eso0634 — Tudományos közlemények

A "Genetic Study" of the Galaxy

Galactic Bulge and Disc Stars Shown To Have Different Oxygen Abundances

2006. szeptember 12.


"For the first time, we have clearly established a 'genetic difference' between stars in the disc and the bulge of our Galaxy," said Manuela Zoccali, lead author of the paper presenting the results in the journal Astronomy and Astrophysics [1]. "We infer from this that the bulge must have formed more rapidly than the disc, probably in less than a billion years and when the Universe was still very young."


To do this, an international team of astronomers [2] analysed in detail the chemical composition of 50 giant stars in four different areas of the sky towards the Galactic bulge. They made use of the FLAMES/UVES spectrograph on ESO's Very Large Telescope to obtain high-resolution spectra.







[1]: "Oxygen abundances in the Galactic bulge: evidence for fast chemical enrichment" by Zoccali et al. It is freely available from the publisher's website as a PDF file.

[2]: The team is composed of Manuela Zoccali and Dante Minniti (Universidad Catolica de Chile, Santiago), Aurelie Lecureur, Vanessa Hill and Ana Gomez (Observatoire de Paris-Meudon, France), Beatriz Barbuy (Universidade de Sao Paulo, Brazil), Alvio Renzini (INAF-Osservatorio Astronomico di Padova, Italy), and Yazan Momany and Sergio Ortolani (Universita di Padova, Italy).

[3]: Type Ia supernovae are a sub-class of supernovae that were historically classified as not showing the signature of hydrogen in their spectra. They are currently interpreted as the disruption of small, compact stars, called white dwarfs, that acquire matter from a companion star. A white dwarf represents the penultimate stage of a solar-type star. The nuclear reactor in its core has run out of fuel a long time ago and is now inactive. However, at some point the mounting weight of the accumulating material will have increased the pressure inside the white dwarf so much that the nuclear ashes in there will ignite and start burning into even heavier elements. This process very quickly becomes uncontrolled and the entire star is blown to pieces in a dramatic event. An extremely hot fireball is seen that often outshines the host galaxy.


Manuela Zoccali
Universidad Catolica de Chile
Santiago, Chile
Telefon: +56 2 354 72 53

Aurelie Lecureur
Observatoire de Paris-Meudon
Paris, France
Telefon: +33 1 45 07 71 61

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A sajtóközleményről

Közlemény száma:eso0634
Legacy ID:PR 34/06
Név:Baade Window, Milky Way Galactic Bulge, Milky Way Galactic Centre
Típus:Milky Way : Galaxy : Component : Center/Core
Facility:Very Large Telescope
Science data:2006A&A...457L...1Z


The field around Baade's window
The field around Baade's window
The oxygen abundance in the bulge
The oxygen abundance in the bulge

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