National Astronomy Meeting Poster Exhibition

Cataclysmic Variables (CVs) are excellent sources to study accretion physics. Many CVs exhibit outbursts as a result of disc instabilities. CVs are binary systems with periods ranging from ~0.5 days to a few minutes. At the extreme short end of this period distribution are the hydrogen deficient AM CVn systems. We present results of our analysis of 15 years of photometric data of 8 AM CVn systems with periods between 22.8 and 26.8 minutes found in the period instability region. Our data is drawn from GOTO, ZTF, Pan-STARRS, ASAS-SN and Catalina all-sky surveys, as well as amateur observations collated by the AAVSO. This long term data has given us the opportunity to characterise the full range of behaviour in these systems and demonstrates that they show the same diversity as the hydrogen accreting CVs. Our results show that AM CVn systems in the period instability region are not a homogeneous group and implies the nature of the mass donating star is a key factor in their outburst properties. We find systems showing long super outbursts and standstills, others showing shorter more regular super outbursts and others only in a high state — something unpredicted by the existing theory. We also used TESS full frame images of KL Dra, from this we detected normal outbursts appearing as an immediate precursor to it super outbursts, a feature which has never been observed before in AM CVn systems. Our results highlight the breadth of the behaviour seen in hydrogen deficient systems and will inform the theoretical modelling of them.

The aim of this project is to see if the Alston Observatory site, an observation site owned by the University of Central Lancashire, and operated by the Jeremiah Horrocks institute, located in Preston, England, is suitable for a small teaching radio telescope. A SDRPlay RSPdx with an OmniLOG 90200 antenna will be used to take readings of the RFI environment at and around 1.42GHz, known as the hydrogen line, which will be the frequency the telescope would observe at. I will record and present the RFI environment of the site. This will allow any sources of interference to be identified and removed, if possible, with a further goal of a permanent RFI survey station that is remotely accessible using a Raspberry Pi.

The model outlined here embodies three distinct, successive mechanisms which both define and characterise the Sun’s chromosphere, transition region and corona. Operating experience from fusion research shows how Spitzer resistivity may render ohmic heating in the chromosphere self-limiting and thus serve to define the lower margin of the transition region; its upper margin is at ~6.103 K, where radiative cooling of He/H plasma decelerates sharply. The third and last stage in the proposed scheme is expansion into the tenuous plasma of space, which leads to the acceleration of ions to high energies, long recorded by spacecraft instruments as He++. There is thus dynamic continuity all the way from the solar interior - the energy source for spinning columns in the Rayleigh–Bénard setting of the convection zone - to the coronal exhalation of the solar wind, a finding which should benefit the analysis of space weather, witness the association between helium in the solar wind and the incidence of coronal mass ejections.

We undergo preparatory work for the WEAVE Wide Field Cluster Survey (WWFCS) – an upcoming survey providing thousands of galaxy spectra for each of ~ 20 galaxy clusters. Each cluster’s observation will be entirely covered out to 5R200. This provides a unique insight into the infall region surrounding clusters,
allowing us to study the effect of pre-processing of galaxies as they enter a cluster’s potential well. We use The ThreeHundred project, a hydrodynamical re-simulation of 324 massive clusters in a 1Gpc/h cubed box. Using a halo finder (AHF), we obtain the halo distribution surrounding each individual cluster. Mock observations are generated using the halo positions from TheThreeHundred and the positions of the WEAVE pointings to determine where fibres should be placed on the fields. We compare the mass distribution of WEAVE clusters to TheThreeHundred clusters to create a mass matched sample. Once we obtain spectra from WEAVE, we aim to extract cosmic filaments using the filament extractor, DisPerSE, at the boundaries of clusters and to quantify how matter is fed through these high-density channels. This enables us to better understand the mass assembly of the universe as matter is accreted from the cosmic web and investigate how galaxy properties (such as SFR, colour, AGN feedback), change
as a function of distance from the filaments. Using the spectra from WEAVE, we also wish to quantify where and how changes in morphology and star formation occur and their related timescales. Further to this, we will look to determine what fraction of galaxies fall into clusters through filaments and how this
varies with the cluster’s dynamical state.

The Atmospheric Imaging Assembly of NASA’s SDO Mission has been an invaluable tool for solar physics research in its 11 years of operation. The AIA has collected a huge quantity of spatially well resolved solar images with a short time cadence in multiple wavelengths, representing many layers of the solar atmosphere and their respective energy regimes.

Despite this, there have been relatively few studies, especially in coronal physics, which make proper use of this extensive lateral coverage. Analysis of bulk properties of coronal loops, and how these properties are related to and vary throughout the solar cycle could provide insight into the changing energy distribution of the corona and its underlying magnetic mechanisms over time.

The work presented in this poster presents results from the largest survey of coronal loops undertaken using SDO AIA data in the 171, 193, 211, and 304 angstrom bands across the solar cycle to date. Some of the key results include an indication of loop widths following an S.O.C (Self-organized criticality) distribution, with a power law slope of 2.7-3.3 with significant variation across the 11 year half cycle captured by the SDO. Loop positional distributions show signs of asymmetry which varies throughout the solar cycle, mirroring N-S asymmetry that is seen in sun spot coverage and other solar activity indicators.

The poster describes a novel means of measuring and analysing coronal loop structures using automated loop tracing to undertake an examination of over ten years of NASA’s SDO/AIA data across solar cycle 24, and its applicability to other datasets and future aims are discussed.

The spatial distribution and kinematics of cool interstellar medium (dust and molecular gas) within early-type galaxies (ETGs) can be used to highlight mechanisms causing galaxy evolution. For example, asymmetries and spatial or kinematic misalignments of cool ISM compared to stellar discs can be used to indicate recent merger activity. High-resolution mm-wavelength observations can reveal the spatial distribution of cool ISM, and allow ISM kinematics to be explored.
ALMA observations were obtained in 2016 of continuum and 12CO(2-1) line emission for a sample of five ETGs in the GAMA equatorial fields with redshifts ~0.04, drawn from a clean and complete sample of visually-classified ETGs. The sample was chosen to have relatively high dust content (10^7.5 – 10^8 Mʘ) determined using Herschel-ATLAS data. The observations revealed massive (~few x 10^9 Mʘ) extended molecular gas reservoirs in three ETGs.
This poster presents the findings from the modelling of molecular gas kinematics for the three ETGs with massive gas reservoirs, using the KINematic Molecular Simulation (KinMS) package. Axisymmetric single-component models are fitted to ALMA data to highlight additional structural components and any asymmetry. The models also allow examination of potential star formation in the cool molecular gas. Kinematic alignments of molecular gas, stars and ionised gas are also compared, using data from the SAMI galaxy survey. Scenarios for the evolutionary history of these ETGs are discussed using the findings. Future work based on results from these observations is also discussed, along with the possibilities for further observations.

The behaviour of the nuclear symmetry energy near saturation density is important for our understanding of dense nuclear matter. This density dependence can be parameterised by the nuclear symmetry energy and its derivatives evaluated at nuclear saturation density. In our work we have found that the quadrupole (ℓ=2) core-crust interface mode of a neutron star is sensitive to these parameters, through the (density-weighted) shear-speed within the crust, which is in turn dependent on the symmetry energy profile of dense matter. We have calculated the frequency at which the neutron star crust-core interface mode must be driven by the tidal field of its binary partner to trigger a Resonant Shattering Flare (RSF). With this, we demonstrate that coincident multimessenger timing of an RSF and gravitational wave chirp from a neutron star merger would enable us to place constraints on the symmetry energy parameters that are competitive with those from current nuclear experiments.

Low frequency quasi-periodic oscillations (QPO) with periods between ~10 s and ~0.05 s are often seen in the X-ray flux of accreting stellar-mass black holes. These are often attributed to the Lense-Thirring precession of the inner accretion flow, a General Relativistic effect caused by the spin of the black hole. QPO phase-resolved spectroscopy (measuring how the X-ray spectrum changes with QPO phase) provides the best test of this model against alternative interpretations, since precession leads to a rocking of the ~6.4 keV iron fluorescence line between Doppler red and blue shift over the course of each QPO cycle. I will present the latest results of our QPO phase-resolved spectral analyses, including the bright black hole X-ray binary system GRS1915+105 for which we utilise simultaneous data from NICER and NuSTAR. The high count rate and broad band X-ray coverage (~0.3-79 keV) provided by the combination of NICER and NuSTAR made this an ideal dataset for our analysis. I will discuss the statistical significance of the asymmetrical illumination profile and of the ‘rocking’ iron line, and the interpretation of these results.

Far-side helioseismology is a technique used to detect activity signatures in the far hemisphere of the Sun, based on near-side wave field interpretation. We evaluated the performance of a new neural network approach, developed to improve the sensitivity of the seismic maps to the presence of far-side active regions, and thoroughly compared it with the standard method commonly applied to predict far-side active regions from seismic measurements, using STEREO extreme ultraviolet observations of the far hemisphere as a proxy of activity.

We have confirmed the improved sensitivity of the neural network to the presence of far-side active regions. Approximately 96% of the active regions identified by the standard method with strength above the threshold commonly employed by previous analyses are related to locations with enhanced extreme ultraviolet emission. For the same percentage of false positives, the neural network can provide a 47% increase in the number of far-side active region detections confirmed by their extreme ultraviolet brightness. Weaker active regions can be detected by relaxing the threshold in their seismic signature. For almost all the range of thresholds, the neural network delivers a higher number of confirmed detections and a lower rate of false positives.

The neural network is a promising approach to improve the interpretation of the seismic maps provided by local helioseismic techniques, which can lead to improvements in space weather forecasting.

Public perceptions of scientific understanding are most often mediated through intermediate channels - including direct outreach efforts, news media and fictionalised scenarios in the form of science fiction. At its best, science fiction provides a powerful tool for widening awareness of and public engagement with aspects of scientific innovation - in particular in astronomy. At its worst, it can distort or entirely misrepresent scientific understanding or the nature of scientific enquiry. Either way, it provides an interesting historical record of the way astronomy and its discoveries are being represented to the public at a point in time - in particular to the children of the past who are the decision makers of the present. In this poster I will discuss representations of our Solar System and the science of astronomy in historical science fiction narratives and what they tell us about the way both understanding and communication of knowledge about our Universe has changed over time.