Wings Of Balmer Lines Research Articles

Emission-line luminosities of Seyfert galaxies

view Abstract Citations (143) References (39) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Emission-line luminosities of Seyfert galaxies. Adams, T. F. ; Weedman, D. W. Abstract New observations of emission-line intensities are presented for 32 Seyfert galaxies. On the basis of correlations among these intensities and continuum properties inferred from UBV photometry, it is concluded that class 1 Seyfert galaxies (those with broad Balmer line wings) are ionized by a strong radiative source and are not significantly reddened by dust. The intrinsic H-alpha luminosities of the nuclei are calculated and found to correspond to a range in U magnitude from -16 to -22.5 and a range in visual absolute magnitude from -16 to -22. Other properties of the nuclei do not seem to be dependent on luminosity. For class 2 Seyfert galaxies (those resembling NGC 1068), the intrinsic H-alpha luminosities after correction for dust reddening are comparable to those of class 1, but the forbidden-line luminosities are typically 30 times stronger in class 2. It is concluded that the properties of class 2 nuclei could be explained by the presence of large numbers of very hot, luminous stars substantially reddened by dust. Publication: The Astrophysical Journal Pub Date: July 1975 DOI: 10.1086/153659 Bibcode: 1975ApJ...199...19A Keywords: Emission Spectra; Galactic Nuclei; H Alpha Line; Luminous Intensity; Seyfert Galaxies; Astronomical Photometry; Galactic Radiation; Galactic Structure; H Beta Line; Ubv Spectra; Astrophysics full text sources ADS | data products SIMBAD (33) NED (32)

Effects of line blanketing on the solar windows

The increasingly high flux predicted to the violet of 4500 A by many model solar atmospheres stands in contradiction to the observations. Since one possible cause of the disagreement is that the solar ‘windows’ by which the observed continuum is established might be obscured by line wings, we have made detailed calculations of these narrow spectral regions. With the exception of a few windows affected by the wings of Balmer lines, those redward of the Balmer discontinuity appear free of line blanketing. Even the assumption that the ultraviolet continuum is depressed 5% by unseen lines not included in our calculations leaves substantial disagreements between the models and observations. The discrepancies could perhaps be explained by a veil of weak lines across the ultraviolet spectrum.

Theory of the first-order Stark broadening by ions and electrons.

view Abstract Citations References Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Theory of the first-order Stark broadening by ions and electrons. Koib, Alan C. Abstract The instantaneous local electric field of an ensemble of ions and electrons removes the degeneracy in a hydrogenic energy level. In the wings of the Balmer lines, where the separation of the Stark components is large, we treat the perturbing field in the adiabatic approximation. The ions and electrons are assumed to have classical paths and the perturbation due to the entire ensemble of ions and electrons is introduced directly into the adiabatic theory. The resulting Fourier integral is expressed in series form and it is found that the electrons and ions are equally important in forming the Balmer line wings. In the limit of zero electron density the series reduces to the Holtsmark distribution. In the limit of zero ion density the radial Cauchy distribution is obtained, in contrast to the usual dispersion line shape. In addition, the electron half- width parameter is numerically different than is obtained by Unsbld. According to this calculation the general effect of the electrons is to depress the central intensity and to increase the intensity on the wings relative to the Holtsmark distribution for ions alone. These features have been observed in Balmer line profiles obtained in the University of Michigan shock tube and at Kiel by H. Griem. This research was partially supported by the Air Research and Development Command. University of Michigan, Ann Arbor, Michigan. Publication: The Astronomical Journal Pub Date: 1955 DOI: 10.1086/107153 Bibcode: 1955AJ.....60R.166K full text sources ADS |