Signatures of the first stars

April 15, 2005

A primitive star with extremely low iron content has been discovered by an international research team from Sweden, Japan, Germany, USA, Australia and Great Britain. This indicates the original composition of the gas from which the star formed had low iron content. The results are published in Nature online this week.

In 2001, the giant star HE0107-5240 was discovered among a large number of stars examined as part of the Hamburg/ESO* survey. Detailed studies revealed that the star had by far the lowest iron content ever recorded - 200 000 times lower than the Sun. Previously, only stars with iron contents up to 10 000 times lower than the solar value were known. Recently, a second star was discovered with similar iron content, designated HE1327-2326.

"These two stars are the most chemically primitive stars known, and therefore provide information on the nature of the first objects that formed in the Universe after the Big Bang," Paul Barklem from Uppsala university, Sweden, says.

Notably, HE1327-2326 is not a giant but a dwarf or sub-giant star, meaning that it is comparatively unevolved. The abundance of some chemical elements in evolved giant stars may have been altered by processes occurring during the star's evolution; however, in an unevolved dwarf or sub-giant star we expect that the chemical composition is close to the original composition of the gas from which the star formed.

Analysis of the spectra for both stars, obtained with the world's largest telescopes, allows the chemical composition of each star to be determined. The stars' chemical abundances show similarities, such as large abundances of carbon and nitrogen, which suggest that these two stars may have formed in a similar way. The detailed interpretation of the chemical signatures of these two stars, and similar stars for which we continue to search, should help us to understand exactly how the first generations of stars were formed, and which elements were produced when they ended their lives in supernova explosions.

Source: Swedish Research Council

Explore further: First clear image made of accretion disk surrounding young star

Related Stories

Pure iron grains are rare in the universe

February 8, 2017

Pure iron grains in interstellar space are far rarer than previously thought, shedding new light on the evolution history of matters in the universe.

Recommended for you

SpaceX to launch classified US govt payload Sunday

April 29, 2017

SpaceX on Sunday is scheduled to make its first military launch, with a classified payload for the National Reconnaissance Office, which makes and operates spy satellites for the United States.

Is dark matter 'fuzzy'?

April 28, 2017

Astronomers have used data from NASA's Chandra X-ray Observatory to study the properties of dark matter, the mysterious, invisible substance that makes up a majority of matter in the universe. The study, which involves 13 ...

Mineral resource exhaustion is just a myth: study

April 28, 2017

Recent articles have declared that deposits of raw mineral materials (copper, zinc, etc.) will be exhausted within a few decades. An international team including the University of Geneva (UNIGE), Switzerland, has shown that ...

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.