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A study of the formation and movement of sequential Sporadic-E layers observed during the night-time hours at two Indian low-latitude stations, SHAR (dip 10°N) and Waltair (dip 20°N) shows that the layer are formed around 19:00 h. IST at altitudes of ~180 km. They descend to the normal E-region altitude of about 100 km in three to four hours and becomes blanketing type of Es before they disappear. However, the absence of these descending layers at an equatorial station, Trivandrum (dip 2°N) gives the experimental evidence for wind shear theory. The meridional neutral wind derived from the height variation of the F-layer showed significant poleward wind during the descent of these layers. Hence it is inferred that these layers are formed as a consequence of the convergence of plasma by the poleward wind and the equatorward propagating gravity waves (inferred from the height fluctuations of F-layer).Key words. Ionosphere (active experiments; equatorial ionosphere · ionospheric irregularities)

Recordings of the variations in phase path, P of reflections, at vertical incidence, from blanketing sporadic-E layers over Kodaikanal (dip 3.5?N) revealed small amplitude, quasi-sinusoidal oscillations of 45-180 s periods in the time rate of change of phase path, (Doppler frequency). Geomagnetic micropulsation activity at ground level in the Pc4 range (45-150 s) was not evident at Trivandrum (dip 0.6?S, located ~ 200 km south of Kodaikanal) on all the 26 occasions (out of the total 29 events studied) when geomagnetic data simultaneous with the phase path observations were available. Besides, the short period quasi-periodic fluctuations in were also consistently seen in the data of equatorial sporadic E reflections. We interpret the observed pulsations in as representative of those in the vertical electron drift associated with the longitudinal electrostatic drift waves generated in the equatorial electrojet by the gradient drift plasma instability mechanism.

Enhanced plasma lines in blanketing sporadic E have been excited by a powerful HF radio wave illuminating the E region over the Arecibo Observatory. The plasma lines are observed by the incoherent scatter radar at the observatory. They originate in the sporadic E layer when the blanketing frequency exceeds the exciting frequency, a result which confirms that the plasma is overdense for the exciting frequency. Around the time when the blanketing frequency falls through the exciting frequency, large fluctuations in the plasma line intensities are observed, and thus the possibility of overdense patches drifting through the sampled volume is suggested.

IN the May, 1933, number of AIRCRAFT ENGINEERING there was published an article by Korvin‐Kroukovsky on the uncontrolled tail spin, in which one of the main points put forward was that during a spin both the body and the tail were very largely shielded by the wings. It was then argued from this that danger might be expected more especially in the low‐wing monoplane type and also the biplane with big forward stagger of wings. At the time there was very little direct evidence on the effect of wings on body and tail moment although an early report on the “ Bantam,” an unstaggered biplane which had spun into the ground, had shown pretty clearly that it was the tailplane which was responsible for the complete blanketing or even reversal of the fin and rudder in a flat spin, and that this could be remedied by raising the tailplanc.

Alloy compositions blanketing the tungsten-columbium-tantalum ternary system were screened by means of hardness tests at 2300° to 2900°F and weight gain in oxygen at 2190°F. These tests delineated areas combining high hot-hardness with at least tenfold improvement in oxidation resistance over that of pure metals.

Analysis of spread E, the spreading frequently observed above the sporadic E layer, shows that it can be caused by the cross-field plasma instability mechanism proposed by Reid [1968] and Chen et al. [1972]. The analysis was based on the determination of the extent of spreading relative to the blanketing frequency of the sporadic E layer, and the results of the analysis were such that they conformed with predictions based on the cross-field instability mechanism.

International audience; The atmospheric CO2 content has increased significantly over recent decades, mostly as a result of the burning of coal and oil; and it could double in less than a century1–4. Because the CO2 molecule absorbs radiation in the thermal long-wavelength domain, it contributes to the blanketing or greenhouse effect of the atmosphere, and an increase in atmospheric CO2 would be expected to lead to a rise in the mean surface temperature of the Earth1–6. Early estimates indicate that for doubled CO2, the surface temperature would be raised by 1–10 K, but recent numerical experiments with radiative-convective or general circulation models (RCM, GCM) of the atmosphere seemed to narrow this range to 2–4 K (see refs 2–6). However, Newell and Dopplick7, and Idso8, argue that these results are inconsistent with the observed or computed values of certain terms of the surface energy budget, which seem to indicate a far smaller sensitivity. Here, I examine all of the terms of the surface energy budget7–11 and find that there is no basic disagreement between the surface energy budget approach and the more elaborate model experiments, provided that there is a clear distinction between external perturbation and atmospheric feedback, and that equivalent representations of surface processes are used. However, the temperature and humidity dependence of the terms of the surface energy budget shows that the surface temperature sensitivity depends critically on the way in which the atmospheric humidity evolves, and on the degree of compensation in the perturbation of the latent and sensible heat fluxes.

It is found by analysis that the performance of direct contact spray condensers at typical OTEC noncondensible loadings is the same to within a percent or so of that which would be obtained if the noncondensible were absent when a short countercurrent finishing section in the flow path leading to the vent pump is included. Blanketing effects by noncondensibles are found to be negligible.

Photoelectric measurements of the β-index were made for six Ap-stars (56 Ari, 41 Tau, φ Dra, HD 188041, HD215441, HD 221568) and one He-rich star (HD 184927) . For all these stars the minimum of β occurs at a phase of maximum light at a wavelength longward of the null-wavelength region. Such coincidence can be explained by the blanketing mechanism proposed by Kodaira (1973) for the explanation of the Hγ line variations in HD 221568. According to Kurucz. (1979), for stars hotter than 9000K an increase of metal abundance in the atmosphere causes an increase of the visible flux and an simultanous decrease of equivalent widths of Balmer lines . The same changes of the visible flux and equivalent widths of Balmer lines can be obtained using a model atmosphere with a suitable higher temperature. Using the Kurucz (1979) model atmospheres, temperature differences were calculated, which are necessary to obtain the observed decrease of the β-index and the increase of the flux in a given photometric band.

The influence of variable blanketing on the photometric variations of hot, silicon Ap star HD 27309 has been estimated. Spectrum variations in the visible are not the principal reason for the observed light variability, but flux redistribution from UV into visible fit well the observational data. An reference is made on the fulfillment of the variable blanketing assumptions at least for silicon Ap stars.

It has been hypothesized that the sun’s irradiance may fluctuate at near UV and blue wavelengths due to changes in solar line blanketing associated with solar activity. Preliminary determinations of the solar spectral irradiance in the visible spectrum, made over a 6 mo period at the Mauna Loa Observatory, indicated that the solar radiation was constant to at least 1%. There were indications, however, that the blue light of the sun (λ ∿ 400 nm) may have varied by a few tenths of one percent. It is recommended that solar spectral irradiance be measured in absolute (SI) units so that long-term (decades) changes, that may be related to terrestrial weather, can be quantized. It is now possible to determine spectral irradiance to + 1% accuracy by incorporating a new dye laser-active cavity radiometer calibration method.

A numerical code has been written which is designed to calculate radiation transport and atmospheric structure under the constraints of statistical equilibrium in atomic transitions and radiative and hydrostatic equilibrium in the medium. In addition to the complete linearization and variable Eddington factor techniques of Auer and Mihalas, it uses a multi-frequency / multi-grey algorithm which admits the inclusion of many spectral lines in full statistical equilibrium. The program can comfortably accept up to about 300 specific lines arising from about 30 lower states and any number of continua. Cleverly constructed artificial model atoms can extend the number of lines to 3000 or more, where opacity sampling techniques can begin to approximate the blanketing accomplished by Kurucz in LTE. By way of example, I present a model of a stellar atmosphere with effective temperature 35,000 K and surface gravity 104 cm s-2. The calculation includes 98 bound-free transitions and 93 bound-bound transitions (57 with radiative rates) between 91 states in 36 ions of 9 cosmically abundant species.

We have modeled the evolution of an impact-generated steam atmosphere surrounding an accreting Earth. The model assumes Safronov accretion; it includes degassing of planetesimals upon impact, thermal blanketing by a steam atmosphere, interchange of water between the surface and the interior, shock heating and convective cooling of Earth's interior, and hydrogen escape, both by a solar extreme ultraviolet (EUV) powered planetary wind and by impact erosion (atmospheric cratering). The model does not include atmophiles other than water, chemical reaction of water with metallic iron, core formation, compression, and spatial and temporal inhomogeneity of accretion. If the incoming planetesimals were too dry or the EUV flux too high, very little water would accumulate at the surface. Essentially all water retained by such a planet would be through rehydration of silicates. If rehydration were inefficient, very little water would be retained in any form. Degassing of wetter planetesimals produces a steam atmosphere over a magma ocean, the energy of accretion being sufficient to maintain a runaway greenhouse atmosphere. The mass of the atmosphere is limited by water's solubility in the (partial) melt. This type of solution is produced for a wide range of model parameters. During accretion, approximately 30 bars of water could have kept the surface at 1500 degrees K. As the accretional energy input declined below the runaway greenhouse threshold, the steam atmosphere rained out. Outgassing of dissolved water at the close of accretion is quantitatively important. These models can leave from approximately 100 to more than 300 bars of water at the surface at the close of accretion. In general, most of the water accreted remains dissolved in the mantle. H2 could have escaped as rapidly as it formed only if the planetesimals were relatively dry. Consequently H2 should have accumulated until it reached chemical equilibrium with water vapor. Impact erosion (escape caused by impact) is a critical but poorly understood process. It can prevent the accumulation of a steam atmosphere if the planetesimals are sufficiently dry, or for wetter impactors if it is much more effective than we have assumed. Impact erosion of a steam atmosphere is less important; it is equivalent to a slightly drier rain of impactors. If a hypothetical Moon-forming impact took place before the collapse of the runaway greenhouse, relatively little water (approximately 30-100 bars) would have been in the atmosphere; hence little could have been lost. If the event took place later, the potential damage could have been greater.

Electron density data obtained over the dip equator using rocket-borne high resolution Langmuir probes is examined during the presence of blanketing (Es-b) as well as diffused type (Es-q) sporadic E layers in the ionosphere. Plasma irregularities are found to exist in both the cases which could be ascribed to the crossfield instability mechanism. It is found that the irregularities are located in the bottomside gradient portion in the E region when Es-q is generated and on the topside gradient portion of a sublayer produced during Es-b. This behaviour is interpreted in terms of the orientation and shape of the plasma irregularities which in both cases are found to have a saw-tooth structure. It is suggested that the presence of long lived metallic ions must be facilitating the formation and maintenance of the observed sharp structure of the irregularities.

Photometric abundance determinations using blanketing in the ultraviolet and violet spectral regions as well as the intensity of strong lines and bands is the most important tool in the study of chemical composition of faint and distant stars. However, this method requires the calibration of different photometric quantities in terms of abundance at given temperatures and luminosities. Two principal methods of calibration are in use. One of them uses stars with abundances determined from high dispersion spectra by curve of growth or model atmosphere analysis of the spectral lines. The other one uses synthetic spectra based on model atmospheres which are integrated to imitate the narrow band photometric indices. This paper will summarize the results of the application of both of these methods to calibrate a number of the important photometric systems. Most attention will be given to the late-type stars, which demonstrate the strongest photometric abundance effects.

The halo program of the Basel observatory, initiated by Becker in 1965, is based on a three colour photometry in test fields along the circle through the galactic centre and the galactic poles. The more favourable direction of the blanketing vector relative to the main sequence in the two colour diagram for RGU makes it possible to separate at least statistically the disk population and the halo populatior within the interval of absolute magnitudes + 3 ≦ MG ≦ + 8. It is therefore possible to derive density functions for both populations and for different intervals in absolute magnitude for each test direction within the test plane defined above. This allows one to draw isodensity curves in the test plane and, assuming rotational symmetry of the halo, also isodensity surfaces. The last assumption is tested at least locally by test fields with different inclinations towards the test plane (Fenkart, R.P. and Wagner, R., 1975).

A new reactor system, in which two adjacent fluidized beds exchange solids but not gases, has been developed, and patented. The partition between the two fluidized beds is designed to permit the movement of solids in both directions, but to provide an effective seal against gas mixing. There are no moving parts. High circulation rates can be achieved, and can easily be controlled. Gas mixing at less than the 2% level can be achieved without a neutral blanketing gas to seal the interface. It should be possible to achieve zero leakage with a blanketing gas. The reactor system was developed as an oil shale retort in which the combustor exchanges solids with the retort - but in which the combustion gases and product gases are kept separate. However the system has many potential applications including gasification and pyrolysis of coal; hydrogen production; heat exchange in difficult conditions; SO//2 removal by absorption or adsorption.

A discussion is presented concerning the preliminary design and hazards evaluation of a H-cooled in-pile experimental loop for operation in the large double-walled through-tube in the Experimental Gas-Cooled Reactor (EGCR) at Oak Ridge. This loop is designed to permit experimentation with full-scale fuel element configurations up to 8 in. OD, at inlet gas temperatures of 600 to 950 deg F at 300 psig, and experimental power levels up to 500 kw. The results of a preliminary hazards evaluation indicate that a loop of this type can be safely operated in the EGCR. The H flammability hazard is controlled by blanketing all H-filled pipes and components with a sufficient quantity of nonreactive gas, such as He or CO/ sup 2/, to produce a noncombustible mixture for all credible H- release situations. (auth)

Pilot unit Zirflex dissolutions were carried out on near prototypical tube-in-tube type elements clad in oxidized Zircaloy. The runs were made with the elements horizontal and at simulated large scale operating conditions. No significant difference was noted between the actual decladding achieved in these experiments and that which was predicted from prior studies on similarly oxidized elements with somewhat different geometries. No gas blanketing nor diffusion effects were observed. Initially, preferential attack was noted on areas where oxide film had been scratched or handled. However, near the end of a run a random distribution of undissolved cladding existed; 90% of the cladding was removed in 6.5 hours. (auth)

Ultraviolet observations of line blanketing in the spectrum variables α Scl and α2 CVn show that the usual procedure of allowing line blocking in model atmospheres has to be revised. It is also suggested that the region around 2900 A could be safely used for determining effective temperatures.

Models of rotating stellar atmospheres have been constructed for masses appropriate to middle and late A stars, and some of the photometric properties of these models are discussed. A specific model for the rapidly rotating star Altair has been constructed matching the observed radius, luminosity, and projected rotational velocity. It is found that the energy distribution predicted for the model agrees well with that observed for Altair, after the latter has been corrected for line blanketing.

Effective temperatures of O-type stars imbedded in diffuse nebulae are derived from measurements of Ha and radio fluxes from the nebulae and the apparent magnitudes of the stars. Accurate model atmospheres, with ultraviolet line blanketing where appropriate, are used for the theoretical relation between effective temperature and the ratio of Lyman continuum to visual stellar fluxes. Although there is considerable scatter in the results, an average temperature of 48000 K is found for spectral type O5, 40000 K for O6, and 35000 K for O7.

Ultraviolet solar observations are compared with predictions from a new solar model. From 3600 to 1700 A there is heavy line blanketing; probably one or more major sources of opacity are missing from the theoretical calculation in this region.

Helium abundance in stellar atmospheres has been the subject of several recent in-vestigations, essentially induced by progresses in the computation of non-grey model atmospheres (including line blanketing in the far U.V.), by considerable advances in the theory of Stark broadening of helium lines, by non local thermodynamic equilibrium (LTE) work for the helium spectrum and more fundamentally by the intrinsic importance of the helium over hydrogen ratio in cosmological theories.

There are up to 14 known Mira variables in seven globular clusters, though several have not yet been confirmed as radial velocity members. The periods of only 5 are known, all near 200 days. The clusters seem to form a compact group of relatively metal rich clusters. In 3 or 4 cases spectroscopy shows that the giant branches of these clusters penetrate into the M types. The Mira-containing clusters also contain red variables of shorter period and smaller amplitude which are generally also M type stars. Stars apparently evolve to the red of the giant tip as variables of increasing amplitude and period. Effects of TiO blanketing on the (B - V) colours may be anticipated in these clusters.

Some of the characteristics of echoes from the two principal daytime types of E s at Ibadan have been investigated by means of vertical incidence pulse transmissions in the frequency range 4 to 8 Mc/s. For the equatorial q -type E s it is found that the fraction of the incident power reflected back varies with frequency f approximately as 1/ f 9·4 The fading rates are of the order of 4 c/s and increase almost linearly with wave frequency. Spaced receiver experiments indicate that the irregularities in the diffraction pattern on the ground are elongated along the geomagnetic field lines with scale sizes of about 20 metres and 300 metres in the east–west and north–south directions respectively. Blanketing E s is observed only occasionally at Ibadan and it is found that its fading characteristics are very similar to those of the normal E layer with fading rates of about 0·8 c/s. The ground amplitude pattern has scale sizes of 60 metres and 500 metres transverse and parallel to the field lines respectively and the fading at midday is consistent with the picture that the irregularities in the ionosphere are moving westwards with a steady horizontal drift velocity of about 60 m/s superimposed upon a random velocity of 30 m/s. The amplitude distributions of the signals reflected or scattered from both types of E s are predominantly of the Rayleigh type.

A description of the behaviour of E s is first given by appropriate statistical means i.e. with auto- and cross-correlation functions and by the fluctuation range. The different effects appearing in monthly median values of top and blanketing frequencies are described. Some results concerning the electron density profile of E s layers can be deduced from routine and special observations. Different methods and results are given in order to describe one of the most unique features of E s viz. its variable transparency properties. A suitable model of the electron density distribution in three coordinates can be given. By comparison of the observations with different theories it is concluded that different from the other ionospheric layers E s has a “meteorological” behaviour; vertical exchange trapped by some discontinuity, eventually wind shears, seems to be the most probable explanation.

We consider the Orion Nebula (M 42) within a project aimed at studying the interaction between massive stars and their surrounding ISM. This is an H ii region ionized by θ1 Ori C, one of the four massive stars in the Trapezium Cluster. θ1 Ori C has the earliest spectral type (O7Vp) among them, emitting an ionizing flux several orders of magnitude larger than those of the other stars. We present a spectral analysis of the Trapezium Cluster stars to determine their stellar parameters. We use spectra between 4250 – 4750 Å and compare them with synthetic spectra obtained by means of an updated version of fastwind that includes an approximated treatment of metal-line blanketing.

The near-maximum spectra of most superluminous supernovae that are not dominated by interaction with a H-rich CSM (SLSN-I) are characterised by a blue spectral peak and a series of absorption lines which have been identified as OII. SN2011kl, associated with the ultra-long gamma-ray burst GRB111209A, also had a blue peak but a featureless optical/UV spectrum. Radiation transport methods are used to show that the spectra (not including SN2007bi, which has a redder spectrum at peak, like ordinary SNe Ic) can be explained by a rather steep density distribution of the ejecta, whose composition appears to be typical of carbon-oxygen cores of massive stars which can have low metal content. If the photospheric velocity is ~10000-15000 km/s, several lines form in the UV. OII lines, however, arise from very highly excited lower levels, which require significant departures from Local Thermodynamic Equilibrium to be populated. These SLSNe are not thought to be powered primarily by 56Ni decay. An appealing scenario is that they are energised by X-rays from the shock driven by a magnetar wind into the SN ejecta. The apparent lack of evolution of line velocity with time that characterises SLSNe up to about maximum is another argument in favour of the magnetar scenario. The smooth UV continuum of SN2011kl requires higher ejecta velocities (~20000 km/s): line blanketing leads to an almost featureless spectrum. Helium is observed in some SLSNe after maximum. The high ionization near maximum implies that both He and H may be present but not observed at early times. The spectroscopic classification of SLSNe should probably reflect that of SNe Ib/c. Extensive time coverage is required for an accurate classification., Comment: 11 pages, 8 figures, in press in MNRAS

We present significant improvements of our approach in constructing detailed atmospheric models and synthetic spectra for hot luminous stars: 1. A sophisticated and consistent description of line blocking and blanketing. Our solution concept renders the line blocking influence on the ionizing fluxes (mainly the EUV and UV are affected) in identical quality as the synthetic high resolution spectra representing the observable region. Line blanketing is properly accounted for in the energy balance. 2. A considerably improved and enhanced atomic data archive providing the basis for a detailed multilevel NLTE treatment of the metal ions (from C to Zn) and an adequate representation of line blocking and the radiative line acceleration. 3. A revised inclusion of EUV and X-ray radiation produced by cooling zones originating from shock heated matter. This new tool not only provides an easy to use method for O-star diagnostics, whereby physical constraints on the properties of stellar winds, stellar parameters, and abundances can be obtained via a comparison of observed and synthetic spectra, but also allows the astrophysically important information about the ionizing fluxes of hot stars to be determined automatically. Results illustrating this are discussed by means of a basic model grid calculated for O-stars with solar metallicity. To further demonstrate the astrophysical potential of our new method we provide a first detailed spectral diagnostic determination of the stellar parameters, the wind parameters, and the abundances by an exemplary application to the O9.5Ia supergiant alpha Cam., Comment: 42 Pages, 39 Figures. LaTeX documentclass aa, packages graphicx and times. Submitted to Astronomy and Astrophysics

In this study, ship- and autonomous underwater vehicle (AUV)-based multibeam data from the German ferromanganese-nodule (Mn-nodule) license area in the Clarion–Clipperton Zone (CCZ; eastern Pacific) are linked to ground-truth data from optical imaging. Photographs obtained by an AUV enable semi-quantitative assessments of nodule coverage at a spatial resolution in the range of meters. Together with high-resolution AUV bathymetry, this revealed a correlation of small-scale terrain variations ( 1.8∘ and concave terrain. On a more regional scale, factors such as the geological setting (existence of horst and graben structures, sediment thickness, outcropping basement) and influence of bottom currents seem to play an essential role for the spatial variation of nodule coverage and the related hard substrate habitat. AUV imagery was also successfully employed to map the distribution of resettled sediment following a disturbance and sediment cloud generation during a sampling deployment of an epibenthic sledge. Data from before and after the “disturbance” allow a direct assessment of the impact. Automated image processing analyzed the nodule coverage at the seafloor, revealing nodule blanketing by resettling of suspended sediment within 16 h after the disturbance. The visually detectable impact was spatially limited to a maximum of 100 m distance from the disturbance track, downstream of the bottom water current. A correlation with high-resolution AUV bathymetry reveals that the blanketing pattern varies in extent by tens of meters, strictly following the bathymetry, even in areas of only slightly undulating seafloor (

We present new dynamical parameters of the AR Pav binary system. Ourobservations consist of a series of high resolution optical/NIR spectra from which we derive the radial velocity curve of the red giant as well as its rotation velocity. Assuming co-rotation, we determine the stellar radius (130 R_solar) of the red giant. Based on this we derive the red giant's luminosity and mass (2.0 M_solar) as well as the distance of the system (4.9 kpc). The binary mass function finally yields the companion's mass (0.75 M_solar) and the binary separation (1.95 AU). We find that the red giant does not fill its Roche lobe. We review the radial velocity data of Thackeray and Hutchings (1974), and compare it with our red giant's orbit. We find that their RV curves of the blue absorption system and the permitted emission lines are in anti-phase with the red giant, and that the forbidden emission lines are shifted by a quarter of a period. The blue absorptions and the permitted emission lines are associated with the hot companion but not in a straightforward way. The blue absorption system only tracks the hot component's orbital motion whilst it is in front of the red giant, whereas at other phases line blanketing by interbinary material leads to perturbations. We finally present UV light curves based on IUE archive spectra. We clearly detect eclipses in the continuum at all wavelengths. The eclipse light curves are unusual in that they show a slow and gradual decline prior to eclipse which is followed by a sharp increase after eclipse., Comment: 9 pages, 5 figures

The first results of simultaneous observations made on the low-latitude field-aligned irregularities (FAI) using the MST radar located at Gadanki (13.5° N, 79.2° E, dip 12.5°) and the Es parameters using an ionosonde at a nearby station Sriharikota (13.7° N, 80.1° E, dip 12.6°) are presented. The observations show that while the height of the most intense radar echoes is below the virtual height of Es (h'Es) during daytime, it is found to be either below or above during nighttime. The strength of the FAI is better correlated with the top penetration frequency (ftEs) and the blanketing frequency (fbEs) during the night (r=0.4 in both cases) as compared to the day (r=0.35 and -0.04, respectively). Furthermore, the signal strength of FAI is reasonably correlated with (ftEs-fbEs) during daytime (r=0.59) while very poorly correlated during nighttime (r=0.18). While the radar observations in general appear to have characteristics close to that of mid-latitudes, the relationship of these with the Es parameters are poorer than that of mid-latitudes. The observations reported here, nevertheless, are quite consistent with the expectations based on the gradient drift instability mechanism.

We present very early, high-cadence photometric observations of the nearby Type Ia SN 2017cbv. The light curve is unique in that it has a blue bump during the first five days of observations in the U, B, and g bands, which is clearly resolved given our photometric cadence of 5.7 hr during that time span. We model the light curve as the combination of early shocking of the supernova ejecta against a nondegenerate companion star plus a standard SN Ia component. Our best-fit model suggests the presence of a subgiant star 56 solar radii from the exploding white dwarf, although this number is highly model-dependent. While this model matches the optical light curve well, it overpredicts the observed flux in the ultraviolet bands. This may indicate that the shock is not a blackbody, perhaps because of line blanketing in the UV. Alternatively, it could point to another physical explanation for the optical blue bump, such as interaction with circumstellar material or an unusual nickel distribution. Early optical spectra of SN 2017cbv show strong carbon absorption up through day -13 with respect to maximum light, suggesting that the progenitor system contains a significant amount of unburned material. These early results on SN 2017cbv illustrate the power of early discovery and intense follow-up of nearby supernovae to resolve standing questions about the progenitor systems and explosion mechanisms of SNe Ia., photometry table available

The recent detection of a double Red Giant Branch in the optical color-magnitude diagram (CMD) of the bulge globular cluster HP1 (Ortolani et al. 1997), a more populated metal-poor steep one corresponding to the cluster itself, and another metal-rich curved, led us to explore in the present Letter the possibility of capture of field stars by a globular cluster orbiting in dense bulge regions over several gigayears. Analytical arguments, as well as N-body calculations for a cluster model of 10^5 solar masses in a bulge-like environment, suggest that a significant fraction of cluster stars may consist of captures. Metal-poor globular clusters in the inner bulge, like HP1, contrasting at least in Delta [Fe/H] = 1.0 dex with respect to the surrounding metal-rich stars, are ideal probes to further test the capture scenario. In turn, if this scenario is confirmed, the double RGB of HP1 could provide direct estimates of blanketing amounts, which is fundamental for the photometric calibration of metal-rich stellar populations., Comment: 6 pages, 2 included figures, aas2pp4,sty Latex style. To be published in Astrophysical Journal Letters

Long-term temperature records at Phoenix, Arizona, indicate the existence of a post-1946 warming trend that may be attributed to the buildup of pollution in the lower layers of the atmosphere. The causative mechanism appears to be an enhancement of the so-called "greenhouse effect," induced by the inter-action of aerosol with long-wavelength thermal radiation in the lower atmosphere.

Various techniques are practiced in the U.S. to prevent deterioration of vegetable oils following the final stage of processing through deodorization. Because oxidation; free fatty acid development, or adulteration by impurities are the primary concerns, the general practice is to keep oils in closed vessels in an atmosphere that excludes oxygen and moisture and where temperatures are controlled at minimum levels. The technology of sparging and blanketing finished oils with nitrogen during storage and transfer from vessel to vessel is shown. Also, a typical blanketing system for a series of vessels, pressure controllers, and techniques to avoid vacuum conditions is described.

I ADMIT that I have asserted too absolutely the principle that for a radiating planet fed by radiation from the sun, the relative change of equilibrium temperature (namely T/T) of the planet is of about the same order as that of the sun which is its cause. This assumes that dynamical processes in a blanketing atmosphere overlying the planet are not in control. All such effects, whether upward or downward, are superficial: the annual variation of temperature is no longer sensible thirty feet underground: and an ice age lasting 10,000 years could not be felt at 10,000 times this depth, which is about half a mile. Astronomers see down to the surface features of the planet Mars, so that there cannot be much of an atmosphere, though I observe that Dr. Simpson1 discovers a different reason in the low temperatures (ranging from 10° C. to – 70° C). On the other hand Venus, which is subject to radiation nearly twice as intense as the earth, is entirely covered with cloud, so that inhabitants below exist in a leaden atmosphere scarcely conscious of the sun: and if the cloudy shield presents a bright surface to the incident radiation, sending most of it back and absorbing little, increased intensity of it might even conceivably diminish the temperature below by increasing the density of the shielding layer and so preventing more of it from penetrating. The Smithsonian pioneers have announced fluctuations up to one or two per cent in the solar radiation, while meteorologists seem to be disinclined to recognise any proportionate change in terrestrial temperatures. Their problem is thus to explore what are the special circumstances in the terrestrial atmosphere which lead to this result.

A method of analysis of blanketing Es data, based on an empirical formula proposed by Smith (1957), is outlined and it is shown that fbEs data can be fitted well by the empirical formula. The empirical method of analysis can provide information on occurrence frequency of Es- layers with fbEs less than foE. Results obtained from empirical analysis of data from Ibadan and Port Stanley indicate that (i) observed time variation of mean fbEs is influenced considerably by the choice of the lower limiting frequency used for the Es count and (ii) that blanketing Es-layers observable at equatorial latitudes could be of comparable intensity as those observable at midlatitudes, though blanketing Es is more frequent at midlatitudes.

TEN years ago a method of calculating the field-strength of the sky wave was developed by one of us1. Apart from the well-known conditions for ionospheric reflexion, it takes account of three independent influences: geometrical optics of the reflecting layer, absorption in the D-layer and blanketing caused by the E- and Es-layers; in a later publication2 considerations of refraction occurring in the reflecting layer led to a slight modification of the analysis of the first influence2. The influence of the blanketing E- and Es-layers is only of interest for reflexions from the F-layer. Until now, this effect has been supposed to be a discontinuous one: a certain transmission path via the F-layer is assumed to be cut off by the E-layer, if, at the angle of transmission used, the frequency is inferior to the maximum usable frequency of the E-layer. If the frequency is greater, the ray will be assumed to pass.

We have measured the circular polarization of sunspots with a sensitivity of less than 3 x 10/sup -6/, over the range from 3700 A to 4.5 ..mu..m. Through all of our passbands of widths > or =0.1 ..mu..m, V has a single sign for a given spot, namely: if H is toward the observer, V is negative, i.e., the E vector rotates clockwise in a stationary plane over the spot. The rough magnitude, sign, and to some extent the spectral shape of V(lambda) for lambda> or =1.5 ..mu..m agree with a continuum magneto-opacity model. But the UV-visible polarization is anomalously large, e.g., > or approx. =0.05% in the B band, seemingly correlated with line blanketing. A new mechanism for this is proposed, magneto-emission by atoms oriented by anisotropic radiation.

The O-type subdwarf (O6p) single-lined spectroscopic binary HD 49798, with an orbital period of 1.5477 d, has been observed by the International Ultraviolet Explorer satellite, to aid in analyses of O type photospheres. Four high resolution (0.1A) spectra are found in the far-ultraviolet region, and two high resolution (0.2A) spectra are found in the mid-ultraviolet region. Numerous absorption lines are identified in the spectra of the star, most of which are attributable to Fe V lines at wavelengths of 1270 to 1500 A. Fe IV lines are also identified at wavelengths of 1500 to 1860 A. The strong Fe V features are found to have no corresponding analogs in the Kurucz and Peytremann (1975) list, and the total line blanketing for stars of spectral type O6 to B0 is discovered to be underestimated by at least a factor of four. In addition, mass loss from the subdwarf observed in the N V resonance doublet at wavelengths of 1238 A and 1242 A is discussed, indicating the existence of a hot stellar wind.

We have derived a relation between 8m1fi values of the Str6mgren four-color system and [Fe/H] values taken from the compilation of Morel et al. (1975). The result is [Fe/H] = + 0.15 - 11 8m1fi. The relation implies a solar 8m1fi = and a Hyades [Fe/H] of 0.15. Key words: four-color photometry - [Fe/H] abundances

The spectroscopic data collected on the HD 200925 variable star in the uvby and beta systems have been analyzed. The results indicate that this variable is multiperiodic, with a reddening value, E(b-y), equal to 0.029 mag. The reddening-corrected normals for y, (b-y), and c1 yielded a mean effective temperature of 7020 K, mean log surface gravity of 3.44, and a mean bolometric magnitude of 0.8 mag. A preliminary mean radius of 4.1 solar radii has been determined. The m1 data show that the blanketing is high, but this index varied in an anomalous way which precluded a definitive determination of Fe/H. Two possible explanations are considered for the behavior of the m1 index: (1) a high microturbulence excited by the secondary pulsation mode, and (2) the Am/Fm phenomenon.

A simple sample holder that provides a rigorous inert gas blanketing of air-sensitive samples without the need for elaborate inert atmosphere enclosures on the spectrometer inlet.

High resolution, high signal-to-noise spectra have provided Li abundances for 31 M giants and supergiants. The spectrum around the Li I 6707 A doublet is depressed by unresolved TiO lines. A spectrum synthesis technique was developed to account for the TiO line blanketing and to extract the Li abundance.

The method of artificial absorption edges is applied to a grid of model atmospheres to include the effects of hydrogen and metal line blanketing on the atmospheric structure. A best-fit model of Sirius is obtained which is free of the discrepancies inherent in unblanketed or partially blanketed models. All major spectral features calculated from the model agree with the corresponding observed features to within the observational uncertainty. Some additional properties of the models are discussed.