al in our So­lar Sys­tem,” said the uni­vers­ity’s Carl Melis, who led the re­search while a grad­u­ate stu­dent.

But this case is diff­er­ent, he said.

“Typic­ally, dust de­bris around oth­er stars, or our own Sun, is of the ol­i­vine, py­rox­ene, or sil­ica va­ri­e­ty, min­er­als com­monly found on Earth,” he noted. But this ma­te­ri­al “is not one of these dust types. We have yet to iden­ti­fy what spe­cies it is.”

Melis re­ported the find­ings last Wednes­day at the annual Amer­i­can As­tro­nom­i­cal So­ci­e­ty meet­ing in Wash­ing­ton, D.C.

The star, known as HD 131488, ap­pears to be sur­rounded by warm dust in a re­gion called the ter­res­tri­al plan­et zone, where tem­per­a­tures are si­m­i­lar to those on Earth, Melis said. He added that the dust seems to harbor rocky, emb­ry­onic planets that have re­cently coll­ided.

“What makes HD 131488 truly un­ique is the un­iden­ti­fied dust spe­cies re­leased from the col­lid­ing bod­ies as well as the pres­ence of cold dust far away from the star,” said as­tron­o­mer Ben­ja­min Zuck­er­man of the univers­ity, a co-author of the re­search. “These two char­ac­ter­is­tics make HD 131488 un­like any oth­er star with ev­i­dence for mas­sive quanti­ties of dust in its ter­res­tri­al plan­et zone.”

The re­search­ers an­a­lyzed the warm in­ner dust through in­fra­red im­ag­ing and spec­tros­co­py us­ing an in­stru­ment called T-ReCS on the Gem­i­ni South tel­e­scope in Chil­e. Spec­tros­co­py is the anal­y­sis of the com­po­si­tion of ob­jects us­ing the spec­trum of light they give off.

Melis and his team ar­gue that the most plau­si­ble ex­plana­t­ion for the un­usu­al abun­dance of warm dust is a re­cent col­li­sion of two rocky plan­e­tary mass bod­ies.

While the mys­te­ri­ous warm dust lies at a dis­tance from HD 131488 that is com­pa­ra­ble to the Earth-Sun separa­t­ion, the team al­so found cool­er dust about 45 times fur­ther out. This out­er dusty re­gion is anal­o­gous to the Kuiper Belt in our own So­lar Sys­tem where many mi­nor plan­ets or­bit the Sun just be­yond the or­bit of Nep­tune.

“The hot dust al­most cer­tainly came from a re­cent cat­a­stroph­ic col­li­sion be­tween two large rocky bod­ies in HD 131488’s in­ner plan­e­tary sys­tem,” Melis said. But the cool­er dust “is probably left over from plan­et forma­t­ion that took place far­ther away from HD 131488.”

HD 131488 lies in the di­rec­tion of the con­stella­t­ion Cen­tau­rus and is three times heav­i­er and 33 times more lu­mi­nous than our own Sun. The star is part of a ma­jor, south­ern-hem­i­sphere star form­ing re­gion known as the Upper-Cen­tau­rus-Lupus as­socia­t­ion whose mem­bers are be­lieved to be about 10 mil­lion years old. By con­trast, the Sun and Earth are about 4.6 bil­lion years old..