×
Department Library

2019

Adam Bugg (Senior Thesis, April 2019, Advisor: Eric Hintz )

Abstract

Spectroscopic observations from the Dominion Astrophysical Observatory of the Cepheid X Cyg show that the star underwent a temperature shift and phase transition sometime between 2013 and 2014. As follow-up work, we conducted a photometric campaign to monitor X Cyg and a collection of 40 other Cepheids, measuring their temperature via a set of Ha filters in addition to the Johnson V filter. While phasing observations in the V filter reproduced clear light curves, Ha light curves were far less successful. The greatest hindrance to properly measuring Ha indices was likely poor signal-to-noise in the narrow Ha filter; the 8-inch telescope used may simply be unable to collect enough light. Accumulating more data, however, would likely reduce scatter and tighten up the results.

2018

Seth Clarke (Senior Thesis, December 2018, Advisor: Eric Hintz )

Abstract

Cygnus OB2 is a large OB association that is relatively close to Earth but highly obscured. Its large population of O and B stars almost certainly includes several emission-line objects, making it an ideal testing ground for the standardized Hα photometric system presented by Joner and Hintz (2015), which is similar to the widely used Hβ system pioneered by Crawford in the 1960s. One of the primary benefits of an Hα system is its potential to distinguish between different categories of emission-line objects without requiring time- and resource-intensive spectroscopy. While several previous papers have proposed such a system, none have received widespread use. The research presented in this thesis used the DAOPHOT program to analyze four years of Cygnus OB2 observations that were made with the filter set described by Joner and Hintz (2015), with the intent to identify standard stars and search for emission-line objects in the field. While persistent difficulties calibrating the data have thus far prevented the publication of such a list of standard stars, the benefits that would arise from the development and widespread implementation of an Hα photometric system warrant continued efforts to resolve the issues inhibiting the system’s creation and adoption.

Andy Hernandez (Senior Thesis, April 2018, Advisor: Eric Hintz )

Abstract

Magnitudes of stars are measured from the energy we measure (apparent) and the total energy output over the entire surface of the star (absolute). In this work we find apparent magnitudes for specified wavelengths of the double cluster h and χ Persei. Apparent magnitudes are attained using point spread function photometry, which is utilized in order to help separate closely spaced stars existing in the clusters. Color-color diagrams are shown detailing the physical properties of h and χ Persei. These are done using the Hα index, described herein, with the Hα magnitude. From these diagrams we can recreate a Hertzsprung-Russel diagram with the addition of Be type stars being easily identifiable. A second, unknown group is discussed. An analysis of the Hα index with the Hβ index shows how Hα emission continues beyond Hβ emission for emission type objects. Using this Hα Hβ index plot emission objects are easily identifiable.

2017

Hugh Bates (Senior Thesis, April 2017, Advisor: Eric Hintz )

Abstract

Hα and Hβ indexes are used in astronomy to compare prominent spectral features for celestial objects. By plotting these two particular indexes against each other, astronomers are able to easily differentiate between spectral types of stars. An extensive amount of research has been carried out to create a list of standard stars that appear in a line on the Hα vs Hβ plot. It has long been wondered if different types of objects occupy a different location on such a plot. For example, where do Seyfert galaxies appear on an Hα vs Hβ plot? There is a vast database of spectra from various Seyfert galaxies that can be used to obtain Ha and Hβ indexes. Before expending the time and resources to extract and manipulate these spectra, it is important to test one specific Seyfert galaxy and see if the location of the data on the final plot deems further research in this direction. Data, in the form of spectra, were obtained from the Dominion Astrophysical Observatory (DAO) in Canada for the Seyfert galaxy NGC 4151. This galaxy was studied for 11 nights over the span of two years. This data was reduced and analyzed to obtain the strength of the Hα and Hβ lines for the spectra at varying redshift values (ranging from a redshift of 0 km/s to 3000 km/s). An Hα vs Hβ plot was created for each redshifted spectrum. The results were compared to Ha vs Hβ plots of standard stars, and it was discovered that NGC 4151 occupies a unique location of the plot. Other active galactic nuclei (AGN) may provide information to other regions of this plot, and using this plot may assist astronomers in detecting Seyfert galaxies in a field of observation.

Karrie Beckstead (Senior Thesis, April 2017, Advisor: Eric Hintz )

Abstract

Many different teachers teach the Physics 127 (intro to astronomy) class at Brigham Young University (BYU). Each teacher has their own tests for their own students and these tests between teachers are so different from one another that there has arisen a need for some unity between them all. It was determined to create 10 multiple-choice questions that could be included in all of the tests some time in the future. To do this, research was done on what makes a good test question, then each teacher’s exams were analyzed for similarities and differences, and finally 10 questions were created based on this research.

2016

Joel Bradley (Senior Thesis, April 2016, Advisor: Eric Hintz )

Abstract

The High Mass X-Ray Binary KRL2007B-367 is observed in the Johnson B, V, R, and I filters from 2010 to 2012 and is analyzed in the optical for periodicity. Although there may be some hints of variability, KRL2007B-367 is for the most part stable. An uncatalogued star that is in the same field, referred to as star Fey, shows sporadic changes in magnitude. It is proposed that star Fey could possibly be the correct optical counterpart of the High Mass X-Ray Binary System. This is because star Fey shows much more variability in magnitude, and may show signs of periodicity. These are signs of evidence one would look for in a High Mass X-Ray Binary System. Even if this conclusion is incorrect, star Fey is still an object worth studying in the future since it shows interesting properties.

Rachael Hunter (Senior Thesis, April 2016, Advisor: Eric Hintz )

Abstract

Current variable star research makes corrections for the Earth’s motion, or Heliocentric correction, to improve period accuracy. However, corrections for the star’s radial motion have not been made, until now. We applied a time correction to variable star data to adjust for the radial velocity of the star and improve the period solution accuracy. From this we are investigated the appropriate number of cycles that must be observed before a reliable period can be determined. Using the time corrected data and the changes in the apparent period, for NR Lyr, V839 Cyg, and V894 Cyg, we recovered the actual radial velocity of the stars and produced the most accurate period solutions. These were, -122.224 km/s, -92.1665 km/s, -226.372 km/s, and 0.682314 days, 0.433902 days, 0.571821 days, respectively. We also used a moving source simulation to show a distinct, repeated observed-minus-calculated ( O-C) pattern, and suggested a self-correcting period theory.Our results of this work suggest that radial velocity time corrections should be considered and implemented in variable star research.

2015

Robert Foster (Senior Thesis, December 2015, Advisor: Eric Hintz )

Abstract

An investigation into possible effects from the radial relative velocity of observed objects. RR Lyrae type variable stars are chosen as the subjects of the research. Light curves from three stars, taken from Kepler observations, are examined. Data reveals that there is a measurable effect: a shift of 0.01\% per 33 km/s velocity. The relevance of this, as well as an anomalous measurement, are discussed.

Muxue Liu (Masters Thesis, April 2015, Advisor: Eric Hintz )

Abstract

The Hubble Space Telescope (HST) was originally proposed and funded in the 1970's with a launch planned for the early 1980's. However, the launch finally occurred on April 24, 1990, largely due to the Challenger accident. Once launched in 1990, one of HST's earliest projects was the Key Project. One of the main purposes of the Key Project was to calibrate the distances to nearby galaxies and determine a definitive value of the Hubble constant H0. All secondary distance determination methods were based on the period-luminosity relation of Cepheid variable stars. This thesis examines the Cepheid data from the Key Project by first redetermining the periods of Cepheids in selected galaxies and then applying a time correction to the data. This time correction is to compensate for the effects of the recessional motion of each galaxies, as caused by the finite speed of light. The recovery stage of the project was mostly successful, but revealed concerns with the original data set. This result led to less compelling results for the time-correction stage due to the larger than anticipated errors. A further examination was performed on part of the sample by using a more accurate form of the time input as found in the HST image headers. Overall we conclude that the short observation baseline of the Cepheids, with medium to long periods, is a major deficiency of the Cepheid data from the Key Project with regard to testing for the effects of recessional motion. Future studies on the effects of the time correction need to be done using data with longer time coverage that spans at least 4 pulsational cycles, perferably more than 30 cycles.

2014

Nathaly Young (Senior Thesis, April 2014, Advisor: Eric Hintz )

Abstract

The star BD+53 2262 is an emission line star that has been hypothesized to be a High Mass X-ray Binary system (HMXB). The only time this star has been looked at in the X-ray wavelength, it was below detection levels. The purpose of this thesis is to see if there is any variability in the visible wavelengths to suggest that this is indeed a HMXB system. After 4 years of observation, BD+53 2262 shows a 1/10th decrease in magnitude and some small variations within each observation year. This long-term variation is small but consistent with a super orbital period that the star may be exhibiting.

2012

Heather Patti Jones (Masters Thesis, December 2012, Advisor: Eric Hintz )

Abstract

This study investigated the effectiveness of commonly used instructional methods for teaching the phases of the Moon to fifth and sixth grade students. The instructional methods investigated were the use of diagrams, animations, and models. The effectiveness of each method was tested by measuring students’ understanding of Moon phases with a pre and post-assessment after receiving instruction with a specific method or combination of methods. These methods were then evaluated for their ability to help students learn essential concepts, reinforce relevant vocabulary and discourage misconceptions. Results showed that students had better scores with less prevalence of misconception when they were taught using two methods instead of one. Students taught with only computer animations had significantly lower scores and a higher prevalence of misconceptions when compared to the other methods. This may be due to some design errors in the animation used in this study. Even though students taught with only computer animations had significantly lower scores, students taught with computer animations followed by instruction with diagrams had significantly higher scores. Why this combination of instruction was more effective for student learning is a question that requires further research.

2011

Jessica Lynn Bugno (Masters Thesis, March 2011, Advisor: Eric Hintz )

Abstract

The high mass X-ray binary 4U 2206+54 has been a very controversial system due to variability in spectral data as well as photometric data. We, at Brigham Young University, have been observing this system in multiple filters with several telescopes. This thesis presents our methods of observations, reductions, and results. It also compares what we have been detecting to other groups looking at the same target in different wavelengths. Furthermore, this thesis discusses some of the peculiarities of 4U 2206+54 and possible theories to explain these phenomena. Based on our photometric observations for the past three years, we believe the period of 4U 2206+54 is 25.1 days. Furthermore, spectral data show an unusual double-peaked Hα feature. We believe the primary star BD +53◦2790 is a single star, and that the system is surrounded by a gas and dust shell.

Kelsey Jorgenson (Senior Thesis, April 2011, Advisor: Eric Hintz )

Abstract

In this study I calculated the Hβ index values for a set of δ Scuti variable stars. The Hβindex is commonly used to measure surface temperature of stars as well as the age of stars or clusters. The survey contained known δ Scuti stars located in the northern hemisphere as well as a few additional well-known variable stars. This provided a sample of approximately 190 stars. Observations were made with the 1.2-m and 1.85-m telescopes at the Dominion Astrophysical Observatory. I present 68 previously unpublished Hβ indexes and compare these index values with other common temperature measurements of stars.

2010

Jeremy Schoonmaker (Senior Thesis, April 2010, Advisor: Eric Hintz )

Abstract

This thesis includes the analysis of photometric and spectroscopic observations of the $\delta$ Scuti variables V873 Herculus and V2455 Cygni, and spectroscopic observations only of $\delta$ Scuti. Using the methods of \citet{cra58} , we found H$_{\beta}$ indices for these stars and plotted them versus time. These spectroscopic time-series were then compared to the photometric data and published periods. We first used $\delta$ Scuti (V$_{mag}$ = 4.71) as a bright test star to find if this method would indeed give us the desired variability. After this confirmation, we moved to the dimmer stars V873 Her (V$_{mag}$ = 8.40) and V2455 Cyg (V$_{mag}$ = 8.53).

Miriam Anne West (Masters Thesis, December 2010, Advisor: Eric Hintz )

Abstract

Using the Dominion Astrophysical Observatory’s 1.2-m McKellar Telescope, we have obtained spectra on 81 stars from the Hyades Cluster, the Coma Cluster, and selected Hβ standard stars. These spectra cover from 4500 ˚A to 6900 ˚A which includes both the Hβ and Hα absorption lines. The Hβ absorption line has a long history of being used as a temperature index and more recently, calibration of an Hα index has been established for photometric observations. Through spectrophotometric comparison of temperature indices from the Hα and Hβ absorption lines we find the expected strong correlation between photometric indices based on the strength of these two lines. This result confirms that the Hα index is a strong indicator of temperature.

2009

Debora Merrell (Senior Thesis, August 2009, Advisor: Eric Hintz )

Abstract

In order to complete the Rodriguez et al. (2000) table of Hydrogen (H ) color indices of  Scuti stars, 167  Scutis north of -01 degrees declanation and brighter than 13th magnitude were spectroscopically observed. An improved method of reduction techniques is used on stars all the stars observed with previously unpublished H color indices.The H color indices of 22  Scuti stars are calculated.

2008

McKay Bonham (Senior Thesis, August 2008, Advisor: Eric Hintz )

Abstract

Star J2030.5+4751, also known as star 123 of the LPH catalogue, and star 2202+501, also known in the LPH catalogue as 127, are high-mass X-ray binaries. Late B-type stars that are part of high-mass X-ray binary systems are likely to be variable stars with a long period. We are studying these systems with the intent of identifying them as variable stars and discovering their period. Our studies have been in the form of differential photometry, which attempts to spot variations in these stars’ magnitude by comparing them with stable stars in their frames. We have seen interesting variations in these stars, but not repeating variations that could be used to determine a period. We conclude that more data, gathered on a much more regular schedule, will be required to reach conclusive results about the variability of these targets. We also report a dramatic shift in the magnitude of one of LPH 123’s neighbors, and present it as a candidate for further variable star research.

Tiffany Brown (Senior Thesis, August 2008, Advisor: Eric Hintz )

Abstract

The high-mass x-ray binary system BD+53 2262 (LPH 115) was studied during spring and summer of 2007 and 2008 to determine its orbital period. No period had previously been documented for LPH 115 although it is thought to be a Be/XRay Binary which can have an orbital period from several weeks to years. Twenty nine nights of data were taken at the Orson Pratt Observatory on the 0.4 m David Derrick Telescope while twenty nights of data were obtained from the 0.81 m Tenagra Observatory Telescope. All the data was analyzed using classical differential photometry techniques. There was a slight upward trend for LPH 115 in 2007 while a point of minimum was seen in 2008. Also, only small amplitude short term variability was seen (about 0.05 magnitude amplitude). More data would make period determination for the long term variation possible. Some variation was also seen for comparison star 3 during a few nights in 2008.

Amanda Henderson (Senior Thesis, April 2008, Advisor: Eric Hintz )

Abstract

This thesis presents time-series photometric data on the open star cluster NGC 6882/6885 based on archival observations from 2004. Out of 228 stars selected four variable stars were observed, two previously known, and two previously suspected. Light curves created from reduced frames suggest that SU Vulpeculae is a possible binary system with orbital period of 45 days and its primary star is a pulsator with period of 0.1751 days and amplitude of 0.0019. Previous analysis by Hintz & Rose (2005) suggests that V382 Vulpeculae is a ¯ Cephei star. This analysis gives a period of 0.4249 days and amplitude of 0.0046 for V382 Vulpeculae. Star 2 in this ensemble is identi¯ed as Star 13 in Hintz & Rose (2005) as a possible ± Scuti with a period of 0.0776 days and amplitude of 0.015. This analysis gives a period of 0.0723 days and amplitude of 0.0152. Star 1 in this ensemble is a previously suspected high amplitude pulsator with a period of 0.2029 days and amplitude of 0.2108. This analysis con¯rms the period for Star 1.

Natalie Porter (Senior Thesis, August 2008, Advisor: Eric Hintz )

Abstract

The brightness of the system V577 Ophiuchi varies for two reasons. It is an eclipsing binary system so the brightness changes as the stars pass in front of each other. Also, one of the components is a  Scuti star whose luminosity changes because of the star’s pulsation. We are studying this system to better understand the  Scuti component. We used differential photometry, which compares the magnitude of the variable star with the magnitude of a constant luminosity star. Initial measurements of the period and amplitude of the  Scuti were made by isolating the variation due to pulsation from the variation due to eclipses. The semi-amplitude of the pulsation is 0.022 mag in the V filter and the period is 0.06949 days. Both of these measurements are consistent with previously published results. A more thorough analysis of the data consisted of Fourier transforming the data to find the main frequency and any other frequencies. We found a total of 7 frequencies greater than one, one of which is the double of the main frequency. We also calculated each time of maximum light and compared them to the observed time. The difference between the two appeared to be slightly sinusoidal. Based on these findings, we conclude that the pulsation of the  Scuti does not have significant long term variation, though there are more than just the main frequency present.

Miriam West (Senior Thesis, August 2008, Advisor: Eric Hintz )

Abstract

We report our search for variable stars in the open cluster NGC 1528. There were 40 stars that were included in this study. Through aperture photometry and analysis of light curves, we concluded that our data does not show variability for the chosen ensemble of stars. We are also unable to confirm that the suspected variable Star 21 is a variable star.

2007

Tabitha Christi Buehler (Masters Thesis, September 2007, Advisor: Eric Hintz )

Abstract

To add to the understanding of the structure and evolution of δ Scuti stars, 167 δ Scutis north of -01◦ declination and brighter than 13th magnitude have been observed spectroscopically. A method for calculating rotational velocity values and Hβ color indices for the stars in the data set with no previously published values is developed, using the stars in the data set brighter than 7th magnitude. Rotational velocity values for four stars with previously unknown values and Hβ index values for five stars with previously unknown values are calculated.

Christian Draper (Senior Thesis, August 2007, Advisor: Eric Hintz )

Abstract

This thesis describes a search for variable stars in the open cluster NGC 6940. I gathered the data using the Tenagra II 32-inch telescope with the V lter at an exposure of 15 seconds. There is one possible variable star, though there is not enough information to determine its period or color index. In this thesis, I present the light curve of this star for a period between September and December 2006.

John Gordon (Senior Thesis, April 2007, Advisor: Eric Hintz )

Abstract

A fiber-optic volatile-organic-compound sensor is described, which consists of a modified D-shaped optical fiber and a polydimethylsiloxane layer. A 2 micron polydimethylsiloxane layer is applied to the D-fiber flat to interact with the evanescent field of the fiber’s propagating modes. Absorption of volatile organic compounds into the polydimethylsiloxane layer alters the polymer’s bulk refractive index, which changes the birefringence of the two fiber modes. The resulting shift in polarization phase between the two modes is monitored and associated with volatile organic compound concentrations. The sensor is characterized to concentrations of dichloromethane gas ranging from 40 000 ppm to 160 000 ppm and liquid acetone from 250 000 ppm to 1 000 000 ppm. The change in polarization phase of the sensor responds exponentially to increasing concentration levels of both chemicals.

Kathleen Elizabeth Moncrieff (Masters Thesis, August 2007, Advisor: Eric Hintz )

Abstract

We are developing a new spectrophotometric temperature index based on the Ca II H and K lines. Because these lines are present even in very cool stars and because the Ca II H line is blended with the H line in hot stars, this index should cover a very broad range of spectral types. Our data set consisted of 95 stars with spectral types ranging from O9 to M1. We examined five different indices based on the Ca II H + H and K lines, as well as single-wavelength indices centered on each of the Hδ and Hγ lines, which are in the same region of the spectrum. We compared our new index value with the Hβ index values for the stars in our data set that had published Hβ values. We found that the Ca II K-H index was the best temperature indicator with the widest range in magnitude of the indices we examined.

Charles Phillips (Senior Thesis, April 2007, Advisor: Eric Hintz )

Abstract

New photometric observations for V919 Her ( 2000 = 16h49m31.s98, 2000 = +2602005.5300) and V927 Her ( 2000 = 16h56m17.s998, 2000 = +5007035.8600). Six nights of photometric observations of V919 Her were obtained at the 0.4-m David Derrick Telescope (DDT) of the Orson Pratt Observatory (OPO), the 0.4-m telescope of the West Mountain Observatory (WMO), and the 1.8-m Plaskett telescope of the Dominion Astrophysical Observatory (DAO). Six nights of photometric observations of V927 Her were obtained at the 0.4-m DDT of the OPO, and the 1.8-m Plaskett telescope at DAO. Spectroscopic observations of both stars were made at the 1.2-m and 1.8-m telescopes at DAO. Rolland et al. (2006) recently quoted a period for V919 Her of 0.1037 days. Hintz & Garvin (2000) has published two closely spaced periods of 0.130512 days and 0.124981 days for V927 Her. With very little published about either star, the current data will extend the baseline of both stars, and will allow us to investigate their periods, frequencies, amplitudes, and radial velocities.

Sarah Schuff (Senior Thesis, December 2007, Advisor: Eric Hintz )

Abstract

The open cluster NGC 7092 was observed over the course of 6 nights during the years 2004-2006. Five nights were taken from the 0.4 m David Derrick Telescope of the Orson Pratt Observatory at Brigham Young University in Provo, Utah. One other employed the 0.3 m telescope at West Mountain Observatory on West Mountain, Utah. All frames were taken using B, V, or R ¯lters; data were analyzed in V using standard aperture photometry techniques. Series of short and long exposures were taken for comparison of surface as well as deep-¯eld study. A total of 238 stars were studied and differential photometry techniques applied to determine variability. Of these, 15 are suspected short-period variables and 3 are known.

Jennifer Stanley (Senior Thesis, April 2007, Advisor: Eric Hintz )

Abstract

This thesis is offered as a resource to astronomy students wishing to become more familiar with radio astronomy at Brigham Young University (BYU). A radio telescope array entitled the Very Small Array (VSA) located on the Clyde Building at BYU is the focus of this thesis. Historical uses and descriptions of the VSA and its accompanying equipment, computer programs, and functions are given. Limitations due to the VSA’s size and positioning are discussed with an example using the bright radio source Cygnus A. An image of several bright radio sources produced with Matlab programming is given to demonstrate the ability of the VSA. Possible future research uses of the VSA are discussed.

Nicholas Stanley (Senior Thesis, July 2007, Advisor: Eric Hintz )

Abstract

This thesis discusses observational techniques for period calculations of rotating variable stars. Long term periods were difficult to distinguish through normal photometry methods. Since precise period calculation is needed for most studies of rotating variables, I analyze how we can get better data to get better measurements. The effects of seeing conditions and focus changes were examined.

2006

Patrick Baugh (Senior Thesis, December 2006, Advisor: Eric Hintz )

Abstract

CCDs are a relatively recent invention that has strongly changed astronomy. Previous methods were either logarithmic or incapable of observing multiple stars simultaneously, and always had comparatively low quantum efficiencies (QE). CCDs, despite having many faults, are a linear detection system that utilizes pixels and can thus observe many stars simultaneously, while also having extremely high QEs, ranging from over 60% to over 90% at the peak wavelength, depending on the specific chip. A major problem that does arise from CCDs is that they require calibration images to be taken in order to generate accurate, repeatable data. Perhaps the most difficult of these calibration frames is the flat field. It is not uncommon to not obtain flat fields on a given night due to a variety of reasons. The focus of this thesis was to determine how detrimental it is to use flat fields from other nights. The effect of the time between observation and flat field was also examined.

Berne Broadbent (Senior Thesis, August 2006, Advisor: Eric Hintz )

Abstract

The sparse regions of NGC 3169 and NGC 5385 were observed fro two and four nights, respectively. Observations were made in the V filter using the 0.4-m David Derrick Telescope at Brigham Young University's Orson Pratt Observatory. Light curves were obtained for the five known variables in NGC 2169 and the two recently identified variables in NGC 5385. These light curves were used to verify the currently accepted periods of V1356 Ori and V917 Ori and confirm that V1154 Ori and V916 Ori are actually not variable stars, but stable in brightness. In addition, two new variable stars are identified in each cluster, for which light curves and phase diagrams are presented with suggested periods.

Steve Gray (Honors Thesis, August 2006, Advisor: Eric Hintz )

Abstract

I observed the NGC6866 star cluster, searching for variable stars, for seven nights, spanning a period from july 2005 to May 2006. Observations were taken mostly in the V ¯lter, using the 0.4 meter David Derrick Telescope at the Brigham Young Orson Pratt Observatory, located at the Eyring Science center, and both the 16 and 8-inch telescopes at the West Mountain Onservatory, near Provo, UT. Previous to this research, there were no published accounts of known variable stars in this cluster. 146 stars were observed and several were found to be potential variables.

Michael Benjamin Rose (Masters Thesis, July 2006, Advisor: Eric Hintz )

Abstract

The detection of variable stars in open clusters is an essential component of testing stellar structure and evolution theories. The ability to detect low-amplitude variability among cluster members is directly related to the quality of the photometric results. Point Spread Function (PSF) fitting is the best method available for measuring accurate magnitudes within crowded fields of stars, while high-precision differential photometry is the preferred technique for removing the effects of atmospheric extinction and variable seeing. In the search for new variable stars among hundreds or thousands of stars, the Robust Median Statistic (RoMS) is proven more effective for finding low-amplitude variables than the traditional error curve approach. A reputable computer program called DAOPHOT was used to perform PSF fitting, whereas programs, CLUSTER and RoMS, were created to carry out high-precision differential photometry and calculate the RoMS, respectively, on the open clusters NGC 225, NGC 559, NGC 6811, NGC 6940, NGC 7142, and NGC 7160. Twenty-two new variables and eighty-seven suspected variable stars were discovered, and timeseries data of the new variables are presented.

Ryan Wessel (Senior Thesis, April 2006, Advisor: Eric Hintz )

Abstract

We present light curves for SN 2005cs and SN 2006x and confirm photometrically and spectroscopically that SN 2005cs is a Type II supernova with a maximum brightness of 14.2. We find the distance modulus to M100 to be 35.17 +- 0.42 using the Type Ia SN 2006x. We also present methods for maximizing a relatively small telescope's capability to observe faint objects.

Oliver Woodland (Senior Thesis, April 2006, Advisor: Eric Hintz )

Abstract

We develop an automated variable star search engine named VARFIND and codedin the MATLAB language. Using a least squares method, VARFIND fits an exponentialfunction to an error vs. magnitude diagram for any given star cluster. It thencalculates a robust median statistic for each star and outputs the likely variable starcandidates based on this statistic. The search engine was tested on clusters NGC6882/85, NGC 188, and NGC 6709, which have been previously searched for variablestars. Results indicate that VARFIND is effective in narrowing a search to the likelyvariable candidates, which can then be further analyzed to find variability. VARFINDis especially suited to large clusters.

2005

Tabitha Buehler (Bush) (Senior Thesis, August 2005, Advisor: Eric Hintz )

Abstract

New times of maximum light are reported for the variable stars GW Ursae Majoris, BO Lyncis, and AN Lyncis. The results of period analysis and (O-C) analysis for each star are presented. Standard Fourier decomposition is used to analyze the most recent data for BO Lyncis and to show taht the star is multiperiodic. Results from spectral analysis are presented that suggest that GW Ursae Majoris is not a Population II object as previously believed. The most recent data are phased with data that has been previously taken and analyzed for GW Ursae Majoris and BO Lyncis. The possiblity that AN Lyncis is a binary star system is reported.

Andrew J. Davis (Honors Thesis, July 2005, Advisor: Eric Hintz )

Abstract

Kathleen Moncrieff (Senior Thesis, August 2005, Advisor: Eric Hintz )

Abstract

n/a

2004

Mariya Ivanushkina (Masters Thesis, August 2004, Advisor: Eric Hintz )

Abstract

In this study we monitor eight High Amplitude Delta Scuti (HADS) stars: AD CMi, BS Aqr, CY Aqr, DY Her, DY Peg, EH Lib, XX Cyg, and YZ Boo. This project reports recently secured times of maximum light which were obtained from differential photometry. The new times of maximum light were combined with previously published data to produce O-C plots and to check for any possible period changes. EH Lib and YZ Boo show no change in their behavior. BS Aqr shows an increase in its period, while CY Aqr has shown an abrupt period break. DY Her and DY Peg indicated changes in their periods, but the nature of changes is still inconclusive. Furthermore, DY Peg has been confirmed to be multiperiodic with a primary period of 0.072926194d and a secondary one of 0.056487027d. The ratio of the secondary period to the primary is 0.775. Ad CMi and XX Cyg show possible indications of period changes, but more data are necessary to understand the exact nature of these changes.

Aubrie Anna Maxwell (Masters Thesis, August 2004, Advisor: Eric Hintz )

Abstract

Radial velocity values are missing from most of the δ Scuti variable star catalogue entries (see Rodriquez et. al). To remedy this, new surveys are being done at Brigham Young University to measure the radial velocity for large number of known variable stars. The purpose of this project is to outline a reduction and analysis procedure for Charge Coupled Device (CCD) spectral images of pulsating variable stars. The thesis will also compare three different methods for determine radial velocities form the CCD spectra and then compare these result sot tones obtained using the Radial Velocity Scanner (RVS) at Dominion Astrophysical Observatory (DAO) in Victoria, B.C., Canada. Six stars have been chosen for these tests, three δ Scuti variables (Al Canum Venaticorum, V966 Herculis, and GW Draconis) and three standard stars (β Virginis, β Geminorum α Bootes). To check for accuracy, the radial velocity values for three pulsating variable stars are compared to the values obtained for three radial velocity standard stars. The CCD data were all obtained at DAO using both the 1.8-m and 1.2-m telescopes and a medium dispersion centered near the H_(β )line. The radial velocities were calculated using IRAF’s rvidlines, fxcor and xcsao tasks. The results show that the advantages of the RVS, namely shorter measurements times and on-site radial velocity calculations, cannot be dismissed. The RVS consistency obtains values for the radial velocities that are more precise as those obtained using a CCD and in many cases more accurate. The results from the data obtained suing a CCD show that the standard stars chosen must have spectral types similar to the object stars; otherwise the errors will be too large, and the radial velocities inaccurate. Comparing the three IRAF tasks showed fxcor to be the best choice due to it consistently accurate results, although its errors tend to be larger. Xcsao performs particularly well in analyzing spectra with broadened lines. Rvidlines is the most straightforward to use and produces accurate and precise results. Overall though, fxcor is second in reliability only to the RVS.

Michael Rose (Senior Thesis, April 2004, Advisor: Eric Hintz )

Abstract

Astronomers working at major observatories can generally depend upon consistant or at least slowly-changing conditions during a given night. This isn't necessarily the case at a campus observatory where a variety of influences can affect the seeing conditions and often cause significant changes from one frame to the next. During 'post-photing' reductions we have found that our campus data can be improved by taking into account the full-width at half-maximum (FWHM) of each stellar image. However, it is a cumbersome process to implement when one is working with hundreds of frames per night and as many as 40 stars on a frame. Therefore, we will present a new reduction technique, designed to work within the Image Reducation and Analysis Facility (IRAF), which will take the FWHM into account during the 'photing' process. This technique also allows the user to pick a multiplier of teh FWHM as their aperature for each star. Results will be presented for V1438 Aquilae to show the improvements in its data.

2000

Liberty Rae Schwendiman (Senior Thesis, January 2000, Advisor: Eric Hintz )

Abstract

Liberty Rae Schwendiman (Senior Thesis, June 2000, Advisor: Eric Hintz )

Abstract

1999

Matthew Bodell Garvin (Honors Thesis, November 1999, Advisor: Eric Hintz )

Abstract