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Senior Theses

Neil Bassett, 2018

Title: Constraints in Internal Stellar Physics from Lithium in NGC 752

Abstract: Observations taken with the Hydra multi-object spectrograph on the WIYN 3.5m telescope were used to study the lithium abundances of main sequence stars in the open cluster NGC 752. High precision UBVRI photometry from the WIYN 0.9m provided updated 10-color based effective temperatures for all but the brightest cluster members. The Li morphology of the cluster was studied by selecting proper motion and radial velocity cluster members consistent with the single star fiducial main sequence with small sigma(Teff) (<75K).

The results confirm that the Li morphology of the cluster displays several striking departures from the predictions of the standard model of stellar evolution. The highly non-standard Li dip in F dwarfs is observed in NGC 752. A second group of depleted stars at temperatures hotter than the Li dip is also observed. Comparison with the younger clusters Praesepe and the Hyades shows that Li depletion continues during the main sequence, contrary to the predictions of standard theory.

Tyler Jones, 2018

Title: Evaluating the Basic Parameters of the Open Cluster NGC 1817 Using UVBRI HDI Photometry

Abstract: This honors thesis presents the results of a study conducted of the open star cluster NGC 1817 using UVBRI photometry taken with the Half Degree Imager (HDI) at the WIYN 0.9m telescope at Kitt Peak National Observatory. We determined the cluster parameters: reddening, metallicity, distance, and age. Using Color-Color diagrams we calculated a reddening of E(B-V)=0.25 ± 0.01 and a metallicity of [Fe/H]=-0.40 ± 0.10. Using color-magnitude diagrams (CMDs) we calculated a distance of 1485 ± 55 parsecs and an age of 1.21 billion years ± 0.027 billion years (with possible additional systematic errors).

Tasman Payne, 2018

Title: Stellar Populations of Nearby Galaxies: Colors and Radial Trends

Abstract: A survey of 32 nearby low-mass galaxies was processed and analyzed to attempt to find trends in the color and star formation rates indicative of various galaxy formation theories. What was found was that, in general, there were no color trends and the star formation rate radial profiles seemed to be independent of the color gradients.

William Bowman, 2016

Title: Detecting Multiple Populations in Globular Clusters

Abstract: We present g´ and intermediate waveband photometry of the blue CN-band in stars in the globular clusters M3, M13 and M71 taken with the WIYN 0.9-m telescope. CN band strengths are correlated with measured sodium abundances to establish whether the CN band can be used to discriminate multiple stellar populations in globular clusters. This project seeks to develop methods of detecting popula­ tion gradients in integrated cluster light, which can then be applied to globular clusters in other local group galaxies.

Andrew Nine, 2016

Title: A UBVRI Photometric Analysis of Open Cluster NGC 2423

Abstract: This honors thesis presents the results of a precision photometric analysis of the open cluster NGC 2423. The data for this analysis were acquired on the WIYN 0.9-meter telescope at Kitt Peak National Observatory, and were analyzed to determine the parameters of age, metallicity, distance, and reddening. Using the color-color diagrams, we determined the metallicity to be [Fe/H] = -0.19 ± 0.02 and the reddening to be E(B-V) = 0.108 ± 0.005. We then compared the color-magnitude diagrams to the Yale-Yonsei isochrones to determine the cluster age to be 1200 ± 100 Myr and the distance to be 977 ± 37 pc. (There may be additional systematic errors.) The work performed for this study also provides data for use in future photometric and spectroscopic studies.

Timothy Braun, 2015

Title: Detection of an Extended Outflow in NGC 4102

Abstract: We report the detection of an extended galactic outflow in narrowband Hα imaging of NGC 4102, a nearby SABsb spiral galaxy that hosts a low-ionization nuclear emission-line region (LINER) and a circumnuclear HII region. NGC 4102 is a moderate luminosity galaxy (MB = -19.3) in the Ursa Major Cluster. The ionized gas outflow protrudes out to 60" (5 kpc at an adopted distance of 17.4 Mpc) to the northwest of the galactic center and may extend as much as 75" (6.3 kpc). Follow-up integral-field spectroscopic observations reveal split line profiles over the outflow region, indicative of both blue- and red-shifted emission-line components where one spectrum shoes emission-lines split approximately 150 km/s. Based on [NII]/Hα and [SII] flux ratios of this region, the line emission appears to be non-thermal and originating from a low density environment. By supplementing this work with the literature, we hypothesize that this outflow originated from a nascent nuclear starburst region, while any supporting wind from the AGN in the past is ambiguous.

Christian Hayes, 2015

Title: A BVI Photometric Study of the Old Open Cluster Czernik 30

Abstract: We present the first BVI photometry of the old open cluster Czernik 30, a distant cluster, subject to high field contamination. In order to account for the field contamination, we employ a statistical field star subtraction method to clean the produced color-magnitude diagram, clearly revealing the cluster sequence. Applying theoretical isochrones from a number of different models, we determine properties which are consistent between the individual models and with the previous study of this cluster. Our best fit model determines the following properties of Czernik 30: age = 2.8 +/- 0.3 Gyr, [Fe/H] = -0.2 +/- 0.2, (m-M)V = 14.8 +/- 0.1, E(B-V) = 0.24 +/- 0.06, and E(V-I) = 0.36 +/- 0.4. This shows that Czernik 30 is an old sub-solar metallicity cluster located at a galactocentric radius of about Rgc ~ 13.3 kpc. Thus, Czernik 30 provides an interesting target for future observations, given that it is one of a small number of known old open clusters and of clusters in the outer disk of the Galaxy. Additionally, given its location in the Galaxy, Czernik 30 falls around the bend or transition of the metallicity gradient seen in open clusters.

Aaron Monk, 2015

Title: A UBVRI Analysis of Open Cluster NGC 2539

Abstract: This honors thesis presents the results of a high-precision UBVRI photometric study of the open star cluster NGC 2539. Data were acquired on the WIYN 0.9m telescope at Kitt Peak National Observatory and analyzed to determine the star cluster parameters of age, metallicity, reddening, and distance. From color-color diagrams, we determined a reddening of E(B-V) = 0.080 +/- 0.005 and a metallicity of [Fe/H] = +0.03 +/- 0.05. We compared color-magnitude diagrams to Yale-Yonsei isochrones and derived a distance of 1515 +/- 50 parsecs and an age of 580 +/- 15 million years. Additionally, this work has provided a high-precision data set that can be used in future studies.

Daniel Wavle, 2015

Title: A Kinematic Analysis of Nine Low Mass Gas-Rich Galaxies

Abstract: We present results from a kinematic study of the neutral hydrogen in nine dwarf irregular galaxies. Six of the galaxies in the sample exhibit extended hydrogen envelopes, providing a useful tracer of structure out to many disk scale lengths. We combine archival HI data from the Very Large Array with optical data from the WIYN 0.9m telescope to model and decompose the galaxy rotation curves into baryonic and dark matter mass components. No correlation was observed between the size or structure of the dark matter halos and extended hydrogen structure, and we show that all of the dwarfs appear roughly similar in the context of the gravitational potential of dark matter. We therefore provide an analysis of the stability of the gaseous disks using a criterion presented by Toomre (1964) and show that all these dwarf galaxies are stable against star formation throughout their disks, explaining in part the apparent inefficiency of star formation in the hydrogen envelopes.

Patricia Moravec, 2014

Title: Photometry of Star Forming Complexes in the EDGES Survey

Abstract: Studying the stellar structures in the outer disks and faint structures surrounding nearby galaxies is important in understanding the star formation history.  Using GALEX near and far UV observations along with B and R optical images the star formation activity is measured in several GALEX and EDGES overlap galaxies.  The techniques we use to identify and measure the flux of the star forming complexes of M83 and NGC3344 show an increase in NUV-FUV color dispersions at higher radius, allowing us to efficiently identify the complexes and identify radial trends.

Jesse Feddersen, 2013

Title: Spectroscopic Analysis of Hα Dots

Abstract: We present spectroscopic measurements of ~200 faint point sources of emission - called Hα dots - found in narrow-band images taken for the ALFALFA Hα project. Our image analysis catalogs emission-line sources that are not optically associated with the target ALFALFA galaxy. Analyzing spectra of these sources, we find isolated extragalactic HII regions, ultra-low luminosity dwarf galaxies, background (higher redshift) galaxies, and QSOs. We give a summary of the photometric and spectroscopic properties of the full sample of Hα dots discovered to date. We illustrate why these objects are of astrophysical interest. For example, using coarse oxygen abundance measurements of the low luminosity dwarf galaxies, we detect signs of possible flattening of the local Luminosity-Metallicity relation. We also find luminous [O III]-detected star-forming galaxies at z ~ 0.33 with unusually low oxygen abundances.

Catherine Gosmeyer, 2013

Title: Early Evolution of Rotating Star Clusters with Clumpy Initial Conditions

Abstract: Recent spectroscopic observational studies have provided evidence that young massive star clusters can be characterized by a significant amount of internal rotation. Such evidence calls for renewed efforts in the investigation of the role of angular momentum in the formation and early stages of dynamical evolution of star clusters. We performed a survey of N-body simulations to follow the dynamics of the collapse of stellar systems with different initial values of total angular momentum and global virial ratio. We present here the preliminary results of simulations starting from initial conditions characterized by different degrees of departure from spatial homogeneity and approximate solid-body rotation. We describe the dynamical properties of the final equilibrium configurations with particular attention to the effects of internal rotation on the dynamical evolution of the early substructures.

Taylor Tobin, 2013

Title: Transmission Spectroscopy for Extrasolar Planet WASP-3b

Abstract: Slitless spectroscopy of transiting exoplanets has for some time now been shown to yield the transmission spectrum of the planetary atmosphere, as well as other planetary characteristics, such as its radius. However, due to operational considerations, in some cases the target spectrum can be contaminated by flux from nearby objects on the detector. We describe our efforts to remedy this situation by performing transit planet spectroscopy using both aXeSIM simulations and Hubble Space Telescope (HST) observations of a system in which a nearby star contaminated the target. This work is an intermediate step towards devising a technique to obtain transmission spectra for exoplanet systems in more crowded fields - a necessity as technology allows the detection of exoplanets around ever-fainter stars.

Cody Minns, 2012

Title: UBVRI Photometry of the Open Cluster NGC 2420

Abstract: This thesis presents the results of a photometric study of the metal-poor open star cluster NGC 2420. Data were taken on the night of 15-16 February, 2010 using the WIYN 0.9m telescope at Kitt Peak National Observatory. Comparison of color-color plots for the cluster fiducial star sequence to the Hyades yields a reddening of 0.08 +/- 0.008 and a metallicity (Fe/H) of -0.363 +/- 0.025. Comparison of color-magnitude plots to the Yale-Yonsei 2002 isochrones yields a distance modulus of 12.21 +/- 0.06 and an age of 2.14 +/- 0.08 Gyr. These errors are merely statistical and do not account for systematic error.

Elaine Snyder, 2012

Title: Determining the Alpha-Abundances of Red Giants in Open Clusters in the Milky Way

Abstract: This paper presents the analysis of a method of determining the alpha-element abundances of red giants stars located in old open clusters in the Milky Way Galaxy. In this method, [alpha/Fe] is found using a stellar parameters code (Lee et al. 2011) that is a part of the SEGUE Stellar Parameter Pipeline (SSPP). Low resolution spectra of red giant stars is inputted into the code, and values for [Fe/H], log(g), Teff, and [alpha/Fe] are the output for each star. In this paper, these results are compared with the values of [Fe/H], log(g), Teff and [alpha/Fe] for the same stars that were found from an analysis of high resolution spectra and have been published in literature. The method worked well within error for Teff and [Fe/H]. A systematic offset was noticed in the comparison of log(g) values, with the calculated values being 0.5 dex higher and becoming increasingly deviant as the log(g) values from literature decreased. For the alpha-abundance, no correlation was found. A correction to the values of [alpha/Fe] determined by the code was attempted using the offset of log(g) found in the values calculated using the code, however no significant improvement was made. Ultimately, it is unlikely that the SSPP in its present state can be used to accurately determine the abundances of the alpha-elements in metal-rich red giant stars.