Astrophysical: H II regions

  • Publication
    The Calibration of the O/H Abundance Indicators for Extragalactic H II Regions based on O II Recombination Lines
    Based on O II recombination lines we present a new calibration (called O II_{RL}) of Pagel's O_{23} indicator to determine the O/H abundance ratio in...
  • Publication
    The chemical composition gradient across M 33
    The abundance gradient in M 33 is studied on the basis of IPCS and CCD data on emission lines in selected H II regions, using O II, O III, S II, and S III in...
  • Publication
    The chemical composition of Galactic ring nebulae around massive stars
    We present deep spectra of ring nebulae associated with Wolf-Rayet (WR) and O-type stars: NGC 6888, G2.4+1.4, RCW 58, S 308, NGC 7635 and RCW 52. The data have...
  • Publication
    The CO structure of NGC 7027 - A bipolar nebula in the making
    Intermediate resolution mapping and limited off-center spectroscopy of the post-main-sequence molecular outflow source NGC 7027 are presented. The CO envelope...
  • Publication
    The core-halo structure of IC 418
    Deep spectra of the planetary nebula IC 418 were obtained in the wavelength range 4190-5850 A. The data made it possible to map an extended halo about the...
  • Publication
    The dependence of the gradients of oxygen and nitrogen-to-oxygen on stellar age in MaNGA galaxies
    We derived the oxygen abundance (O/H), the nitrogen-to-oxygen (N/O) abundance ratio, and their corresponding radial gradients for a sample of 1431 galaxies from...
  • Publication
    The diffuse ionized gas in galaxies
    An investigation of the diffuse ionized gas (DIG) and its underlying physical processes is the focal point of this study. We aim to survey the prevalence...
  • Publication
    The Effect of Collisional Enhancement of Balmer Lines on the Determination of the Primordial Helium Abundance
    This paper describes a new determination of the primordial helium abundance (YP), based on the abundance analysis of five metal-poor extragalactic H II regions...
  • Publication
    The embedded cluster IRAS17136 - 3617 associated with the nebulosity GM24
    Radio, infrared, and optical observations of the embedded infrared cluster IRAS17136 - 3617 are reviewed. The cluster consists of more than 25 stars with a...