Brightness Ratio Research Articles

ALMA Maps of Dust and Warm Dense Gas Emission in the Starburst Galaxy IC 5179*

Abstract We present our high-resolution (0.″15 × 0.″13, ∼34 pc) observations of the CO (6−5) line emission, which probes the warm and dense molecular gas, and the 434 μm dust continuum emission in the nuclear region of the starburst galaxy IC 5179, conducted with the Atacama Large Millimeter Array (ALMA). The CO (6−5) emission is spatially distributed in filamentary structures with many dense cores and shows a velocity field that is characteristic of a circumnuclear rotating gas disk, with 90% of the rotation speed arising within a radius of ≲150 pc. At the scale of our spatial resolution, the CO (6−5) and dust emission peaks do not always coincide, with their surface brightness ratio varying by a factor of ∼10. This result suggests that their excitation mechanisms are likely different, as further evidenced by the southwest to northeast spatial gradient of both CO-to-dust continuum ratio and Pa-α equivalent width. Within the nuclear region (radius ∼ 300 pc) and with a resolution of ∼34 pc, the CO line flux (dust flux density) detected in our ALMA observations is 180 ± 18 Jy km s−1 (71 ± 7 mJy), which accounts for 22% (2.4%) of the total value measured by Herschel.

Brightness scaling of periodic tones

Brightness is an attribute often used by musicians when describing timbral characteristics. It is related to the spectral distribution of energy, as is sharpness, studied by Zwicker (Psychoacoustics: Facts and Models, 1990). In the current work, subjects adjusted the spectral slope and thus the spectral centroid (SC) of one of a pair of sounds to make it twice as bright as the other, so as to build a perceptual scale. The ratio of SC required to double brightness is a little less than 2 and decreases as the SC of the tones increases. For these tones, the ratio of brightness is statistically different from the ratio of sharpness calculated from published models.

Nuclear absorption and emission in the AGN merger NGC 6240 : the hard X-ray view

We present the analysis of four NuSTAR observations of the luminous infrared galaxy merger NGC 6240 , hosting a close pair of highly obscured active galactic nuclei (AGNs). Over a period of about 2 yr, the source exhibits hard X-ray variability of the order of 20 per cent, peaking around 20 keV. When the two AGNs are resolved with Chandra , column densities in the range of NH ∼ 1–2 × 1024 cm−2 are estimated for both of them. The exact values are hard to determine, as they appear to depend on aspects that are sometimes overlooked in Compton-thick objects, such as the covering factor of the absorber, iron abundance and the contamination in the Fe K band from foreground hot-gas emission. Nearly spherical covering and slightly subsolar iron abundance are preferred in this case. While the southern nucleus is suggested to be intrinsically more powerful, as also implied by the mid-IR and 2–10 keV brightness ratios, solutions involving a similar X-ray luminosity of the two AGNs cannot be ruled out. The observed variability is rather limited compared to the one revealed by the Swift /BAT light curve, and it can be fully explained by changes in the continuum flux from the two AGNs, without requiring significant column density variations. NGC 6240 is hereby confirmed to represent a unique opportunity to investigate the X-ray (and broad-band) properties of massive galaxy mergers, which were much more frequent in the early Universe.

조도 연출 변화에 따른 표면색 별 불쾌감 및 피로도 평가 연구

Previous lighting methods featured dynamic changes only when turning lighting devices on and off, and glares causing discomfort were controlled based on the brightness of the light source and the solid angle at the time of turning on the light. Current system lighting, however, is projected in multiple forms originating from the spatial action, and there are no proposed methods of controlling discomfort glares in response to dynamic changes. This study evaluated discomfort glared and fatigue caused by the glare, When directly looking at, the surface color due to the change in the illuminance of the lighting. The results are as follows: When illuminance changes, glares causing discomfort and fatigue were found to increase as the ratio of brightness and surface reflection rate increased. In some extreme cases, the glares were found to be “intolerable,” and fatigue rose to “warning” and “danger” levels. Therefore, there is need for the requirement for adequate design based on permitted ranges when designing lighting system using illuminance changes. Further research should become more complex, dealing with the relationship among glare, fatigue, area of lighting, user location variance, and background illuminance.

Optical method for in situ monitoring of electrospinning process and porosity characterization of microporous membrane

We present an optical-based, rapid method for the in situ porosity measurement of membranes through the electrospinning process. The method was developed by combining an optical method with in situ monitoring of the porosity of the electrospun membranes based on the measured reflected power density. The results showed that the area of bright and dark ratio is consistently proportional to the porosity of the electrospun membranes, which can potentially be used for actual characterization of the membranes. In addition, the effect of different incident angles of a laser beam was performed and compared. The porosity ratio of the electrospun membranes can be empirically evaluated as the determination coefficient R 2 = 0.9945 to 0.9876 can be obtained. The proposed method is successfully demonstrated and validated by the SEM images of the binary method. The potential applications include the in situ monitoring of the electrospinning process for the bioassembly and biomimicking of a human tissue with a great accuracy.

Intelligent image analysis (IIA) using artificial neural network (ANN) for non-invasive estimation of chlorophyll content in micropropagated plants of potato

An artificial neural network (ANN) was used to analyze photometric features extracted from the digitized images of leaves from in vitro-regenerated potato plants for non-invasive estimation of chlorophyll content. A MATLAB®-based, feed-forward, backpropagation-type network was developed for an input layer (three input elements), with one hidden layer (one node) and one output layer representing the predicted chlorophyll content. A significant influence of training function during optimization of ANN modeling was observed. Among the 11 training functions tested, “trainlm” was found to be the best on the basis of comparative analysis of root-mean-square error (RMSE) at zero epoch. A significant correlation between the model-predicted and Soil-Plant Analysis Development (SPAD) meter-measured relative chlorophyll contents was obtained when the mean brightness ratio (rgb) parameters were used. Compared to a red (R), green (G), and blue (B) color space model, the rgb model exhibited better performance with a significant correlation (R 2 = 0.85). Incorporation of photometric features, such as luminosity (L), blue (B)/L, and green (G)/L, with rgb failed to improve the performance of the network. The developed Intelligent image analysis (IIA) system was able to estimate in real time the chlorophyll content of in vitro-regenerated leaves for assessment of plant nutrient status during micropropagation.

SDSS IV MaNGA: Deep observations of extra-planar, diffuse ionized gas around late-type galaxies from stacked IFU spectra

We have conducted a study of extra-planar diffuse ionized gas using the first year data from the MaNGA IFU survey. We have stacked spectra from 49 edge-on, late-type galaxies as a function of distance from the midplane of the galaxy. With this technique we can detect the bright emission lines Halpha, Hbeta, [OII]3726, 3729, [OIII]5007, [NII]6549, 6584, and [SII]6717, 6731 out to about 4 kpc above the midplane. With 16 galaxies we can extend this analysis out to about 9 kpc, i.e. a distance of ~2R_e, vertically from the midplane. In the halo, the surface brightnesses of the [OII] and Halpha emission lines are comparable, unlike in the disk where Halpha dominates. When we split the sample by specific star formation rate, concentration index, and stellar mass, each subsample's emission line surface brightness profiles and ratios differ, indicating that extra-planar gas properties can vary. The emission line surface brightnesses of the gas around high specific star formation rate galaxies are higher at all distances, and the line ratios are closer to ratios characteristic of HII regions compared with low specific star formation rate galaxies. The less concentrated and lower stellar mass samples exhibit line ratios that are more like HII regions at larger distances than their more concentrated and higher stellar mass counterparts. The largest difference between different subsamples occurs when the galaxies are split by stellar mass. We additionally infer that gas far from the midplane in more massive galaxies has the highest temperatures and steepest radial temperature gradients based on their [NII]/Halpha and [OII]/Halpha ratios between the disk and the halo.

Morphology of Ganymede's FUV auroral ovals

AbstractWe study the morphology of Ganymede's FUV aurora by analyzing spectral images obtained over the past two decades by the Space Telescope Imaging Spectrograph on board the Hubble Space Telescope. The observations cover the eastern and western elongation as well as various magnetic latitudes of Ganymede within the Jovian plasma sheet. We find both asymmetries in the spatial distribution of auroral brightness on the observed moon disk and temporal variation correlated to Ganymede's changing magnetic latitude. The total disk brightness is on average 1.42 ± 0.07 times brighter on the leading side (95.4 ± 2.1 R) than on the trailing side (67.2 ± 2.9 R). The brightness ratio of the sub‐Jovian hemisphere to the anti‐Jovian hemisphere is 1.81 ± 0.06 on the leading side and 1.41 ± 0.14 on the trailing side, respectively. Inside the Jovian current sheet, the brightness of the auroral ovals increases by a factor of 1.45 ± 0.02 on the leading side and decreases by a factor of 0.80 ± 0.02 on the trailing side. At the current sheet center, the auroral ovals shift 4.1° ± 0.7°latitude toward Ganymede's planetographic equator on the leading side and 2.9° ± 1.5° toward the poles on the trailing side. Both effects, the variation of brightness and the movement of the ovals are correlated to a stronger interaction of Jupiter's magnetospheric plasma with Ganymede's minimagnetosphere inside the current sheet. Finally, we calculate the latitudinal difference of the northern and southern ovals from Ganymede's magnetic equator. The result suggests a farther westward orientation of Ganymede's dipole magnetic moment at approximately 47° + 58°/−43°west longitude compared to previous estimates.

GEMINGA’S PUZZLING PULSAR WIND NEBULA

ABSTRACT We report on six new Chandra observations of the Geminga pulsar wind nebula (PWN). The PWN consists of three distinct elongated structures—two ≈ 0.2 d 250 pc long lateral tails and a segmented axial tail of ≈ 0.05 d 250 pc length, where d 250 = d / ( 250 pc ) . The photon indices of the power-law spectra of the lateral tails, Γ ≈ 1 , are significantly harder than those of the pulsar ( Γ ≈ 1.5 ) and the axial tail ( Γ ≈ 1.6 ). There is no significant diffuse X-ray emission between the lateral tails—the ratio of the X-ray surface brightness between the south tail and this sky area is at least 12. The lateral tails apparently connect directly to the pulsar and show indications of moving footpoints. The axial tail comprises time-variable emission blobs. However, there is no evidence for constant or decelerated outward motion of these blobs. Different physical models are consistent with the observed morphology and spectra of the Geminga PWN. In one scenario, the lateral tails could represent an azimuthally asymmetric shell whose hard emission is caused by the Fermi acceleration mechanism of colliding winds. In another scenario, the lateral tails could be luminous, bent polar outflows, while the blobs in the axial tail could represent a crushed torus. In a resemblance to planetary magnetotails, the blobs of the axial tail might also represent short-lived plasmoids, which are formed by magnetic field reconnection in the relativistic plasma of the pulsar wind tail.

Novel Approach for Detection and Removal of Moving Cast Shadows Based on RGB, HSV and YUV Color Spaces

Cast shadow affects computer vision tasks such as image segmentation, object detection and tracking since objects and shadows share the same visual motion characteristics. This unavoidable problem decreases video surveillance system performance. The basic idea of this paper is to exploit the evidence that shadows darken the surface which they are cast upon. For this reason, we propose a simple and accurate method for detection of moving cast shadows based on chromatic properties in RGB, HSV and YUV color spaces. The method requires no a priori assumptions regarding the scene or lighting source. Starting from a normalization step, we apply canny filter to detect the boundary between self-shadow and cast shadow. This treatment is devoted only for the first sequence. Then, we separate between background and moving objects using an improved version of Gaussian mixture model. In order to remove these unwanted shadows completely, we use three change estimators calculated according to the intensity ratio in HSV color space, chromaticity properties in RGB color space, and brightness ratio in YUV color space. Only pixels that satisfy threshold of the three estimators are labeled as shadow and will be removed. Experiments carried out on various video databases prove that the proposed system is robust and efficient and can precisely remove shadows for a wide class of environment and without any assumptions. Experimental results also show that our approach outperforms existing methods and can run in real-time systems.

Response of Jupiter's inner magnetosphere to the solar wind derived from extreme ultraviolet monitoring of the Io plasma torus

AbstractBecause Jupiter's magnetosphere is huge and is rotationally dominated, solar wind influence on its inner part has been thought to be negligible. Meanwhile, dawn‐dusk asymmetric features of this region have been reported. Presence of dawn‐to‐dusk electric field is one of the leading explanations of the asymmetry; however, the physical process of generating such an intense electric field still remains unclear. Here we present long and continuous monitoring of the extreme ultraviolet emissions from the Io plasma torus in Jupiter's inner magnetosphere made by the Hisaki satellite between December 2013 and March 2014. We found five occasions where the dusk/dawn brightness ratio was enhanced above 2.5 in response to rapid increase of the solar wind dynamic pressure. The enhancement is achieved as the dusk region brightens and the dawn region dims. The observation indicates that dawn‐to‐dusk electric field in the inner magnetosphere is enhanced under compressed conditions.

Multi-energy SXR cameras for magnetically confined fusion plasmas (invited).

A compact multi-energy soft x-ray camera has been developed for time, energy and space-resolved measurements of the soft-x-ray emissivity in magnetically confined fusion plasmas. Multi-energy soft x-ray imaging provides a unique opportunity for measuring, simultaneously, a variety of important plasma properties (Te, nZ, ΔZeff, and ne,fast). The electron temperature can be obtained by modeling the slope of the continuum radiation from ratios of the available brightness and inverted radial emissivity profiles over multiple energy ranges. Impurity density measurements are also possible using the line-emission from medium- to high-Z impurities to separate the background as well as transient levels of metal contributions. This technique should be explored also as a burning plasma diagnostic in-view of its simplicity and robustness.

On the distance to the North Polar Spur and the local CO-H2 factor.

Most models identify the X-ray bright North Polar Spur (NPS) with a hot interstellar (IS) bubble in the Sco-Cen star-forming region at ≃130 pc. An opposite view considers the NPS as a distant structure associated with Galactic nuclear outflows. Constraints on the NPS distance can be obtained by comparing the foreground IS gas column inferred from X-ray absorption to the distribution of gas and dust along the line of sight. Absorbing columns towards shadowing molecular clouds simultaneously constrain the CO-H2 conversion factor. We derived the columns of X-ray absorbing matter N Habs from spectral fitting of dedicated XMM-Newton observations towards the NPS southern terminus (l II ≃ 29°, b II ≃ +5 to +11°). The distribution of the IS matter was obtained from absorption lines in stellar spectra, 3D dust maps and emission data, including high spatial resolution CO measurements recorded for this purpose. N Habs varies from ≃ 4.3 to ≃ 1.3 × 1021 cm-2 along the 19 fields. Relationships between X-ray brightness, absorbing column and hardness ratio demonstrate a brightness decrease with latitude governed by increasing absorption. The comparison with absorption data, local and large-scale dust maps rules out a NPS near side closer than 300 pc. The correlation between N Habs and the reddening increases with the sightline length from 300 pc to 4 kpc and is the tightest with Planck τ 353GHz -based reddening, suggesting a much larger distance. N(H)/E(B-V) τ ≃ 4.1 × 1021 cm-2 mag-1, close to Fermi-Planck determinations. N Habs absolute values are compatible with HI-CO clouds at -5 ≤ V LSR ≤ +25 to +45 km s-1 and a NPS potentially far beyond the Local Arm. A shadow cast by a b=+9° molecular cloud constrains X CO in that direction to ≤ 1.0 × 1020 cm-2 K-1 km-1 s. The average X CO over the fields is ≤ 0.75 × 1020 cm-2 K-1 km-1 s.

An analysis of the yellow duty ratio and quantization noise of head-up displays

ABSTRACTThis paper presents the brightness and light-emitting diode (LED) synthesis ratios of three LEDs that minimize the quantization noise for the head-up display, consisting of a digital microdevice panel and red, green, and blue high-luminance LED, to increase the brightness of the display system. In this study, the operation ratio and junction temperature influencing the brightness of a green LED were analyzed. The results of this study demonstrated that the luminance of the head-up display exhibits a high increment by synthesizing the secondary colors (yellow and cyan) through a 39% LED-overlapping operating method. Moreover, the display reduced the quantization noise and obtained outstanding hue accuracy.

Constraints on the microphysics of Pluto's photochemical haze from New Horizons observations

The New Horizons flyby of Pluto confirmed the existence of hazes in its atmosphere. Observations of a large high- to low- phase brightness ratio, combined with the blue color of the haze (indicative of Rayleigh scattering), suggest that the haze particles are fractal aggregates, perhaps analogous to the photochemical hazes on Titan. Therefore, studying the Pluto hazes can shed light on the similarities and differences between the Pluto and Titan atmospheres. We model the haze distribution using the Community Aerosol and Radiation Model for Atmospheres assuming that the distribution is shaped by downward transport and coagulation of particles originating from photochemistry. Hazes composed of both purely spherical and purely fractal aggregate particles are considered. General agreement between model results and solar occultation observations is obtained with aggregate particles when the downward mass flux of photochemical products is equal to the column-integrated methane destruction rate ∼1.2×10−14gcm−2s−1, while for spherical particles the mass flux must be 2–3 times greater. This flux is nearly identical to the haze production flux of Titan previously obtained by comparing microphysical model results to Cassini observations. The aggregate particle radius is sensitive to particle charging effects, and a particle charge to radius ratio of 30e−/µm is necessary to produce ∼0.1–0.2µm aggregates near Pluto's surface, in accordance with forward scattering measurements. Such a particle charge to radius ratio is 2–4 times higher than those previously obtained for Titan. Hazes composed of spheres with the same particle charge to radius ratio have particles that are 4 times smaller at Pluto's surface. These results further suggest that the haze particles are fractal aggregates. We also consider the effect of condensation of HCN, C2H2, C2H4, and C2H6 on the haze particles, which may play an important role in shaping their altitude and size distributions.

RELATIVISTIC DOPPLER BEAMING AND MISALIGNMENTS IN AGN JETS

ABSTRACT Radio maps of active galactic nuclei often show linear features, called jets, on both parsec and kiloparsec scales. These jets supposedly possess relativistic motion and are oriented close to the line of sight of the observer, and accordingly the relativistic Doppler beaming makes them look much brighter than they really are in their respective rest frames. The flux boosting due to the relativistic beaming is a very sensitive function of the jet orientation angle, as seen by the observer. Sometimes, large bends are seen in these jets, with misalignments being 90° or more, which might imply a change in the orientation angle that should cause a large change in the relativistic beaming factor. Hence, if relativistic beaming does play an important role in these jets such large bends should usually show high contrast in the brightness of the jets before and after the bend. It needs to be kept in mind that sometimes a small intrinsic change in the jet angle might appear as a much larger misalignment due to the effects of geometrical projection, especially when seen close to the line of sight. What really matters are the initial and final orientation angles of the jet with respect to the observer’s line of sight. Taking the geometrical projection effects properly into account, we calculate the consequences of the presumed relativistic beaming and demonstrate that there ought to be large brightness ratios in jets before and after the observed misalignments.

Two-color spatial and temporal temperature measurements using a streaked soft x-ray imager.

A dual-channel streaked soft x-ray imager has been designed and used on high energy-density physics experiments at the National Ignition Facility. This streaked imager creates two images of the same x-ray source using two slit apertures and a single shallow angle reflection from a nickel mirror. Thin filters are used to create narrow band pass images at 510 eV and 360 eV. When measuring a Planckian spectrum, the brightness ratio of the two images can be translated into a color-temperature, provided that the spectral sensitivity of the two images is well known. To reduce uncertainty and remove spectral features in the streak camera photocathode from this photon energy range, a thin 100 nm CsI on 50 nm Al streak camera photocathode was implemented. Provided that the spectral shape is well-known, then uncertainties on the spectral sensitivity limits the accuracy of the temperature measurement to approximately 4.5% at 100 eV.

Seasonal changes on Jupiter: 1. Factor of activity of the hemispheres

To identify temporal variations of the characteristics of Jupiter’s cloud layer, we take into account the geometric modulation caused by the rotation of the planet and planetary orbital motion. Inclination of the rotation axis to the orbital plane of Jupiter is 3.13°, and the angle between the magnetic axis and the rotation axis is β ≈ 10°. Therefore, over a Jovian year, the jovicentric magnetic declination of the Earth φm varies from–13.13° to +13.13°, and the subsolar point on Jupiter’s magnetosphere is shifted by 26.26° per orbital period. In this connection, variations of the Earth’s jovimagnetic latitude on Jupiter will have a prevailing influence in the solar-driven changes of reflective properties of the cloud cover and overcloud haze on Jupiter. Because of the orbit eccentricity (e = 0.048450), the northern hemisphere receives 21% greater solar energy inflow to the atmosphere, because Jupiter is at perihelion near the time of the summer solstice. The results of our studies have shown that the brightness ratio Aj of northern to southern tropical and temperate regions is an evident factor of photometric activity of Jupiter’s atmospheric processes. The analysis of observational data for the period from 1962 to 2015 reveals the existence of cyclic variations of the activity factor Aj of the planetary hemispheres with a period of 11.86 years, which allows us to talk about the seasonal rearrangement of Jupiter’s atmosphere.

THE NATURE AND FREQUENCY OF THE GAS OUTBURSTS IN COMET 67P/CHURYUMOV–GERASIMENKO OBSERVED BY THE ALICE FAR-ULTRAVIOLET SPECTROGRAPH ON ROSETTA

ABSTRACT Alice is a far-ultraviolet imaging spectrograph on board Rosetta that, among multiple objectives, is designed to observe emissions from various atomic and molecular species from within the coma of comet 67P/Churyumov–Gerasimenko. The initial observations, made following orbit insertion in 2014 August, showed emissions of atomic hydrogen and oxygen spatially localized close to the nucleus and attributed to photoelectron impact dissociation of H2O vapor. Weaker emissions from atomic carbon were subsequently detected and also attributed to electron impact dissociation, of CO2, the relative H i and C i line intensities reflecting the variation of CO2 to H2O column abundance along the line of sight through the coma. Beginning in 2015 mid-April, Alice sporadically observed a number of outbursts above the sunward limb characterized by sudden increases in the atomic emissions, particularly the semi-forbidden O i λ1356 multiplet, over a period of 10–30 minutes, without a corresponding enhancement in long-wavelength solar reflected light characteristic of dust production. A large increase in the brightness ratio O i λ1356/O i λ1304 suggests O2 as the principal source of the additional gas. These outbursts do not correlate with any of the visible images of outbursts taken with either OSIRIS or the navigation camera. Beginning in 2015 June the nature of the Alice spectrum changed considerably with CO Fourth Positive band emission observed continuously, varying with pointing but otherwise fairly constant in time. However, CO does not appear to be a major driver of any of the observed outbursts.

Electrodynamics and energy characteristics of aurora at high resolution by optical methods

AbstractTechnological advances leading to improved sensitivity of optical detectors have revealed that aurora contains a richness of dynamic and thin filamentary structures, but the source of the structured emissions is not fully understood. In addition, high‐resolution radar data have indicated that thin auroral arcs can be correlated with highly varying and large electric fields, but the detailed picture of the electrodynamics of auroral filaments is yet incomplete. The Auroral Structure and Kinetics (ASK) instrument is a state‐of‐the‐art ground‐based instrument designed to investigate these smallest auroral features at very high spatial and temporal resolution, by using three electron multiplying CCDs in parallel for three different narrow spectral regions. ASK is specifically designed to utilize a new optical technique to determine the ionospheric electric fields. By imaging the long‐lived O+ line at 732 nm, the plasma flow in the region can be traced, and since the plasma motion is controlled by the electric field, the field strength and direction can be estimated at unprecedented resolution. The method is a powerful tool to investigate the detailed electrodynamics and current systems around the thin auroral filaments. The two other ASK cameras provide information on the precipitation by imaging prompt emissions, and the emission brightness ratio of the two emissions, together with ion chemistry modeling, is used to give information on the energy and energy flux of the precipitating electrons. In this paper, we discuss these measuring techniques and give a few examples of how they are used to reveal the nature and source of fine‐scale structuring in the aurora.