Forbidden lines of Ca II in the photospheric spectrum.
Ca II forbidden lines in photospheric spectrum identified with weak Fraunhofer line by photoelectric spectrometer scans
Lambert, D. L.↗
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Ca II resonance lines in non-homogeneous chromospheres
K line profiles of Ca II for two component chromosphere, obtaining line source function and optical depth from steady state and radiative transfer equations
Beebe, H. A.↗
Ca-Al rich phases in the Allende meteorite
Allende meteorite showing presence of Ca-Al-rich glasses associated with other crystalline phases
Dickey, J. S., Jr.↗
The excitation of the forbidden coronal lines. II - Forbidden Ca XV lines at 5694 and 5446 A
Electron and proton excitation of forbidden transition lines in Ca XV ground configuration determined for coronal densities and temperature
Chevalier, R. A.↗
Further studies on regulation of betacyanin efflux from beetroot tissue - Ca-ion- reversible effects of hydrochloric acid and ammonia water
Ca ion reversible effects of hydrochloric acid and ammonia water on betacyanin leakage from beetroot sections
Siegel, S. M.↗
Comparative study of Li, Na, K, Rb, Cs, Ca, Sr and Ba abundances in achondrites and in Apollo 11 lunar samples
Chemical analysis for Li, Na, K, Rb, Cs, Ca, Sr and Ba in achondrites and Apollo 11 lunar rocks, breccia and soil samples
Burnett, D. S.↗
Absolute oscillator strengths for some resonance multiplets of Ca I,II, Mg I,II, B I, and Al I
Ca, Mg, B and Al prominent resonance transitions radiative lifetimes and absolute oscillator strengths
Liszt, H. S.↗
High resolution spectroscopy of the disk chromosphere. II - Time sequence observations of Ca II H and K emissions.
Two independent sets of high resolution time series spectra of the Ca II H and K emission obtained at the Solar Tower and at the Big Dome of the Sacramento Peak Observatory on September 11th, 1971 are reported. The evolutionary behavior of the emission first reported by Wilson and Evans is confirmed, but the detail of the evolution is found to be more complex. In one case, a doubly peaked feature showing some K3 emission evolves into a single K2 (red) peak with no K3 emission. Coincidentally, a neighboring doubly peaked feature evolves to a very strong blue peak. In an entirely independent sequence a doubly peaked feature evolves into a single red peak. The K2 emission then fades completely although the continuum threads are still strong. Finally a strong K2 blue peak appears. It is concluded that the observed evolution of the K2 emission is due to temporal variations in the physical conditions which give rise to them.
Wilson, P. R.↗
Interstellar Na I, K I, Ca II, and CH/+/ line profiles toward zeta Ophiuchi.
Comparison of interferometric, photoelectric scans of interstellar absorption-line profiles of Na I, K I, Ca II, and CH(+) toward zeta Ophiuchi. Near a heliocentric velocity of -15 km/sec, there is a strong composite feature showing four components. The atomic and molecular absorption lines do not arise in a common volume of gas but rather in essentially different clouds whose atomic abundances and/or ionization balances vary substantially.
Hobbs, L. M.↗
2s-2p transitions in the spectra of Ca XVII and Ti XIX.
Identifications of energy level transitions in the Ca XVII and Ti XIX spectra in the regions of 190-360 A and 160-300 A, respectively, are presented for the first time. Lines corresponding to the transition arrays concerned are identified and classified. Extrapolation procedures are described in detail.
Goldsmith, S.↗
Line profiles and turbulence generated by acoustic waves in the solar chromosphere. II - Contours of the Ca II and Mg II K lines
Making use of the time-averaged absorption profiles derived by Oster and Ulmschneider, non-LTE line formation in the context of a two-level atom is investigated for an isothermal atmosphere and for the Ca II and Mg II K lines in the solar chromosphere as represented by the Harvard-Smithsonian Reference Atmosphere. Source functions and emergent line profiles are computed for a variety of assumptions concerning the acoustically broadened profiles and the solar velocity fields.
Shine, R. A.↗
A comparison of interstellar Na I, Ca II, and K I absorption
The strongest and generally most useful optical interstellar absorption lines include the D lines of Na I, the H and K lines of Ca II, and the resonance doublet at 7600 A and 7664 A of K I. The interferometric data for these strongest atomic lines are examined in a comprehensive manner. The numerical results pertaining to the total column densities are collected in a table, which lists 82 stars. The correlations among some of the quantities listed in the table are displayed in a number of graphs.
Hobbs, L. M.↗
A possible width-luminosity correlation of the Ca II K1 and Mg II k1 features
Existing high resolution stellar profiles of the Ca II and Mg II resonance lines suggest a possible width-luminosity correlation of the K1 minimum features. It is shown that such a correlation can be simply understood if the continuum optical depth of the stellar temperature minimum is relatively independent of surface gravity as suggested by three stars studied in detail.
Ayres, T. R.↗
Resonance line transfer with partial redistribution. IV - A generalized formulation for lines with common upper states. V - The solar Ca II lines
A generalized formulation is given for treating partial redistribution effects in transfer problems in resonance lines with common upper states. The formulation allows explicitly for the possibility that several spectral lines may arise in transitions from a given upper level to several sharp lower levels, including, for example, the ground state and metastable states. Line profiles for the Ca II H and K lines have been calculated, accounting for the partial frequency coherence of scattered photons. These profiles are compared with calculations made with identical atomic and atmospheric models but assuming complete redistribution. Very significant differences between the profiles obtained using these two different physical descriptions of the scattering process are found, and it is now apparent that the assumption of complete redistribution is a serious oversimplification of the actual physical situation. The results question the validity of equating brightness temperatures observed at K(sub 1) in stellar spectra with minimum temperatures in stellar chromospheres; it appears likely that such a procedure will systematically underestimate the value of T-min.
Milkey, R. W.↗
Observation of subordinate 2p/5/4d-2p/5/3p transitions in neon-like ions from Ca XI to Ni XIX
Subordinate 2p(5)4d-2p(5)3p transitions in the neon-like ions from Ca XI through Ni XIX are identified. Such transitions between excited levels have not previously been reported for ionization stages higher than Al IV, although the resonance lines are known through Zn XXI in the neon isoelectronic sequence. Measurement of the solar flux in such transitions may aid in establishing the relative importance of the several cascade processes giving rise to the observed Fe XVII resonance lines.
Kastner, S. O.↗
Measurements of line emission in quiescent prominences - Ca/+/, H and He
The paper presents observations of Ca(+) H, K, and infrared-triplet integrated line intensities, as well as H-beta, H-gamma and He 5876-A throughout eight quiescent prominences. The data were obtained with a multichannel coronal spectrophotometer system. The presently available theoretical models appear to be insufficient to provide a consistent basis for the interpretation of the data.
Landman, D. A.↗
Measurements of H-beta, He D3, and Ca/+/ 8542-A line emission in quiescent prominences
Measurements of H-beta, He D3, and Ca(+) 8542-A line emission in 18 quiescent prominences are presented which were performed with a 25-cm coronagraph/coude spectrograph system and an optical multichannel analyzer utilizing a Si-vidicon detector assembly mounted at the single-pass spectrograph port. The data obtained show that the line profiles deviate in the wings from those calculated on the basis of an isothermal atmosphere and a Gaussian absorption coefficient. Both a non-Gaussian microturbulence component and a temperature gradient from prominence-core to coronal values can successfully account for this phenomenon. The line widths from a given line of sight of prominence material are reduced on the basis of a common core emitting region with a temperature of 7500 to 11,600 K and a microturbulent velocity of 4.5 to 7.1 km/s for the isothermal model (these values are 5% to 10% less for the two-temperature model). It is noted that long-period low-amplitude oscillations in the D3 line width and intensity were observed when a specific line of sight in a quiescent prominence was followed. These oscillations are found to remain coherent for as many as 3 or 4 cycles and to be associated with prominence structural activation.
Landman, D. A.↗
The Ca II V/R ratio and mass loss
High-dispersion coude spectrograms of 181 MK standards of types early F through late M, including luminosity classes Ia, Ib, II, and III, are analyzed. It is shown that the brightness ratio of the V and R self-reversed emission peaks (denoted V/R) in the center of the Ca II K line is correlated with spectral type as well as with certain other spectral-type and luminosity-sensitive parameters, including indicators of mass loss and the H-K wing emission lines. The observations indicate that V/R varies smoothly from less than unity in late K and M giants to greater than unity for G giants. This trend appears to be true for bright giants as well but not necessarily for supergiants and seems to hold for the average V/R for a given star, although short-term variations in V/R occur. It is suggested that the V/R values, which can be interpreted in terms of atmospheric motions, may indirectly relate to effects of evolutionary changes in stellar structure and that V/R among late-type stars could be useful as an indicator of both chromospheric activity and the state of stellar evolution.
Stencel, R. E.↗