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Galactic Chemical Evolution

Projects:

  • The origin of the Galactic bulge

I am involved in research investigating the origin of the elements and especially the chemical evolution of the Galactic Bulge. Observations of Bulge stars at IR wavelengths have been done with Gemini/Phoenix and VLT/CRIRES.  Red giants are very luminous stars and are useful as probes for galactic and extragalactic studies, for example, bulge studies. Thus my experience and knowledge of infrared spectroscopic studies of the atmospheres and stellar winds of red giants, which has been reported in several papers,  is of relevance to my planned research.

  • Chemical evolution of Sulfur and Carbon in the Milky Way

I am engaged in near-infrared studies of the chemical evolution of the Milky Way. Especially, I am studying the behaviour of carbon and sulphur. With data from the McDonald, Kitt Peak, and Gemini South Observatories,  I am studying solar-type stars in order to discern the origin of sulfur and the life-baring atom carbon.

Sulphur is an important element since it can be used in the study of the chemical enrichment of damped Ly-alpha systems, believed to be embryonic galaxies in the early universe. However, it is a difficult element to study due to the rarity of suitable spectral lines at low metallicities. In spite of these difficulties, I was able to show that sulphur is safe to use for such studies, despite earlier claims to the contrary, and that its behaviour is as expected for an alpha  element.
 


Docent Nils Ryde
Lund Observatory 
Box 43
SE-221 00 Lund, Sweden

Office: B207, Sölvegatan 27 
Phone: +46-46-222 1574, Fax: +46-46-222 4614 
Email: ryde@astro.lu.se