Analysis of the profiles of the solar S I lines at 1807 and 1900 A

view Abstract Citations (119) References (23) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Measurements of extreme-ultraviolet emission-line profiles near the solar limb. Mariska, J. T. ; Feldman, U. ; Doschek, G. A. Abstract Line profiles of optically thin extreme-ultraviolet emission lines observed in a quiet sun region at positions within and above the white-light limb with the NRL slit spectrograph (S082-B) on Skylab are discussed. Absolute line intensities and full widths at half-maximum are presented for lines formed over the temperature range from about 10,000 to 22,000 K. The line intensities are compared with the predictions of simple atmospheric models consisting of a spicule component and a thin spherically symmetric or network models, but can be explained by assuming that the emission arises from spicule-like inhomogeneities. Random mass-motion velocities are calculated. The velocity increases with increasing temperature of line formation. Near the limb and above about 4000 K the calculated velocity is consistent with the predictions of a constant acoustic flux passing through the transition zone. For the ions formed at temperatures not less than about 63,000 K, the velocity is found to increase with increasing height above the white-light limb. Publication: The Astrophysical Journal Pub Date: December 1978 DOI: 10.1086/156652 Bibcode: 1978ApJ...226..698M Keywords: Astronomical Spectroscopy; Chromosphere; Far Ultraviolet Radiation; Solar Limb; Solar Spectra; Atmospheric Models; Emission Spectra; Line Spectra; Mass Flow; Skylab Program; Solar Temperature; Spectral Line Width; Spectrographs; Spicules; Velocity Measurement; Solar Physics; Extreme UV:Solar Spectrum; Line Profiles:Solar Spectrum full text sources ADS |

view Abstract Citations (4) References (15) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS SKYLAB observations of the solar C I multiplets at 1560- and 1657-A Roussel-Dupre, D. Abstract Skylab spectrograph profile observations of the solar C I multiplets are presented, and the profile variations from center to limb and at various heights above the quiet solar limb are noted. These lines are of interest both because they are formed in the midchromosphere, thereby providing checks and constraints on chromospheric models, and because they are sensitive to the magnitude of the nonthermal microvelocities included in theoretical calculations. The present observations are compared with the C I profiles calculated by Shine et al (1978), discussing the many inconsistencies that emerge, notably between the observed and computed 1560/1657-A ratio and in the center-to-limb and above-the-limb variations of the integrated intensity. The multiplet central cores are discussed in terms of several microturbulent velocity structures. Publication: The Astrophysical Journal Pub Date: December 1983 DOI: 10.1086/161583 Bibcode: 1983ApJ...275..892R Keywords: Carbon; Fine Structure; Line Spectra; Skylab Program; Solar Atmosphere; Solar Spectra; Atmospheric Turbulence; Chromosphere; Solar Limb; Ultraviolet Spectra; Solar Physics full text sources ADS |

view Abstract Citations (28) References (16) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS A new solar carbon abundance based on non-LTE CN molecular spectra. Mount, G. H. ; Linsky, J. L. Abstract A detailed non-LTE analysis of solar CN spectra strongly suggest a revised carbon abundance for the sun. We recommend a value of log carbon abundance = 8.35 plus or minus 0.15 which is significantly lower than the presently accepted value of log carbon abundance = 8.55. This revision may have important consequences in astrophysics. Publication: The Astrophysical Journal Pub Date: November 1975 DOI: 10.1086/181978 Bibcode: 1975ApJ...202L..51M Keywords: Carbon; Cyanides; Line Spectra; Molecular Spectra; Solar Atmosphere; Solar Spectra; Abundance; Atmospheric Temperature; Luminous Intensity; Photosphere; Solar Limb; Thermodynamic Equilibrium; Solar Physics full text sources ADS |

view Abstract Citations (11) References (12) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS The solar XUV He I and He II emission lines. II. Intensity ratios and distribution functions. Glackin, D. L. ; Linsky, J. L. ; Mango, S. A. ; Bohlin, J. D. Abstract From high-resolution solar images we show that the He ii A256 line intensity is very nearly uncorrelated with He ii A3O4 at the same location on the Sun and that the A256 line is formed mainly by the photoionization-recombination process. We also derive center-to-limb variations of He ii A3O4 and A256 and He I A584 and A537 for network and cell regions separately and find that (1), in both network and cells, A3O4 and A584 each limb-brighten in the quiet Sun and limbdarken in coronal holes and (2), for both A3O4 and A584, network and cell regions are each brighter in the quiet Sun than in coronal holes. We conclude that the appearance of dark coronal holes in the helium lines is not a geometrical effect involving the chromospheric network, but is rather an intrinsic property of the atmosphere in both network and cell regions. We suggest that the network and cells can be treated as isolated atmospheres in the solution of the transfer equation in the helium lines. Subject headings: Sun: chromosphere - Sun: corona - Sun: spectra - ultraviolet: spectra Publication: The Astrophysical Journal Pub Date: June 1978 DOI: 10.1086/156189 Bibcode: 1978ApJ...222..707G Keywords: Distribution Functions; Far Ultraviolet Radiation; Helium; Line Spectra; Solar Atmosphere; Solar Spectra; Ultraviolet Spectra; Atomic Spectra; Chromosphere; Electromagnetic Scattering; Emission Spectra; Solar Corona; Solar Physics; Extreme UV:Solar Corona full text sources ADS |

view Abstract Citations (75) References (12) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS High Time Resolution Observations of H alpha Line Profiles during the Impulsive Phase of a Solar Flare Wuelser, Jean-Pierre ; Marti, Hans Abstract H-alpha observations of the impulsive phase of a 1B/M1 solar flare on May 24, 1987, were carried out with high temporal resolution. A line center imaging system and an imaging spectrograph for line profile acquisition have been operated simultaneously with 0.3 s and 2.3 s temporal resolution, respectively. The temporal evolution at line center and in the blue and red wing have been correlated with hard X-ray data from HXRBS. The observed line profiles have been analyzed in terms of dynamic H-alpha line profile calculations by Canfield and Gayley. The combined H-alpha and hard X-ray signatures of two flare kernels are compatible with the theoretical predictions for strong nonthermal electron heating and the formation of a downward moving chromospheric condensation. A third kernel also shows the predicted downward moving chromospheric material, but its temporal evolution is not compatible with electron beam heating. Publication: The Astrophysical Journal Pub Date: June 1989 DOI: 10.1086/167567 Bibcode: 1989ApJ...341.1088W Keywords: H Alpha Line; Solar Flares; Solar Spectra; Spectrum Analysis; Temporal Resolution; Line Spectra; Solar X-Rays; X Ray Spectra; Solar Physics; LINE PROFILES; SUN: FLARES full text sources ADS |

view Abstract Citations (30) References (34) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Extreme-ultraviolet limb spectra of a prominence observed from Skylab. Mariska, J. T. ; Doschek, G. A. ; Feldman, U. Abstract Line profiles of extreme ultraviolet emission lines observed in a solar prominence at positions above the white-light limb with the NRL slit spectrograph on Skylab are discussed. Absolute line intensities and full widths at half-maximum are presented, and emission measures, electron densities, and mass motions are derived at several locations within the prominence. For electron temperatures less than 40,000 K, the calculated mass motions are found to be near zero, while for electron temperatures greater than 40,000 K, the nonthermal velocity decreases with increasing height in the prominence. It is suggested that falling material is responsible for the fact that the measured electron density decreases with height less rapidly than the decrease predicted for a hydrostatic gas. In addition, from the He II 1640 A line profile, an average temperature of 27,000 K is derived for the region in which He II is emitted. Publication: The Astrophysical Journal Pub Date: September 1979 DOI: 10.1086/157356 Bibcode: 1979ApJ...232..929M Keywords: Skylab Program; Solar Limb; Solar Prominences; Solar Spectra; Ultraviolet Spectra; Electron Density (Concentration); Electron Energy; Helium; Line Spectra; Solar Physics; Extreme UV:Solar Prominences full text sources ADS |

view Abstract Citations (74) References (20) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS The Mg II h and k lines. I. Absolute center and limb measurements of the solar profiles. Kohl, J. L. ; Parkinson, W. H. Abstract We report new measurements of the solar Mg II h and k lines with uncertainties in the absolute intensities at k1 and h1 of - 20 to + 12 percent with smaller uncertainties for higher intensities. The spectral resolution, defined by the full width at half-maximum of the instrumental profile, was 0.028 A, and the angular resolution element was 184" by 1,5. Measurements were made for a quiet region near the disk center and for a quiet region at cos 0 = 0.23. The measured profiles are suitable for detailed comparisons with theoretical solar and stellar profiles, as will be discussed in the paper by Ayres and Linsky (Paper II) that will follow in a later issue. Our measured minimum intensities (k1 and h1) relative to the core intensities (k3 and h3) and to the average peak intensities (k2 and h2) are fainter than the corresponding intensities that were reported by Lemaire and Skumanich. Subject headings: line profiles - Sun: spectra - ultraviolet: spectra Publication: The Astrophysical Journal Pub Date: April 1976 DOI: 10.1086/154317 Bibcode: 1976ApJ...205..599K Keywords: Line Shape; Magnesium; Solar Limb; Solar Spectra; Ultraviolet Spectra; Angular Resolution; Metal Ions; Solar Instruments; Spectral Resolution; Telescopes; Solar Physics full text sources ADS |

view Abstract Citations (41) References (21) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS The effect of chromospheric activity on metallicity measurements. Giampapa, M. S. ; Gilliam, L. B. ; Worden, S. P. Abstract The intermediate band uvby-beta photometric system is used to observe solar active (plage) regions and quiescent regions in an effort to determine the effect of chromospheric activity on photometric metallicity measurements. It is found that the active regions appear metal deficient with respect to the quiet sun by approximately 35%. Publication: The Astrophysical Journal Pub Date: May 1979 DOI: 10.1086/157049 Bibcode: 1979ApJ...229.1143G Keywords: Abundance; Chromosphere; Faculae; Metals; Photometry; Solar Atmosphere; Hypotheses; Line Spectra; Solar Limb; Solar Spectra; Solar Physics; Metal Abundances:Solar Photosphere; Photometry:Solar Active Regions; Solar Activity:Solar Chromosphere full text sources ADS |

view Abstract Citations (44) References (15) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Observations of the 12 Micron MG i Lines in Various Solar Features Zirin, Harold ; Popp, Bruce Abstract Measurements of the solar Mg I line at 812/cm are presented, confirming the ubiquitous narrow emission from the quiet sun with secant limb brightening observed by Brault and Noyes (1983). It is found that the central intensity of 12-micron emission lines is greater in plages than in the quiet sun, with an equivalent width up to 3 times greater than for the quiet sun. The magnetic fields measured in plages range from 300 to 800 Gauss. The secant-like limb brightening, and line ratios suggest that the lines are optically thin and are formed in collisional equilibrium with Mg II in a thin layer just above the temperature minimum. Publication: The Astrophysical Journal Pub Date: May 1989 DOI: 10.1086/167418 Bibcode: 1989ApJ...340..571Z Keywords: Infrared Spectra; Metallicity; Solar Magnetic Field; Solar Spectra; Field Strength; Line Spectra; Magnesium; Stellar Activity; Solar Physics; INFRARED: SPECTRA; SUN: TRANSITION REGION; SUN: MAGNETIC FIELDS full text sources ADS |

view Abstract Citations (25) References (12) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Chromospheric oscillations observed with OSO 8. I. Basic measurements and analytical methods. White, O. R. ; Athay, R. G. Abstract Time series of solar EUV line profiles observed with OSO 8 have fluctuations arising from instrumental, satellite, and solar sources. The fluctuations are partly noiselike, partly from long-term drifts, and partly from periodic oscillations. The Sun contributes to all three types of fluctuations. However, instrumental effects also contribute to the noiselike fluctuations and long-term drifts, and the satellite wheel rotation induces spurious oscillations. Analytical procedures are discussed for applying Fourier transform techniques and related statistical tests to isolate the different types of fluctuations and, in particular, to study the solar oscillations. Strong solar oscillations are identified near 3 mHz, and aliases of the wheel rotation frequency are identified at 10.5 and 27 mHz. Publication: The Astrophysical Journal Supplement Series Pub Date: March 1979 DOI: 10.1086/190573 Bibcode: 1979ApJS...39..317W Keywords: Chromosphere; Oso-8; Satellite Observation; Solar Atmosphere; Solar Oscillations; Far Ultraviolet Radiation; Line Spectra; Power Spectra; Satellite Rotation; Solar Spectra; Time Series Analysis; Ultraviolet Astronomy; Solar Physics; Line Profiles:Solar Chromosphere; Oscillations:Solar Chromosphere; Solar Chromosphere:UV Spectra full text sources ADS |

view Abstract Citations (13) References (19) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Solar Atmospheric Dynamics. III. The Effect of Acoustic Waves on the MG II K Line Profile Gouttebroze, Pierre Abstract The use of acoustic waves to obtain realistic profiles for the solar Mg II resonance lines without using ad hoc parameters such as micro- and macroturbulence is studied. One-dimensional models are used which treat the waves nonlinearly. Line profiles are calculated with radiative transfer equations which are expressed in the observer's frame, accounting for the effects of partial redistribution in frequency and direction. It is found that the model can reproduce the observed k3 reversal and the global intensity. It is suggested that two-dimensional computations are necessary to reproduce the observed peak-to-peak distance. Publication: The Astrophysical Journal Pub Date: February 1989 DOI: 10.1086/167122 Bibcode: 1989ApJ...337..536G Keywords: Radiative Transfer; Resonance Lines; Solar Atmosphere; Magnesium; Nonlinearity; Solar Spectra; Sound Waves; Specific Heat; Thermodynamic Equilibrium; Velocity Distribution; Solar Physics; LINE PROFILES; RADIATIVE TRANSFER; SUN: ATMOSPHERE; ULTRAVIOLET: SPECTRA; WAVE MOTIONS full text sources ADS |

view Abstract Citations (25) References (19) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS A reduced upper limit to the solar boron abundance. Hall, D. N. B. ; Engvold, O. Abstract A new upper limit on the solar boron abundance has been obtained from observations of the photospheric spectrum in the 16240 A region. We flnd N0(B)/N0(H) < 1.2 i 0.6 >c 10-10. The implications of this result for the boron abundance in the primitive solar material are discussed. Subject headings: abundances, solar - spectra, infrared - spectra, solar Publication: The Astrophysical Journal Pub Date: April 1975 DOI: 10.1086/153537 Bibcode: 1975ApJ...197..513H Keywords: Abundance; Boron; Infrared Spectrometers; Photosphere; Solar Atmosphere; Solar Spectra; Absorption Spectra; Atmospheric Models; Atomic Spectra; Chemical Composition; Computer Programs; Continuous Spectra; Luminous Intensity; Molecular Spectra; Solar Physics full text sources ADS |

view Abstract Citations (26) References (17) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Formation of spectral lines with partial frequency redistribution. Heasley, J. N. ; Kneer, F. Abstract A method for treating the effects of partial frequency redistribution (PRD) in non-LTE radiative-transfer problems is presented in which the rate equations may be kept in their usual form and the PRD effects may be included by altering the form of the radiative-transfer equation. The required modifications of the transfer and statistical-equilibrium equations are outlined along with the changes these necessitate in the complete linearization method. The formulation is compared with that of Milkey et al. (1973), and sample PRD calculations are given for the solar chromospheric Ly-alpha and Ca II K line profiles. The results are found to be in excellent quantitative agreement with previous computations. Publication: The Astrophysical Journal Pub Date: February 1976 DOI: 10.1086/154124 Bibcode: 1976ApJ...203..660H Keywords: Astronomical Spectroscopy; Frequency Distribution; Line Spectra; Radiative Heat Transfer; Solar Spectra; Coherent Scattering; Electron Transitions; H Alpha Line; K Lines; Lyman Alpha Radiation; Spectrum Analysis; Thermodynamic Equilibrium; Solar Physics full text sources ADS |

view Abstract Citations (11) References (19) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Emission lines in the wings of Ca II H and K. I. Initial solar observations and implications. Canfield, R. C. ; Stencel, R. E. Abstract We apply solar observations to the problem of proper identification of the atomic species and the mechanism of formation of emission lines in the wings of the Ca ii H and K lines. Emission lines of both rare earths and metals appear to be present in the Sun. Their behavior in the solar spectrum implies that emission lines of metals will be useful in studies of chromospheres of other stars in which they are observed. Subject headings: line identifications - Sun: chromosphere - Sun: spectra Publication: The Astrophysical Journal Pub Date: October 1976 DOI: 10.1086/154758 Bibcode: 1976ApJ...209..618C Keywords: Atomic Spectra; Chromosphere; Emission Spectra; Solar Spectra; Calcium; Hydrogen; K Lines; Line Spectra; Spectroheliographs; Solar Physics full text sources ADS |

view Abstract Citations (11) References (24) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Atomic Transition Probabilities of Fe II Lines Determined from Solar Emission Spectra. I. The 2000--2800 Angstrom Wavelength Range Ekberg, J. O. ; Feldman, U. Abstract Intensities of Fe II lines were measured at a number of positions above the white light limb of the quiet sun, using photographic spectra obtained by the Naval Research Laboratory normal incidence spectrometer on Skylab. With the aid of experimental spontaneous decay rates previously published in the scientific literature we have calculated the spontaneous decay rates of over 550 Fe II transitions in the 2000-2800 A wavelength range. Two-hundred twenty of the measured spontaneous decay rates are published for the first time. It was determined that the Fe II levels in the solar chromosphere achieve a Boltzmann population corresponding to a about 0.78 eV temperature. The accuracy of the new rates is comparable to the accuracy of the previously published experimental rates. Publication: The Astrophysical Journal Supplement Series Pub Date: June 1993 DOI: 10.1086/191792 Bibcode: 1993ApJS...86..611E Keywords: Iron; Skylab Program; Solar Radiation; Solar Spectra; Transition Probabilities; Ultraviolet Radiation; Calibrating; Chromosphere; Data Reduction; Solar Limb; Spectral Line Width; Solar Physics; ATOMIC DATA; SUN: UV RADIATION; ULTRAVIOLET: SOLAR SYSTEM full text sources ADS |