The HI and Ionized Gas Disk of the Seyfert Galaxy NGC 1144 = Arp 118: A Violently Interacting Galaxy with Peculiar Kinematics

We present observations of the distribution and kinematics of neutral and ionized gas in NGC 1144, a galaxy that forms part of the Arp 118 system. Ionized gas is present over a huge spread in velocity (1100 km/s) in the disk of NGC 1144, but HI emission is detected over only 1/3 of this velocity range, in an area that corresponds to the NW half of the disk. In the nuclear region of NGC 1144, a jump in velocity in the ionized gas component of 600 km/s is observed. Faint, narrow HI absorption lines are also detected against radio sources in the SE part of the disk of NGC 1144, which includes regions of massive star formation and a Seyfert nucleus. The peculiar HI distribution, which is concentrated in the NW disk, seems to be the inverse of the molecular distribution which is concentrated in the SE disk. Although this may partly be the result of the destruction of HI clouds in the SE disk, there is circumstantial evidence that the entire HI emission spectrum of NGC 1144 is affected by a deep nuclear absorption line covering a range of 600 km/s, and is likely blueshifted with respect to the nucleus. In this picture, a high column-density HI stream is associated with the nuclear ionized gas velocity discontinuity, and the absorption effectively masks any HI emission that would be present in the SE disk of NGC 1144.Comment: manuscript, arp118.ps: 28 pages; 1 Table: arp118.tab1.ps; 16 Figures: arp118.fig1-16.ps; Accepted to Ap

Using graphical and pictorial representations to teach introductory astronomy students about the detection of extrasolar planets via gravitational microlensing

The detection and study of extrasolar planets is an exciting and thriving field in modern astrophysics, and an increasingly popular topic in introductory astronomy courses. One detection method relies on searching for stars whose light has been gravitationally microlensed by an extrasolar planet. In order to facilitate instructors' abilities to bring this interesting mix of general relativity and extrasolar planet detection into the introductory astronomy classroom, we have developed a new Lecture-Tutorial, "Detecting Exoplanets with Gravitational Microlensing." In this paper, we describe how this new Lecture-Tutorial's representations of astrophysical phenomena, which we selected and created based on theoretically motivated considerations of their pedagogical affordances, are used to help introductory astronomy students develop more expert-like reasoning abilities.Comment: 10 pages, 10 figures, accepted for publication in the American Journal of Physic

Radio-Luminous Southern Seyfert Galaxies. I. Radio Images and Selected Optical/Near-Infrared Spectroscopy

This is the first of two papers in which a study is made of a sample of 12 southern radio-luminous Seyfert galaxies. Our aim is to investigate possible correlations between radio morphology and nuclear/circumnuclear emission-line properties. In this paper we present radio images at 13, 6, and 3 cm taken with the Australia Telescope Compact Array (ATCA), global far-infrared (FIR) properties for the whole sample, and optical and near-infrared (NIR) spectroscopy of an interesting subset. We find a mixture of radio morphologies, including linear, diffuse and compact sources. When the FIR colors of the galaxies are considered there is an indication that the compact radio sources have warmer FIR colors than the diffuse sources, whereas the linear sources span a wide range of FIR colors. There is a wide variation in radio spectral-indices, suggesting that free-free absorption is significant in some systems, particularly IRAS 11249-2859, NGC 4507, and NGC 7213. Detailed emission-line studies are presented of 4 galaxies IC 3639, NGC 5135, NGC 3393 & IRAS 11249-2859. In IC 3639 we present evidence of vigorous, compact star formation enclosed by very extended [OI]6300 emission, suggestive of the boundary between a diffuse outflow and the surrounding ISM. In another galaxy, IC 5063, we see evidence for the possible interaction of a highly collimated outflow and the surrounding rotating inner disk. Of the 5 galaxies which show compact radio emission, 4 have radio/FIR flux ratios consistent with an energetically dominant AGN, whereas IC 4995 exhibits evidence for a very compact starburst.Comment: 42 pages, including 7 tables, latex, 19 jpeg figures, Accepted to ApJ. Replacement updates coordintes of galaxies in Table

Conceptual learning : the priority for higher education

The common sense notion of learning as the all-pervasive acquisition of new behaviour and knowledge, made vivid by experience, is an incomplete characterisation, because it assumes that the learning of behaviour and the learning of knowledge are indistinguishable, and that acquisition constitutes learning without reference to transfer. A psychological level of analysis is used to argue that conceptual learning should have priority in higher education

Technology-Rich Ethnography for Examining the Transition to Authentic Problem-Solving in a High School Computer Programming Class

This study utilized elements of technology-rich ethnography to create a rich description of a multi-user virtual environment in a high school computer programming class. Of particular interest was the transition that took place in classroom culture from one characterized by a well-defined problem solving approach to one more indicative of open learning environment. Using technology, high school students created learning activities and resources for use by younger students in the virtual environment. Evidence supported that high school students initially benefitted from the new open environment; however, some immutable elements of the classroom environment presented barriers to peer collaboration and motivation for high-level, creative work. Our findings lend support to the argument that teachers in high school computer programming classes should incorporate the following features in their curricula: open-ended problem solving, real-world clients, group work, student autonomy and ample opportunities for student creative expression.Yeshttps://us.sagepub.com/en-us/nam/manuscript-submission-guideline

Powerful H2_2 Emission and Star Formation on the Interacting Galaxy System Arp 143: Observations with Spitzer and GALEX

We present new mid-infrared ($5 - 35\mu$m) and ultraviolet (1539 -- 2316 \AA) observations of the interacting galaxy system Arp 143 (NGC 2444/2445) from the Spitzer Space Telescope and GALEX. In this system, the central nucleus of NGC 2445 is surrounded by knots of massive star-formation in a ring-like structure. We find unusually strong emission from warm H$_2$ associated with an expanding shock wave between the nucleus and the western knots. At this ridge, the flux ratio between H$_2$ and PAH emission is nearly ten times higher than in the nucleus. Arp 143 is one of the most extreme cases known in that regard. From our multi-wavelength data we derive a narrow age range of the star-forming knots between 2 Myr and 7.5 Myr, suggesting that the ring of knots was formed almost simultaneously in response to the shock wave traced by the H$_2$ emission. However, the knots can be further subdivided in two age groups: those with an age of 2--4 Myr (knots A, C, E, and F), which are associated with $8\mu$m emission from PAHs, and those with an age of 7-8 Myr (knots D and G), which show little or no $8\mu$m emission shells surrounding them. We attribute this finding to an ageing effect of the massive clusters which, after about 6 Myr, no longer excite the PAHs surrounding the knots.Comment: 19 pages, 11 figures, including tables at the end; accepted by Ap

Student interpretations of the terms in first-order ordinary differential equations in modelling contexts

A study of first-year undergraduate students′ interpretational difficulties with first-order ordinary differential equations (ODEs) in modelling contexts was conducted using a diagnostic quiz, exam questions and follow-up interviews. These investigations indicate that when thinking about such ODEs, many students muddle thinking about the function that gives the quantity to be determined and the equation for the quantity's rate of change, and at least some seem unaware of the need for unit consistency in the terms of an ODE. It appears that shifting from amount-type thinking to rates-of-change-type thinking is difficult for many students. Suggestions for pedagogical change based on our results are made

Second chances: Investigating athletes’ experiences of talent transfer

Talent transfer initiatives seek to transfer talented, mature individuals from one sport to another. Unfortunately talent transfer initiatives seem to lack an evidence-based direction and a rigorous exploration of the mechanisms underpinning the approach. The purpose of this exploratory study was to identify the factors which successfully transferring athletes cite as facilitative of talent transfer. In contrast to the anthropometric and performance variables that underpin current talent transfer initiatives, participants identified a range of psychobehavioral and environmental factors as key to successful transfer. We argue that further research into the mechanisms of talent transfer is needed in order to provide a strong evidence base for the methodologies employed in these initiatives