Discrimination of α and β/γ interactions in a TeO2 bolometer

TeO₂ crystals have proven to be superb bolometers for the search of neutrinoless double beta decay in many respects. However, if used alone, they do not exhibit any feature that allows to discriminate an α energy deposit from a β/γ one. This fact limits their ability to reject the background due to natural radioactivity and eventually affects the sensitivity of the search. In this paper we show the results of a TeO₂ crystal where, in coincidence with its bolometric heat signal, also the luminescence light escaping the crystal is recorded. The results show that we are able to measure the light produced by β/γ particles, which can be explained as due to Cerenkov emission. No light is detected from α particles, allowing the rejection of this background source.     

Theoretical interpretation of the 0.7820 μm CO2 band and 0.8226 μm H2O line on Venus

We have analyzed the P6, P8, and P10 lines in the 0.7820 μm CO₂ band of Venus using a scattering model. Our new results compare favorably with previous results from the 1.05 μm CO₂ band. We considered nonabsorbing and absorbing clouds. We found that the anisotropic scattering mean free path for both models at the 0.2atm level is between 0.55 and 0.73km, a range close to the value of 1 km for terrestrial hazes. We used our scattering models to synthesize the 0.8226 μm H₂O line, assuming that the clouds are composed of sulfuric acid drops, and found our nonabsorbing cloud required a sulfuric acid concentration of 82% by weight, while our thicker absorbing cloud required a concentration of 89%. A comparison of the variation of optical depth with height for our cloud models with the variation reported by Prinn (1973, Science182, 1132–1134) showed that, within a factor of 2, the variation for Prinn's thinnest cloud agreed with ours. Whitehill and Hansen (1973, Icarus20, 146–152) have recently confirmed the work of Regas et al. (1973a, J. Quant. Spectry. Radiative Transfer13, 461–463) which showed that two cloud layers are not required to explain the CO₂ phase variation of Venus. Prinn's recent photochemical study of sulfuric acid clouds further supports a single, continuous cloud layer in the line formation region instead of two cloud layers with an extensive clear region between. The single layer model appears more likely because the maximum particle density in Prinn's cloud occurs in the clear region between the two layers in the models of Hunt (1972, J. Quant. Spectry. Radiative Transfer12, 405–419) and Carleton and Traub (1972, Bull. Amer. Astron. Soc.4, 362.).     

A measurement of the O2(b1Σg+−X3Σg−) atmospheric band and the OI(1S) green line in the nightglow

Simultaneous measurements of the nightglow profiles of the O₂(b¹Σ_g⁺?X³Σ_g^?) A-band, the atomic oxygen green line and the OH (8?3) Meinel band are presented. The altitude profiles are used to determine both the excitation mechanisms for the oxygen emissions and the atomic oxygen altitude distribution. It is shown that the measurements are consistent with a green line excitation through the Barth mechanism and that the molecular oxygen emission is excited through oxygen recombination and the reaction between OH¹ and atomic oxygen. The derived atomic oxygen concentrations,6.2 × 10¹¹cm^?3at 98km, are consistent with the Jacchia (1971) model.     

A laboratory atlas of the 5ν1 NH3 absorption band at 6475 Å with applications to Jupiter and Saturn

The 5ν₁ absorption band of NH₃ is displayed from 6418 to 6550 Å. The total band intensity has been measured: S_B = 0.66 cm^?1m^?1amagat^?1. Line intensities and self-broadening coefficients have been measured for some of the prominent lines. Our line intensities are in good agreement with those of Rank et al. (1966), but are about 2 times greater than those of Mason (1970). The spectrum displayed was obtained photoelectrically at a pressure of 0.061 atm, and shows many more lines than the spectrum obtained by McBride and Nicholls (1972a) at a pressure of 0.39 atm. Therefore, our new measurements can provide the basis for making a more complete rotational analysis than those of McBride and Nicholls (1972a).Since the total band absorption has previously been measured by others on moderate resolution photoelectric scans of the spectra of Jupiter and Saturn, we can use the band intensity to derive the NH₃ abundance in the atmospheres of these two planets. The NH₃ abundances in a single vertical path obtained by this method are about 10m amagat for Jupiter and 2m amagat for Saturn. These results are in agreement with previous results obtained from higher resolution photographic spectra.     

O2 1.27 μm emission maps as derived from OMEGA/MEx data

We present a method to derive the 2D maps of the O₂ (a¹Δ_g) airglow emission at 1.27 μm from the OMEGA/MEx nadir observations. The OMEGA imaging capabilities allow monitoring the 2D distribution, daily and seasonal variation of the O₂ emission intensities with a detection limit of 4 MR. The highest values, of the order of ∼31 MR, are found on the south pole for 11 h < LT < 13 h, during the early spring (186° < Ls < 192°) of martian year (MY) 27, according to the Mars Year numbering scheme of Clancy et al. [Clancy, R.T., Wolff, M.J., Christensen, P.R., 2003. Mars aerosol studies with the MGS TES emission phase function observations: Optical depths, particle sizes, and ice cloud types versus latitude and solar longitude. J. Geophys. Res. 108. doi: 10.1029/2003JE002058]. In the polar regions the day-by-day variability, associated with polar vortex turbulences, is obtained of the order of 30-50% as predicted by the model [Lefévre, F., Lebonnois, S., Montmessin, F., Forget, F., 2004. Three-dimensional modeling of ozone on Mars. J. Geophys. Res. 109, E07004. doi: 10.1029/2004JE002268] and found by SPICAM [Perrier, S., Bertaux, J.-L., Lebonnois, S., Korablev, O., Fedorova, A., 2006. Global distribution of total ozone on Mars from SPICAM/MEX UV measurements. J. Geophys. Res. 111, E09S06. doi: 10.1029/2006JE002681]. In the considered set of data a maximum of the O₂ emission is observed between 11 h and 15 h LT in the latitude range 70-85° during early spring on both hemispheres, while for the southern autumn-winter season a maximum is found between 50° and 60° in the southern hemisphere for MY28. Increase of intensity of the O₂ emission observed from Ls 130° to 160° at southern high latitudes may be explained by increase of solar illumination conditions in the maps acquired during the considered period.Atmospheric waves crossing the terminator on the southern polar regions are observed for the first time during the MY28 early spring. The spatial scale of the waves ranges from 100 to 130 km, and the intensity fluctuations are of the order of 4MR.This study confirms the high potentiality of O₂ (a¹Δ_g) day glow as a passive tracer of the martian atmosphere dynamics at high latitudes.     

Distributions of the Venus 1.27-μm O2 airglow and rotational temperature

Imaging spectroscopic observations of the Venus 1.27-μm O₂ airglow were carried out with ground-based telescopes from 2002 to 2007. Spectral image cubes were taken with the Okayama Astrophysical Observatory/infrared imaging spectrometer (superOASIS), the Gunma Astronomical Observatory/near-infrared camera and NASA's Infrared Telescope Facility/cryogenic echelle spectrograph (CSHELL). The rotational temperature shows weak positive correlation with the airglow intensity. However, there are some regions that have almost same intensities but different temperatures. The intensities tend to decrease from the anti-solar point to the terminator besides local features. These results indicate that there are local strong downward flows superimposed on the subsolar-to-antisolar circulation.     

2002 AA29: Earth's recurrent quasi-satellite?

We study the dynamical evolution of Asteroid 2002 AA₂₉. This object moves in the co-orbital region of the Earth and is the first known asteroid which experiences recurrent horseshoe-quasi-satellite transitions. The transitions between the HS and QS states are unique among other known Earth co-orbital asteroids and in the QS state 2002 AA₂₉ remains very close to Earth (within 0.2 AU for several decades [Connors, M., Chodas, P., Mikkola, S., Wiegert, P., Veillet, C., Innanen, K., 2002. Meteorit. Planet. Sci. 37, 1435-1441]). Based on results obtained analytically by Brasser et al. [Brasser, R., Heggie, D.C., Mikkola, S., 2004b. Celest. Mech. Dynam. Astron. 88, 123-152] we developed a simple analytical method to describe and analyze the motion of 2002 AA₂₉. We distinguish a few moments in time crucial for understanding its dynamics. Near 2400 and 2500 this object will be close to going through the maxima of the averaged disturbing function and it will either change its co-orbital regime by transition from the HS into QS state, or leave the librating mode. These approaches generate instability in the motion of 2002 AA₂₉. By means of 66 observations, covering a two-year interval, we extend the analysis of the long term evolution of this object presented by Connors et al. [Connors, M., Chodas, P., Mikkola, S., Wiegert, P., Veillet, C., Innanen, K., 2002. Meteorit. Planet. Sci. 37, 1435-1441] and Brasser et al. [Brasser, R., Innanen, K.A., Connors, M., Veillet, C., Wiegert, P., Mikkola, S., Chodas, P.W., 2004a. Icarus 171, 102-109]. Our analysis is based on a sample of 100 cloned orbits. We show that the motion of 2002 AA₂₉ is predictable in the time interval [−2600,7100] and outside of this interval the past and future orbital history can be studied using statistical methods.     

An auroral enhancement of O2λ1.27-μm emission

The ground-level zenith radiance of the atmospheric emission at λ1.27 μm was radiometrically observed to increase by a factor of approximately two with the onset of an IBC III⁺ auroral breakup above Chatanika, Alaska, on 10 March 1975. Time-resolved optical spectra clearly show that the slow component of the enhancement is associated with the (0,0) band of the infrared atmospheric system of O₂. Photometric and incoherent scatter radar data are used to define the energy-deposition profile and the absolute energy flux for the event. The magnitude of the O₂λ1.27-μm enhancement compares favourably with the predictions of an auroral excitation model which includes only secondary-electron excitation of molecular oxygen in the O₂(a¹Δ_g) source term.     

A Study of the [OII]λ3727/Hα Flux Ratio of Emission Line Galaxies

With the sample of 10⁵ emission line galaxies selected from the Sloan Digital Sky Survey Data Release 4 (SDSS DR4), we have investigated the relations of the [O_II]λ3727/H_α flux ratio with the dust extinction, the ionization state of interstellar gas and the metal abundance of galaxies. It is found that the dust extinction correction has a significant effect on the [O_II]λ3727/H_α flux ratio. Before and after the dust distinction correction is made, the mean [O_II]λ3727/H_α flux ratios are 0.48 and 0.89, respectively. After the dust extinction is corrected, the dispersion of the distribution of F([O_II]λ3727) as a function of F(H_α) is obviously reduced. The [O_II]λ3727/H_α flux ratio of metal-poor galaxies decreases with the increasing ionization degree of interstellar gas, but this relation does not exist in metal-rich galaxies. Besides, it is found that the [O_II]λ3727/H_α flux ratio is correlated with the metal abundance. When 12 + lg(O/H) > 8.5, the [O_II]λ3727/H_α flux ratio decreases with the increasing metal abundance; for the galaxies of 12 + lg(O/H) > 8.5, the spectral flux ratio correlates positively with the metal abundance. Finally, by using the parameters of gas ionization degree and metal abundances of galaxies, the formulae for calculating the [O_II]λ3727/H_α flux ratios of different types of galaxies are given. With the [O_II]λ3727/H_α flux ratio given by these formulae, the star formation rate can be derived by using the [O_II]λ3727-line flux, for the galaxies of the redshift z > 0.4, such as the large number of galaxies to be observed by the LAMOST telescope.     

High dispersion observations of Venus during 1972: The CO2 band at 7820Å

Forty-seven well exposed photographic plates of Venus which show the spectrum of the carbon dioxide band at 7820Å were obtained at Table Mountain Observatory in September and October 1972. These spectra showed a semiregular four-day variation in the CO₂ abundance over the disk of the planet (Young et al., 1974). We also find evidence for temporal variations in the rotational temperature of this band and temperature variations over the disk. The two quantities, CO₂ abundance and temperature, do not show any obvious relationship; however, an increase in the temperature usually is accompanied by a decrease in the abundance of CO₂. The average temperature, found from a curve-of-growth analysis assuming a constant CO₂ line width, is 249±1.4K (one standard deviation). This temperature is noticeably higher than the rotational temperature of 242±2K found for this same band in 1967 (Schorn et al., 1969) and of 242±1.2K in 1968–1969 (Young et al., 1971).     

Modeling the atmospheric limb emission of CO2 at 4.3 μm in the terrestrial planets

The MIPAS instrument on board Envisat, in Earth orbit, the PFS and OMEGA instruments on Mars Express, and VIRTIS on board Venus Express are currently providing a dataset of limb measurements of the CO₂ atmospheric fluorescence emission at 4.3‐μm from the upper atmosphere of the three planets. These measurements represent an excellent dataset to perform comparative studies between the terrestrial planets’ upper atmospheres, and also to test our theoretical understanding of these emissions. In order to exploit these datasets, we apply a set of non-local thermodynamic equilibrium (non-LTE) models developed at the IAA/CSIC, in Granada, Spain, to a selection of data. In general, the models can explain the main spectral features of the measurements, and also the altitude and solar zenith angle variations. However, the simulations for Mars and Venus give an incorrect ratio of the emissions at two wavelengths, 4.4 and . In order to explain this deficiency, a revision of the most uncertain non-LTE energy transfer parameters has been performed. The quenching rate of ν₃ quanta of high-energy CO₂ states by CO₂ itself could reduce the model-data discrepancy if increased by a factor 2-4, still within its current uncertainty range. This factor, however, is subject to the uncertainty in the thermal structure. A number of simulations with the non-LTE models were also used to study and compare the role of radiative transfer in this spectral region in the three terrestrial planets. Sensitivity studies of density and temperature are also presented, and they permit an analysis of how the differences between the planets and between the three instruments affect their sounding capabilities.     

On the interpretation of the “inverse phase effect” for CO2 equivalent widths on Venus

Computations of the equivalent widths of absorption lines as a function of planetary phase angle are made for a homogeneous cloud with particles having the properties (shape, refractive index, and size distribution) deduced from polarimetry of Venus. The computed equivalent widths show an “inverse phase effect” comparable to that which is observed for CO₂ lines on Venus. This result verifies a recent suggestion of Regas et al. that the existence of an inverse phase effect does not by itself imply the presence of multiple layers of scattering particles in the atmosphere of Venus.     

Observation of the Comet Kohoutek (1973f) in the resonance light (A2Σ+−X2 ∏) of the OH radical

Two monochromatic pictures of the Comet Kohoutek (1973f) were taken on January 15, 1974 in the resonance light (A²Σ ? X² ∏) of the radical OH with a photographic telescope placed on board the NASA 990 Convair airplane. From an intensity profile we derive the production rate of OH radicals Q_OH = 4 xsx 10²⁸ moleculesec ^?1sr^?1 at 0.6 AU and the lifetime of the OH radical which is τ_OH = 4.5 × 10⁴ sec at 0.6 AU. This short lifetime (very similar to the lifetime of H₂O) combined with the high total production rate of gas in comets can explain the observed velocity of 8km sec^?1 for the H-atoms: The H-atoms produced by photodissociation of H₂O are thermalized at short distancesfrom the nucleus; the H-atoms produced by photodissociation of OH have a velocity of ?8km sec^?1 and can reach the outer part of the hydrogen envelope.     

Modelling the atmospheric CO2 10-μm non-thermal emission in Mars and Venus at high spectral resolution

A study of the CO₂ atmospheric emissions at 10-μm in the upper atmospheres of Mars and Venus is performed in order to explain a number of ground-based measurements of these emissions recently taken at very high spectral resolution in both planets. The measurements are normally used to derive atmospheric temperatures and winds, but uncertainties on the actual emission layers were so far a serious drawback for their correct interpretation. The non-LTE models used for Mars and Venus in the present analysis are entirely similar in order to perform consistent comparisons between the two planets. In particular, the same scheme of CO₂ states and ro-vibrational bands are used, with similar assumptions on collisional routes and rate coef?cients, and also the same radiative transfer approximations. The emissions at 10-μm are produced in both atmospheres by the same excitation mechanism: radiative pumping of the CO₂(00⁰1) vibrational state by direct solar absorption(at 4.3 μm) and indirect absorption (at 2.7 μm, followed by collisional quenching). The computed radiances are specially strong in the upper mesosphere and lower thermosphere of the two planets during maximum solar illumination, producing a population inversion in such conditions with the lower states of the bands, the CO₂ (10⁰0) and CO₂(02⁰0). We obtained that other population inversions are also possible, involving higher energy CO₂ states. The larger solar ?ux available on Venus is found to produce larger vibrational populations and stronger emissions than equivalent atmospheric layers on Mars, in agreement with the observations. A number of perturbation studies were used to determine the exact emission altitudes, or weighting function peaks, for usual nadir sounding. The sensitivity of the emission to non-LTE model uncertainties and to atmospheric variations in temperature and CO₂ density is also presented. The dependence with the solar zenith angle and with the emission angle, as obtained with this model, could also be useful for guiding future observations.     

Calculation of the Intensity Ratio and Intrinsic Redshift Ratio of the Cerenkov Iron Kα and Kβ Lines and Its Possible Application in the Study of AGNs

We have pointed out that, when thermal relativistic electrons with an isotropic velocity distribution move through a region of dense gas or impinge upon its surface, the Cerenkov effect will produce a particular kind of atomic or ionic emission line, which we have called the “Cerenkov line-like radiation”. This prediction for the optical wavebands has been verified by laboratory experiments. In this paper, we extend this line-like radiation theory to the X-ray waveband and give the basic formulae for calculating the intensity ratio and intrinsic redshift ratio of the Cerenkov iron K_α and K_β lines, for different ionization orders of iron. Potential application of this calculated result may be found in the study of AGNs. The recent observations of NGC3783 show that besides the iron K_α line at ∼6.4 keV, there is also a very strong iron Kβ line at ∼7.0 keV, and that the ratio of equivalent widths between the two is anomalous: EWK_α/EWK_β ≈ 3.43. It is difficult to explain this by the conventional mechanism of “photoelectric absorption-fluorescence emission”. We suggest that the mechanism of Cerenkov line-like radiation can provides a way of solving this puzzle. Besides, we expect that the calculated intrinsic redshift ratio of Cerenkov iron K_α and K_β lines could be tested in future observations. If our suggestion is further supported by observations, then our view on the physical environment around the central massive black hole of an AGN will be greatly modified: the activity becomes more energetic and violent, and the gas, much denser than previously thought.     

FT-IR measurements of cold C3H8 cross sections at 7–15 μm for Titan atmosphere

We present absorption cross sections of propane (C₃H₈) at temperatures from 145 K to 297 K in the 690–1550 cm⁻¹ region. Pure and N₂-broadened spectra were measured at pressures from 3 Torr to 742 Torr using a Bruker IFS125 FT-IR spectrometer at JPL. The gas absorption cell, developed at Connecticut College, was cooled by a closed-cycle helium refrigerator. The cross sections were measured and compiled for individual spectra recorded at various experimental conditions covering the planetary atmosphere and Titan. In addition to the cross sections, a propane pseudoline list with a frequency grid of 0.005 cm⁻¹, was fitted to the 34 laboratory spectra. Line intensities and lower state energies were retrieved for each line, assuming a constant width. Validation tests showed that the pseudoline list reproduces discrete absorption features and continuum, the latter contributed by numerous weak and hot band features, in most of the observed spectra within 3%. Based on the pseudoline list, the total intensity in the 690–1550 cm⁻¹ region was determined to be 52.93 (±3%) × 10⁻¹⁹ cm⁻¹/(molecule cm⁻²) at 296 K; this value is within 3% of the average from four earlier studies. Finally, the merit of the pseudoline approach is addressed for heavy polyatomic molecules in support of spectroscopic observation of atmospheres of Titan and other planets. The cold cross sections will be submitted to the HITRAN database (hitran.harvard.edu), and the list of C₃H₈ pseudolines will be available from a MK-IV website of JPL (http://mark4sun.jpl.nasa.gov/data/spec/Pseudo).     

The Pressure Gradient and the Progenitor Model Ws15M⊙ for Supernova Explosion

With specific focus on at the progenitor model, Ws15 M_⊙, we have carried out numerical simulation of the instantaneous supernova explosion process using the programWLYW89. It is indicated that a proper adjustment of the pressure gradient without altering the pressure during the collapse and rebound phases can lead to successful instant explosion. In the case of limited energy release by gravity, the adjustment of the pressure gradient can strengthen the mechanism of convective transfer of energy, shorten the duration of the explosion and increase the explosion energy, so making a success of strong instantaneous explosion.     

Astrophysically useful radiative transition parameters for?the?e1Π–X1Σ+ and 1Σ+–X1Σ+ systems of zirconium oxide

The zirconium oxide (ZrO) is well known for its astrophysical importance. The radiative transition parameters that include Franck-Condon (FC) factor, r-centroid, electronic transition moments, Einstein coefficient, band oscillator strengths, radiative life time and effective vibrational temperature have been estimated for e ¹Π–X ¹Σ⁺ and ¹Σ⁺–X ¹Σ⁺ band systems of ⁹⁰ZrO molecule for the experimentally known vibrational levels using RKR potential energy curves. A reliable numerical integration method has been used to solve the radial Schr?dinger equation for the vibrational wave functions of upper and lower electronic states based on the latest available spectroscopic data and known wavelengths. The estimated radiative transition parameters are tabulated. The effective vibrational temperatures of these band systems of ⁹⁰ZrO molecule are found to be below 4200 K. Hence, the radiative transition parameters help us to ascertain the presence of ⁹⁰ZrO molecule in the interstellar medium, S stars and sunspots.