Author name code: jefferies-john ADS astronomy entries on 2022-09-14 author:"Jefferies, John T." ------------------------------------------------------------------------ Title: Frank Quimby Orrall (15 October 1925 - 4 February 2000). Authors: Jefferies, J. T.; Zirker, J. B. Bibcode: 2000SoPh..194..185J Altcode: No abstract at ADS Title: A legendary polyglot... and lovely days Authors: Jefferies, John T. Bibcode: 1998ASSL..222...96J Altcode: 1998ream.conf...96J No abstract at ADS Title: A Stochastic Model of the Solar Atmosphere Authors: Gu, Yeming; Jefferies, John T.; Lindsey, Charles; Avrett, E. H. Bibcode: 1997ApJ...484..960G Altcode: We present a model for the lower solar atmosphere based on continuum observations of the Sun spanning the 2-1200 μm wavelength range. We have shown that the data, in particular the center-to-limb brightness profiles at 50-350 μm, cannot be accounted for by any model which is plane-parallel and homogeneous in the height range in which this radiation is formed. We accordingly set out to develop a two-component model as the natural generalization. Making use of a theory for radiation transfer in a stochastic multi-component atmosphere, we find that one can indeed obtain an inhomogeneous model which satisfies center-to-limb data over the 2-1200 μm range. This composite model is made up of hot ``flux tubes'' randomly embedded in a cool medium, the flux tubes expanding to occupy an increasing proportion of the atmosphere as we move up in height.

The cool ambient component shows a monotonic decrease in temperature in the range defined by the data. The temperature in the hot component is constant at about 6500 K up to about 400 km and increases monotonically above that height. The center-to-limb observations demand that the gas in the interiors of the flux tubes be recessed downward with respect to a hydrostatic equilibrium distribution of density. This appears to constitute a chromospheric Wilson depression consistent with a magnetic field of about 120 G in the flux-tube interior at a height of about 600 km.

The new model is shown to be consistent with other spectral measurements independent of those used to define it. It gives a very good fit to the 0.5 μm continuum intensities across the disk, and provides an excellent accounting for the disk-center brightness temperature in the center of the 3-2 R14 CO line at 4.667 μm. A boundary temperature of less than about 3000 K in the cold component is suggested from the limb-darkening data available for this line.

In an appendix we mention a procedure for an analogous study based on the intensities of multiplet lines, which may hold promise for modeling over a wider range of heights that can be spanned by the IR data. Title: Radiative Transfer in Stochastic Media Authors: Gu, Yeming; Lindsey, Charles; Jefferies, John T. Bibcode: 1995ApJ...450..318G Altcode: We review some basic concepts arising in the study of radiative transfer in a stochastic atmosphere and consider their application to realistic atmospheric models. In particular, we examine the theory of Lindsey and Jefferies which deals with multicomponent atmospheres whose stochastic nature is entailed in the morphology of a network of boundaries separating different atmospheric components. This theory is based on the Markov assumption, that the probability, per unit path length along a ray, for transition into another component 15 independent of the distance already traveled in the current component. We examine the applicability of the theory to models that are non-Markovian, paying particular attention to the assignment of transition rates of such atmospheres. We consider in detail transition probabilities for spherical, tubular, conical, and other fluted structures, and show how the effects of overlap are to be incorporated for the case of a two-component atmosphere. Comparisons of results obtained from the theory of Lindsey and Jefferies with those found from Monte Carlo calculations, for models based on identical structures randomly embedded into an ambient medium, show that the Markov assumption promises to be a good approximation for the determination of the statistics of radiative transfer in a wide variety of stochastic atmospheres, even when they are markedly non-Markovian. Title: Infrared Applications for Radiative Transport in Stochastic Media Authors: Lindsey, C.; Gu, Y.; Jefferies, J. T. Bibcode: 1995itsa.conf..313L Altcode: No abstract at ADS Title: Radiative Transfer in Stochastic Atmospheres Authors: Gu, Y.; Lindsey, C.; Jefferies, J. T. Bibcode: 1994AAS...185.0702G Altcode: 1994BAAS...26Q1316G We describe a general statistical perspective for the study of radiative transfer through inhomogeneous media and apply it to simple stochastic atmospheric models. The particular context for our applications considers a stochastic atmosphere to be a multi-component medium in which any individual component of the medium is locally smooth. The stochastic nature of the atmosphere resides in the statistical character of the complex network of boundaries that separate various species of media one from another. We illustrate the theory with simple atmospheric models based on an ambient medium into which are randomly embedded structural elements containing alternative species of medium. We consider structures of various shapes and sizes, ranging from simple spheres to elongated or fluted structures with preferred orientation. An important distinctive quality of a stochastic atmosphere is whether the medium contains structures that individually may be optically thick. Atmospheres containing only optically thin structures tend to be statistically amenable to representation by equivalent smooth atmospheres. The theory we have developed is fully applicable to atmospheres that contain optically thick elements as well as optically thin ones. Such conditions apply to a broad variety of radiative transfer problems in astrophysics and stellar physics, for example, to emission from interstellar gas clouds, from solar or stellar chromospheres or from photospheres that contain heated magnetic flux tubes. In this work we concentrate on a formalism that rests on the Markov assumption, which states that the probability of encountering a transition from one type of medium, A, to another, B, is independent of the cumulative distance since the transition into medium A, as one proceeds along the optical path. We examine the importance of this assumption and its utility as a first approximation by illustrating the consequences of its application to atmospheric models that are non-Markovian. Title: Overview of Infrared Solar Physics Authors: Jefferies, J. T. Bibcode: 1994IAUS..154....1J Altcode: No abstract at ADS Title: Infrared solar physics: proceedings of the 154th Symposium of the International Astronomical Union, held in Tucson, Arizona, U.S.A., March 2-6, 1992. Authors: Rabin, D. M.; Jefferies, John T.; Lindsey, C. Bibcode: 1994IAUS..154.....R Altcode: No abstract at ADS Title: An active solar prominence in 1.3 MM radiation Authors: Harrison, R. A.; Carter, M. K.; Clark, T. A.; Lindsey, C.; Jefferies, J. T.; Sime, D. G.; Watt, G.; Roellig, T. L.; Becklin, E. E.; Naylor, D. A.; Tompkins, G. J.; Braun, D. Bibcode: 1993A&A...274L...9H Altcode: We present new millimetre-wavelength observations of an active solar prominence. Observations made over a two-day period with the James Clerk Maxwell Telescope on Manna Kea, Hawaii, give a unique view in 1.3 mm radiation of the spectacular prominence that appeared on the west solar limb in the total solar eclipse of 11 July 1991. Title: Measurement of the Height of the Solar CO Layer During the 11 July 1991 Eclipse Authors: Clark, T. A.; Naylor, D. A.; Tompkins, G. J.; Lindsey, C. A.; Becklin, E. E.; Jefferies, J. T.; Harrison, R. A.; Roellig, T. L.; Carter, M.; Braun, D. C.; Watt, G. Bibcode: 1992AAS...181.8108C Altcode: 1992BAAS...24.1253C No abstract at ADS Title: Extreme-infrared brightness profile of the solar chromosphere obtained during the total eclipse of 1991 Authors: Lindsey, C.; Jefferies, J. T.; Clark, T. A.; Harrison, R. A.; Carter, M. K.; Watt, G.; Becklin, E. E.; Roellig, T. L.; Braun, D. C.; Naylor, D. A. Bibcode: 1992Natur.358..308L Altcode: THE solar chromosphere is a thin layer of gas that is several thousand degrees hotter than the underlying photosphere, and responsible for most of the Sun's ultraviolet emission. The mechanism by which it is heated to temperatures exceeding 10,000 K is not understood. Millimetre and submillimetre radiometry can be used to obtain the chromospheric temperature profile, but the diffraction-limited resolution for the largest telescopes is at best 17 arcsec, or ~12,500 km at the Sun's distance. This is greater than the thickness of the quiet chromosphere itself. The total eclipse of July 1991, which passed over the Mauna Kea Observatory in Hawaii, provided a rare opportunity to make limb occultation observations with a large submillimetrewavelength telescope, the 15-m James Clerk Maxwell Telescope, and in this way we obtained a temperature profile in 1.3-mm radiation with ~300 km resolution at the Sun. Our observations indicate that spicules (magnetically entrained funnels of gas) reach a temperature of 8,000 K at 3,000-4,000 km above the photosphere, a temperature lower than those of many spicule models. Title: Chromospheric Dynamics Based on Infrared Solar Brightness Variations Authors: Kopp, G.; Lindsey, C.; Roellig, T. L.; Werner, M. W.; Becklin, E. E.; Orrall, F. Q.; Jefferies, J. T. Bibcode: 1992ApJ...388..203K Altcode: The NASA Kuiper Airborne Observatory was used to observe far-infrared continuum brightness fluctuations in the lower chromosphere due to solar 5 minute oscillations on the quiet sun. Brightness measurements made at 50, 100, 200, and 400 microns show a strong correlation with visible-line Doppler measurements from photospheric and chromospheric altitudes. The motion of the chromosphere is nearly in phase over a large range of heights, while the infrared brightness lags the Doppler velocity by phases varying from significantly less than 90 deg at low altitudes to nearly 90 deg at higher altitudes. It is proposed that this is the result of a nonadiabatic response of the chromospheric gas to compression and may indicate an important mechanism for wave dissipation. Thermal relaxation times ranging from about 40 s at 340 km above the tau(5000) = 1 photosphere to about 300 s at 600 km are proposed. Title: The Solar Chromospheric Supergranular Network in 850 Micron Radiation Authors: Lindsey, Charles A.; Jefferies, John T. Bibcode: 1991ApJ...383..443L Altcode: The first submillimeter solar observations are examined of the chromospheric supergranular network, made on the 15-m James Clerk Maxwell Telescope on Mauna Kea in 850-micron radiation. These observations are useful for thermal diagnostics of the low and middle chromospheres of the quiet-sun and magnetic regions, where mechanical heating of the atmospheric medium first becomes manifest. The models of Vernazza, Avrett and Loeser appear to be consistent with these observations. Title: Submillimeter Solar Limb Profiles Determined from Observations of the Total Solar Eclipse of 1988 March 18 Authors: Roellig, T. L.; Becklin, E. E.; Jefferies, J. T.; Kopp, G. A.; Lindsey, C. A.; Orrall, F. Q.; Werner, M. W. Bibcode: 1991ApJ...381..288R Altcode: Observations were made of the extreme solar limb in six far-infrared wavelength bands ranging from 30 to 670 micron using the Kuiper Airborne Observatory during the total eclipse of the sun on 1988 March 18. By observations of the occultation of the solar limb by the moon, it was possible to obtain a spatial resolution of 0.5 arcsec normal to the limb. The solar limb was found to be extended with respect to the visible limb at all of these wavelengths, with the extension increasing with wavelength. Limb brightening was observed to increase slightly with increasing wavelength, and no sign of a sharp emission spike at the extreme limb was found at any of these wavelengths. The observations can be well fitted by a chromospheric model incorporating cool dense spicules in the lower chromosphere. Title: The Solar MG i Spectrum from ATMOS. I. Identification and Preliminary Discussion Authors: Jefferies, John T. Bibcode: 1991ApJ...377..337J Altcode: As an initial step in a program to understand some puzzling aspects of the infrared solar Mg I spectrum, the set of high-resolution, high SNR lines of this spectrum are examined in the 1985 ATMOS experiment on Spacelab 3. Wavenumbers were obtained for the Mg I transitions lying in or near the range covered by ATMOS, namely 650 to 4800/cm. Lines involving principal quantum numbers up to n = 10 are seen in the data; some striking features of the Mg I spectrum are described and some directions of interest for future analytical studies and for future flights of the experiment are indicated. Title: On the Inference of Magnetic Field Vectors from Stokes Profiles Authors: Jefferies, John T.; Mickey, Donald L. Bibcode: 1991ApJ...372..694J Altcode: A study is made of the range of applicability of the weak-field approximation for the inference of magnetic field vectors from the profiles of the Stokes parameters. It is shown that, for typical solar lines in the visible, this approximation may be applied with an accuracy of 20 percent for field strengths as great as 3500/gL G (where gL is the Lande factor) in the line wings. A systematic underestimate of the field strength seems to occur for strong fields - observations in several related spectral lines may allow a calibration of this effect, and so for an increase in accuracy of the inferences. The procedures have been tested using solar data obtained in two lines of Fe I, near 6300 A, with the Stokes Polarimeter at the Mees Solar Observatory of the University of Hawaii. Title: Physics of the infrared spectrum. Authors: Deming, Drake; Jennings, Donald E.; Jefferies, John; Lindsey, Charles Bibcode: 1991sia..book..933D Altcode: The authors describe the diagnostic value and principal results derived from solar studies at wavelengths exceeding 1.6 μm. The infrared is a favorable region to conduct studies of the solar magnetic field. The high-n emission lines in the 12-μm spectrum are of special interest. However, the LTE or NLTE nature of the lines, and the mechanism of their excitation, remain poorly understood. The far-infrared continuum is an excellent thermometer for the upper photosphere and chromosphere, allowing study of the average thermal state and the compressional effects of wave motions. Observations of limb brightening at far-infrared wavelengths have shown that the structure of the chromosphere is spatially inhomogeneous, even at the lowest chromospheric altitudes. Time-series observations in the far-infrared show that the chromosphere exhibits a substantial thermal response to the 5-min oscillations. Further progress in far-infrared studies will result from the new generation of large-aperture submillimeter telescopes, and from the development of the theory of radiative transfer in inhomogeneous media. Title: Direct inference of magnetic field vectors from Stokes profiles. Authors: Jefferies, J. T.; Mickey, D. L. Bibcode: 1991sopo.work..373J Altcode: No abstract at ADS Title: Submillimeter Observations of the Sun from the James Clerk Maxwell Telescope Authors: Lindsey, Charles A.; Yee, Selwyn; Roellig, Thomas L.; Hills, Richard; Brock, David; Duncan, William; Watt, Graeme; Webster, Adrian; Jefferies, John T. Bibcode: 1990ApJ...353L..53L Altcode: The first submillimeter solar observations from the 15 m James Clerk Maxwell Telescope (JCMT) on Mauna Kea are reported. The JCMT submillimeter heterodyne receiver is used to observe the sun in 850 micron radiation. These are the first submillimeter observations of features on the size scale of the chromospheric supergranular network and of sunspots. A comparison is made between 850 micron images and calcium K line images of the chromospheric supergranular network in the quiet sun and in plage. Images of sunspots are given, noting that their 850 micron brightness is comparable to, or somewhat greater than, that of the quiet sun. Title: Far-Infrared Intensity Variations Caused by 5 Minute Oscillations Authors: Lindsey, C.; Kopp, G.; Becklin, E. E.; Roellig, T.; Werner, M. W.; Jefferies, J. T.; Orrall, F. Q.; Braun, D.; Mickey, D. L. Bibcode: 1990ApJ...350..475L Altcode: Observations of solar IR intensity variations at 50, 100, and 200 microns were made simultaneously and cospatially with Doppler measurements in the sodium D1 line at 5896 A. Brightness temperature variations of several K in amplitude are highly correlated with five minute Doppler oscillations. The brightness variations are attributed to work done on the chromospheric medium by compression, driven by the five minute oscillations. The Doppler oscillations lead the brightness variations by about 47 deg in phase at 50 and 100 microns and by about 72 deg in phase at 200 microns. Title: Statistical Concepts in Radiative Transfer through Inhomogeneous Media Authors: Lindsey, C.; Jefferies, J. T. Bibcode: 1990ApJ...349..286L Altcode: The theory of radiative transfer in inhomogeneous media is extended to handle transfer for scale lengths small compared to the scale size of the inhomogeneity. This is called the microscopic domain of inhomogeneous radiative transfer. A concept called the vector intensity distribution is introduced to characterize the statistical properties of radiation in various species of medium. Radiative transfer in an inhomogeneous atmosphere is expressed in terms of the evolution of this vector intensity distribution and its various moments along the optical path. Title: Transfer of Line Radiation in a Magnetic Field Authors: Jefferies, John; Lites, Bruce W.; Skumanich, A. Bibcode: 1989ApJ...343..920J Altcode: Using a classical approach, the transfer equations are derived for spectral-line radiation in a medium which is permeated by a magnetic field. Consideration is given to solutions of these equations for the 'weak-field' case, when the Zeeman splitting is a fraction of the Doppler width, and the range of validity of such solutions. Some approximate expressions allow a simple inference of the vector-field characteristics directly from the line profiles. Title: Profiles of the Extreme Solar Limb at Far Infrared and Submillimeter Wavelengths Authors: Roellig, T. L.; Werner, M. W.; Kopp, G.; Becklin, E. E.; Lindsey, C.; Orrall, F. Q.; Jefferies, J. T. Bibcode: 1989BAAS...21..765R Altcode: No abstract at ADS Title: Radiative Transfer in Inhomogeneous Atmospheres: A Statistical Approach Authors: Jefferies, John T.; Lindsey, Charles A. Bibcode: 1988ApJ...335..372J Altcode: A procedure is presented for calculating the statistical properties of the radiation which emerges from a multicomponent gas when the absorption and emission coefficients vary statistically along the direction of propagation. A relation describing the evolution of the intensity distribution through the gas is derived, and, from that, a transfer equation for the expected value of the intensity is obtained which is analogous to the standard transfer equation for a continuous medium and to which it reduces in the limit of a homogeneous medium. General solutions for this transfer equation, and the analogous transfer equation for the variance, are found for a special class of situations. As a representative example, consideration is given to the transfer of radiation through a spherical atmosphere consisting of radial structures, with an exponential height distribution, which are immersed according to a given probability distribution in an ambium, itself inhomogeneous, whose properties also vary with height. Title: Submillimeter Observations of the Extreme Solar Limb by Occultation in the Total Solar Eclipse of 18 March 1988 Authors: Roellig, T. R.; Werner, M. W.; Kopp, G.; Becklin, E. E.; Lindsey, C.; Orrall, F. Q.; Jefferies, J. T. Bibcode: 1988BAAS...20..689R Altcode: No abstract at ADS Title: Modeling the Solar Chromosphere by Airborne Solar Eclipse Observations Authors: Orrall, F. Q.; Becklin, E. E.; Lindsey, C.; Roellig, T. R.; Werner, M. W.; Kopp, G.; Jefferies, J. T. Bibcode: 1987BAAS...19.1014O Altcode: No abstract at ADS Title: Observations of Far-Infrared Solar Continuum Variations Due to Compression Waves Authors: Lindsey, C.; Becklin, E. E.; Orrall, F. Q.; Werner, M. W.; Roellig, T. R.; Kopp, G.; Jefferies, J. T. Bibcode: 1987BAAS...19S1014L Altcode: No abstract at ADS Title: Extreme Limb Profiles of the Sun at Far-Infrared and Submillimeter Wavelengths Authors: Lindsey, C.; Becklin, E. E.; Orrall, F. Q.; Werner, M. W.; Jefferies, J. T.; Gatley, I. Bibcode: 1986ApJ...308..448L Altcode: Thirty, 50, 100, and 200 microns solar limb intensity profiles determined with arcsecond resolution from airborne observations of the occultation of the solar limb during the total eclipse of July 31, 1981, are presented. Two points of particular importance emerge: (1) the longer-wavelength (100 and 200 micron) limbs are significantly brighter than disk center. At 200 microns the extreme limb is about 1.22 times the brightness of disk center. This is consistent with the 6000 K temperature-plateau structure of the model chromospheres of Vernazza, Avrett, and Loeser (1973, Ap. J., 184, 605; 1981; Ap. J. Suppl., 45, 635); and (2) the longer wavelength limbs are extended significantly further above the visible limb than Vernazza, Avrett, and Loeser predict. These results provide a strong basis for modeling of the solar chromosphere free from the assumption of gravitational-hydrostatic equilibrium. Title: Extreme limb profiles of the sun at far-infrared and submillimeter wavelengths Authors: Lindsey, C.; Becklin, E. E.; Orrall, F. Q.; Werner, M. W.; Jefferies, J. T.; Gatley, I. Bibcode: 1986STIN...8632375L Altcode: Thirty, 50, 100, and 200 microns solar limb intensity profiles determined with arcsecond resolution from airborne observations of the occultation of the solar limb during the total eclipse of 1981 July 31 are presented. Two points of particular importance emerge: (1) the longer-wavelength (100 and 200 micron) limbs are significantly brighter than disk center. At 200 microns the extreme limb is about 1.22 times the brightness of disk center. This is consistent with the 6000 K temperature-plateau structure of the model chromospheres of Vernazza, Avrett, and Loeser (1973, Ap. J., 184, 605; 1981; Ap. J. Suppl., 45, 635;) and (2) the longer wavelength limbs are extended significantly further above the visible limb than Vernazza, Avrett, and Loeser predict. These results provide a strong basis for modeling of the solar chromosphere free from the assumption of gravitational-hydrostatic equilibrium. Title: The SHIRSOG Workshop. Proceedings of a workshop on prospects for a new synoptic high resolution spectroscopic observing facility, held at the National Solar Observatory, National Optical Astronomy Observatories, Tucson, Arizona, USA, 3 September 1986. Authors: Giampapa, M. S.; Jefferies, J. T.; Linsky, J. L. Bibcode: 1986swpw.book.....G Altcode: No abstract at ADS Title: Extreme limb profiles of the sun at far infrared and submillimeter wavelengths. Authors: Becklin, E. E.; Lindsey, C.; Orrall, F. Q.; Jefferies, J. T.; Werner, M.; Gatley, I. Bibcode: 1985NASCP2353...58B Altcode: The authors present results of analysis of 30 to 200 μm observations of the occultation of the solar limb during the total solar eclipse of 1981 July 31. The observations were made from the Kuiper Airborne Observatory. The 30 to 200 μm continuum radiation from the solar limb originates in the lower and middle chromosphere. By measuring the brightness profiles, one is able to fix important constraints on both the temperature of the material and its density structure. Title: Extreme limb profiles of the Sun at far infrared and submillimeter wavelengths Authors: Becklin, E. E.; Lindsey, C.; Orrall, F. Q.; Jefferies, J. T.; Werner, M. W.; Gatley, I. Bibcode: 1984abas.symp...58B Altcode: Limb intensity profiles at 30, 50, 100, and 200 microns, determined from Kuiper airborne observatory (KAO) observations of the occultation of the solar limb during the total eclipse of July 31, 1981, are presented. Significant but gradual limb brightening was found at the longer wavelengths consistent with the 6000 K temperature-plateau structure of the model chromospheres of Vernazza, Avrett, and Loeser. The 100 and 200 micrometers limbs are extended significantly further above the visible limb than the Vernazza, Avrett, and Loeser model predicts. These results show that the solar chromosphere is strongly perturbed from gravitational-hydrostatic equilibrium to heights as low as 1000 km. These profiles can serve as a powerful diagnostic for modeling the temperature and density of chromospheric structure free from the assumption of gravitational-hydrostatic equilibrium. Title: Extreme Limb Profiles of the Sun at Far Infrared and Submillimeter Wavelengths Authors: Lindsey, C.; Becklin, E. E.; Orrall, F. Q.; Werner, M. W.; Jefferies, J. T.; Gatley, I. Bibcode: 1984BAAS...16..992L Altcode: No abstract at ADS Title: In Memoriam: R. G. Giovanelli Authors: Jefferies, John T. Bibcode: 1984SoPh...94....1J Altcode: No abstract at ADS Title: Observations of the brightness profile of the sun in the 30-200 micron continuum Authors: Lindsey, C.; Becklin, E. E.; Jefferies, J. T.; Orrall, F. Q.; Werner, M. W.; Gatley, I. Bibcode: 1984ApJ...281..862L Altcode: The authors observed the brightness profile of the quiet Sun in broad continuum passbands centered at 30, 50, 100, and 200 μm with a resolution of 2arcmin. Weak radial darkening was seen at all four wavelengths near disk center. This reverses to brightening toward the limb in the 100 and 200 μm continuum. Radial darkening at 100 and 200 μm is not expected from smooth model chromospheres consistent with absolute brightness measurements. These results do not support a homogeneous model of the low chromosphere, where the temperature reversal occurs. Title: Coronal and chromospheric physics Authors: Jefferies, J. T.; Landman, D. A.; Orrall, F. Q. Bibcode: 1983huha.rept.....J Altcode: Achievements and completed results are discussed for investigations covering solar activity during the solar maximum mission and the solar maximum year; other studies of solar activity and variability; infrared and submillimeter photometry; solar-related atomic physics; coronal and transition region studies; prominence research; chromospheric research in quiet and active regions; solar dynamics; eclipse studies; and polarimetry and magnetic field measurements. Contributions were also made in defining the photometric filterograph instrument for the solar optical telescope, designing the combined filter spectrograph, and in expressing the scientific aims and implementation of the solar corona diagnostic mission. Title: Submillimeter extensions of the solar limb determined from observations of the total eclipse of 1981 July 31 Authors: Lindsey, C.; Becklin, E. E.; Jefferies, J. T.; Orrall, F. Q.; Werner, M. W.; Gatley, I. Bibcode: 1983ApJ...264L..25L Altcode: The authors present first results of observations of a lunar occultation of the solar limb made from the Kuiper Airborne Observatory in the 30, 50, 100, and 200 μm continuum during the total solar eclipse of 1981 July 31. The solar limb is found to be extended at the longer wavelengths up to 1000 km higher than predicted from smooth plane-parallel chromospheric models. Results at both second and third contact show the infrared limb extensions to be approximately 0arcsec.8, 1arcsec.5, 2arcsec.5, and 3arcsec.0 above the visible limb in the 30, 50, 100, and 200 μm bands, respectively. Title: Submillimeter extensions of the solar limb determined from observations of the total eclipse of 1981 July 31 Authors: Lindsey, C.; Becklin, E. E.; Jefferies, J. T.; Orrall, F. Q.; Werner, M. W.; Gatley, I. Bibcode: 1982STIN...8314047L Altcode: First results are presented of observations of a lunar occultation of the solar limb made from the Kuiper Airborne Observatory in the 30 micrometr, 50 micrometer, 100 micrometer, and 200 micrometer continuum during the total solar eclipse of 1981 July 31. The solar limb was extended at the longer wavelengths up to 1000 km higher than predicted from smooth plane-parallel chromospheric models. Results at both second and third contact show the infrared limb extensions to be approximately 0".8, 1"5, 2".5 and 3".0 above the visible limb in the observed bands, respectively. A possible interpretation proposes chromospheric fine structure inhomogeneities of greater density than presently incorporated in models of the middle chromosphere. Title: University of Hawaii, Institute for Astronomy, Honolulu, Hawaii 96822. Report. Authors: Jefferies, J. T. Bibcode: 1982BAAS...14..177J Altcode: No abstract at ADS Title: Astronomical studies of the major planets, natural satellites and asteroids using the 2.24 M telescope Authors: Jefferies, J. T. Bibcode: 1982huha.reptR....J Altcode: Ground based detection of east-west asymmetries in the Jovian torus, three dimensional models of the plasma conditions in the Jovian torus, rotational variations in methane band images of Neptune, Io's rapid flickering, thermophysical models, the diameters and albedos of the satellites of Uranus from radiometric observations, the diameters of Pluto and Triton, standard stars are discussed. Title: Research in planetary astronomy and operation of Mauna Kea Observatory Authors: Jefferies, J. T. Bibcode: 1982huha.reptS....J Altcode: Highlights of the programs including the major planets, satellites, asteroids, and comets are presented. The operation of the 2.24 m telescope is discussed. Title: Astronomical studies of the major planets, natural satellites and asteroids using the 2.24 M telescope Authors: Jefferies, J. T. Bibcode: 1982huha.reptQ....J Altcode: Directional features in the Jovian sodium torus, high quality CCD images of the major planets, methane bands in the spectrum of Triton, the central wavelength of the SO2 absorption band on Io, a component on the icy surfaces of the satellites of Uranus, fluctuation of Io's volcanic radiation, standard stars, and thermal radiation from the four brightest satellites of Uranus are discussed. Title: Submillimeter observations of solar limb-brightening in the total solar eclipse of 31 July 1981 Authors: Becklin, E. E.; Jefferies, J. T.; Lindsey, C.; Orrall, F.; Gatley, I.; Werner, M. Bibcode: 1981huha.rept.....B Altcode: Eight flights of the Kuiper Airborne Observatory (KAO) were devoted to solar observation. The successful observation of a total solar eclipse was accomplished. The observations were made simultaneously at 30, 50, 100, and 200 microns. The successful adaptation of the KAO for solar observations thus provided the most detailed data to date in this spectral band. The results from a preliminary analysis of the KAO data are summarized: (1) the 200 micron limb is extended about 3 arc sec above the 30 micron limb, indicating the prescence of cool dense material up to the altitudes of spicules; (2) strong radial darkening of the quiet sun intensity profile appeared at 200 microns, probably an indication that hot material in the low chromosphere is recessed into vertical magnetic flux tubes embedded in a cooler nonmagnetic substrate, which obscures the heated material approaching the limb; (3) active regions were observed to undergo a strong increase in contrast above the quiet sun background at wave lengths of 100 microns and longer; and (4) the moon was mapped for use as a photometric standard for determining the absolute intensity of the sun in all four wavelength bands. Title: Submillimeter Continuum Observations of Solar Plages Authors: Jefferies, J. T.; Becklin, E. E.; Lindsey, C.; Orrall, F. Q.; Gatley, I.; Werner, M. Bibcode: 1981BAAS...13Q.881J Altcode: No abstract at ADS Title: Observations of the Center-to-Limb Intensity of the Quiet Sun at 30-200 μm Authors: Orrall, F. Q.; Becklin, E. E.; Jefferies, J. T.; Lindsey, C.; Gatley, I.; Werner, M. Bibcode: 1981BAAS...13..880O Altcode: No abstract at ADS Title: Submillimeter Observations of the Extreme Solar Limb Obtained in the Total Eclipse of 1981 July 31 Authors: Lindsey, C.; Becklin, E. E.; Jefferies, J. T.; Orrall, F. Q.; Gatley, I.; Werner, M. Bibcode: 1981BAAS...13..880L Altcode: No abstract at ADS Title: A Comprehensive Study of the Sun in the Submillimeter Continuum Authors: Becklin, E. E.; Jefferies, J. T.; Lindsey, C.; Orrall, F. Q.; Gatley, I.; Werner, M. Bibcode: 1981BAAS...13..880B Altcode: No abstract at ADS Title: Institute for Astronomy, University of Hawaii, Honolulu, Hawaii 96822. Report. Authors: Jefferies, J. T. Bibcode: 1981BAAS...13..177J Altcode: No abstract at ADS Title: Hawaii, University-Of Authors: Jefferies, J. T. Bibcode: 1980BAAS...12..117J Altcode: No abstract at ADS Title: Ca II emission from stellar chromospheres. Authors: Cram, L. E.; Krikorian, R.; Jefferies, J. T. Bibcode: 1979A&A....71...14C Altcode: Measurements are presented of the separations of the K2 peaks and the K1 dips of the emission core of the Ca II K line observed on high-dispersion spectra of 33 late-type stars. These separations (called W1 and W2) are compared with the emission core width W which satisfies the Wilson-Bappu correlation. With some qualifications, it is found that W is directly proportional to the 1.3 power of W1 and the 1.06 power of W2. Some consequences of this result are discussed. Title: University of Hawaii, Institute for Astronomy, Honolulu, Hawaii 96822. Report. Authors: Jefferies, J. T. Bibcode: 1979BAAS...11..115J Altcode: No abstract at ADS Title: Requests for Observing Time on the CFHT Authors: Locke, J. L.; Jefferies, J. T. Bibcode: 1979BCFHT...2....3L Altcode: No abstract at ADS Title: University of Hawaii, Institute for Astronomy, Honolulu, Hawaii. Observatory report. Authors: Jefferies, J. T. Bibcode: 1977BAAS....9..106J Altcode: No abstract at ADS Title: High resolution atlas of the solar spectrum 2678-2931 A Authors: Allen, M. S.; McAllister, H. C.; Jefferies, J. T. Bibcode: 1977STIN...7831029A Altcode: A portion of the ultraviolet solar spectrum is presented in this high resolution atlas. The data, originating from a rocket echelle spectrogram obtained on 19 June 1974 of a quiet area near the center of the solar disk, extend from 2678 to 2931 A. The instrument had a nominal resolving power of 200,000 at these wavelengths and the rms precision of the rectified wavelength scale is 15 mA. Absolute intensities are computed by calibration to the absolute measurements of Kohl and Parkinson. Title: University of Hawaii, Institute for Astronomy, Honolulu, Hawaii. Observatory report. Authors: Jefferies, J. T. Bibcode: 1976BAAS....8...99J Altcode: No abstract at ADS Title: The abundance determination in a stellar atmosphere. I. LTE experimentation using an artificial non-LTE spectrum. Authors: Dumont, S.; Heidmann, N.; Jefferies, J. T.; Pecker, J. -C. Bibcode: 1975A&A....40..127D Altcode: It is shown that the classical LTE analysis of an atomic spectrum of a solar-like star leads to values of the abundance (A) which may be different from the real values. Various uncertainties affect the results derived from neutral lines. However, proper selection of the observational data, for instance use of ion lines, can lead, in similar cases at least, to good values of A. These conclusions concern the solar-like case; however, they emphasize that, in all cases, the effect of departures from LTE needs very careful discussion. Title: High-Resolution Solar Spectra in the 2900 A and the 1700 A Range Authors: McAllister, Howard C.; Smith, Peter H.; Jefferies, John T. Bibcode: 1975BAAS....7..365M Altcode: No abstract at ADS Title: The Linear Polarization of Continuum Radiation in Sunspots Authors: Finn, G. D.; Jefferies, J. T. Bibcode: 1975BAAS....7..349F Altcode: No abstract at ADS Title: University of Hawaii, Institute for Astronomy, Honolulu, Hawaii. Observatory report. Authors: Jefferies, J. T. Bibcode: 1975BAAS....7...62J Altcode: No abstract at ADS Title: The Polarization of Continuum Radiation in Sunspots. I: Rayleigh and Thomson Scattering Authors: Finn, G. D.; Jefferies, J. T. Bibcode: 1974SoPh...39...91F Altcode: Expressions are derived for the Stokes parameters of light scattered by a layer of free electrons and hydrogen atoms in a sunspot. A physically reasonable sunspot model was found so that the direction of the calculated linear polarization agrees reasonably with observations. The magnitude of the calculated values of the linear polarization agrees generally with values observed in the continuum at 5830 Å. Circular polarization in the continuum also accompanies electron scattering in spot regions; however for commonly accepted values of the longitudinal magnetic field, the predicted circular polarization is much smaller than observed. Title: Fine Structure of the Upper Chromosphere Authors: Jefferies, J. T. Bibcode: 1974IAUS...56...71J Altcode: No abstract at ADS Title: Non-LTE Profiles of the A1 I Autoionization Lines Authors: Finn, G. D.; Jefferies, J. T. Bibcode: 1974SoPh...34...57F Altcode: A non-LTE formulation is given for the transfer of radiation in the autoionizing lines of neutral aluminum at λ1932 and λ1936 through both the Bilderberg and Harvard-Smithsonian model atmospheres. Numerical solutions for the common source function of these lines and their theoretical line profiles are calculated and compared with the corresponding LTE profiles. Our results show that the non-LTE profiles provide a better match with the observations. They also indicate that the continuous opacity of the standard solar models should be increased in this wavelength region if the center-limb variations of observed and theoretical profiles of these lines are to be in reasonable agreement. Title: University of Hawaii, Institute for Astronomy, Honolulu, Hawaii. Observatory report. Authors: Jefferies, J. T. Bibcode: 1974BAAS....6...48J Altcode: No abstract at ADS Title: Inversion of the Solar Limb-darkening Equation in the Presence of Noise Authors: Kunasz, C. V.; Jefferies, J. T.; White, O. R. Bibcode: 1973A&A....28...15K Altcode: Summary. We discuss the formulation and application of the Phillips-Twomey method for inverting the integral equation of solar limb darkening in the presence of noise. We show, through numerical experiments, that the method can be successfully applied to real data and that it has clear advantages over those standard methods that rely on the expression of the source function in an analytic form. In addition, we briefly discuss some potentially interesting methods of a different kind, which are still under examination. Key words: solar limb-darkening - Phillips-Twomey inversion - source function Title: Inversion of the Limb Darkening Equation in the Presence of Noise Authors: Kunasz, Chela V.; Jefferies, J. T.; White, O. R. Bibcode: 1973BAAS....5S.274K Altcode: No abstract at ADS Title: Analysis of Si II Solar UV Emission Lines Authors: McAllister, H. C.; Jefferies, J. T. Bibcode: 1973BAAS....5T.276M Altcode: No abstract at ADS Title: University of Hawaii, Institute for Astronomy, Honolulu, Hawaii. Observatory report for the period July 1971 through June 1972. Authors: Jefferies, J. T. Bibcode: 1973BAAS....5..120J Altcode: No abstract at ADS Title: Temperature Distribution in a Stellar Atmosphere, Diagnostic Basis Authors: Jefferies, John T.; Morrison, Nancy D. Bibcode: 1973NASSP.317....3J Altcode: 1973stch.coll....3J; 1973IAUCo..19....3J No abstract at ADS Title: Solar activity (Activité solaire). Authors: Jefferies, J. T.; Simon, P.; Beckers, J. M.; McLean, D. J. Bibcode: 1973IAUTA..15...75J Altcode: No abstract at ADS Title: Hawaii's Mauna Kea Observatory Today Authors: Morrison, David; Jefferies, John T. Bibcode: 1972S&T....44..361M Altcode: No abstract at ADS Title: The Interpretation of Total Line Intensities from Optically Thin Gases. III: Application to Coronal Forbidden Line Spectra Authors: Jefferies, J. T.; Orrall, F. Q.; Zirker, J. B. Bibcode: 1972SoPh...22..327J Altcode: The diagnostic method developed in the two preceding papers of this series is applied to coronal forbidden line intensity data obtained at eclipses in 1952, 1961, 1965, 1966, and 1970. The application of the method is limited by the nature of the data but allows a first inference of the relationship between electron density and temperature in the condensations observed at these eclipses, and of the distribution of the electrons within the temperature range samples by the observations effectively 106 to 2.4 × 106 K. We determine the relative abundance of nickel to iron in the corona, finding a value in agreement with latest photospheric determinations and with a similar (factor of two) uncertainty. We are also able to set lower limits to the abundance of iron with respect to hydrogen, again finding values consistent with recent photospheric determinations. Title: The Interpretation of Total Line Intensities from Optically Thin Gases. II: The Coronal Forbidden Lines Authors: Jefferies, J. T.; Orrall, F. Q.; Zirker, J. B. Bibcode: 1972SoPh...22..317J Altcode: We discuss the application of a general diagnostic procedure, developed in the preceding paper of this series, to the inference of the physical state of coronal condensations from a knowledge of their forbidden line emission. We consider the limitations set on such an analysis by inadequacies in existing data and indicate the additional observations in the infrared and ultraviolet, as well as the visible, which will be needed for development of the full power of the diagnostic method. Title: The Interpretation of Total Line Intensities from Optically Thin Gases. I: A General Method Authors: Jefferies, J. T.; Orrall, F. Q.; Zirker, J. B. Bibcode: 1972SoPh...22..307J Altcode: We describe a general method for inferring, from the line emission of an optically thin medium, the physical state of the gas along the column in the line of sight which is sampled by the observations. Since it is not possible to infer the distribution of the physical state parameters with position in the line of sight - any arbitrary rearrangement of material giving equivalent line emission - we seek instead to specify the state in another way. A unique specification is found in terms of the bivariate distribution function μ (n, T), describing the partitioning of the matter in the gas over the density and temperature. We show that, given sufficient observational data, it is in principle possible to determine both μ (n, T), and the chemical composition. With less complete data the acuity of the analysis is correspondingly reduced. Title: University of Hawaii, Institute for Astronomy, Honolulu, Hawaii. Observatory report for the period July 1970 through June 1971. Authors: Jefferies, J. T. Bibcode: 1972BAAS....4...45J Altcode: No abstract at ADS Title: Guest Investigators at the Mauna Kea Observatory Authors: Jefferies, John T. Bibcode: 1971PASP...83..693J Altcode: No abstract at ADS Title: Population Inversion in the Outer Layers of a Radiating Gas Authors: Jefferies, J. T. Bibcode: 1971A&A....12..351J Altcode: On the basis of solutions to the coupled radiative transfer equations for multiplet lines, we present simple physical arguments on the expected distribution of population among closely spaced energy levels in the ground, or a low-lying state, of an atom or molecule. It is shown that, because uncoupling of multiplet lines will occur in the outer layers of a radiating gas, population "anomalies" will occur in the fine structure states associated with the upper and/or lower levels of the multiplet transitions. Order of magnitude estimates suggest that the mechanism is able to account for some aspects of the 18 cm OH emission, though better solutions of the coupled transfer equations are needed before proper observational comparison is possible. It is suggested that atoms with p and p2 configurations may be expected to have inverted populations among the ground state levels in the outer layers of an optically thick gas. A list is given of infrared and submillimetric atomic lines which may show amplification in astronomical sources. Two lines of C T are accessible to ground based (high altitude) instrumentation, and these may merit a diligent search. Key words: population inversion - radiative transfer Title: The spectrum of the chromosphere and corona from lambda 3000 to lambda 7000 on March 7, 1970. Authors: Jefferies, J. T.; Orrall, F. Q.; Zirker, J. B. Bibcode: 1971BAAS....3Q.262J Altcode: No abstract at ADS Title: Coronal models and coronal chemical abundances. Authors: Jefferies, J. T.; Orrall, F. Q.; Zirker, J. B. Bibcode: 1971BAAS....3..261J Altcode: No abstract at ADS Title: Population inversion in the outer layers of radiating gas. Authors: Jefferies, J. T. Bibcode: 1971JQSRT..11..545J Altcode: No abstract at ADS Title: The Spectrum of the Inner Corona Observed during the Total Solar Eclipse of 30 May, 1965 Authors: Jefferies, John T.; Orrall, Frank Q.; Zirker, J. B. Bibcode: 1971SoPh...16..103J Altcode: A series of spectrograms of the inner solar corona were obtained at the total solar eclipse of 30 May 1965 using a fast spectrograph with a circular slit that recorded the spectrum from λ3000 to λ9000 at all position angles around the limb simultaneously. In this paper absolute intensity is given as a function of position angle for the stronger lines and the continuum. In the coronal enhancement or condensation centered at heliocentric position angle 293°, absolute intensity is given for 34 forbidden emission lines and the continuum. Title: Formation of Line Spectra—A Review Authors: Jefferies, J. T. Bibcode: 1970PASA....1..356J Altcode: 1970PASAu...1..356J A typical stellar spectrogram shows a vast number of spectral lines. Each of these has its characteristic shape and strength which must, in some way, reflect the structure of the atmosphere in which the radiation arose. It seems reasonable that from all this profile data we should be able (and with considerable redundancy) to infer a good deal about the physical structure of the radiating gas, and a major effort has correspondingly been devoted to clarifying the physical basis of spectral line formation, i.e., exactly how the atmospheric structure and the atomic properties are reflected in the line profiles. This problem, however, is far from solved : Few, if any, of the profiles of strong lines can be predicted in detail from model atmospheres, nor have analyses of the profiles yielded unambiguous data on the atmospheric structure. Indeed, as recently as 1967, the participants at a conference in Bilderberg (Holland) concluded that no data at all which had been obtained from line profile analyses was worthy of inclusion in specifying the solar atmospheric model. Evidently, then, the problem of line formation is not trivial ; in this paper we discuss some of the difficulties and review the not inconsiderable progress which has been made in this area of astrophysical research. Title: Institute for Astronomy, University of Hawaii, Honolulu, Hawaii. Report 1968-1969. Authors: Jefferies, J. T. Bibcode: 1970BAAS....2...49J Altcode: No abstract at ADS Title: Models for Coronal Condensations Authors: Jefferies, J. T.; Orrall, F. Q.; Zirker, J. B. Bibcode: 1969BAAS....1Q.246J Altcode: No abstract at ADS Title: 22. Eission Line Spectrum of the Solar Corona Authors: Jefferies, J. T.; Orrall, F. Q.; Zirker, J. B. Bibcode: 1969LIACo..15..235J Altcode: 1969MSRSL..17..235J No abstract at ADS Title: 21. Forbidden Lines in the Solar Corona, Introductory Report Authors: Jefferies, J. T. Bibcode: 1969LIACo..15..213J Altcode: 1969MSRSL..17..213J No abstract at ADS Title: Emission line spectrum of the solar corona. Authors: Jefferies, J. T.; Orrall, F. Q.; Zirker, J. B. Bibcode: 1969MSRSL..25..235J Altcode: 1969tisa.conf..235J No abstract at ADS Title: Forbidden lines in the solar corona. Authors: Jefferies, J. T. Bibcode: 1969MSRSL..25..213J Altcode: 1969tisa.conf..213J No abstract at ADS Title: Studies in spectral line formation. III. Non-linear multi-level atom problems. Authors: Finn, G. D.; Jefferies, J. T. Bibcode: 1969JQSRT...9..469F Altcode: No abstract at ADS Title: Stellar aerodynamics. Introductory remarks. Authors: Jefferies, J. T. Bibcode: 1969JQSRT...9..191J Altcode: No abstract at ADS Title: Progress at Mauna Kea Observatory Authors: Jefferies, John T.; Sinton, William M. Bibcode: 1968S&T....36..140J Altcode: No abstract at ADS Title: The Chromospheric Spectrum at the 1962 Eclipse Authors: Dunn, R. B.; Evans, J. W.; Jefferies, J. T.; Orrall, F. Q.; White, O. R.; Zirker, J. B. Bibcode: 1968ApJS...15..275D Altcode: A joint expedition of the High Altitude Observatory, Sacramento Peak Observatory, and the National Bureau of Standards obtained slitless spectrograms of the flash spectrum at the February 5,1962, total eclipse of the Sun. The spectrograms covered the wavelength range of about 3200 to 9100 A with a height resolution of 100 km. The spectrographic equipment, the observations, the photometric calibration procedures, and the methods adopted to reduce the large quantity of data are described. The results are presented in a set of tables that show the wavelength and identification (where known) of each of the 3500 lines recorded. A separate set of tables lists the intensity of each line at each height. The latter tables are ordered according to the element, ionization stage, and multiplet number associated with the line. Title: Formation and Analysis of Line Spectra-A Review of Some Recent Progress. Authors: Jefferies, John T. Bibcode: 1968AJS....73R..65J Altcode: Within the past five years substantial progress has been made in the self- consistent (or non-LTE) theory of line formation. The current situation is reviewed, and outstanding questions raised, both in the "analytical" problem of deriving an atmospheric structure from an observed line spectrum, and in the "synthetic" problem of computing the spectrum emitted by a gas of given physical properties. The emphasis throughout is on the physical meaning of the results rather than on the mathematical problems. A brief discussion of basic principles is given to illustrate the fundamental role played by the score function. The successes and shortcomings of the work of the 1950's is then briefly summarized. A major limitation in earlier work lay in its restriction to a two-level atom which was, in turn, associated with numerical difficulties encountered in the solution of two-point boundary value problems or, equivalently in this case, of the integral equations for the line source functions. The different methods developed to overcome these problems will be sketched and some representative results given for some multilevel configurations. The physical interpretation of the results will be stressed, especially as concerns the predicted relationships between the different spectral line profiles arising from a given configuration of levels. On this basis the concepts of thermalization length and net-radiative bracket are examined. The analysis of an observed spectrum introduces different but related problems. It is shown how predictions from the self-consistent theory of line formation can be applied to allow a solution of the analytical problem and how and why this analysis differs from the LTE case. Limitations to the general analytical procedure are outlined. Title: Spectral line formation Authors: Jefferies, John T. Bibcode: 1968slf..book.....J Altcode: 1968QB465.J4....... No abstract at ADS Title: The Analysis of Spectral-Line Profiles. I. a. Generalized Theory for the Solar Case Authors: Jefferies, J. T.; White, O. R. Bibcode: 1967ApJ...150.1051J Altcode: Recent studies of spectral-line formation are shown to provide a basis for the analysis of profiles of multiplet lines in the "solar case," i e., when limb-darkening data are available. The theoretical foundation is more general than that assuming local thermodynamic equilibrium, which is included as a special case. A detailed analytical procedure is given along with a discussion of its shortcomings and limitations. Title: The Analysis of Spectral-Line Profiles. II. an Application to the Solar Sodium D-Lines Authors: Curtis, G. W.; Jefferies, J. T. Bibcode: 1967ApJ...150.1061C Altcode: On the basis of general principles set down in the first paper of this series, an analysis is made of Waddell's solar D-line observations The results show a large measure of seff-consistency and, among other conclusions, suggest that the temperature minimum in the solar atmosphere lies above T5 10- , and that to a factor of order 2 the solar abundance of sodium is that given by LTE analyses. Title: The Solar Observatory of the University of Hawaii Authors: Jefferies, J. T. Bibcode: 1967SoPh....2..369J Altcode: No abstract at ADS Title: Inference of Velocities from Line Asymmetries Authors: Kulander, John L.; Jefferies, John T. Bibcode: 1966ApJ...146..194K Altcode: Synthetic line profiles are generated for a variety of model atmospheres containing linear and quadratic velocity fields. Both weak and strong lines are considered. Comparison of the actual velocity structures with those inferred from the bisector shifts of the asymmetrical profiles show qualitative agreement only in the line cores and in general only for velocities small compared with the thermal velocity. Approximate expressions relating the observed profile parameters to atmospheric velocity parameters, for small linear velocities, are obtained and tested. Observed rms displacements in the solar Ha line are used to infer the amplitude of the oscillatory velocity field in that region of the solar chromosphere where the core is formed. Title: Loop Prominences and Coronal Condensations. III. The Abundances of Iron and Calcium Authors: Jefferies, J. T.; Orrall, F. Q. Bibcode: 1966ApJ...145..231J Altcode: Measured total intensities of the continuum and of the red, green, and yellow forbidden coronal lines emitted by discrete features of a sporadic coronal condensation are shown to yield firm lower limits to the abundances of iron and calcium. These strict lower limits exceed the photospheric abundances (derived by curve-of-growth analysis of Fraunhofer lines) by a factor of 3 for iron and 12 for calcium; the actual coronal abundance will be higher still. Title: Eclipse Determination of Chemical Abundances in the Solar Corona. Authors: Curtis, G. W.; Jefferies, J. T.; Orrall, F. Q. Bibcode: 1966AJ.....71S.382C Altcode: Chemical abundance determinations from observations of the coronal emission spectrum (particularly for iron) have consistently exceeded those determined from curve of growth analyses of photospheric absorption lines. Although the coronal abundances are somewhat uncertain because they depend on uncertain coronal models and uncertain theories of coronal ionization and excitation, Jefferies and Orrall (Astrophy. J. 1966, to be published) have shown that it is possible to set rigorous lower limits to the abundances that are insensitive to these uncertainties. Applying this method to coronagraph observations of the red, yellow, and green coronal lines they found lower limits to the calcium and iron abundances in excess of the photospheric values by factors of 2 or 3. We have applied this method to the very complete observations of the coronal spectrum between A3000 and A9000 obtained by the University of Hawaii- Sacramento Peak Observatory expedition to observe the eclipse of 30 May 1965. Emission lines arising from 15 different ions were studied. The resulting lower limits to the coronal abundances are given below, along with the photo spheric abundances taken from the careful curve of growth studies by C. R. Cowley (Astrophys. J. 143, 352, 1966) for Ni, and E. A. Mu~ller and J. P. Mutschlecner (Astrophys. J. Suppl. 9, No. 85, 1964) for the remainder of the elements. Abundance per 106 protons Element V Cr Mn Fe Co Ni Corona (lower limit) 0.22 1.0 0.042 5.0 1.1 1.1 Photosphere 0.013 0.12 0.065 5.0 0.026 0.49 The coronal abundances shown are strict lower limits. The actual values can be that low only if there is a specially favorable temperature distribution to make ionization a maximum and only if the local electron density is high enough that the excitation is governed completely by collisions. But within the ions Fe XI and Ni XIII, which give rise to two observable emission lines, it is clear that both radiation and collision processes enter to determine the degree of excitation. We conclude that the coronal abundances are higher than the lower limits shown and that they therefore exceed the photospheric values. Title: The Solar Abundance of Iron Authors: Jefferies, J. T. Bibcode: 1966IAUS...26..207J Altcode: No abstract at ADS Title: Survey of the Problem Authors: Jefferies, J. T. Bibcode: 1965SAOSR.174....3J Altcode: No abstract at ADS Title: Multilevel Problems Authors: Jefferies, J. T. Bibcode: 1965SAOSR.174..177J Altcode: No abstract at ADS Title: Loop Prominences and Coronal Condensations. I. Non-Thermal Velocities Within Loop Prominences. Authors: Jefferies, J. T.; Orrall, F. Q. Bibcode: 1965ApJ...141..505J Altcode: Profiles of the Ha-line observed in loop prominences at the limb with the coronagraph show much more extended wings than ordinary prominences, and a detailed study of the profiles of the loop system of February 19, 1962, shows that these wings are caused neither by instrumental effects nor by the Stark effect but arise from non-thermal motions of emitting hydrogen atoms. The possibility that these fast neutral atoms were produced by charge exchange or recombination from equally fast protons is considered and rejected since the particles would produce far too much heating. It is shown, however, that the observed wings could reasonably be interpreted as a jetlike streaming, along the loops, of matter accelerated from a region near their tops. Title: Loop Prominences and Coronal Condensations. II. The Source of Mass and Energy and a Model of the Loop Prominence Mechanism. Authors: Jefferies, J. T.; Orrall, F. Q. Bibcode: 1965ApJ...141..519J Altcode: Estimates of the mass and energy requirements of loop prominences indicate difficulties in the generally accepted "condensation process." An alternative process is considered in which super thermal particles drift or are injected into the magnetic field of the loop. It is found that all the mass required to maintain a loop (or quiescent) prominence can be supplied in the form of particles moving at tO cm/sec and that their energy will then just balance that lost by radiation Since it is now known that loop prominences are associated with those flares that produce copious amounts of fast plasma, it is suggested that the loops arise naturally as a coronal configuration by which this flare plasma is returned to the chromosphere The mass and energy required to feed the loop are provided by the injection into the system of fast particles of this plasma. The applicability of this mechanism to other types of prominences is discussed. Title: The Theory of the Chromospheric Spectrum Authors: Jefferies, John T. Bibcode: 1965ASSL....1..131J Altcode: 1965sosp.conf..131J No abstract at ADS Title: Solar Flares and the Loop Prominence Mechanism Authors: Jefferies, J. T.; Orrall, F. Q. Bibcode: 1964NASSP..50...71J Altcode: 1964psf..conf...71J No abstract at ADS Title: On the Interpretation of Prominence Spectra.VI. Temperature Determination and a Model for Quiescent Prominences. Authors: Jefferies, J. T.; Orrall, F. Q. Bibcode: 1963ApJ...137.1232J Altcode: Temperatures estimated from the widths of Balmer lines and from the continuum intensities of q prominence emission have previously been shown to be discordant. In this paper we show how the crepancy can be accounted for in terms of a variable temperature model, and we derive the characterisi of such a model. In particular, we show that, to account for the observed emission, we can allow onl comparatively small amount of material in the line of sight to be at temperatures above 15000 K Title: The Structure of Regions of Coronal-Line Emission. Authors: Jefferies, J. T.; Pecker, C. W.; Thomas, R. N. Bibcode: 1962ApJ...135..653J Altcode: No abstract at ADS Title: On the Interpretation of Prominence Spectra. V. The Emission Lines in Quiescent Prominences. Authors: Jefferies, J. T.; Orrall, F. Q. Bibcode: 1962ApJ...135..109J Altcode: Observations are presented of emission-line total intensities and widths in the range XX for two quiescent prominences. In one of these prominences, total intensities are also given for emission lines in the range XX . From the total intensities it is found that (1) the excitation temperature describing the populations of the energy levels of Fe 1 is 3600 K; (2) the ratio of intensity of the 0 1 lines at X 7775 and X 8446 (known to be variable in astronomical sources) is 18(3) the electron kinetic temperature of the region emitting He 1 must be greater than 11000 K Estimates are made of the theoretical strengths of one line of He 1 and five lines of Fe 1. The shapes of the lines in the range XX 3600- 3800 are Gaussian to within the limit of error of measurement except for the higher Balmer lines of H 1 and the lines of He 1. These lines are all free from self-absorption. The line widths of H i correspond to atom kinetic temperature of about 8200 K, but this is an upper limit, since non-thermal motions also broaden the lines It is shown that the usual method of employing the widths of metal lines to correct for these non-thermal motions overcorrects in quiescent prominences, yielding too low a temperature; however, the hydrogen and metal line widths are consistent with atom kinetic temperatures between 6500 and 8200 K. In Paper IV the electron kinetic temperature was found to be 12500 K from continuum measures in one of these same prominences. The difference between the temperatures given by the two methods cannot be attributed to observational error. Although a real difference between the atom and electron kinetic temperatures may exist, it is suggested rather that these temperatures are averages over steep temperature gradients and the averages are weighted differently by the two methods. Title: On the Interpretation of Prominence Spectra.IV. The Balmer and Paschen Continua in a Quiet Prominence. Authors: Jefferies, J. T.; Orrall, F. Q. Bibcode: 1961ApJ...134..747J Altcode: Observations of the Balmer and Paschen continua in a quiet prominence are discussed. Their self- consistency is considered and the observations analyzed for derivation of mean values of the electron temperature and density. A graphical method is given for determining these mean values from the magnitude of the Balmer or Paschen jump, together with the emission per unit volume in the appropriate freebound continuum. It is pointed out that, because of the relatively small jump at the series limit, Paschen continuum observations are much less useful than those at the Balmer limit The Balmer jump and total emission is found to be consistent with the mean values T 12000 K and n 8 X 1O . These results are compared with those derived previously in the same way, for a flare-type loop, namely, T 15000 K and n, 2 X 1O , and for a chromospheric flare T __ 12000 K and n __ 3 X tO . Title: Vertical Velocities in the Solar Chromosphere Authors: Giovanelli, R. G.; Jefferies, J. T. Bibcode: 1961AuJPh..14..212G Altcode: No abstract at ADS Title: On the Interpretation of Prominence Spectra. II. The Line and Continuous Spectrum of the Spray-Type Limb Event of March 7, 1959. Authors: Jefferies, J. T.; Orrall, F. Q. Bibcode: 1961ApJ...133..946J Altcode: The line and continuum emission of a limb flare of March 7, 1959, are discussed. An analysis of the continuum emission near the almer limit shows that the kinetic temperature of the flare must be considerably less than 20000 K in that region where the hydrogen is excited. On the assumption that the hydrogen emission is axially symmetric, a model is derived for the temperature, electron density, and gas pressure as a function of distance from the axis. The temperatures so derived are much lower than those obtained from the usual methods of line-width analysis, which, it is suggested, are of questionable value in application to active limb events. Title: On the Interpretation of Prominence Spectra. III. The Line and Continuous Spectrum of a Loop Prominence and Limb Flare. Authors: Jefferies, J. T.; Orrall, F. Q. Bibcode: 1961ApJ...133..963J Altcode: A detailed photometric study is presented of the line and continuous spectrum of the limb flare of June 9, 1959. The electron temperature is found to be certainly less than 24000 K in the bright, dense central portion of the flare, where the hydrogen lines and continuum are excited. The flare occurred as a condensation in an active coronal region, yet the temperature is only slightly higher than that observed in a spray-type flare that originated at the chromospheric level We tentatively suggest temperatures of 10000 and 20000 K, respectively, for "cool" and "hot" prominence classes suggested by Zirin and Tandberg-Nanssen. Title: A Comment of the NRL Solar Lyman-Alpha Results. Authors: Jefferies, J. T.; Thomas, R. N. Bibcode: 1961ApJ...133..606J Altcode: Supplementary comments are made on the Morton-Widing analysis of the NRL Ly-a observations; they serve to bring into sharper focus its relation to current attempts at analysis of self-reversed emission cores of collison-dominated lines for gradients of T , for chromospheric structure, and for differential structure between quiet sun and plage, sunspot and flare regions. Title: Source Function in a Non-Equilibrium Atmosphere.VI. The Frequency Dependence of the Source Function for Resonance Line. Authors: Jefferies, J. T.; White, O. R. Bibcode: 1960ApJ...132..767J Altcode: The frequency dependence of the line source function is investigated for the case of pure coherent scattering in the reference frame of the atom. It is shown that the thermal redistribution due to Doppler effect gives a form of scattering similar to complete redistribution in the line core and coherency in the wings. Using a modified form for this redistribution and allowing for some residual non-coherency due to collisions in the frame of the atom, an algebraic solution of the transfer equation is obtained, and emergent line profiles are computed, for an isothermal atmosphere. It is shown that the line shape in the transition region from line core to wing is strongly influenced by the proportion of this residual non-coherency. It is finally suggested that, until the strength of collisional perturbations is better understood from theoretical or laboratory studies, theoretical work on line spectra should adopt complete redistribution in scattering. Title: Source Function in a Non-Fquilibrium Atmosphere. VII. The Interlocking Problem. Authors: Jefferies, J. T. Bibcode: 1960ApJ...132..775J Altcode: A general solution to the equations of statistical equilibrium is presented and applied to the problem of determining the influence of interlocking on the depth variation of line source functions. Approximate uncoupled transfer equations are derived for a simple three-level atom, and their quality is tested against exact solutions. A discussion is given-exemplified by hydrogen-of the influence of coupling for models consisting of larger numbers of levels. The general form of the depth variation in the H and K lines of Ca ii is shown to be little different from that derived in earlier papers of this series where interlocking was neglected. It is shown, however, that the strong coupling results in a common a given depth-of the H and K line source functions. Title: The Source Function in a Non-Equilibrium Atmosphere. V. Character of the Selfreversed Emission FO CA^{+} H and K. Authors: Jefferies, J. T.; Thomas, R. N. Bibcode: 1960ApJ...131..695J Altcode: The methodology of Paper III is applied to delineate the principal parameters affecting the characteristics of the self-reversed emission cores of Ca+ H and K, in order to clarify whether current discussions in terms only of are adequate. We find two additional factors to be significant-c and the Te gradient. The factor E provides an effect in the correct direction to interpret the Wilson-Bappu effect, but of too small a size, subject to a more complete treatment of the region outside the Doppler core. The effect of the T6 gradient seems more significant, particularly as a basis for interpreting the observed solar variations. Title: Thermally Broadened Stark Profiles of Some High Balmer Lines. Authors: Jefferies, J. T. Bibcode: 1960ApJ...131..690J Altcode: Results are given of some computations of the thermally broadened Stark profiles of the Balmer lines H12, H16, H18, and H26. The calculations are made for ion densities and kinetic temperatures likely to be of interest in solar prominences and flares. The degree of overlap between 1126 and H27 is also computed as a function of ion density and mean random atomic velocity. Title: The line and continuous emission observed in two limb flares Authors: Dunn, R. B.; Jefferies, J. T.; Orrall, F. Q. Bibcode: 1960Obs....80...31D Altcode: No abstract at ADS Title: Source Function in a Non-Equilibrium Atmosphere. III. The Influence of a Chromosphere. Authors: Jefferies, John T.; Thomas, Richard N. Bibcode: 1959ApJ...129..401J Altcode: We apply the methods developed in the preceding two papers to investigate the depth dependence of the source function for resonance lines in an atmosphere having a chromospheric distribution of T, superposed upon a photospheric one. The derived behavior of SL( ) for the neutral and ionized metals differs and mimics the observed behavior of such lines. The hydrogen Balmer lines should behave like the neutral metals, and the predicted behavior agrees with our earlier empirical results. Title: The nova outburst: III. The ionization of hydrogen gas by an exciting star Authors: Jefferies, J.; Pottasch, S. Bibcode: 1959AnAp...22..318J Altcode: No abstract at ADS Title: The Flare of September 18, 1957. Authors: Jefferies, J. T.; Smith, E. V. P.; Smith, H. J. Bibcode: 1959ApJ...129..146J Altcode: A set of spectra of the disk flare of September 18,1957, is discussed. The spectra, covering simultaneously a wave-length range of XX 390() 7200 at a dispersion of 2 A/mm, cover the period through the maximum phase. The Balmer lines reached a central intensity in excess of three times the neighboring continuum and were at that time exceedingly wide. Several helium lines were in emission,including X 4686 of He II, as well as the prominent neutral lines. The data indicate that the excitation conditions in the visible flare vary rapidly with depth and suggest that the flare is merely an extension of a more powerful excitation. The Balmer series wing shapes are shown to be compatible either with Stark effect or with a particular form of velocity field of macroscopic or microscopic motions. Title: The Source Function in a Non-Equilibrium Atmosphere. II. The Depth Dependence of the Source Function for Resonance and Strong Subordinate Lines. Authors: Jefferies, John T.; Thomas, Richard N. Bibcode: 1958ApJ...127..667J Altcode: We obtain an algebraic solution for the depth variation of the source function 8L (r) for resonance and strong subordinate lines by using the Eddington approximation plus the method of discrete ordinates. We show that if an observed line profile, produced in an atmosphere with the above SL (r), is analyzed under the assumption of local thermodynamic equilibrium, an underestimate of T.(r) in the outer atmospheric layer results. The derived SL(r) agrees in qualitative behavior with the source function found empirically by Athay and Thomas for the early Balmer lines of hydrogen. Title: On the Interpretation of Prominence Spectra. I. Balmer Series Line Widths. Authors: Jefferies, J. T.; Orrall, F. Q. Bibcode: 1958ApJ...127..714J Altcode: Line widths, derived from a set of high-dispersion spectra in Balmer series Ha-H have been used to show that the assumption of a constant-source function for Ha in prominences is not, in general, correct. It is pointed out that, with our present ignorance of prominence conditions, very little information can be obtained from the Ha line alone but that, when coupled with spectra in other Balmer lines, the Ha line may possibly provide a basis for inferring the run of physical conditions with depth. It is suggested that the common procedure of determining a kinetic temperature and turbulence from hydrogen and helium lines may also be erroneous. Title: The interpretation of Balmer line profiles in solar prominences. Authors: Jefferies, John T.; Orrall, Frank Q. Bibcode: 1957AJ.....62..143J Altcode: In the past, it has been the usual practice to interpret prominence observations on the assumption that the observed radiation is the intrinsic radiation of the prominence itself. It has been recently pointed out, however, that a major component of the observed radiation-at least in Ha should be scattered disk radiation; the prominence thus acting as a diffuser as well as an emitter. In order to get a better understanding of the process of line formation in prominences as well as to obtain a consistent approach to the determination of prominence temperatures, high dispersion profiles have been obtained of the hydrogen Balmer lines Ha through HE and the helium lines X5876 and X447I in prominences showing a minimum of internal motions. The prominences were observed, at the limb, with the i6-inch coronagraph at Sacramento Peak. Several years ago, Conway (1952) and Ellison (1952) observed that Ha prominence line profiles could be fitted very well to theoretical profiles computed on the assumption of a source function constant in frequency across the line and constant in depth in the prominence. The same remarkable agreement has been obtained for our observations, except of course, for those cases where the Ha line is self-reversed. For subordinate lines like these, it is almost certain that the source function is in fact frequency independent. The good agreement obtained between the observed profiles, and those computed on the assumption of a source function constant in depth, however, is probably largely fortuitous. It seems that almost any monotonic source function could be fitted by one of the family of curves. In any case, the occurrence of double- peaked profiles in Ha shows that for this line the assumption is not generally valid. In order to test this assumption further, the optical depth at the center of the Ha line has been computed from the run of widths of the Balmer lines H~ through HE. This method was found to give a higher optical depth than that implied by the shape of the Ha line using the assumption of a source function constant in depth. It seems clear that the usual method of estimating prominence temperatures from the Ha profile is very unreliable. Conway, M. 1955, Contr. Dunsink Obs. No. 3. Ellison, M. A. 1952, Pub. Royal Obs. Edinburgh I, No. 5. Sacramento Peak Observatory, Sunspot, N. Mex. Title: Temperatures and electron densities in flares as derived from spectroscopic data Authors: Jefferies, J. T. Bibcode: 1957MNRAS.117..493J Altcode: It is shown that model ares with electron concentrations and temperatures in the ranges 5Xio11-io13cm-3 and io4- .K respectively have emissions consistent with the observed hydrogen and helium line intensities in solar flare spectra. Some difficulties are shown to exist in interpreting the observed great line width of H and a possible solution is given. Title: The D3 emission of prominences Authors: Jefferies, J. T. Bibcode: 1956MNRAS.116..629J Altcode: The computed emission of H and D3 from an isothermal slab model prominence is shown to give agreement with observational data of Bruck and Moss when the model has helium abundance one fifth that of hyd gen, thickness z X I0 km, temperature between X 1o deg. K and 2.0 X I0 deg. K and electron concentration between 1010 cm-3 to 5 X 1010 . Some evidence has been found that the higher temperatures are generally associated with lower electron concentrations. Comparison of the present computations with earlier results obtained by the author from an analysis of the contour of the H emission of prominences shows that the ratio of the abundances of helium and hydrogen atoms in solar prominences lies in the range to 04. As for H , the self emission in D3 is generally small compared with the diffusely reflected and transmitted component. Title: The High Temperature Excitation of Helium Authors: Jefferies, J. T. Bibcode: 1955AuJPh...8..335J Altcode: No abstract at ADS Title: The Hα emission of prominences Authors: Jefferies, J. T. Bibcode: 1955MNRAS.115..617J Altcode: It is shown that M radiation from the solar disk is strongly reflected by prominences and is an important component of their radiation. An analysis of their observed Ha emission at the limb indicates a range of kinetic temperatures of about io4 to z X i04 deg. K and electron concentrations of about i010 to X 1010 cm-3 for stable prominences. Two alternative explanations are given for the double peaked profiles of Ha sometimes observed in solar prominences, depending on whether scattering is coherent or incoherent. Title: The Emission of Radiation from Model Hydrogen Chromospheres. II Authors: Jefferies, J. T.; Giovanelli, R. G. Bibcode: 1954AuJPh...7..574J Altcode: No abstract at ADS Title: The Albedo for the Atomic Scattering of Optical Radiation Authors: Giovanelli, R. G.; Jefferies, J. T. Bibcode: 1954AuJPh...7..570G Altcode: No abstract at ADS Title: Some Electron Collision Cross Sections of CaII Authors: Jefferies, J. T. Bibcode: 1954AuJPh...7...22J Altcode: No abstract at ADS Title: Emission of Radiation from Model Hydrogen Chromospheres Authors: Jefferies, J. T. Bibcode: 1953AuJPh...6...22J Altcode: No abstract at ADS