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Thumbnail of Ou4: The Giant Squid Nebula
Difficult to capture, this mysterious, squid-shaped interstellar cloud spans nearly three full moons in planet Earth's sky. Discovered in 2011 by French astro-imager Nicolas Outters, the Squid Nebula's bipolar shape is distinguished here by the telltale blue emission from doubly ionized oxygen atoms. Though apparently surrounded by the reddish hydrogen emission region Sh2-129, the true distance and nature of the Squid Nebula have been difficult to determine. Still, one investigation suggests Ou4 really does lie within Sh2-129 some 2,300 light-years away. Consistent with that scenario, the cosmic squid would represent a spectacular outflow of material driven by a triple system of hot, massive stars, cataloged as HR8119, seen near the center of the nebula. If so, this truly giant squid nebula would physically be over 50 light-years across.
Mount Timpanogos with sky above
Temp:  75 °FN2 Boiling:75.9 K
Humidity: 30%H2O Boiling:   368.5 K
Pressure:86 kPaSunrise:6:03 AM
Sunlight:0 W/m²   Sunset:8:59 PM
Image for Dr. Stephens’ Sabbatical to University of Arizona
Dr. Stephens participated in a research project at the University of Arizona focused on studying brown dwarfs using the James Webb Space Telescope (JWST).
Image for Kent Gee Forum: Lessons from Noise, Crackle to Calm
This year’s Karl G. Maeser Distinguished Faculty Lecturer, Kent Gee, delivered his forum address on the science of sound and how he and BYU students have contributed to significant research in the acoustics industry.
Image for Drs. Campbell and Stokes Awarded Top Crystallographic Association Award
In July 2025, Drs. Branton Campbell and Harold Stokes (BYU Emeritus Professor) will receive the Kenneth N. Trueblood Award from the American Crystallographic Association for exceptional achievement in computational crystallography.
Image for New Weather Station
A group of undergraduate students braved the heat and heights of the ESC roof to install a new weather station. The station is up and running, and will hopefully record data for years to come.

Selected Publications

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Peter K. Jensen, Joshua T. Mills, and Micah R. Shepherd

Modern additive manufacturing techniques have enabled an endless number of design possibilities. Naturally, it is important to understand how material properties, including the internal damping, differ for these structures. An experimental procedure has been developed to measure the internal damping of metal beams in the audial range by minimizing the effects of energy dissipation through the supports and acoustic radiation into the surrounding air. Loss factor measurements for steel and stainless steel beams manufactured traditionally are compared to samples constructed by powder bed fusion at varying angles. The results are also compared to Zener’s thermoelasticity model, developed for isotropic Euler beams in flexure. Differences in the internal damping due to the manufacturing technique are identified and their deviation from Zener’s theory is explored.

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G. Apolonio and M. D. Joner (et al.)

Context. Blazars are beamed active galactic nuclei (AGNs) known for their strong multi-wavelength variability on timescales ranging from years down to minutes. Many different models have been proposed to explain this variability.

Aims. We aim to investigate the suitability of the twisting jet model presented in previous works to explain the multi-wavelength behaviour of BL Lacertae, the prototype of one of the blazar classes. According to this model, the jet is inhomogeneous, curved, and twisting, and the long-term variability is due to changes in the Doppler factor due to variations in the orientation of the jet-emitting regions.

Methods. We analysed optical data of the source obtained during monitoring campaigns organised by the Whole Earth Blazar Telescope (WEBT) in 2019–2022, together with radio data from the WEBT and other teams, and γ-ray data from the Fermi satellite. In this period, BL Lacertae underwent an extraordinary activity phase, reaching its historical optical and γ-ray brightness maxima.

Results. The application of the twisting jet model to the source light curves allows us to infer the wiggling motion of the optical, radio, and γ-ray jet-emitting regions. The optical-radio correlation shows that the changes in the radio viewing angle follow those in the optical viewing angle by about 120 days, and it suggests that the jet is composed of plasma filaments, which is in agreement with some radio high-resolution observations of other sources. The γ-ray emitting region is found to be co-spatial with the optical one, and the analysis of the γ-optical correlation is consistent with both the geometric interpretation and a synchrotron self-Compton (SSC) origin of the high-energy photons.

Conclusions. We propose a geometric scenario where the jet is made up of a pair of emitting plasma filaments in a sort of double-helix curved rotating structure, whose wiggling motion produces changes in the Doppler beaming and can thus explain the observed multi-wavelength long-term variability.

 

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A report from the International Union of Crystallography Commission on Magnetic Structures outlining the recommendations for communicating commensurate magnetic structures.

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Devin M. Lewis, Tanner D. Rydalch, and David D. Allred (et al.)

Astronomical instrumentation for measurements in the Far Ultraviolet (FUV, 90−200 nm) have historically considered aluminum (Al) thin film mirrors due to this material high reflectance over this wavelength range. However, the native aluminum oxide layer that forms on Al upon exposure to the atmosphere is strongly absorbing in this wavelength range, requiring that the films be protected with a dielectric that inhibits oxidation. Typically, magnesium fluoride (MgF2) or lithium fluoride (LiF) coatings are used as protective layers, but each has shortcomings. For example, MgF2 has an absorption cutoff at 115 nm that reduces performance below this wavelength, which is a critical part of the FUV spectrum for observational astrophysics. The use of LiF as a protection for Al provides a lower absorption cutoff at 100 nm, but it is hygroscopic and thus susceptible to degradation in humid conditions. Our team at GSFC has developed a new reactive Physical Vapor Deposition (rPVD) process that consists of a fluorination process with XeF2 gas combined with our traditional PVD process. We have found that this new rPVD process produces Al+XeF2+LiF (XeLiF) and Al+XeF2+MgF2 (XeMgF2) mirror coatings with unprecedented reflectance. In addition, the rPVD process seems to produce much more environmentally stable coatings (when compared to the conventional process without the XeF2 fluorination). We report on IR/Vis/UV reflectance of XeLiF and XeMgF2 mirrors. The surface roughness as well as the FUV reflectance measured over a period of 8 months for a XeLiF sample with a relatively thin (≃ 30 nm) Al layer are also reported. We have also been investigating the compatibility of this rPVD coating process for potential efficiency enhancements of Si-based gratings. Since it is known that the XeF2 vapor is a strong Si etchant, we are investigating if the native SiO2 layer on Si is sufficient to protect the groove profile of E-beam-ruled Si gratings from degradation. Preliminary results indicate that the native SiO2 layer is an effective barrier against etching of Si by XeF2.

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Karen A. Della Corte, Dennis Della Corte, and David Camacho (et al.)

Purpose

To examine the associations and substitutions of dietary sugars [extrinsic (free) or intrinsic (non-free)] as well as dietary starch and fiber intakes for indices of body fat and cardiometabolic health.

Methods

Dietary intake was assessed at multiple times using multi-day 24-hour recalls over 18-months for indices of body fat (body fat %, waist circumference, BMI, and weight change) (n = 1066) and at baseline and 12 months for cardiometabolic outcomes (LDL, HDL, HbA1c) (n = 736). Bayesian modeling was applied to analyze the probabilistic impact of dietary carbohydrate components using credible intervals for association and substitution analyses with repeated measures random effects modeling.

Results

A higher starch intake significantly associated with higher body fat %, BMI and waist circumference (WC) (all CrI > 0). Conversely, intrinsic sugar and fiber intakes were significantly linked to lower body fat indices, while free sugar showed no association. A 20 g substitution of free sugars with intrinsic sugars significantly associated with lower body fat (CrI: -4.2; -1.0%), BMI (CrI: -1.8; -0.4) and WC (CrI: -4.2; -1.0 cm), while substituting intrinsic sugars with starch resulted in significantly higher body fat, BMI, WC and weight change. Replacing starch with fiber associated with higher HDL-C (CrI: -0.0; 0.3) and lower LDL-C (CrI: -0.6; 0.1). Replacing free sugars with starch associated with a higher HbA1c level (CrI: 0.0;0.2).

Conclusion

These results underscore the importance of distinguishing between intrinsic versus extrinsic sugars and highlight the potential benefits of increasing intrinsic sugars and fiber while reducing starch for better body fat management and cardiometabolic health.

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S. Hales Swift and Kent L. Gee

Prior work has shown a robust relationship between crackle from high-performance jets and the skewness of the distribution of the first time derivative of the pressure waveform; however, prior efforts have characterized this relationship in terms of a linear relationship between the log of the derivative skewness and the category scaling responses. While the relationship is linear over important portions of its range, the use of a logistic curve fit more fully captures the characteristics of the relationship between log first time derivative skewness and category scaling relationship including implied non-negativity, and saturation. Additionally, time-varying sound quality metrics including loudness and sharpness have shown sensitivity to jet crackle. Accordingly, the subject data of a prior study –in which the “crackliness” of jet sounds was rated– are re-analyzed using the derivative skewness of the pressure waveform and sound quality metric-based variables as potential predictors of a crackling sound quality. After accounting for nonlinear trends in some of the predictor variables, a relationship using the derivative skewness and the standard deviation of the sharpness is able to account for all but 1.1% of the variance in the mean subjective crackle ratings for the waveforms in the prior study.