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Paragangliomas are rare extra-adrenal tumors originating from chromaffin cells. We discovered a large intrapericardial mass confirmed to be a primary cardiac paraganglioma encasing the left main stem coronary artery in a 38-year-old woman who presented with dyspnea and subscapular pain. Genetic predisposition related to succinate dehydrogenase A mutation was identified.

This article reports on the design and findings of the first iteration of a classroom-based design research project which endeavours to design a professional development intervention for teachers' mathematical problem-solving pedagogy. The major outcome of this study is the generation of design principles that can be used by other researchers developing a professional development (PD) intervention for mathematical problem-solving pedagogy. This study contributes to the mathematical problem-solving pedagogy and PD body of knowledge by working with teachers in an under-researched environment (an informal settlement in Gauteng, South Africa). In this iteration, two experienced Grade 9 mathematics teachers and their learners at a public secondary school in Gauteng, South Africa, participated in a 6-month intervention. Findings from the data are discussed in light of their implications for the next cycle and other PD studies.

This study investigates the detectability of intermediate-mass black holes (IMBHs) within the mass range 10 ^2 M _⊙ ≤ M _BH ≤ 10 ^5 M _⊙ in the globular star clusters of NGC 1399 at a frequency of 300.00 MHz. Employing the theoretical Bondi accretion model and the empirical fundamental plane (FP) of black hole accretion, we estimate IMBH masses based on bolometric luminosity and X-ray/radio luminosities, respectively. By simulating a 3 hr observation of 77 globular cluster (GC) candidates using the Square Kilometre Array, we identify radio detection benchmarks indicative of accretion onto IMBHs. Our results show that IMBHs inside the globular star clusters located in NGC 1399 are indeed detectable, with the Bondi accretion model providing IMBH mass estimates ranging from 2.93 × 10 ^3.0±0.39 M _⊙ to 7.43 × 10 ^4.0±0.39 M _⊙ and the empirical FP relation suggesting IMBH mass estimation with 3.41 × 10 ^5.0±0.96 M _⊙ . These findings highlight the presence and detectability of IMBHs in GCs, offering insights into their role as precursors to supermassive black holes and enriching our understanding of black hole formation and evolution in astrophysical environments.

Gaia Data Release 3 (DR3) provides the first classifications for the sources in Gaia 's all-sky database. Most Gaia sources are stars in the Milky Way, but DR3 also contains many sources that belong to nearby galaxies, as well as background galaxies and quasars. In this work, we compare the Gaia classifications from the Discrete Source Classifier (CU8-DSC) module to the more detailed and heterogeneous classifications in NED (NASA Extragalactic Database) and/or SIMBAD (Set of Identifications, Measurements and Bibliography for Astronomical Data) for sources with sky positions within twice the Holmberg radius of nearby galaxies. Matching these catalogues gives approximately |$3.2\times 10^5$| unique Gaia matches for |$4\times 10^5$| sources over 1040 galaxies (excluding some large Local Group galaxies) in the Local Volume Galaxy catalogue. Matched sources contain a lower fraction of Gaia -classified stars and higher fractions of galaxies and quasars (⁠|$\sim 95$| per cent, 2 per cent, and 2 per cent, respectively) than DR3 overall. Considering NED (SIMBAD) classifications as truth values, the balanced accuracy of Gaia classification is 0.80 (0.83): the most common disagreements are literature-classified galaxies Gaia -classified as stars and literature-classified stars Gaia -classified as quasars. Purity (P) and completeness (C) metrics show that agreement between Gaia classification and NED/SIMBAD classification is best for stars (⁠|$P\, \mathrm{ and}\, C\sim 0.9$|⁠), and decreases for quasars (⁠|$P\lt 0.3$| and |$0.7\lt C\lt 0.8$|⁠), galaxies (⁠|$0.7\lt P\lt 0.8$| and |$0.3\lt C\lt 0.6$|⁠), white dwarfs (⁠|$0.04\lt P\lt 0.6$| and |$C\sim 0.6$|⁠), and binary stars (⁠|$P\, \mathrm{ and}\, C\lt 0.1$|⁠). NED or SIMBAD sources classified only by detection wavelength are most often Gaia -classified as stars, while non-stellar components of galaxies appear in all Gaia classes. [ABSTRACT FROM AUTHOR]

Writing assessment is a key feature of most education systems, yet there are limitations with traditional methods of assessing writing involving rubrics. In contrast, comparative judgement appears to overcome the reliability issues that beset the assessment of performance assessment tasks. The approach presented here extends previous work on comparative judgement by directly involving teachers in a large number of schools in the judging of young pupils' writing. To ensure quality control the process incorporated a process of 'anchoring' that ensured that teachers could not artificially inflate their own pupils' scores. The approach was used to assess the writing of 55,599 primary pupils in England in 2017-2018. Overall, the results showed that a comparative judgement approach to writing incorporating anchoring shows promise in providing a fair and robust large-scale method to assess writing.

The COSMOS field has been extensively observed by most major telescopes, including Chandra, HST, and Subaru. HST imaging boasts very high spatial resolution and is used extensively in morphological studies of distant galaxies. Subaru provides lower spatial resolution imaging than HST but a substantially wider field of view with greater sensitivity. Both telescopes provide near-infrared imaging of COSMOS. Successful morphological fitting of Subaru data would allow us to measure morphologies of over 10 ^4 known active galactic nucleus (AGN) hosts, accessible through Subaru wide-field surveys, currently not covered by HST. The morphological parameters indicate the types of galaxies that host AGNs. For 4016 AGNs between 0.03 < z < 6.5, we study the morphology of their galaxy hosts using GALFIT, fitting components representing the AGN and host galaxy simultaneously using the i -band imaging from both HST and Subaru. Comparing the fits for the differing telescope spatial resolutions and image signal-to-noise ratios, we identify parameter regimes for which there is strong disagreement between distributions of fitted parameters for HST and Subaru. In particular, the Sérsic index values strongly disagree between the two sets of data, including sources at lower redshifts. In contrast, the measured magnitude and radius parameters show reasonable agreement. Additionally, large variations in the Sérsic index have little effect on the ${\chi }_{\nu }^{2}$ of each fit, whereas variations in other parameters have a more significant effect. These results indicate that the Sérsic index distributions of high-redshift galaxies that host AGNs imaged at ground-based spatial resolution are not reliable indicators of galaxy type and should be interpreted with caution.

The South African curriculum emphasizes the teaching of problem solving in mathematics. However, little is known about South African teachers' views on the teaching of mathematical problem solving (MPS). The purpose of this study was to establish Grade 9 South African teachers' views, teaching strategies and the support required in their teaching of MPS. We worked with teachers who teach MPS to large, under-resourced and multilingual classes. Data for the study were collected using an open-ended questionnaire and classroom observations. The questionnaire sample consisted of 31 teachers from 20 schools in a district in Gauteng, South Africa. Data was analysed through grounded theory techniques and the findings indicate that overcrowded classes and learners' problems with English as the language of learning and teaching compel teachers to retain strict ownership of the MPS process. The findings also uncovered that teachers' adoption of the MPS as a step-by-step guided sense-making strategy is a response to learners' perceived lack of mastery of basic algorithms. All participants in the study stated that they required support on the teaching of MPS that included practical demonstration of MPS pedagogy in the context of their classes where discipline is a challenge and learners are under-prepared, lack basic MPS skills and struggle with the language of learning and teaching.

This study describes a comparison of how worked examples in selected textbooks from England and Shanghai presented possible learning trajectories towards understanding linear function. Six selected English textbooks and one Shanghai compulsory textbook were analysed with regards to the understanding required for pure mathematics knowledge in linear function. Understanding was defined as being at five levels: Dependent Relationship, Connecting Representations, Local Properties Noticing, Object Analysis and Inventising. These levels were developed by examining the most prominent theories from the existing literature on understanding function. Findings suggested that the English textbooks constrained the structural aspect of understanding linear function due to a point-to-point view of function, while the Shanghai textbook which focussed on a variable view of function overemphasised the algebraic approach. The discussion explored the drawbacks to each approach and what teachers or textbook writers could do to balance these two approaches in order to facilitate students' understanding towards a structural view of linear function.

This study investigates how students in England and Shanghai understand linear function. Understanding is defined theoretically in terms of five hierarchical levels: Dependent Relationship; Connecting Representations; Property Noticing; Object Analysis; and Inventising. A pilot study instrument presented a set of problems to both cohorts, showing that the English cohort generally operated at the levels of Property Noticing and Object Analysis, whereas the Shanghai cohort reached the higher level of Inventising. The main study explored understanding levels and students' errors within each cohort in detail, in order to gain insights into reasons for apparent differences. The instrument used in the main study included two overlapping items, which were the same for both cohorts, while others were pitched at levels of understanding revealed in the pilot. Analysis of students' solutions revealed that the English students' errors were manifested in a lack of basic skills including dealing with negative numbers, while the Shanghai students showed weaknesses in their ability to use graphs. The discussion highlights different views of understanding as a possible background reason for the contrasts observed. Errors and apparent difficulties suggest implications for teaching linear function in each context.

Observational astrophysics uses sophisticated technology to collect and measure electromagnetic and other radiation from beyond the Earth. Modern observatories produce large, complex datasets and extracting the maximum possible information from them requires the expertise of specialists in many fields beyond physics and astronomy, from civil engineers to statisticians and software engineers. This article introduces the essentials of professional astronomical observations to colleagues in allied fields, to provide context and relevant background for both facility construction and data analysis. It covers the path of electromagnetic radiation through telescopes, optics, detectors, and instruments, its transformation through processing into measurements and information, and the use of that information to improve our understanding of the physics of the cosmos and its history.

Background: It has been shown that mathematical representations can aid children's understanding of mathematical concepts but that children can sometimes have difficulty in interpreting them correctly. New advances in eye-tracking technology can help in this respect because it allows data to be gathered concerning children's focus of attention and so indicate on what aspects of the representations they are focussing. However, recent eye-tracking technology has not been used to any great degree in investigating the way children view and interpret mathematical representations. Purpose: This research explored the use of new advances in eye-tracking technology in investigating how young children view and interpret mathematical representations of multiplication. Sample: Nine Year 5 children (four boys, five girls, aged 9-10 years of age) from a local primary (elementary) school in the North-East of England were asked to complete the test during school time. The children represented a range of attainment levels across the mathematical domain (three higher-, three middle- and three lower-attaining children) and were selected accordingly by their class teacher. We recognise that this study was only based on a small sample of children, however, this number still allowed us to make meaningful comparisons in particular between the different types of representations presented. Design and methods: The study consisted of each child looking at 18 static slides, one after the other, with each slide presenting a symbolic and a picture representation of multiplication problems. The data that was captured by the eye tracker and recorded was then analysed quantitatively (e.g. time on each slide, time on each area of interest specified within the software) and qualitatively (video recordings of each child's gaze trajectory during each representation was carried out, thereby allowing a categorisation of the different approaches adopted). Results: The study showed that (a) the particular form of the number line representation used in this study was less successful than the other picture representations used (equal groups, array) in promoting multiplicative thinking in children, and (b) the success of children to think multiplicatively with the "groups" and the array representation was related to their general mathematics attainment levels. Conclusion: These findings have implications for teacher practice in that teachers need to be clear about the possible drawbacks of particular representations. Even in using more successful representations, for lower-attaining children, the progression in their understanding of the representation needs to be taken into account by the teacher. The study also highlighted that the eye-tracking technology does have some limitations but is useful in investigating young children's focus of attention whilst undertaking a mathematics assessment task.

Heating requirements inside greenhouses are affected by outdoor climates, structure characteristics, types of heating systems, and the strategies of operation and management. A properly maintained greenhouse can reduce the energy consumption and thus contribute to energy savings. This article addresses the issues that might lower the system efficiency and provides a checklist to ensure the best performance of the system.

Background: The research on diagrammatic representations highlights their importance for the teaching and learning of mathematics. However, the empirical evidence to support their use in the classroom is mixed and somewhat lacking. Purpose: The aim of this study was to develop the use of diagrammatic representations of mathematical concepts in primary classrooms, through introducing primary teachers to the research literature in this area, and researching the subsequent impact on children and teachers. A professional development programme was designed, involving three one-day training sessions for mathematics co-ordinators. They were asked to implement the ideas from the training back in their schools. Sample: Mathematics co-ordinators from eight primary schools attended the professional development programme. The study focussed on Year 3 pupils (aged seven- eight) and Year 5 pupils (aged nine-10). Design and methods: In this paper, we report the qualitative findings from the larger project looking at the overall impact of the professional development programme. The paper focuses on semi-structured interviews carried out with the mathematics co-ordinators attending the professional development sessions, and the Year 3 and Year 5 class teachers who subsequently worked with the co-ordinators on their use of diagrammatic representations in their teaching of mathematics. Lesson observations involving the class teachers were also carried out in order to explore further the possible impact of the project on classroom practice. Results: The qualitative results identified the impact of the project on mathematics co-ordinators and class teachers' knowledge and practice. However, the nature of this impact was complex, with a variety of facilitating and hindering factors identified for the transfer of the professional development ideas on the use of diagrammatic representations. In addition, different levels of sophistication of class teachers' use of diagrammatic representations were identified. Conclusions: Implications for the development of professional development programmes to facilitate the transfer of research into practice were identified. Recommendations for the use of diagrammatic representations are also put forward.

This article reports on the design and findings of the first iteration of a classroom-based design research project which endeavours to design a professional development intervention for teachers’ mathematical problem-solving pedagogy. The major outcome of this study is the generation of design principles that can be used by other researchers developing a professional development (PD) intervention for mathematical problem-solving pedagogy. This study contributes to the mathematical problem-solving pedagogy and PD body of knowledge by working with teachers in an under-researched environment (an informal settlement in Gauteng, South Africa). In this iteration, two experienced Grade 9 mathematics teachers and their learners at a public secondary school in Gauteng, South Africa, participated in a 6-month intervention. Findings from the data are discussed in light of their implications for the next cycle and other PD studies.

Background: Successfully selecting students for undergraduate courses and for teaching is notoriously difficult. Traditionally, in England, A level grades and interviews have been used in conjunction with a variety of other approaches. Purpose: This paper examines the predictive validity of students' A level grades and of scores from a structured interview on their subsequent degree classification as well as the ratings from their final teaching placements. Sample: A cohort of 71 students who started studying for a Bachelor of Arts (BA) degree in Primary Education in 2007 and graduated in 2010. Design and methods: The A level grades and the ratings from structured interviews, carried out prior to the start of the course, were linked to the final degree classification and to the teaching placement grades. Results: A-level scores correlated significantly with degree classification but not with the placement grade whereas the interview grades correlated significantly with both outcome measures. Conclusions: These results are discussed in the light of the restricted range available for A-level grades. (Contains 8 tables and 2 notes.)

We examine whether the array representation can support children's understanding and reasoning in multiplication. To begin, we define what we mean by understanding and reasoning. We adopt a "representational-reasoning" model of understanding, where understanding is seen as connections being made between mental representations of concepts, with reasoning linking together the different parts of the understanding. We examine in detail the implications of this model, drawing upon the wider literature on assessing understanding, multiple representations, self explanations and key developmental understandings. Having also established theoretically why the array representation might support children's understanding and reasoning, we describe the results of a study which looked at children using the array for multiplication calculations. Children worked in pairs on laptop computers, using Flash Macromedia programs with the array representation to carry out multiplication calculations. In using this approach, we were able to record all the actions carried out by children on the computer, using a recording program called Camtasia. The analysis of the obtained audiovisual data identified ways in which the array representation helped children, and also problems that children had with using the array. Based on these results, implications for using the array in the classroom are considered.

This study, carried out in England, examined the variation of attitudes towards science over the first three years of secondary schooling and with gender. The study in question was part of an evaluation of the "Lab in a Lorry" project, and involved 932 pupils completing a pre-measure questionnaire containing items looking at six separate attitude constructs. From these data, two main patterns emerged; pupils' attitudes towards science declined as they progressed through secondary school, and this decline was more pronounced for female pupils. These conclusions are largely in agreement with previous studies in this field. However, in examining separate attitude constructs, we were also able to identify that the sharpest decline occurred specifically for pupils' attitude towards learning science in school. Furthermore, using linear regression, we identified that, as pupils progress through school, this construct becomes a greater influence on attitudes towards future participation in science. Therefore, we also concluded that learning science in school is a particular area that needs to be concentrated upon, if we are to improve children's attitudes towards science. In the final part of the paper, we drew on interview data obtained from 44 pupils involved in the Lab in a Lorry study. Pupils' comments in these interviews provided further insight into why pupils are "switched off" by school science. We drew out the most prevalent themes that emerged in the interviews, in order to provide further insight into why pupils do not enjoy science in school. (Contains 6 tables, 5 figures, and 3 notes.)

In this study, the authors wish to explore the use of visual representations in facilitating the understanding of multiplication. In doing so, they examine the different aspects of multiplication that they can access through different representations. In addition, they draw on a study that they have been carrying out looking at pupils' actual use of one of the representations--the array. By bringing together their theoretical views and actual experiences in the classroom, the authors put forward suggestions for teaching multiplication and also future directions for research. (Contains 8 figures.)

In this study, we describe the development of measures used to examine pupils' attitudes towards science. In particular, separate measures for attitudes towards the following areas were developed: learning science in school, practical work in science, science outside of school, importance of science, self-concept in science, and future participation in science. In developing these measures, criticisms of previous attitude studies in science education were noted. In particular, care was taken over the definition of each of the attitude constructs, and also ensuring that each of the constructs was unidimensional. Following an initial piloting process, pupils aged 11-14 from five secondary schools throughout England completed questionnaires containing the attitude measures. These questionnaires were completed twice by pupils in these schools, with a gap of four weeks between the first and second measurements. Altogether, 932 pupils completed the first questionnaire and 668 pupils completed the second one. Factor analysis carried out on the resulting data confirmed the unidimensionality of the separate attitude constructs. Also, it was found that three of the constructs--learning science in school, science outside of school, and future participation in science--loaded on one general attitude towards science factor. Further analysis showed that all the measures showed high internal reliability (Cronbach's alpha greater than 0.7). A particular strength of the approach used in this study was that it allowed for attitude measures to be built up step-by-step, therefore allowing for the future consideration of other relevant constructs. (Contains 5 tables, 4 figures and 3 notes.)

This paper describes the analysis of data collected by Durham University's YELLIS project, over the period of 1999 to 2004. Included in this data was the degree to which pupils in England at the end of their secondary education "liked" or "disliked" different subjects, and their expected examination grades in these subjects. The authors' study focused on the perceptions of pupils in the science subjects of biology, chemistry and physics. Using the available data, they were able to analyse the perceptions of a large number of pupils (e.g. 9827 pupils in 2004) who took examinations in the separate sciences. The study found that physics was perceived as the least popular science, particularly by female pupils. We also found that the expected grade in a particular science subject correlated quite strongly (Spearman's rho of around 0.5) with the liking of that subject. These expected grades were found to be the lowest in physics, again particularly for female pupils. The authors therefore concluded that in order to redress the gender imbalance in physics, they need to tackle this problem that physics is perceived as difficult by female pupils. (Contains 5 tables and 13 figures.)

Background: The shortage of teachers in England and Wales continues to be a high profile area of scrutiny. Particular subjects (including mathematics, science and English) are categorized by the Training and Development Agency (TDA) for schools as priority or shortage subjects, and London especially has experienced particular shortages in teacher numbers over recent years. Purpose: This paper reports on the findings from a telephone survey with teachers, examining the issues of teacher recruitment and retention. The paper highlights the important factors, as perceived by teachers, that impact on why teachers enter the profession, and also why they choose to leave. Sample: The survey involved 246 teachers in England and Wales, teaching the shortage subjects of English, maths and science. The sample was chosen such that 25% of the teachers taking part in the study would be working in London. Our intention was to have sample numbers for teachers inside and outside London from which meaningful comparisons could be made regarding their views, and so highlight particular issues that were important for teachers in London. The 75% sample not from London was geographically representative of the rest of England and Wales. Design and methods: Prior to the survey, a provisional examination of recent research findings was carried out, leading us to categorize relevant issues into three areas: (1) reasons for wanting to enter teaching; (2) reasons for not wanting to enter teaching; and (3) reasons for wanting to leave teaching. The telephone survey with teachers therefore looked at these three broad areas. A pilot study was carried out with 22 teachers, trialling the survey questions to be used in the telephone interviews. With the agreement of the teachers, the telephone interviews were recorded to aid the data gathering process. Copies of the interview script were sent out beforehand to the teachers being interviewed, in order to try to reassure teachers that no "unexpected" questions would be asked of them, and also to give teachers the opportunity to provide considered responses during the interviews. Results: The survey found that although more "intrinsic" and "altruistic" reasons were given by teachers for going into teaching, the issues of workload and pupil behaviour were found to be most important in dissuading teachers from entering the profession or possibly causing them to leave teaching. Conclusions: The study concluded that in order to have an impact on teacher numbers, the two issues regarding workload and pupil behaviour should be seen to be tackled from the perspectives of teachers. (Contains 8 tables and 2 notes.)

Mathematics in Education and Industry (MEI), with funding from Gatsby Technical Education Projects (GTEP), ran the "Enabling Access to Further Mathematics" project from 2000 to 2003. This pilot project was designed to provide AS- and A-level students with additional opportunities to study Further Mathematics, through the use of distance-learning materials. This was in response to the dramatic decline in the numbers of students taking Further Mathematics over the last four decades. An independent evaluation of the project was commissioned by GTEP, and this paper describes the methodology of the evaluation and its findings. In addition to highlighting the benefits of the project for the students and institutions involved, the paper discusses how the project could be developed in the future, based on the issues and difficulties raised in the evaluation.

Nearby galaxies provide populations of stellar and non-stellar sources at a common distance and in quantifiable environments. All are observed through the Milky Way foreground, with varying degrees of contamination that depend on observed Galactic latitude and the distance and size of the target galaxy. This work uses Gaia Data Release 3 (DR3) to identify foreground sources via astrometric measurements and thus quantify foreground contamination for a large sample of nearby galaxies. There are approximately half a million Gaia  sources in the directions of 1401 galaxies listed in the Local Volume Galaxy catalogue (D < 11 Mpc), excluding the largest Local Group galaxies. About two-thirds of the Gaia  sources have astrometric properties consistent with foreground sources; these sources are brighter, redder, and less centrally concentrated than non-foreground sources. Averaged over galaxies, foreground sources make up 50 per cent of Gaia  sources at projected radius r 50 = 1.06 a 26, where a 26 is the angular diameter at the B = 26.5 isophote. Foreground sources make up 50 per cent of Gaia  sources at apparent magnitude m G , 50 = 20.50. This limit corresponds to the tip of the red giant branch absolute magnitude at D = 450 kpc, and to the globular cluster luminosity function peak absolute magnitude at 5 Mpc. Gaia  data provide a powerful tool for removing foreground contamination in stellar population studies of nearby galaxies, although Gaia  foreground removal will be incomplete beyond distances of 5 Mpc. [ABSTRACT FROM AUTHOR]

Cataloguing and classifying celestial objects is one of the fundamental activities of observational astrophysics. In this work, we compare the contents of two comprehensive data bases, the NASA Extragalactic Database (NED) and Set of Identifications, Measurements and Bibliography for Astronomical Data (SIMBAD) in the vicinity of nearby galaxies. These two data bases employ different classification schemes – one flat and one hierarchical – and our goal was to determine the compatibility of classifications for objects in common. Searching both data bases for objects within the respective isophotal radius of each of the ∼1300 individual galaxies in the Local Volume Galaxy sample, we found that, on average, NED contains about 10 times as many entries as SIMBAD and about two-thirds of SIMBAD objects are matched by position to a NED object, at 5 arcsec tolerance. These quantities do not depend strongly on the properties of the parent galaxies. We developed an algorithm to compare individual object classifications between the two data bases and found that 88 per cent of the classifications agree; we conclude that NED and SIMBAD contain consistent information for sources in common in the vicinity of nearby galaxies. Because many galaxies have numerous sources contained only in one of NED or SIMBAD, researchers seeking the most complete picture of an individual galaxy's contents are best served by using both data bases. [ABSTRACT FROM AUTHOR]

Precise and accurate measurements of distances to Galactic X-ray binaries (XRBs) reduce uncertainties in the determination of XRB physical parameters. We have cross-matched the XRB catalogues of Liu, van Paradijs & van den Heuvel to the results of Gaia  Data Release 2. We identify 86 XRBs with a Gaia  candidate counterpart, of which 32 are low-mass X-ray binaries (LMXBs) and 54 are high-mass X-ray binaries (HMXBs). Distances to Gaia  candidate counterparts are, on average, consistent with those measured by Hipparcos and radio parallaxes. When compared to distances measured by Gaia  candidate counterparts, distances measured using Type I X-ray bursts are systematically larger, suggesting that these bursts reach only 50 per cent of the Eddington limit. However, these results are strongly dependent on the prior assumptions used for estimating distance from the Gaia  parallax measurements. Comparing positions of Gaia  candidate counterparts for XRBs in our sample to positions of spiral arms in the Milky Way, we find that HMXBs exhibit mild preference for being closer to spiral arms; LMXBs exhibit mild preference for being closer to interarm regions. LMXBs do not exhibit any preference for leading or trailing their closest spiral arm. HMXBs exhibit a mild preference for trailing their closest spiral arm. The lack of a strong correlation between HMXBs and spiral arms may be explained by star formation occurring closer to the mid-point of the arms, or a time delay between star formation and HMXB formation manifesting as a spatial separation between HMXBs and the spiral arm where they formed. [ABSTRACT FROM AUTHOR]

Identifying X-ray binary (XRB) candidates in nearby galaxies requires distinguishing them from possible contaminants including foreground stars and background active galactic nuclei. This work investigates the use of supervised machine learning algorithms to identify high-probability XRB candidates. Using a catalogue of 943 Chandra X-ray sources in the Andromeda galaxy, we trained and tested several classification algorithms using the X-ray properties of 163 sources with previously known types. Amongst the algorithms tested, we find that random forest classifiers give the best performance and work better in a binary classification (XRB/non-XRB) context compared to the use of multiple classes. Evaluating our method by comparing with classifications from visible-light and hard X-ray observations as part of the Panchromatic Hubble Andromeda Treasury, we find compatibility at the 90 per cent level, although we caution that the number of source in common is rather small. The estimated probability that an object is an XRB agrees well between the random forest binary and multiclass approaches and we find that the classifications with the highest confidence are in the XRB class. The most discriminating X-ray bands for classification are the 1.7–2.8, 0.5–1.0, 2.0–4.0, and 2.0–7.0 keV photon flux ratios. Of the 780 unclassified sources in the Andromeda catalogue, we identify 16 new high-probability XRB candidates and tabulate their properties for follow-up. [ABSTRACT FROM AUTHOR]

SIGNALS, the Star formation, Ionized Gas, and Nebular Abundances Legacy Survey, is a large observing programme designed to investigate massive star formation and H  ii regions in a sample of local extended galaxies. The programme will use the imaging Fourier transform spectrograph SITELLE at the Canada–France–Hawaii Telescope. Over 355 h (54.7 nights) have been allocated beginning in fall 2018 for eight consecutive semesters. Once completed, SIGNALS will provide a statistically reliable laboratory to investigate massive star formation, including over 50 000 resolved H  ii regions: the largest, most complete, and homogeneous data base of spectroscopically and spatially resolved extragalactic H  ii regions ever assembled. For each field observed, three datacubes covering the spectral bands of the filters SN1 (363–386 nm), SN2 (482–513 nm), and SN3 (647–685 nm) are gathered. The spectral resolution selected for each spectral band is 1000, 1000, and 5000, respectively. As defined, the project sample will facilitate the study of small-scale nebular physics and many other phenomena linked to star formation at a mean spatial resolution of ∼20 pc. This survey also has considerable legacy value for additional topics, including planetary nebulae, diffuse ionized gas, and supernova remnants. The purpose of this paper is to present a general outlook of the survey, notably the observing strategy, galaxy sample, and science requirements. [ABSTRACT FROM AUTHOR]

Aims. We derived the dust properties for 753 local galaxies and examine how these relate to some of their physical properties. We present the derived dust emission properties, including model spectral energy distribution (SEDs), star formation rates (SFRs) and stellar masses, as well as their relations. Methods. We modelled the global dust-SEDs for 753 galaxies, treated statistically as an ensemble within a hierarchical Bayesian dust-SED modelling approach, so as to derive their infrared (IR) emission properties. To create the observed dust-SEDs, we used a multi-wavelength set of observations, ranging from near-IR to far-IR-to-submillimeter wavelengths. The model-derived properties are the dust masses (Mdust), the average interstellar radiation field intensities (Uav), the mass fraction of very small dust grains ("QPAH" fraction), as well as their standard deviations. In addition, we used mid-IR observations to derive SFR and stellar masses, quantities independent of the dust-SED modelling. Results. We derive distribution functions of the properties for the galaxy ensemble and as a function of galaxy type. The mean value of Mdust for the early-type galaxies (ETGs) is lower than that for the late-type and irregular galaxies (LTGs and Irs, respectively), despite ETGs and LTGs having stellar masses spanning across the whole range observed. The Uav and "QPAH" fraction show no difference among different galaxy types. When fixing Uav to the Galactic value, the derived "QPAH" fraction varies across the Galactic value (0.071). The specific SFR increases with galaxy type, while this is not the case for the dust-specific SFR (SFR/Mdust), showing an almost constant star formation efficiency per galaxy type. The galaxy sample is characterised by a tight relationship between the dust mass and the stellar mass for the LTGs and Irs, while ETGs scatter around this relation and tend towards smaller dust masses. While the relation indicates that Mdust may fundamentally be linked to M⋆, metallicity and Uav are the second parameter driving the scatter, which we investigate in a forthcoming work. We used the extended Kennicutt–Schmidt (KS) law to estimate the gas mass and the gas-to-dust mass ratio (GDR). The gas mass derived from the extended KS law is on average ∼20% higher than that derived from the KS law, and a large standard deviation indicates the importance of the average star formation present to regulate star formation and gas supply. The average GDR for the LTGs and Irs is 370, and including the ETGs gives an average of 550. [ABSTRACT FROM AUTHOR]

We present an unprecedented, deep study of the primordial low-mass X-ray binary population in an isolated, lower metallicity environment. We perform follow-up observations of previously identified X-ray binary candidates in the Sculptor Dwarf Galaxy by combining a second Chandra observation with Spitzer and Gemini photometry, as well as Gemini spectroscopy of selected targets. Of the original nine bright X-ray sources identified, we are able to classify all but one as quasars, active galactic nuclei, or background galaxies. We further discover four new X-ray sources in the second-epoch Chandra observation. Three of these new sources are background sources and one is a foreground flaring star. We have found that Sculptor is effectively devoid of X-ray sources above a few 1034 erg s−1. If Sculptor is able to retain primordial binaries at a similar rate to globular clusters, this implies that bright X-ray binaries observed in globular clusters in the present epoch are all formed dynamically. [ABSTRACT FROM AUTHOR]

We present multiwavelength global star formation rate (SFR) estimates for 326 galaxies from the Star Formation Reference Survey in order to determine the mutual scatter and range of validity of different indicators. The widely used empirical SFR recipes based on 1.4 GHz continuum, 8.0  |$\mu$| m polycyclic aromatic hydrocarbons (PAHs), and a combination of far-infrared (FIR) plus ultraviolet (UV) emission are mutually consistent with scatter of |$\lesssim$| 0.3 dex. The scatter is even smaller, |$\lesssim$| 0.24 dex, in the intermediate luminosity range |$9.3\lt \log ({L_{60}\, \rm{\mu\,\,m}}/{\mbox{L$_\odot $}})\lt 10.7$|⁠. The data prefer a non-linear relation between 1.4 GHz luminosity and other SFR measures. PAH luminosity underestimates SFR for galaxies with strong UV emission. A bolometric extinction correction to far-UV luminosity yields SFR within 0.2 dex of the total SFR estimate, but extinction corrections based on UV spectral slope or nuclear Balmer decrement give SFRs that may differ from the total SFR by up to 2 dex. However, for the minority of galaxies with UV luminosity >5 × 109 L⊙ or with implied far-UV extinction <1 mag, the UV spectral slope gives extinction corrections with 0.22 dex uncertainty. [ABSTRACT FROM AUTHOR]

What do we see when we look at a nearby, well-resolved galaxy? Thousands of individual sources are detected in multiband imaging observations of even a fraction of a nearby galaxy, and characterizing those sources is a complex process. This work analyses a ten-band photometric catalogue of nearly 70 000 point sources in a 7.3 square arcmin region of the nearby spiral galaxy Messier 83, made as part of the Early Release Science programme with the Hubble Space Telescope's Wide Field Camera 3. Colour distributions were measured for both broad-band and broad-and-narrow-band colours; colours made from broad-bands with large wavelength differences generally had broader distributions although B - V was an exception. Two- and three-dimensional colour spaces were generated using various combinations of four bands and clustered with the K-Means and Mean Shift algorithms. Neither algorithm was able to consistently segment the colour distributions: while some distinct features in colour space were apparent in visual examinations, these features were not compact or isolated enough to be recognized as clusters in colour space. K-Means clustering of the UBVI colour space was able to identify a group of objects more likely to be star clusters. Mean Shift was successful in identifying outlying groups at the edges of colour distributions. For identifying objects whose emission is dominated by spectral lines, there was no clear benefit from combining narrow-band photometry in multiple bands compared to a simple continuum subtraction. The clustering analysis results are used to inform recommendations for future surveys of nearby galaxies. [ABSTRACT FROM AUTHOR]