Glow sticks: Spectra and color mixing revisited

A previous TPT article discussed using glow sticks to demonstrate color mixing by comparing the spectra of red, green, and blue glow sticks to those of yellow and magenta glow sticks.1 More recently, a paper in the Journal of Chemical Education describes a method to separate glow stick dyes using chromatography with chalk and a solvent of acetone or alcohol.2 This method, while a valuable experience in a chemistry class, requires the glow stick to be opened. Care must be taken by preparers to remove glass shards, and participants are exposed to possible skin irritants. Here we propose a non-destructive, hazard-free method to “separate” the dyes using the RSpec Explorer spectroscope that can be used as a laboratory experiment or a student project

Acceleration of Coronal Mass Ejection Plasma in the Low Corona as Measured by the Citizen CATE Experiment

The citizen Continental-America Telescopic Eclipse (CATE) Experiment was a new type of citizen science experiment designed to capture a time sequence of white-light coronal observations during totality from 17:16 to 18:48 UT on 2017 August 21. Using identical instruments the CATE group imaged the inner corona from 1 to 2.1 RSun with 1 43 pixels at a cadence of 2.1 s. A slow coronal mass ejection (CME) started on the SW limb of the Sun before the total eclipse began. An analysis of CATE data from 17:22 to 17:39 UT maps the spatial distribution of coronal flow velocities from about 1.2 to 2.1 RSun, and shows the CME material accelerates from about 0 to 200 km s−1 across this part of the corona. This CME is observed by LASCO C2 at 3.1–13 RSun with a constant speed of 254 km s−1. The CATE and LASCO observations are not fit by either constant acceleration nor spatially uniform velocity change, and so the CME acceleration mechanism must produce variable acceleration in this region of the corona

Period Analyses of Variable Stars Alpha Orionis and Beta Lyrae

Variable stars change in brightness over regular or semiregular periods of time. Causes of variability include pulsation (changes in size) or the presence of a companion star or planet that eclipses part of the stellar surface. We examine period changes of the bright variable stars Alpha Orionis (Betelgeuse) and Beta Lyrae using data from the American Association of Variable Star Observers (AAVSO). Periods were analyzed by applying Fourier and weighted wavelet z-transforms to the light curves of each star over a 30-year time span. Our analyses showed that both the short and long secondary periods of Betelgeuse changed with time. The long period decreased at a nearly constant rate, and the short period increased in sudden “jumps” before suddenly decreasing. The period of Beta Lyrae had only small variations surrounding the expected period, with the exception of a sudden 3-day decrease which immediately increased back to the expected period again. The AAVSO database contains contributions from amateur and student observers: our ultimate goal is to use an older DSLR to contribute to the AAVSO database of bright variable stars.https://scholarworks.moreheadstate.edu/celebration_posters_2023/1012/thumbnail.jp

Studying solar limb darkening in H-Alpha with a Coronado PST

https://scholarworks.moreheadstate.edu/student_scholarship_posters/1033/thumbnail.jp

Sky Brightness at Zenith During the January 2019 Total Lunar Eclipse

Lunar eclipses occur during the full moon phase when the moon is obscured by Earth’s shadow. During these events, the night sky brightness changes as the full moon rises and then passes first into the penumbral and then the umbral shadow. We acquired sky brightness data at zenith using a Unihedron Sky Quality Meter during the 20–21 January 2019 total lunar eclipse as seen from Morehead, Kentucky. The resulting sky brightness curve shows an obvious signature when the moon enters the umbral (partial) eclipse phases and the total eclipse phase. During the total eclipse phase, the brightness curve is flat and measures 19.1 ± 0.1 mag / arcsec2. The observed brightness at totality is close to typical new moon in January night at our location, which measures 19.3 ± 0.1 mag / arcsec2. The partial eclipse phase is symmetric on either side of totality. The penumbral phase is more difficult to identify in the plot, without comparison to a typical full moon night. There is a clear asymmetry in the curve just before and just after the umbral phase. This asymmetry is probably due to changes in terrestrial atmospheric conditions, such as high altitude clouds

Estimating the size of Earth’s umbral shadow using sky brightness light curves during a lunar eclipse

We present a simple method to estimate the size of Earth’s umbral shadow in a classroom setting. The method uses the published sky brightness curves obtained during a total lunar eclipse and requires only a conceptual understanding of lunar eclipses and simple geometric considerations. It is suitable for use in introductory and upper level astronomy courses

A REGION OF DROSOPHILA SLBP DISTINCT FROM THE HISTONE PRE-MRNA BINDING AND PROCESSING DOMAINS IS ESSENTIAL FOR DEPOSITION OF HISTONE MRNA IN THE OOCYTE

Metazoan histone mRNAs are the only eukaryotic mRNAs that are not polyadenylated. Instead they end in a 3’end Stemloop (SL). Processing of the histones pre-mRNAs is accomplished by an endonucleolytic cleavage after the SL. The stem loop binding protein (SLBP) binds to the SL, and SLBP is a key factor in all steps of the life cycle of histone mRNAs. We are studying the role of SLBP in Drosophila melanogaster in vivo. In Drosophila each histone gene contains a cryptic polyA site after the histone processing site, and when histone pre-mRNA processing is defective histone mRNAs are polyadenylated. Using FLY-CRISPRCas9 we obtained a 11 deletion (SLBP∆11) null mutant and a 30 nucleotide deletion (SLBP∆30) in the N-terminal domain (NTD) of SLBP. The 30nt deletion removed 10aa from the N-terminal domain of SLBP in a region of unknown function distinct from the processing domain. The SLBP∆30 mutant was viable, but females were sterile. They laid eggs, but the eggs didn’t hatch, because they didn’t store histone mRNA in the egg. In Drosophila nurse cells produce large amounts of histone mRNA at the end of oogenesis which is translated and stored in the egg to allow the development of the embryo until zygotic histone gene transcription turns on. The stored histone mRNA is produced in absence of DNA replication. Despite having normal amount of SLBP, the SLBP∆30 mutant expresses small amounts of polyadenylated histone mRNA at all stages. In the ovary histone mRNA expression is normal in the rapidly replicating nurse cells throughout oocyte development but very little histone mRNA is expressed at the end of oogenesis after nurse cell replication is completed. Immunofluorescence data shows that the SLBP∆30 protein is mainly localized in the cytoplasm at this stage, suggesting the deleted region is important for nuclear import of SLBP at the end of oogenesis. The histone locus bodies present at the histone genes are also defective, and do not activate transcription of the histone genes. These results suggest that defective nuclear import of SLBP∆30 may lead to a defect in HLBs and histone gene transcription.Doctor of Philosoph