Globular clump are spherical collecting of stars that field extragalactic nebula . More than 150 of them have been observe around the Milky Way alone . Comprehensive studies of these and many others orbit distant galaxies suggest they formed from the former coevals of star , but a new discovery might add this scenario .
An external squad of investigator has discovered a structure around the Milky Way , dubbed the Phoenix Stream . This is a paste out typewriter ribbon of stars that ’s believe to be what remain of an ancient globular cluster rip aside by the Milky Way about 2 billion year ago .
What is sincerely unique about the Phoenix Stream is its composition of stars . As reported in the journalNature , the researchers probably found what remains of the oldest known globular cluster , a keepsake of a departed age .
“ Once we have sex which stars belong to the watercourse , we value their teemingness of elements toilsome than hydrogen and atomic number 2 ; something astronomer refer to as metallicity . We were really surprised to rule that the Phoenix Stream has a very modest metallicity , make it distinctly dissimilar to all of the other globose clusters in the Galaxy , ” conduct generator Zhen Wan , a graduate researcher at the University of Sydney , said in astatement . “ Even though the cluster was destroy billions of years ago , we can still tell it formed in the early Universe from the composition of its stars . ”
globose clusters are believed to have a “ metallicity storey ” , below which they ca n’t forge in the agency we anticipate them to . This minimum value come from the expected enrichment from the earliest stars that were made exclusively of H and helium , and their explosive demise that spread heavier elements into the cosmos . If the Phoenix Stream was indeed a globular cluster , then maybe the universe has more than one means to form these compact collections of stars .
“ This current come from a cluster that , by our understanding , should n’t have existed , ” explained co - writer Associate Professor Daniel Zucker from Macquarie University .
“ One possible account is that the Phoenix Stream represents the last of its sort , the end of a population of globular clusters that was stick out in radically unlike environments to those we see today , ” added Dr Ting Li from Carnegie Observatories and loss leader of theS5 international collaborationism , which analyze stellar streams .
There are many unanswered question . The squad remains unsure of how the Phoenix Stream might have take form and if it is unique , but they design to study more stellar streams to find out .
