The Fragmenting Superbubble Associated with the HII Region W4

New observations at high latitudes above the HII region W4 show that the structure formerly identified as a chimney candidate, an opening to the Galactic halo, is instead a superbubble in the process of fragmenting and possibly evolving into a chimney. Data at high Galactic latitudes (b > 5 degrees) above the W3/W4 star forming region at 1420 and 408 MHz Stokes I (total power) and 1420 MHz Stokes Q and U (linear polarization) reveal an egg-shaped structure with morphological correlations between our data and the H-alpha data of Dennison, Topasna, & Simonetti. Polarized intensity images show depolarization extending from W4 up the walls of the superbubble, providing strong evidence that the radio continuum is generated by thermal emission coincident with the H-alpha emission regions. We conclude that the parts of the HII region hitherto known as W4 and the newly revealed thermal emission are all ionized by the open cluster OCl 352. Assuming a distance of 2.35 kpc, the ovoid structure is 164 pc wide and extends 246 pc above the mid-plane of the Galaxy. The shell's emission decreases in total-intensity and polarized intensity in various locations, appearing to have a break at its top and another on one side. Using a geometric analysis of the depolarization in the shell's walls, we estimate that a magnetic field line-of-sight component of 3 to 5 uG exists in the shell. We explore the connection between W4 and the Galactic halo, considering whether sufficient radiation can escape from the fragmenting superbubble to ionize the kpc-scale H-alpha loop discovered by Reynolds, Sterling & Haffner.Comment: 42 pages, 14 figures; Accepted for publication in Ap

Probing the Interstellar Medium using HI absorption and emission towards the W3 HII region

HI spectra towards the W3 HII complex are presented and used to probe the Galactic structure and interstellar medium conditions between us and this region. The overall shape of the spectra is consistent with the predictions of the Two-Arm Spiral Shock model wherein the gas found in the -40 km/s to -50 km/s range has been accelerated by some 20 km/s from its rotation curve velocity. Spin temperatures of ~100 K are derived for the Local Arm gas, lower than found in a previous, similar study towards DR 7. For the interarm region, values on the order of 300 K are found, implying a negligible filling factor for the Cold Neutral Medium (<< 1%). Some of the absorbing gas at velocities near -40 km/s is confirmed to be associated with the HII regions.Comment: 23 pages, 6 figures, accepted for publication in the Astronomical Journa

The HI shell G132.6-0.7-25.3: A Supernova Remnant or an Old Wind-Blown Bubble?

Data from the Canadian Galactic Plane Survey reveal an abundance of HI shells and arcs in the disk of our galaxy. While their shape is suggestive of stellar winds or supernovae influence, very few of these structures have been examined in detail thus far. A fine example is an HI shell in the outer Galaxy with no continuum counterpart discovered in the survey's pilot project. Its size and kinematics suggest that it was created by the winds of a single late-type O star which has since evolved off the main sequence or by a supernova explosion. A B1 Ia star at the centre of the shell, in projection, is a possible candidate for energy source if the shell is assumed to be wind-blown. The shell's shape implies a surprisingly small scale height of less than about 30 pc for the surrounding gas if the elongation is due to evolution in a density gradient.Comment: 25 pages, 6 figures. Accepted for publication in the Astronomical Journa

The galactic plane survey pilot project: the interstellar medium environment of the W3/W4/W5 star formation complex

Bibliography: p. 219-229

The Presence of Gender Disparity on the Force Concept Inventory in a Sample of Canadian Undergraduate Students

Concept inventories (CI) are validated, research-based, multiple-choice tests, which are widely used to assess the effectiveness of pedagogical practices in bringing about conceptual change. In order to be a useful diagnostic tool, a CI must reflect only the student understanding of the conceptual material. The Force Concept Inventory (FCI) is arguably the standard for testing conceptual understanding of Newtonian mechanics. Studies in the United States and United Kingdom have shown the existence of a gender gap in FCI scores and gains between male and female students. This study aimed to examine whether such a gap exists for Canadian students at a mid-sized university. Four-hundred and thirty-four men and 379 women taking first-term introductory physics courses from the past nine years were assessed with the FCI prior to and after receiving instruction. A gender gap in the pre-instruction and post instruction scores was revealed in favour of male students (p \u3c 0.01). There also existed a gender disparity in the learning gains between the two tests, where males had significantly higher gains (p \u3c 0.01), although the effect size was small. Further analysis found that both male and female students who studied in classes that included interactive engagement methods had somewhat higher gains than students in traditional lecture courses, but that the interactive engagement methods did not eliminate the gender gap between male and female students (p \u3c 0.01). Our results sound a cross-disciplinary note of caution for anyone using concept inventories as research or self-assessment tools. Les inventaires de concepts sont des questionnaires à choix multiples validés basés sur la recherche qui sont largement utilisés pour évaluer l’efficacité de pratiques pédagogiques en instaurant un changement conceptuel. Afin d’être des outils diagnostiques utiles, les inventaires de concepts doivent refléter uniquement la compréhension qu’a l’étudiant de la matière conceptuelle. Le « Force Concept Inventory (FCI) » est sans aucun doute la norme pour tester la compréhension conceptuelle de la mécanique newtonienne. Des études menées aux États-Unis et au Royaume-Uni ont montré l’existence d’un écart hommes-femmes dans les résultats du FCI et ainsi que dans les acquis. Cette étude vise à déterminer si un tel écart existe parmi les étudiants canadiens dans une université de taille moyenne. Un total de 434 hommes et 379 femmes inscrits à un premier cours d’introduction à la physique au fil des neuf dernières années ont été évalués avec le FCI au tout début et à la toute fin de la session. Les résultats ont révélé un écart hommes-femmes dans les résultats des tests, aussi bien ceux effectués avant le cours que ceux après le cours, en faveur des étudiants masculins (p \u3c 0.01). Ils ont également révélé une disparité entre hommes et femmes dans les acquis d’apprentissage entre les deux tests : les hommes avaient atteint des acquis plus élevés (p \u3c 0.01), bien que l’ampleur de l’effet ait été faible. Des analyses complémentaires ont montré que tant les hommes que les femmes qui avaient étudié dans des classes qui comprenaient des méthodes d’engagement interactif avaient obtenu davantage d’acquis que les étudiants qui avaient suivi des cours magistraux traditionnels, mais que les méthodes d’engagement interactif n’avaient pas éliminé l’écart hommes-femmes parmi les étudiants (p \u3c 0.01). Nos résultats présentent une mise en garde à l’intention de ceux qui utilisent les inventaires de concepts en tant qu’outils de recherche ou d’auto-évaluation, quelle que soit leur discipline

Participer à une conversation académique : comment publier votre travail d’ACEA

The path to publication is often long, emotional, and bewildering. We share key insights from our experience as authors, educators, and members of the editorial board with The Canadian Journal for the Scholarship of Teaching and Learning that we hope will help authors better understand and navigate the path to publication. In writing a compelling story, we suggest that it is necessary to join a conversation with self, the scholarly community, and the journal. We unpack each of these dimensions and offer considerations on how to craft a powerful manuscript that could ultimately get published.Le chemin qui mène à la publication est souvent long, émotionnel et déconcertant. Nous partageons des idées clés basées sur notre expérience en tant qu’auteurs, éducateurs et membres de l’équipe de rédaction de La revue canadienne sur l’avancement des connaissances en enseignement et en apprentissage. Nous espérons qu’elles aideront les auteurs à mieux comprendre et à parcourir avec succès le chemin menant à la publication. Nous suggérons que pour rédiger un récit captivant, il est nécessaire de se joindre à une conversation avec soi-même, avec la communauté des chercheurs et avec la revue. Nous déballons chacune de ces dimensions et offrons des considérations sur la manière de créer un manuscrit puissant qui pourrait être publié