West Limb Research Articles

New Results on the Onset of a Coronal Mass Ejection from 5303 Å Emission Line Observations with VELC/ADITYA-L1

We report on the onset of a coronal mass ejection (CME) using spectroscopic observations in the 5303 Å coronal emission line with the Visible Emission Line Coronagraph (VELC) onboard ADITYA-L1, the recently launched first Indian space solar mission. The CME was observed on 2024 July 16 in association with an X1.9 class soft X-ray flare from heliographic location S05W85. The VELC observations were near the west limb of the Sun during the CME. The results obtained helped to constrain the onset time of the CME. In addition, they indicate a ≈50% decrease in the coronal intensity near the source region of the CME due to mass depletion, a ≈15% enhancement in the emission line width, and a redshifted Doppler velocity of about ≈10 km s−1. The nonthermal velocity associated with the line broadening is ≈24.87 km s−1.

Direct Evidence of the Hybrid Nature of Extreme-ultraviolet Waves and the Reflection of the Fast-mode Wave

We performed an analysis of the extreme-ultraviolet (EUV) wave event on 2022 March 31. The event originated from active region (AR) 12975 located at N13W52 in the field of view of the Atmospheric imaging Assembly (AIA) and exactly at the west limb viewed by the EUV Imager (EUVI) of the Solar Terrestrial Relations Observatory-Ahead (STEREO-A) satellite. The EUV wave was associated with an M9.6 class flare. The event was also well observed by Mauna Loa Solar Observatory and COR1 coronagraphs. We revealed here evident coexistence of two components of EUV waves in AIA as well as in EUVI images, i.e., a fast-mode wave and a nonwave, which was predicted by the EUV wave hybrid model. The speeds of the fast-mode and nonwave EUV wave components in AIA vary from ∼430 to 658 km s−1 and ∼157 to 205 km s−1, respectively. The computed speeds in STEREO-A for the fast-mode wave and nonwave components are ∼520 and ∼152 km s−1, respectively. Another wave emanated from the source AR and interacted with ambient coronal loops, showing evident reflection in the EUV images above the solar limb. The speed of the reflected wave in the plane of the sky is ∼175 km s−1. With the precise alignments, we found that the fast-mode EUV wave is just ahead of the coronal mass ejection (CME), and the nonwave component is cospatial with the frontal loop of the accompanied CME. The event also showed stationary fronts.

Comparative Analysis of Type III Radio Bursts and Solar Flares: Spatial Localization and Correlation with Solar Flare Intensity

We present a comprehensive study of type III radio bursts and their association with solar flares of magnitude M1.0 and larger, as observed by four widely separated spacecraft (Parker Solar Probe, Solar Orbiter, STEREO-A, and Wind). Our main focus is the introduction and validation of two methods for localizing radio bursts using the available multispacecraft data. The first method utilizes intensity fitting with a circular Gaussian distribution, while the second method is based on the time arrival of radio bursts. We demonstrate the effectiveness of these methods through the analysis of a single type III burst event and compare their results with the traditional radio triangulation technique. Furthermore, we conduct a statistical study of 17 type III bursts associated with M- and X-class solar flares in years 2020–2022. Our findings suggest a possible correlation between solar flare intensities and longitudes, with east limb flares tending to be weaker than west limb flares. We also observe a systematic drift of radio burst longitudes toward the east, potentially explained by a poleward component of the local density gradient. Our results suggest a strong correlation between solar flare intensities and radio burst properties, enhancing our understanding of the relationship between solar flares and type III radio bursts.

High-altitude Spider-type Prominence above the Magnetic Null Point

Rather unique observations of a high-altitude spider-type prominence in 2023 February are presented. The prominence or corresponding filament on the disk was not visible all the time but could appear and disappear in the course of a particular day. However, it persisted during the whole half of a solar rotation, being observable from day to day starting from the east limb of the Sun to the west limb. We show that the prominence was located in sagged coronal field lines just above a coronal magnetic null point. The presence of the null point and magnetic dips above it is confirmed by calculations of the potential magnetic field. The mass of the prominence apparently was appearing due to the condensation of hot coronal plasma after several eruptions that occurred in an active-region complex where the prominence was located. The prominence material flowed down along widely spread large coronal loops as coronal rain and was sometimes swept away by subsequent eruptions.

Concurrent Kink and Sausage Waves in A Crescent Shaped Structure Over A Limb Prominence

Abstract A Crescent shaped prominence Structure (CS), over the solar west limb is studied using EIS/HINODE and AIA/SDO. First, the time varying positions of the top and below borders of the CS, along with its central axis are derived. Time evolutions of the Doppler shifts, and Line width of Fe XII 195.119 line are studied over the CS borders. Transverse kink oscillations are observed both in the Solar-Y direction and in the Doppler shifts over the observers’ LOS. One explanation could be the oscillatory direction of the main kink wave build an angle with the observers LOS. This angle is calculated to be equal to 27 degrees for the CS top border. The main kink amplitude velocity and periods are obtained to be 5.3 $\rm km/s$, and 33.4 minutes, respectively. The anti-correlation observed between the brightness and thickness of the CS (with -178.1○) suggests the presence of sausage modes with periods of 20.8 minutes. Based on the AIA imaging, it is suggested that the occurred jets and their afterward dimming are responsible to trigger the sausage mode. The average electron densities of the CS over the time of the study is obtained to be log($\rm n_e$)=9.3$\rm [cm^{-3}]$. The Alfvén velocity, magnetic field, and energy flux of the observed fast kink mode over the CS are estimated to be 16.7 $\rm km/s$, 2.79 $\rm G$, 41.93 $\rm W/m^2$. Considering the magnetic flux conservation inside the CS, expanding the CS cross section, causes the magnetic field to decay with the rate of $\rm 4.95 \times 10^{-4} \, G/sec$.

Recurrent solar density transients in the slow wind observed with the Metis coronagraph

Aims We aim to investigate and characterize the morphology and dynamics of small-scale coronal plasma density inhomogeneities detected as brighter, denser features propagating outward through the solar corona in the visible-light images of the Metis coronagraph on board Solar Orbiter on February 22, 2021. Our main focus is on investigating their possible origin and contribution to the slow wind variability and dynamics and their dependence on coronal magnetic field configurations and structure. Methods. The method adopted is based on the computations of autocorrelation and cross-correlation functions applied to temporal and spatial series of total brightness as a function of the heliocentric distance and solar latitudes. Results. We find that the plasma density inhomogeneities studied here are small-scale structures with typical radial and transverse sizes, as projected on the plane of sky, on the order of 500 Mm and 40 Mm, respectively, and that they are up to 24 times brighter than the ambient solar wind. The brighter density structures exhibit longer lifetime and more stable shape and dimensions as they travel toward the outer edge of the field of view. The enhanced density structures are ejected with a most probable cadence of about 80 min at or below the inner edge of the Metis field of view (within 3.1 R⊙–5.7 R⊙ at the time of observations) in a wide latitudinal region corresponding to the site of a complex web of separatrix and quasi-separatrix layers, as resulting from the simulated magnetohydrodynamic configuration of the west limb of the solar corona. Some of the moving density enhancements clearly show morphological characteristics compatible with the switchback phenomenon, supporting the results indicating that the switchbacks occur at the coronal level. The enhanced density structures were ejected into the ambient slow wind with a mean velocity of about 240 ± 40 km s−1, which is significantly higher than that deduced for the ambient solar wind on the basis of previous Metis observations during the solar minimum of cycle 24. The absence of acceleration observed across the coronagraph field of view suggests that the ejected plasmoids are progressively reaching the expansion rate of the ambient wind. Conclusions. The results suggest that the quasi-periodic enhanced-density plasmoids might be the consequence of reconnection phenomena occurring in the complex web of the separatrix and quasi-separatrix layers present in the solar corona. Moreover, the structural characteristics of some of the detected plasmoids are in favor of the presence of switchbacks that originate during interchange reconnection processes occurring at or below 3 R⊙ in the S-web. The speed of the plasma ejected in the reconnection process is higher than that of the ambient slow solar wind and is likely to be related to the energy involved in the process generating the propagating structures.

Discussion on ‘Paleozoic sedimentation and Caledonian terrane architecture in NW Svalbard: indications from U–Pb geochronology and structural analysis’ by Koglin et al . 2022 ( JGS , 179, jgs2021-053)

Koglin et al. (2022) present valuable new isotopic and field data regarding northwest Spitsbergen's tectonic history, and propose the existence of the Germaniahalvøya terrane with Scandian (Late Caledonian) igneous activity and deformation. Within this terrane, the Lerner Deformation zone (LDZ), is cast as an east-directed thrust, with the Liefdefjorden Migmatite Complex in the footwall and Lenerøyane Group meta-sediments above. The LDZ occurs on the west limb of the major, shallowly north plunging, Bockfjorden anticline. We suggest their data supports the unmentioned and discussed idea (Dallmann & Piepjohn 2018, Braathen et al. 2018) that a Scandian metamorphic core complex exists here and that the LDZ is part of the Keisarhjelmen extensional detachment (Braathen et al. 2017, Maher et. al. 2022). The detachment consists of ductile to brittle, retrogressive, fault rocks up to several hundred meters thick along the contact between metamorphic basement and overlying Devonian basin strata. In addition, we note that Koglin et al's (2022) evidence for Scandian activity is consistent with core complex dynamics.

Origin of Quasi-periodic Pulsation at the Base of a Kink-unstable Jet

We studied a blowout jet that occurred at the west limb of the Sun on 2014 August 29 using high-resolution imaging/spectroscopic observations provided by the Solar Dynamics Observatory/Atmospheric Imaging Assembly and the Interface Region Imaging Spectrograph. An inverse γ-shaped flux rope appeared before the jet–morphological indication of the onset of kink instability. The twisted field lines of the kink-unstable flux rope reconnected at its bright knot and launched the blowout jet at ≈06:30:43 UT with an average speed of 234 km s−1. Just after the launch, the northern leg of the flux rope erupted completely. The time–distance diagrams show multiple spikes or bright dots, which is the result of periodic fluctuations, i.e., quasi-periodic fluctuations (QPPs). The wavelet analysis confirms that QPPs have a dominant period of ≈3 minutes. IRIS spectra (Si iv, C ii, and Mg ii) may also indicate the occurrence of magnetic reconnection through the existence of broad and complex profiles and bidirectional flows in the jet. Further, we found that line broadening is periodic with a period of ≈3 minutes, and plasma upflow always occurs when the line width is high, i.e., multiple reconnection may produce periodic line broadening. The emission measure (EM) curves also show the same period of ≈3 minutes in different temperature bins. The images and EM show that this jet spire is mainly cool (chromospheric/transition region) rather than hot (coronal) material. Further, line broadening, intensity, and EM curves have a period of ≈3 minutes, which strongly supports the fact that multiple magnetic reconnection triggers QPPs in the blowout jet.

Coronal Densities, Temperatures, and Abundances during the 2019 Total Solar Eclipse: The Role of Multiwavelength Observations in Coronal Plasma Characterization

The Airborne Infrared Spectrometer (AIR-Spec) offers an unprecedented opportunity to explore the near-infrared (NIR) wavelength range. It has been flown at two total solar eclipses, in 2017 and 2019. The wavelength range of the much-improved instrument on the second flight (2019 July 2) was shifted to cover two density-sensitive lines from S xi. In this paper we study detailed diagnostics for temperature, electron density, and elemental abundances by comparing results from AIR-Spec slit positions above the east and west limbs with those from Hinode/EIS, the PolarCam detector, and SDO/AIA. We find very good agreement in the electron densities obtained from the EIS EUV line ratios, those from the NIR S xi ratio, and those obtained from the polarized brightness PolarCam measurements. Electron densities ranged from log N e [cm−3] = 8.4 near the limb to 7.2 at R 0 = 1.3. EIS spectra indicate that the temperature distribution above the west limb is near isothermal at around 1.3 MK, while that on the east has an additional higher-T component. The AIR-Spec radiances in Si x and S xi, as well as the AIA data in the 171, 193, and 211 Å bands, are consistent with the EIS results. EIS and AIR-Spec data indicate that the sulfur abundance (relative to silicon) is photospheric in both regions, confirming our previous results of the 2017 eclipse. The AIA data also indicate that the absolute iron abundance is photospheric. Our analysis confirms the importance of the diagnostic potential of the NIR wavelength range and that this important wavelength range can be used reliably and independently to determine coronal plasma parameters.

Suitability of Injana Clays for filling Materials

The study aims to evaluate suitability of injana formation clays for filling material in Sharqad area / North of Iraq, The exposed rocks are Fat’ha & Injana Formations in addition to Quaternary deposits. Three stations are studied in southern west limb of Khanuqa anticline near the north western plunge of this anticline, Geotechnical properties show that the type of soil are low plasticity (CL)and low plasticity silt(ML).The specific gravity values ranges between (2.65-2.72), the chemical analysis show that the ratio of total dissolved salts ranges between (3.9-5.2)% ,while the ratio of gypsum content ranges(2.7-3.0)%, pH values ranges between (7.8-8.0).In last the most geotechnical properties of Injana clays are accepted as filling materials for earth fill dams when compare with Iraq specification (Sorb/rs) except the ratio of (TDS) for stations,1&3.

Evaluation of Subsurface Hydraulic Conditions, between Ajeel and Al-Shari Basins

This research work aims to recognize the contact between Ajeel and Shari ground water basins on the South west limb of the Northern hemrien Anticline, depending on the hydraulic Conditions and Pumping test which carried out on three Wells in the Study area.
 According to the result, it is found that the Transmissivity(T) = 1177.605 m2/day, hydraulic conductivity (K)= 52.754 m/day, and Storage coefficient (Sc)= 0.00053, East the contact.
 While west of the contact T= 717.10 m2/day, K= 24.34 m/day, and Sc = 0.0001 .

An Analytical Model of Turbulence in Parker Spiral Geometry and Associated Magnetic Field Line Lengths

Understanding the magnetic connections from the Sun to interplanetary space is crucial for linking in situ particle observations with the solar source regions of the particles. A simple connection along the large-scale Parker spiral magnetic field is made complex by the turbulent random walk of field lines. In this paper, we present the first analytical model of heliospheric magnetic fields where the dominant 2D component of the turbulence is transverse to the Parker spiral. The 2D wave field is supplemented with a minor wave field component that has asymptotic slab geometry at small and large heliocentric distances. We show that turbulence spreads field lines from a small source region at the Sun to a 60° heliolongitudinal and heliolatitudinal range at 1 au, with a standard deviation of the angular spread of the field lines of 14°. Small source regions map to an intermittent range of longitudes and latitudes at 1 au, consistent with dropouts in solar energetic particle intensities. The lengths of the field lines are significantly extended from the nominal Parker spiral length of 1.17 au up to 1.6 au, with field lines from sources at and behind the west limb considerably longer than those closer to the solar disk center. We discuss the implications of our findings for understanding charged particle propagation and the importance of understanding the turbulence properties close to the Sun.

Geotechnical Modeling of Optimal Pit: West Limb of the Tarkwaian of Ghana

Tarkwa Gold Mine is depleting its reserves to the east of the mine, on the Tarkwaian paleo placer deposit. It has, as a result embarked on vigorous near mine exploratory works to the west of the concession for reserve generation. Results indicate gold mineralisation of economic interest. The Mine seeks to provide optimal slope design that would satisfy shareholders and employees in the context of safety, ore recovery, and financial returns. Rock Mass Rating (RMR) and subsequent adjustment to obtain the Mining Rock Mass Rating (MRMR) was done for rock characterisation. The ratings for the various geotechnical zones ranged from 40.91 to 67.72 and rated from fair to very good. Kinematic stability analyses were performed for all the three design sectors using stereographic techniques to determine the failure modes kinematically possible in bench and/or multi-bench scale slopes. Multi-bench scale planar and wedge failures were kinematically possible in all sectors. Limit equilibrium analysis gave factors of safety that exceeded the minimum acceptable factor of safety of 1.05 for completely weathered material and 1.20 for fresh rock. The probability of failure was however less than 5%. Pit wall architecture for the geotechnical domains were 8 meters, 18 meters, 75 degrees for the berm width, bench height, and bench face angle respectively. Indicative overall slope angles fell between 50.02 to 59.21 degrees and rated from fair to very good.

High-resolution observations with ARTEMIS/JLS and the NRH

Context.Narrowband bursts (spikes) are very small duration and bandwidth bursts which appear on dynamic spectra from microwave to decametric frequencies. They are believed to be manifestations of small-scale energy release through magnetic reconnection.Aims.We study the position of the spike-like structures relative to the front of type-II bursts and their role in the burst emission.Methods.We used high-sensitivity, low-noise dynamic spectra obtained with the acousto-optic analyzer (SAO) of the ARTEMIS-JLS solar radiospectrograph, in conjunction with high-time-resolution images from the Nançay Radioheliograph (NRH) in order to study spike-like bursts near the front of a type-II radio burst recorded at the west limb during the November 3, 2003 extreme solar event. The spike-like emission in the dynamic spectrum was enhanced by means of high-pass-time filtering.Results.We identified a number of spikes in the NRH images. Due to the lower temporal resolution of the NRH, multiple spikes detected in the dynamic spectrum appeared as single structures in the images. These spikes had an average size of ≈200″ and their observed brightness temperature was 1.4 to 5.6 × 109K, providing a significant contribution to the emission of the type-II burst front. At variance with a previous study on the type-IV associated spikes, we found no systematic displacement between the spike emission and the emission between spikes. At 327.0 MHz, the type II emission was located about 0.3R⊙above the pre-existing continuum emission, which, in turn, was located 0.1R⊙above the western limb.Conclusions.This study, combined with our previous results, indicates that the spike-like chains aligned along the type II burst MHD shock front are not a perturbation of the type II emission, as in the case of type IV spikes, but a manifestation of the type II emission itself. The preponderance of these chains, together with the lack of isolated structures or irregular clusters, points towards some form of small-scale magnetic reconnection, organized along the type-II propagating front.

Structural geometry and kinematic history of the southern Kicking Horse Rim Cambrian carbonate platform: out-of-sequence thrust faulting in the southern Canadian Rocky Mountains

Abstract The structure of the southern Kicking Horse Rim Cambrian carbonate platform is spectacularly exposed in the Rocky Mountains southwest of Calgary, Alberta, Canada. Episodic uplift along the approximately 100 km long, north-northwest-trending Kicking Horse Rim during the middle and upper Cambrian controlled the position of the Cambrian carbonate platform to basin facies change. Extensive hydrothermal alteration, with local magnesite and/or Pb-Zn mineralization occurred along the west margin of the Rim. Spectacular slump scars, escarpments, megaconglomerates and slide masses locally mark the edge of the southern Kicking Horse Rim platform. Megaconglomerates form a unique and indisputable stratigraphic tie between the basin and platform and show that there is no stratigraphic gap or suture along this boundary. The change from carbonate- to shale-dominated lithologies resulted in a major change in structural style and the boundary between the Eastern and Western Main Ranges structural subprovinces. Serial and regional cross-sections across the area document the southward plunge of Kicking Horse Rim strata and the Eastern Main Ranges structural subprovince and show that this is due to underlying structure, and not stratigraphic thinning of the Cambrian carbonate platform. Prospective horizons for mineralization extend southward in the subsurface beyond their current southern limit of exposure. Kicking Horse Rim and associated Cambrian strata were carried northeastward along the Fatigue Thrust - blind thrust fault system. Because of a prominent hanging wall ramp through the entire Cambrian succession along the east side of the Kicking Horse Rim, the southern Kicking Horse Rim and Cambrian platform formed an asymmetric, east-facing anticline with a long gently-dipping west limb as they were uplifted and carried northeastward. In the northern part of the study area, displacement was along the Fatigue Thrust and the fault climbed through the Paleozoic section. In the south, most displacement on this fault system went into a blind detachment fault near the base of the thick basinal lower Ordovician section and overlying faulted detachment folds. The Simpson Pass Thrust truncated and overrode in its footwall the east-facing anticline and other structures developed in the hanging wall of the Fatigue Thrust. The Simpson Pass Thrust is out-of-sequence relative to the Fatigue Thrust and is one of the few larger displacement, out-of-sequence thrust faults recognized in the southern Canadian Rocky Mountains. Deformation of the Western Main Ranges and thrust faults near the Cambrian facies change occurred prior to the main motion along the Fatigue Thrust - blind thrust system. Motion on this thrust system, and the formation of faulted detachment folds that extend southward into the eastern part of the Porcupine Creek fan structure, occurred prior to motion on the Simpson Pass Thrust. Deformation of all these structures occurred during Jurassic–Early Cretaceous deformation most likely sometime prior to 125 Ma.

White-light Continuum Observation of the Off-limb Loops of the SOL2017-09-10 X8.2 Flare: Temporal and Spatial Variations

Abstract Observations of the Sun’s off-limb white-light (WL) flares offer rare opportunities to study the energy release and transport mechanisms in flare loops. One of the best such events was SOL2017-09-10, an X8.2 flare that occurred near the Sun’s west limb on 2017 September 10 and produced a WL loop system lasting more than 60 minutes and reaching an altitude higher than 30 Mm. The event was well observed by a suite of ground- and space-based instruments, including the Solar Dynamics Observatory/Helioseismic and Magnetic Imager (SDO/HMI) that captured its off-limb loops in WL continuum near Fe i 6173 Å, and the Atmospheric Imager Assembly (SDO/AIA) that observed its ultraviolet (UV) and extreme-ultraviolet (EUV) counterparts. We found quasi-periodic pulsations in the WL and UV emissions at the flare loop-top with a period around 8.0 minutes. Each pulsation appears to have an EUV counterpart that occurs earlier in time and higher in altitude. Despite many similarities in the WL and UV images and light curves, the WL flux at the loop-top continues to grow for about 16 minutes while the UV fluxes gradually decay. We discuss the implication of these unprecedented observations on the understanding of the enigmatic off-limb WL flare emission mechanisms.

Intracontinental deformation of the western Ordos Basin in North China and sandstone‐type uranium mineralization: Constraints from AFT chronology of the Helan Mountain

Apatite fission track (AFT) sampled from Helan Mountain, of the western Ordos Basin, North China shows that the study area located in the western part of the North China Craton (NCC) has undergone four‐stage exhumation since Mesozoic time, that is, Late Jurassic to Early Cretaceous, Late Cretaceous, Early Cenozoic, and post‐late Miocene. Helan Mountain had slowly uplifted and eroded from the Late Jurassic to the beginning of the Cenozoic. The intensive deformation within NCC is attributable dynamically to the gently angular subduction of the Pacific Plate under the Eurasian Plate (EP). Helan Mountain has undergone sinistral strike‐slipping with a 60‐km maximum displacement caused by the collision of the southeast margin of EP during the Late Cretaceous. The Early Cenozoic tectonic event in the study area is respondent to collision between the Indian Plate and Eurasian Plate, whereas, the post‐late Miocene event is likely related to the eastward extension of Tibet Plateau. Based on the available AFT ages, the partial annealing zone for the palaeo‐Helan Mountain is ascertained to elevation ~1,200 m to ~2,100 m. The tectonic events occurring from Mesozoic to Cenozoic in Helan Mountain is directly related to the plate margin tectonism and representative for the intracontinental deformation of Eurasian Plate convergence. The sandstone‐type uranium deposits in the western margin thrust belt of Ordos Basin are related to the Late Jurassic to Early Cretaceous and Late Cretaceous exhumation events. Immediately after the host rock, the Zhiluo Formation sedimentation during the Middle Jurassic, the Late Jurassic ~ Late Cretaceous exhumations resulted in north–south‐trending anticlines, synclines, and thrust faults; meanwhile, the Zhiluo Formation was uplifted to the surface and infiltrated by uranium‐bearing oxidized fluids originated from the Helan Mountain. Uranium deposits were formed in both east and west limbs of folds. Finally, uranium mineralization ceased since the Cenozoic because the Yinchuan and Hetao faulted grabens have separated the Helan Mountain provenance from the western margin thrust belt.

The impact of mixing treatments on cloud modelling in 3D simulations of hot Jupiters

ABSTRACT We present results of 3D hydrodynamical simulations of HD209458b including a coupled, radiatively active cloud model (eddysed). We investigate the role of the mixing by replacing the default convective treatment used in previous works with a more physically relevant mixing treatment (Kzz) based on global circulation. We find that uncertainty in the efficiency of sedimentation through the sedimentation factor fsed plays a larger role in shaping cloud thickness and its radiative feedback on the local gas temperatures – e.g. hotspot shift and day-to-night side temperature gradient – than the switch in mixing treatment. We demonstrate using our new mixing treatments that simulations with cloud scales that are a fraction of the pressure scale height improve agreement with the observed transmission spectra, the emission spectra, and the Spitzer 4.5 µm phase curve, although our models are still unable to reproduce the optical and ultraviolet transmission spectra. We also find that the inclusion of cloud increases the transit asymmetry in the optical between the east and west limbs, although the difference remains small ($\lesssim 1{{\ \rm per\ cent}}$).

Gross Anatomical Studies on the Hind Limb of the West African Giraffe (Giraffa camelopardalis peralta).

This study on the gross anatomy of the West African giraffe's hind limb was aimed at investigating the unique morphological features and number of bones making up this region of the skeleton. Two (2) adults obtained as carcasses at different times after postmortem examination were prepared to extract the bones via cold water maceration for use in the study. The appearance of the ossa coxarum and its features presented similarities to that of the horse. However, differences were evident in the convex cranial border of the ilium, small less prominent coxal tuber, and wider interval between the opposite sacral tuber and an oval obturator foramen. Common features reported in most species such as the gluteal line and psoas tubercle were absent. The long femur presented proximally; the greater trochanter connected obliquely via the trochanteric crest to the lesser trochanter. The supracondyloid fossa, obliquely directed medial condyle, and trochlea with two unequal ridges were presented distally. The fibula was absent while the tibia was typical of ruminant presentation with one popliteal line and no muscular lines on its caudal surface. The five (5) tarsals were arranged three proximally and two distally. One (1) metatarsal (3rd and 4th fused) presented two condyles that anchor two (2) digits with 3 phalanges and 3 sesamoid bones each. The total number of bones making up the hind limb was accounted to be 45. In conclusion, this study has provided a baseline data for further biological, archeological, and comparative anatomical studies.

Solar flares and geomagnetic storms of September 2017: Their impacts on the TEC over 75°E longitude sector

• Solar flare effect on TEC at a specific longitude sector is studied. • A special case of co-occurrence of geomagnetic storm and solar flare is examined. • A delayed TEC response is observed during recovery phase of solar flare. This study investigates the ionospheric Total Electron Content (TEC) responses over 75°E longitude to the solar flares and geomagnetic storms of September 6–9, 2017. The results of this study provide the impacts of solely solar flares on the ionosphere and such impact when the effects of solar flares and geomagnetic storm are combined. On September 6, two X class solar flares, namely X2.2 at 0857 UT and X9.3 at 1153 UT, were recorded with quiet geomagnetic conditions. The EUV/X-ray intensity of X9.3 flare was significantly greater than that of X2.2 flare, and the recovery phase of both the flares was slower than their respective impulsive phase. The slower recovery rate in EUV/X-ray intensity is reflected as a delayed TEC response. A nearly 8% higher crest to trough TEC change on flare day than the pre-flare day suggests an enhanced level of the equatorial electrojet. The overall weak TEC response to X9.3 solar flare is attributed to solar zenith angle dependency and shifting of solar flare location from disk center to west limb. The solar flares on September 7–8 were co-occurred with geomagnetic storms and observed large increments in TEC are additionally induced by prompt penetration electric field and the enhanced level of thermospheric compositional changes. On September 9, an increase in TEC is observed during M class solar flares under effect of solar flares and disturbed dynamo electric field.