Browsing by Author "Cartledge, Stefan"
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ItemFar-ultraviolet dust extinction and molecular hydrogen in the diffuse Milky Way interstellar medium(2023) Putte, Dries Van De; Cartledge, Stefan; Gordon, Karl; Geoffrey, Chiekwero; Roman-Duval, JuliaWe aim to compare variations in the full-UV dust extinction curve (912–3000 Å), with the H I/H2/total H content along diffuse Milky Way sightlines, to investigate possible connections between ISM conditions and dust properties. We combine an existing sample of 75 UV extinction curves based on IUE and FUSE data, with atomic and molecular column densities measured through UV absorption. The H2 column density data are based on existing Lyman–Werner absorption band models from earlier work on the extinction curves. Literature values for the H I column density were compiled, and improved for 23 stars by fitting a Lyα profile to archived spectra. We discover a strong correlation between the H2 column and the far-UV extinction, and the underlying cause is a linear relationship between H2 and the strength of the far-UV rise feature. This extinction does not scale with H I, and the total H column scales best with A(V) instead. The carrier of the far-UV rise therefore coincides with molecular gas, and further connections are shown by comparing the UV extinction features to the molecular fraction. Variations in the gas-to-extinction ratio N (H) A(V) correlate with the UV-to-optical extinction ratio, and we speculate this could be due to coagulation or shattering effects. Based on the H2 temperature, the strongest far-UV rise strengths are found to appear in colder and denser sightlines. ItemInterstellar dust and other stuff: what's it made of?(2012) Cartledge, StefanHave you ever wondered how you came to be? This talk will discuss the details of one small piece of the puzzle: knowing the current composition of the galaxy around us. ItemScanning the auroral skies: the Athabasca University robotic telescope(2019) Cartledge, Stefan; Schofield, Ian; Connors, Martin; Langill, PhilThe Athabasca University Robotic Telescope (AURT) is a moderate aperture (0.36 m) networked robotic telescope that supports teaching and research at Athabasca University, a pioneering and prominent distance learning university in Canada. This paper reviews the establishment and implementation of a robotic, Internet-based astronomical observatory whose development parallels and complements Athabasca University’s auroral observatory. We discuss the unique features and challenges of the northern observing environment, give examples of teaching and research activities underway at AURT, and discuss an investigation into dark sky conditions over the AURT site. ItemSearch for exoplanets: are we alone in the universe?(2013) Cartledge, StefanJoin Dr. Cartledge as he explores our current knowledge of the search for Earth-like planets and life beyond the Solar System.