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Linsky, J. L.

Publications and source records attributed to Linsky, J. L..

At least 199 records · Page 11
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NASA NTRS1975

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.↗
NASA NTRS1974

Evidence for a corona of beta Geminorum

A spectrometer was used on the satellite Copernicus to observe a chromospheric L alpha emission from the K0 giant beta Gem at 1218.4 A. This emission appears to be in the corona at temperatures near 260,000 deg K, since the ion it is identified with requires 77.4 eV to be produced.

Gerola, H.↗
NASA NTRS1974

Physical properties of solar chromospheric plages. II - Chromospheric plage models

Chromospheric models of plages are proposed to explain profiles of the Ca II H, K, 8498-A, 8542-A, and 8662-A lines. These models are consistent with boundary conditions imposed by the photosphere and the Lyman continuum. It is found that increasing emission in these lines is consistent with a picture of increasing temperature gradient in the low chromosphere and the resulting increase in pressure and electron density at similar line optical depths. With this picture it is shown how the distribution of chromospheric parameters across the solar disk can be empirically determined directly from Ca II filtergrams. It is also proposed that the high-density aspects of solar activity are produced by steep temperature gradients in the low chromosphere and thus by the enhanced heating mechanisms that steepen these gradients.

Shine, R. A.↗
NASA NTRS1974

Stellar model chromospheres. II - Procyon /F5 IV-V/

Derivation of a model for the chromosphere and upper photosphere of Procyon (F5 IV-V) based on calibrated observations of the K and 8542-A lines of Ca II, the k(2796-A) line of Mg II, and the K-line wings. The feasibility of this model synthesis approach to derive a preliminary model chromosphere is demonstrated despite the lack of spatial and spectral resolution associated with solar chromospheric studies. The proposed upper photosphere model is very similar to the radiative equilibrium Procyon model of Strom and Kurucz (1966), while the proposed chromospheric model is similar to the quiet solar chromosphere temperature distribution of Shine (1973) in the 6000 to 8000 K range.

Ayres, T. R.↗
NASA NTRS1974

A facular model based on the wings of the Ca II lines

An approach is shown for using the extensive damping wings of the Ca II lines in a direct analysis of photospheric temperature structures. Questions concerning the formation of the Ca II wings are considered. The low angular resolution photoelectric observations reported by Shine and Linsky (1972) are used to derive the spatially averaged differences between faculae and the quiet sun. Data regarding a photospheric facula model are presented in a table.

Shine, R. A.↗
NASA NTRS1974

High-spectral-resolution measurements of the H I 1216 and Mg II 2800 emissions from Arcturus

High-spectral-resolution scans of H I 1216 and Mg II 2796, 2803 obtained using the ultraviolet spectrometer abroad the Copernicus satellite show broad and very asymmetrical emission profiles. The ratio of the line widths to the solar values is consistent with a law similar to the Wilson-Bappu relation for the calcium K reversal. A fit of the interstellar absorption profile indicates that the average H density toward this nearby star is low, 0.02-0.1 per cu cm.

Moos, H. W.↗
NASA NTRS1973

One- and multi-component models of the upper photosphere based on molecular spectra. I - The violet system of CN /0, 0/

Spectroheliograms taken in the CN (0, 0) violet band near 3883 A show very small scale network and cell structures with high contrast. The bandhead itself, which is a broad feature due to overlap of several CN lines, allows the diagnostic simplicity of a continuum since motions, magnetic fields, and broadening mechanisms are unimportant. We have obtained spectroheliograms in the bandhead and center-to-limb photoelectric spectra of CN (0, 0) at Kitt Peak National Observatory. From the photoelectric spectra and a detailed analysis of the formation of the CN (0, 0) spectrum we derive a best-fit one-component upper photospheric model differing from that of the HSRA and recommend a change in solar carbon abundance from the HSRA value.

Mount, G. H.↗
NASA NTRS1973

The moon as a proposed radiometric standard for microwave and infrared observations of extended sources.

Measured values of the average midnight and morning terminator infrared brightness temperatures of the central portion of the lunar disk can quite accurately determine the mean surface temperature despite likely horizontal and vertical inhomogeneities of the thermal properties of the lunar soil. These data together with laboratory measurements on lunar soil and in situ temperature measurements in and on the lunar surface lead to a mean surface temperature of 220.5 K plus or minus 2.5 per cent and a mean temperature 35 K hotter at a depth of 1 m. The monthly average brightness temperature is then estimated as a function of wavelength between 10 microns and 100 cm taking into account likely temperature dependencies of the thermal conductivity and loss tangent, and the variation of emissivity with wavelength.

Linsky, J. L.↗
NASA NTRS1972

Physical properties of solar chromospheric plages. I - Line profiles of the CaII H, K, and infrared triplet lines.

Double pass photoelectric observations are presented of five CaII lines (H, K, 8498 A, 8542 A, and 8662 A) in a number of solar plages of different degrees of activity, quiet regions, and a sunspot. The data are compared with previous work. All five lines show increasing emission together in plages, and the least opaque of the infrared triplet lines appears to exhibit core emission prior to the more opaque members of the multiplet. The question of source function equality is considered and the differences and similarities among plage profiles and between plage and quiet profiles are shown qualitatively and quantitatively.

Shine, R. A.↗
NASA NTRS1970

The solar H and K lines

Solar Ca II H and K lines formation, discussing double reversal, limb darkening, plage and spot lines and anomalous line ratios

Avrett, E. H.↗