DEFPOS and Its First Results

A spectrometer was built to examine the interstellar medium (ISM) using the hydrogen Balmerline. It is called Dual Etalon Fabry-Perot Optical Spectrometer (DEFPOS). DEFPOS will be coupled to coude exit of the 150 cm telescope (RTT150) installed at T¨ UBu National Observatory (TUG). DEFPOS was ready for observations about two years ago, but work was still con- tinuing on the RTT150 coude exit alignment. So we have started observing HII regions with DEFPOS without the RTT150. We present here some characteristics of the instrument and some of the results obtained. Interstellar medium (ISM) plays a fundamental role in the process of galactic evolution. This process involves a complex interplay between interstellar matter and stars. The stars are born from interstellar matter. During their lives, they deposit energy into the ISM in the form of electromagnetic radiation and stellar winds. When they die, they return some of their matter and energy back into the ISM. More massive stars do this in dramatic supernova events. The matter returned to the ISM is enriched with heavy elements produced by the nuclear burning in the stars' interior and in processes occurring during the explosions. This enriched ejecta becomes the material for future generations of stars which behave rather differently due to the presence of the metals. The process is not 100% efficient; someof the matter remains locked up forever in compact objects such as white dwarfs, neutron stars and black holes. Therefore, the composition of a galaxy slowly proceeds from all ISM to no ISM. The chemical evolution of the galaxy results from this cycle of stellar birth, death, and enriched rebirth. The growth in the quantity of heavy elements allows, along the way, the possible formation of planets, rocks, and in at least one case living organisms (Reynolds 1997; Tufte 1997; Ferriere 2001). The main components of ISM have been identified, but the structure is still largely a mys- tery. The galaxy consists of primarily hydrogen (90%), some helium (10%), and only trace