This dissertation concerns the the problem that natural science teachers with limited astronomy backgrounds have to teach new curriculum content about lunar motion, phases and eclipses. My study aims to establish: 60 teachers’ knowledge of lunar phenomena through surveys; whether an intervention incorporating models and activities is effective at improving a case study group’s understandings; how the case study teachers use these activities and models in the classroom. My results indicate that the majority of natural science teachers have little formal astronomy education. Only two teachers held a scientific understanding of lunar phenomena. The intervention led towards a more scientific understanding amongst the case study group. Scale is essential for developing an understanding of lunar phenomena and models are extremely beneficial, but participants experience spatial problems when viewing models from an external perspective. I propose in-service training in small groups for building knowledge and increasing confidence for teaching this content.

Of the billions of stars which compose a galaxy, a few will be members of the so called eclipsing binary star systems. These are systems in which two stars orbit a common center of mass and the orbital plane is oriented along the observer's line of sight. Even though such systems appear as a single point of light, due to the extreme distance from the earth, the structure can be inferred from the observed light variations produced as each star eclipses its companion.The writer constructed the necessary equipment and carried out photoelectric observations of the star system V566 Ophiuchi. A mathematical model was also constructed which produced some approximate dimensions of this system. Three time:; of minimum light were found that indicate that the orbital period has undergone some change during the last few years. The most likely cause for this change is some type of physical interaction between the two stellar components.

The total solar eclipse over the continental United States on August 21, 2017 offered a unique opportunity to study the dependence of the ionospheric density and morphology on incident solar radiation. Unique responses may be witnessed during eclipses, including changes in radio frequency (RF) propagation at high frequency (HF). Such changes in RF propagation were observed by the Super Dual Auroral Radar Network (SuperDARN) radars in Christmas Valley, Oregon and in Fort Hays, Kansas during the 2017 eclipse. At each site, the westward looking radar observed an increase in slant range of the backscattered signal during the eclipse onset followed by a decrease after totality. In order to investigate the underlying processes governing the ionospheric response to the eclipse, we employ the HF propagation toolbox (PHaRLAP), created by Dr. Manuel Cervera, to simulate SuperDARN data for different models of the eclipsed ionosphere. Thus, by invoking different hypotheses and comparing simulated results to SuperDARN measurements, we can study the underlying processes governing the ionosphere and improve our model of the ionospheric responses to an eclipse. This thesis presents three studies using this method: identification of the cause of the increase in slant range observed by SuperDARN during the eclipse; evaluation of different eclipse obscuration models; and quantification of the effect of the neutral wind velocity on the simulated eclipse data. / Master of Science / The ionosphere is the charged layer of the upper atmosphere, which is generated and sustained by sunlight ionizing neutral particles to form a plasma. In the absence of sunlight, ions and electrons can recombine into neutral particles. The total solar eclipse over the continental United States on August 21, 2017 offered a unique opportunity to study the dependence of the ionospheric density and plasma motion on sunlight as the period of the eclipse is much shorter than night. Observations of the ionosphere during past eclipses indicate that unique ionospheric behavior may be witnessed during eclipses, including changes in radio wave propagation for radio waves in the high frequency (HF) regime. Such changes in radio propagation were observed by the Super Dual Auroral Radar Network (SuperDARN) ionospheric HF radars in Christmas Valley, Oregon and in Fort Hays, Kansas during the 2017 eclipse. At each site, the westward looking radar observed an increase in distance that the radio waves traveled before they were reflected back to the radar during the eclipse onset followed by a decrease in this distance after totality. In order to investigate the mechanisms that produce these observed effects, we employed the HF propagation toolbox (PHaRLAP), created by Dr. Manuel Cervera, to simulate radio propagation and generate simulated SuperDARN data for different models of the eclipsed ionosphere. Thus, different models can be tested by comparing simulated data to measured data. Hence, we can study the underlying processes governing the ionosphere and improve our model of the ionospheric responses to an eclipse. This thesis presents three studies using this method to: identify the cause of the increase in the distance radio waves traveled during the eclipse; evaluate different models of change in eclipse magnitude over time; and investigate the effect of the neutral wind velocity on the simulated eclipse data.

HD 3167 is a bright (V = 8.9), nearby KO star observed by the NASA K2 mission (EPIC 220383386), hosting two small, short-period transiting planets. Here we present the results of a multi-site, multi-instrument radial-velocity campaign to characterize the HD 3167 system. The masses of the transiting planets are 5.02 +/- 0.38 M-circle plus for HD 3167 b, a hot super-Earth with a likely rocky composition (rho(b) = 5.6(-1.43)(+2.15) g cm(-3)), and 9.80(-1.24)(+1.30) M-circle plus for HD 3167 c, a warm sub-Neptune with a likely substantial volatile complement (rho(c) = 1.97(-0.59)(+0.94) g cm(-3)). We explore the possibility of atmospheric composition analysis and determine that planet c is amenable to transmission spectroscopy measurements, and planet b is a potential thermal emission target. We detect a third, non-transiting planet, HD 3167 d, with a period of 8.509 +/- 0.045 d (between planets b and c) and a minimum mass of 6.90 +/- 0.71 M-circle plus. We are able to constrain the mutual inclination of planet d with planets b and c: we rule out mutual inclinations below 1.degrees 3 because we do not observe transits of planet d. From 1.degrees 3 to 40 degrees, there are viewing geometries invoking special nodal configurations, which result in planet d not transiting some fraction of the time.

Open clusters have been the focus of several exoplanet surveys, but only a few planets have so far been discovered. The Kepler spacecraft revealed an abundance of small planets around small cool stars, therefore, such cluster members are prime targets for exoplanet transit searches. Kepler's new mission, K2, is targeting several open clusters and star-forming regions around the ecliptic to search for transiting planets around their low-mass constituents. Here, we report the discovery of the first transiting planet in the intermediate-age (800 Myr) Beehive cluster (Praesepe). K2-95 is a faint (Kp = 15.5 mag) M3.0 +/- 0.5 dwarf from K2's Campaign 5 with an effective temperature of 3471 +/- 124 K, approximately solar metallicity and a radius of 0.402 +/- 0.050 R-circle dot. We detected a transiting planet with a radius of 3.47(-0.53)(+0.78)R(circle plus) and an orbital period of 10.134 days. We combined photometry, medium/high-resolution spectroscopy, adaptive optics/speckle imaging, and archival survey images to rule out any false-positive detection scenarios, validate the planet, and further characterize the system. The planet's radius is very unusual as M-dwarf field stars rarely have Neptune-sized transiting planets. The comparatively large radius of K2-95b is consistent with the other recently discovered cluster planets K2-25b (Hyades) and K2-33b (Upper Scorpius), indicating systematic differences in their evolutionary states or formation. These discoveries from K2 provide a snapshot of planet formation and evolution in cluster environments and thus make excellent laboratories to test differences between field-star and cluster planet populations.

The first transiting planetesimal orbiting a white dwarf was recently detected in K2 data of WD 1145+017 and has been followed up intensively. The multiple, long and variable transits suggest the transiting objects are dust clouds, probably produced by a disintegrating asteroid. In addition, the system contains circumstellar gas, evident by broad absorption lines, mostly in the u' band, and a dust disc, indicated by an infrared excess. Here we present the first detection of a change in colour of WD 1145+017 during transits, using simultaneous multiband fast-photometry ULTRACAM measurements over the u'g'r'i' bands. The observations reveal what appears to be 'bluing' during transits; transits are deeper in the redder bands, with a u' - r' colour difference of up to similar to-0.05 mag. We explore various possible explanations for the bluing, including limb darkening or peculiar dust properties. 'Spectral' photometry obtained by integrating over bandpasses in the spectroscopic data in and out of transit, compared to the photometric data, shows that the observed colour difference is most likely the result of reduced circumstellar absorption in the spectrum during transits. This indicates that the transiting objects and the gas share the same line of sight and that the gas covers the white dwarf only partially, as would be expected if the gas, the transiting debris and the dust emitting the infrared excess are part of the same general disc structure (although possibly at different radii). In addition, we present the results of a week-long monitoring campaign of the system using a global network of telescopes.

Les régions d'interface du Soleil de la photosphère à la chromosphère et au delà de la basse couronne ont été étudiées depuis longtemps à partir des spectres éclairs obtenus durant les éclipses totales de Soleil. Les éclipses sont les plus adaptées à ce type d'observation, car l'occultation a lieu en dehors de l'atmosphère terrestre et sont exemptes de lumière parasite provenant du " disque occulteur " (c'est-à-dire la Lune), une propriété de grande importance lorsqu'on observe très près du limbe. La résolution temporelle des premiers spectres éclairs ne permettait pas de résoudre les basses couches de la région de transition et étaient dégradés par des effets non-linéaires qui affectaient les films photographiques. Les images Extrême-UV des régions du limbe obtenues récemment dans l'espace sont analysées avec des modèles hydrostatiques à une dimension, comme les modèles VAL, mais cette méthode ne tient pas compte du phénomène d'émergence du champ magnétique, associé au réseau chromosphérique qui est responsable de: i) les spicules et le milieu interspiculaire, ii) les jets coronaux et macrospicules, et iii) l'ovalisation de la chromosphère. Les composants de la région d'interface sont dynamiques et différents types d'ondes et de reconnexions magnétiques sont supposées agir. Un saut de température de 0.01 à 1 MK est observé autour de 2 Mm d'altitude plus loin, et produit plus loin le flot du vent solaire permanent. Le processus de chauffage responsable du saut de température et la source du vent solaire ne sont pas encore compris. Dans cette thèse, nous traitons ces problèmes à partir de spectres éclairs récents réalisés avec les technologies actuelles de détecteurs CCD rapides, images d'éclipse en lumière blanche et des images EUV obtenues avec des instruments de missions spatiales. Nous illustrons les mécanismes des émissions des raies à faible potentiel de première ionisation (FIP) présents dans les basses couches de l'atmosphère solaire. Nous identifions plus précisément les raies associées aux éléments low FIP à la fois à l'intérieur et en dehors des protubérances. Nous caractérisons en détail les enveloppes d'hélium dans les interfaces. Méthodes: 1) technique des spectres éclairs sans fente avec imagerie CCD rapide (éclipses 2006, 2008, 2009, 2010 et 2012). 2) Analyses des spectres du continu entre la myriade de raies d'émission au delà du limbe solaire et construction de courbes de lumière de quelques raies d'émission low FIP et high FIP. 3) Evaluations d'inversions d'intégrales d'Abel pour déduire des échelles de hauteurs et discussion de variations de température et de densité. 4) Analyse d'images EUV obtenues aux mêmes instants depuis AIA/SDO, SWAP, SOT/Hinode des missions spatiales, images en lumière blanche pour discuter des constituants de la couronne. Principaux résultats: i) Le bord du Soleil et la bifurcation de température : le vrai continu à partir du spectre observé aux altitudes de 400 à 600 km au dessus du limbe dans le contexte de de mesures de diamètre solaire et processus d'émission. ii) raies d'émission visibles dans les régions d'interface comprenant les raies He I et surtout la raie He II Pα visible à partir de 800 km au dessus du limbe, produite par photo-ionisation, montrant des enveloppes autour du Soleil et permettant le sondage de l'interface protubérance-couronne. iii) La contribution de structures de petite taille comme les spicules et macrospicules commençant à 1 Mm au dessus du limbe et montrant que les modèles hydrostatiques stratifiés 1D ne sont pas adaptés pour les couches supérieures. Nous montrons que les raies low FIP sont sur-abondantes dans l'interface photosphère-chromosphère, que la couronne solaire est alimentée en permanence par ces éléments. Le titane est un élément abondant dans le milieu interspiculaire, et une analogie sur les gradients de température entre les interfaces photosphère-chromosphère et protubérance-couronne peut être établie.

Les régions d’interface du Soleil de la photosphère à la chromosphère et au delà de la basse couronne ont été étudiées à partir des spectres éclairs. Les éclipses sont les plus adaptées à ce type d’observation, car l’occultation a lieu en dehors de l’atmosphère terrestre et sont exemptes de lumière parasite. Les images Extrême-UV des régions du limbe obtenues récemment dans l’espace sont analysés avec des modèles hydrostatiques à une dimension, comme les modèles VAL, mais cette méthode ne tient pas compte du phénomène d’émergence du champ magnétique, associé au réseau chromosphérique qui est responsable de: i) les spicules et le milieu interspiculaire, ii) les jets coronaux et macrospicules. Un saut de température de 0.01 à 1 MK est observé autour de 2 Mm d’altitude plus loin, et produit plus loin le flot du vent solaire permanent. Le processus de chauffage responsable du saut de température et la source du vent solaire ne sont pas encore compris. Dans cette thèse, nous traitons ces problèmes à partir de spectres éclairs récents réalisés avec les technologies actuelles de détecteurs CCD rapides, images d’éclipse en lumière blanche et des images EUV obtenues avec des instruments de missions spatiales. Nous illustrons les mécanismes des émissions des raies à faible potentiel de première ionisation (FIP) présents dans les basses couches de l’atmosphère solaire. Nous identifions plus précisément les raies à bas FIP à la fois dans les interfaces, à l’intérieur et en dehors des protubérances. Nous caractérisons en détail les enveloppes d’hélium et la région de l’interface solaire. Nous discutons de l'enrichissement de la couronne en éléments low FIP. / The solar interface region from the photosphere to the chromosphere and to the lower corona has been studied using flash spectra obtained during solar total eclipses. Eclipses are very favourable for this type of observation as the occultation takes place outside the Earth atmosphere and are free of parasitic scattered light. Independently, EUV filtergrams of the limb region obtained in space were analyzed using one dimensional hydrostatic models like the VAL models but this method ignores the ubiquitous magnetic field emergence phenomenon associated with the chromospheric network and responsible for: i) spicules and interspicular regions, ii) coronal jets and macrospicules. The components of the solar interface region are dynamical and different type of waves and magnetic reconnections are suggested to be at work. A jump of temperature from 0.01 to 1 MK is observed near the 2 Mm heights and higher, further producing a permanent solar wind flow. The heating processes responsible for this temperature jump and for the flow are not yet fully understood. In this thesis, we reconsider these problems on the basis of original, superior flash spectra which benefit from present technology such as CCD detectors, white light (W-L) eclipse images and new EUV images obtained with space-borne instruments. We illustrate the mechanisms of low First Ionisation Potential (FIP) emission lines present in the low layers of the solar atmosphere and interfaces. We identify more precisely low FIP lines both inside and nearby prominences. We characterize in detail the He shells and the solar interface region. We discuss the enrichment of low FIP elements in the corona.