PhD project: The cosmic origin of fluorine and sulphur: Infrared spectroscopic studies of red giants

Projekt: Avhandling

Forskningsområden

Ämnesklassifikation (UKÄ)

  • Astronomi, astrofysik och kosmologi

Beskrivning

How galaxies form and evolve is one of the great questions in contemporary Astronomy. One piece of information
leading to the possible answer to this question is how and where different elements formed in our
own galaxy, the Milky Way. is area of research is called Galactic chemical evolution. Progress in chemical
evolution is made by observing elemental abundances in different stars produced during different phases of the
Milky Way’s evolution and comparing them with computer models of galaxy formation.
In this thesis I am determining abundances of two of the least studied elements, sulphur and fluorine, in three
different stellar populations in the Milky Way.
Recently there have been several proposed trends for the sulphur content in old galactic stars. Interestingly some
of these observations cannot be explained with classic models of Galactic evolution, thereby questioning some
of our understanding of the formation and evolution of the Milky Way. e first aim of this thesis is to clarify
this situation.
Concerning fluorine the situation is even more unclear because the number of previous observations are very
small. e cosmic origin of fluorine could still be one or more of three different sources. One of the proposed
sources are massive, metal-rich stars called Wolf-Rayet stars, and if this source is confirmed by observations,
fluorine would make a great proxy for the importance of these stars in the formation of the Bulge. Some previous
works determining the abundances of oxygen and magnesium in the Bulge seem to indicate Wolf-Rayet stars
are important, while other works do not. If they turn out to be important that would tell us that the initial
mass function of the Bulge was skewed towards higher-mass stars as compared to the solar neighborhood, and
that in turn would help us understand the formation of the Bulge better. To determine the chemical evolution
of fluorine in the solar neighborhood and in the Bulge are the second and third aims of this thesis.
StatusSlutfört
Gällande start-/slutdatum2009/03/012015/06/05

Participants

Relaterad forskningsoutput

Henrik Jönsson, 2015, Department of Astronomy and Theoretical Physics, Lund University. 94 s.

Forskningsoutput: AvhandlingDoktorsavhandling (sammanläggning)

Henrik Jönsson, Nils Ryde, G. M. Harper, K. Cunha, M. Schultheis, K. Eriksson, C. Kobayashi, V. V. Smith & M. Zoccali, 2014, I: Astronomy & Astrophysics. 564, A122.

Forskningsoutput: TidskriftsbidragArtikel i vetenskaplig tidskrift

Henrik Jönsson, Nils Ryde, G. M. Harper, M. J. Richter & K. H. Hinkle, 2014, I: Astrophysical Journal Letters. 789, 2, L41.

Forskningsoutput: TidskriftsbidragArtikel i vetenskaplig tidskrift

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