Galactic Hα emission line studies using DEFPOS at the TUBİITAK National Observatory

Özet

Hα spectral line (6563 ˚A) profiles of eight northern H II regions in our galaxy (Sh2-25, Sh2-131, Sh2-237, IC434, IC 1318, NGC 1982, NGC 6543, and NGC 6611) have been obtained using the Dual Etalon Fabry–P´erot Opticalspectrometer (DEFPOS) with a 4’ field of view, located at the coud´e focus of the 150 cm RTT150 telescope at theTUB¨ ˙ITAK National Observatory (TUG, Antalya, Turkey). Observations were carried out during the nights of 25–27December 2015 and 6–7 June 2017 with different long exposure times ranging from 900 s to 3600 s. These spectra provideinformation about the local standard of rest (LSR) velocities, the full width at half maximum (FWHM), and densitiesof the sources. The LSR velocities and the FWHM of the Hα emission lines were found to be in the range of –50.31km/s to 27.57 km/s and 34.88 km/s to 44.54 km/s (mean FWHM: 37.19 km/s), respectively. The NGC 6543 (Cat’s EyeNebula) is the faintest one (75.06 R), while the NGC 1982 H II region is brightest source (38,477.3 R). The LSR velocityand the FWHM results of the DEFPOS/RTT150 system were compared with the data by several authors given in theliterature and the results of DEFPOS data were found to be in good agreement with data given in the literature. Sincethere is not enough information on LSR velocities and intensities of such galactic sources with low angular size in theliterature, we believe that this spectrometer will provide a powerful tool for the study of diffuse ionized gas and thesenew results may have significant contributions to the literature. In the future, we are planning to prepare Hα maps withthe 4’ field of view of some diffuse ionized emission sources selected from VTSS and WHAM Hα maps with large fieldsof view.