Thursday, September 1, 2011

Ens Sidus Quod non Debet Esse: The Star Which Should not ße

Literally speaking from the Latin, this 'existing star' is being when it should not be. Astronomers, using European Southern Observatory's VLT to examine the star, have come to the conclusion that this star is one which should be not present - with the composition of only hydrogen and helium and the lowest amount of 'metals' heavier than helium, this star sits in the 'forbidden zone' of a universally accepted theorem concerning star formation, which means that it should never have come into being.

The star, named SDSS J102915+172927, due to the fact of its presence in the Sloan Digital Sky Survey or SDSS, while the numbers refer to the object’s position in the night sky, is one of small magnitude, emitting lethargic light; needless to consider its distance. SDSS J102915+172927 is 13 billion light years away, a nice addition to the early universe, in the constellation Leo, and shines at the magnitude of 16.92. Although not impossibly dark, this star is still very dim.

Included in the abstract of An Extremely Primitive Halo Star, the astronomers which found and discovered this irregular, hav noted some key things in the composition and structure of SDSS J102915+172927. "The early Universe had a chemical composition consisting of hydrogen, helium and traces of lithium, almost all other elements were created in stars and supernovae." Yet, a conglomeration of exorbitantly metalpoor stars have been pinpointed. Plenitudes of iron have not been located, but from what they lack in iron, they fashion in carbon, nitrogen, and oxygen. From what astronomers have learned so far about this fact, they have come to the conclusion that "stars with metallicities lower than Z=1.5×105, are ones that cannot form until the interstellar medium that has been enriched above a critical value, estimated to lie in the range 1.5×108≤Z≤1.5×106." Not to mention the exceptions. Astronomers have located the exception - and that is SDSS J102915+172927.

“It was surprising to find, for the first time, a star in this ‘forbidden zone’, and it means we may have to revisit some of the star formation models," said Elisabetta Caffau (Zentrum für Astronomie der Universität Heidelberg, Germany and Observatoire de Paris, France), lead author of the paper. Using specially designed instruments on the VLT, the team of astronomers analyzed the properties and composition as well as allowing them to allot the abundance of chemicals amidst the star. According to that research, another conclusion was based: the proportion of the chemicals of SDSS J102915+172927 are approximately 20 thousand times more bantam than that of our Sun. 

The star is faint, and so metal-poor that we could only detect the signature of one element heavier than helium — calcium — in our first observations,” said Piercarlo Bonifacio (Observatoire de Paris, France), who supervised the project. “We had to ask for additional telescope time from ESO’s Director General to study the star’s light in even more detail, and with a long exposure time, to try to find other metals.” “The star we have studied is extremely metal-poor, meaning it is very primitive. It could be one of the oldest stars ever found,” adds Lorenzo Monaco (ESO, Chile), also involved in the study. “It is a mystery how the lithium that formed just after the beginning of the Universe was destroyed in this star.” Bonifacio added

The researchers also point out that this freakish star is probably not unique. “We have identified several more candidate stars that might have metal levels similar to, or even lower than, those in SDSS J102915+172927. We are now planning to observe them with the VLT to see if this is the case,” concludes Caffau.

Watch the VIDEO here!


  1. The exact literal translation of "Ens Sidus Quod non Debet Esse" is "An existing star which ought not be," or more idiomatically, "An existing star which shouldn't be."

  2. THIS POST HAS RECEIVED THE 2011 BEST ENTRY AWARD! 1st place in eloquence, and simplicity.