Huge stellar dust cloud vanishes, leaving only questions

As­tro­no­mers are re­port­ing a baf­fling dis­cov­ery nev­er seen be­fore: A huge cloud of dust around a near­by star has dis­ap­peared.

“It’s like the clas­sic ma­gi­cian’s trick — now you see it, now you don’t,” said Carl Melis, a post­doc­tor­al schol­ar at Uni­vers­ity of Cal­i­for­nia San Die­go and lead au­thor of the re­search. “Only in this case, we’re talk­ing about enough dust to fill an in­ner so­lar sys­tem, and it really is gone!”

“It’s as if the rings around Sat­urn had dis­ap­peared,” said co-au­thor Ben­ja­min Zuck­er­man, a Uni­vers­ity of Cal­i­for­nia Los An­ge­les as­tron­o­mer. “This is even more shock­ing be­cause the dusty disc of rocky de­bris was big­ger and much more mas­sive than Sat­urn’s rings. The disc around this star, if it were in our so­lar sys­tem, would have ex­tend­ed from the sun half­way out to Earth, near the or­bit of Mer­cury.”

Re­search on the cos­mic van­ish­ing act ap­pears July 5 in the jour­nal Na­ture. The eerie event oc­curred around a star some 450 light years from Earth, in the di­rec­tion of the con­stella­t­ion Cen­tau­rus. A light year is the dis­tance light travels in a year.

“We don't have a satisfactory explanation,” said Melis. “There is no ev­i­dence to sug­gest that the star zapped the dust with some sort of mega-flare or any oth­er vi­o­lent event.”


[link to www.world-science.net]