Solar System genealogy revealed by meteorites

Aug 29, 2012
Solar System genealogy revealed by meteorites
Infrared image of cold gas (blue) accumulated around a massive star(masked, at the centre of the image) which is a few million years old. Solar mass stars will form in this cold gas shell having a mass of 1000 solar masses, and located at roughly 10 pc (300 000 billion kilometres) from the central massive star. Our Sun was born in such a shell 4.5 billion years ago, together with some hundred of twin stars. © Picture from Deharveng et al. (2010) Astronomy & Astrophysics 523, A6.

(—The stellar environment of our Solar System at its birth is poorly known, as it has accomplished some twenty revolutions around the Galactic centre since its formation 4.5 billion years ago. Matthieu Gounelle from the Laboratoire de Minéralogie et Cosmochimie du Muséum (Muséum national d'Histoire naturelle/CNRS) and Georges Meynet from the Observatoire de Genève established the Solar System genealogy in elucidating the origin of a radioactive element, 26Al, which was present in the nascent Solar System. Their results are published this week in the journal Astronomy & Astrophysics.

Aluminium-26, a radioactive isotope of aluminium with a mean life of one million years was present in some meteoritic inclusions during the very first stages of the Solar System, 4.5 billion years ago. Its presence in the nascent Solar System had long been attributed to a supernova which would have exploded nearby the forming Solar System. However, the rarity of the association of a supernova and a forming star would imply that very special conditions lead to the Solar System formation.

From astronomical observations of young stars and astrophysical modelling, the two authors showed that the 26Al originated instead from the wind of a massive star born a few million years before the Solar System. This star, not only synthesized the 26Al found in meteoritic inclusions but also lead to the formation of the Solar System in accumulating gigantic quantities of hydrogen gas, from which a new
star generation (including our Sun) formed. This massive star can therefore be considered as the parent star of our Solar System.

The authors show that the parent massive star, which they propose to call Coatlicue (the Sun's mother in the Aztec cosmogony), and which is roughly 30 times more massive than our Sun, was born together with roughly 2000 stars. Coatlicue died since then in a supernova explosion. The Sun was born together with a few hundred twin stars whose chemical composition was identical to ours. These stars had a mass comparable to that of the Sun, but did not influence its development nor that of its planets. These twin stars are now dispersed in the Galaxy and cannot be identified. The proposed mechanism being a generic star formation process, it implies that the birth of our did not require special conditions as was believed until now. Numerous in the Galaxy were formed under similar conditions, suggesting that the Sun is a banal star.

Explore further: A colorful gathering of middle-aged stars

More information: Matthieu Gounelle & Georges Meynet. The Solar System Genealogy revealed by Meteorites. Astronomy & Astrophysics 545, A4 (2012) - DOI: 10.1051/0004-6361/201219031

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3 / 5 (1) Aug 29, 2012
Neat! I don't think earlier models all required special conditions as much as finetuning the models; supernovas in molecular clouds do happen and this model includes them as well.

But the model (free access!) separates 26Al and 60Fe observations so it is much more relaxed. Even better, it predicts better why the Sun has the average metallicity of the MW despite being enriched by previous stellar populations, it is a segregated process that has room for mixing and happens to many stars.

Also, they can predict the relatively small cluster size that dynamics of our planetary system necessitates. It is very predictive!
not rated yet Aug 29, 2012
Curious to me is that the other 19 star siblings of the sun are now broadly distributed about the galaxy after only 20 galactic revolutions. All being born of the same gas cloud, shouldn't they all have had comparable velocity magnitudes and directions, resulting in very similar present locations?
SnowballSolarSystem _SSS_
1 / 5 (3) Aug 30, 2012
A 30 solar-mass star will end in a SN after a mere 2 million years, but we have no solar system evidence for a second local SN following the first local SN that supposedly created the 60Fe, by nucleosysthesis.
where: stellar lifespan (30 solar mass) = 1x10^10/30^2.5 = 2 Myr

This article suggests 2 local SNe over 2 million years and 3 stellar generations.

An alternative model simply requires the merger of a binary pair of stars at 4.567 Ga in a luminous red nova (LRN), creating SLRs and CAIs in the LRN followed by molten chondrules from the super-intense solar magnetic field following the binary merger.

Binary stars are thought to be more common than solitary stars--in addition to eliminating two local SNe and two stellar generations--and we get a bonus of CAIs and chondrules.

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