Keynote Presentations
NASA’s Space Launch System: Big Science on the Big Rocket
By Dr. John Blevins
NASA Space Launch System (SLS) Chief Engineer Dr. John Blevins will discuss SLS—a super-heavy lift launch vehicle that is helping return astronauts to the Moon through NASA’s Artemis campaign. In addition to the success of the Artemis I mission, he will also present SLS’s capabilities for interplanetary science missions, telescope missions, and even a concept interstellar mission.
Image: NASA.
The Precision Frontier of Dark Matter Constraints from Direct Acceleration Measurements
By Dr. Sukanya Chakrabarti
For over a century, our understanding of dark matter has hinged on kinematic estimates derived from static snapshots of stellar positions and velocities. However, these methods are inaccurate for a time-dependent potential, and there are now many lines of observational evidence that show that our Galaxy has had a highly dynamic history. Recent technological advancements now empower us to carry out precision time-series measurements of the acceleration of stars that live within the gravitational potential of our Galaxy. I will discuss our comprehensive observational strategy to directly measure Galactic accelerations. Central to this discussion is our recent analysis of compiled pulsar timing data from which we were able to measure the Galactic acceleration for the first time, and derive fundamental Galactic parameters. Discernible differences in sub-structure exist among popular dark matter models on small scales, presenting testable nuances. I will discuss the potential for measuring dark matter sub-structure in the Milky Way by leveraging the diverse set of techniques we have developed, including pulsar timing, eclipse timing, and extreme-precision radial velocity observations. I will review initial results from our multi-pronged observing campaign, and end by discussing synergies between Galactic dark matter constraints and constraints on theories of gravity.
Image: ESO/S. Brunier, CC BY 4.0, via Wikimedia Commons.
T CrB: Brightest Nova in Generations
By Dr. Brad Schaefer
T Coronae Borealis is a recurrent nova with observed eruptions in the years 1217, 1787, 1866, and 1946, plus a fifth eruption widely expected sometime in the year 2024. This peak will presumably get to V=1.7 (the same as the discovery by Mr. A. S. Kamenchuk in 1946), and be the brightest novae seen since 1946 (for T CrB itself). T CrB displays several unique and mysterious effects in its visual light curve, and it plays into the Grand Challenge Type Ia supernova progenitor problem. To solve these with the 2024 eruption, small telescope photometry and spectroscopy is the way to answer the big questions. For example, if T CrB displays bright [Ne III] lines three weeks after the peak, then the most-prominent single-degenerate models suffer a big failure. And the myriad of visual measures will define the orbital phase for measuring the apparently-huge orbital period change across the nova event. Already, AAVSO spectroscopy has solved the case of the `pre-eruption dip' (as discovered by L. Peltier), with this turning out to be a turning-off of the pre-eruption high state.
Image: AAVSO LCGv2
Contributed Talks
The Power of Combining AAVSO Photometry and High Angular Resolution CHARA Imaging
By Narsireddy Anugu
CHARA Array (Owned by Georgia State University), Mount Wilson Observatory, Los Angeles, California
Co-Authors: Douglas R. Gies, Rachael Roettenbacher, Gail Schaefer, and CHARA collaboration
This study presents high-angular-resolution interferometric images of variable stars, captured using the CHARA Array. By combining these images with AAVSO photometric light curves, we investigate the underlying astrophysical phenomena driving stellar variability. Our analysis of RW Cep during its dimming and re-brightening phases suggests that the Great Dimming was caused by the formation of new dust, similar to the event observed in Betelgeuse. Additionally, we have imaged four red supergiants and one yellow hypergiant, detecting convection cells on their surfaces. These giant convection cells may have played a crucial role in driving the high mass-loss events, such as the Great Dimming observed in these evolved stars. Furthermore, we observed the rotation of these convection cells on the stellar surface of the yellow hypergiant, rho Cas. Overall, our findings demonstrate the power of combining CHARA imaging and AAVSO photometry to investigate a wide range of astrophysical phenomena associated with variable stars.
Rapid and Periodic Spectroscopic Variation of the Hα Line of the Be Shell Star Omicron Andromedae
By Rick Diz
St. Simons Island, Georgia
The variable star omicron Andromedae (o And) is a Be shell star that has been reported to have rapid variations in its spectrum, including the Hα line at λ6562.85Å. This study provides quantitative documentation of that variation and identifies periodic behavior over short time frames. The 332 spectra used in this study, unless otherwise attributed, were obtained by the author, an amateur astronomer using a 203 mm SCT telescope equipped with a 3D-printed spectroscope during the period from August 2023, through January 2024. Analysis of a light curve for o And derived from TESS data yielded a period of 1.56 days in close agreement with that reported in the literature, and a previously unreported period of 0.695 days that fits the data well. Additionally, spectra obtained from the BeSS database established that o And has a recent history of forming circumstellar disks that last about seven years before they dissipate. The current disk began to form about one year prior to the beginning of this study. The spectra of o And revealed continuous rapid changes in the Hα line during the course of individual nights as well as over a longer time frame. Being a shell star, the Hα emission line is complex, consisting of a double peak separated by a central depression. The relationship of the two peaks (wings) is expressed by the V/R ratio. Analysis using CLEANest revealed multiple periods for the variation of the features of the Hα line. The following rapid periods (less than a day) were found: for the central depression a period of 0.683 days, for the V wing a period of 0.49 days, for the R wing a period of 0.66 days, and for the V/R ratio a period of 0.92 days. On a slightly longer timescale, the period for the V wing was found to be 11.92 days and for the V/R ratio it was 12.04 days. The R wing occasionally exhibited a 1.95 day period but often deviated from this. A discussion of possible explanations for this behavior is presented which may be helpful in understanding the variability observed.
Using TESS Data to Discover New Exoplanets Around Binary Stars
By Erika Dunning
Astronomy Department, San Diego State University
About half of the star systems in the Milky Way contain two or more gravitationally bound stars. In spite of the large number of binary systems nearby the Sun, the vast majority of the ~5500 known exoplanets reside in single-star systems. The GAIA survey estimates there are 10 million binary systems closer than 250 pc to the sun. However, there are less than two dozen known exoplanets that orbit both stars in surveyed systems. These planets are known as circumbinary planets (CBPs). NASA’s Transiting Exoplanet Survey Satellite (TESS) is conducting a comprehensive all-sky photometric survey to find planets via the transit method. The transit method applies to exoplanets with a nearly edge-on orbit around its host star (or host binary star) along the observed line of sight. When the planet transits in front of the star it will block part of the light from the star in every orbit. Our project seeks to find signatures of CBPs in the TESS survey by first cataloging systems as eclipsing binaries (EB) as part of team creating a comprehensive catalog of EB systems in TESS data. We selected systems with visually apparent eclipses with clear signal to noise and eclipse period longer than 6 days. So far, we have found one new circumbinary planetary candidate in over 11,000 surveyed systems. We will outline the methods we use and give a review of the results to date.
An Innovative Approach to Eclipse Timing Variations Reveals the New Planet BX Trianguli b
By Mark Eaton
Waterloo Collegiate Astronomy Club, Canada
We present the discovery of a new planet orbiting the BX Trianguli binary star system, identified through the analysis of eclipse timing variations (ETVs). Our research team, consisting of a 17-year-old high school student and his teacher, observed irregularities in the system’s 0.192634-day orbital period, which changes by approximately 8 minutes over a 10.74-year cycle. This behavior strongly suggests the gravitational influence of a third body. After systematically ruling out alternative explanations, such as mass transfer between the stars, orbital precession, and magnetic energy transfer (Applegate mechanism), we concluded that a planet is almost certainly responsible for the observed variations. Based on our analysis, the planet is estimated to have a mass of 7.5 Jupiter masses, an average orbital radius of 4.5 AU, and an orbital eccentricity of 0.4. Our study, combining original observations and historical data, provides compelling evidence in support of the planet hypothesis and enhances our understanding of the dynamics of binary star systems. This discovery also underscores the utility of ETV analysis in detecting exoplanets in such systems.
Engaging Amateur Astronomers with Dark Skies
By Vayujeet Gokhale
Professor of Physics, Truman State University, Kirksville, Missouri
Co-Authors: John Barentine, James Lowenthal, Jessica Heim
We present an overview of the American Astronomical Society’s Committee for the Protection of Astronomy and the Space Environment (COMPASSE). Light pollution has always presented a challenge to both amateur and professional astronomers, but this problem has become increasingly acute with the advent of unshielded outdoor LED lights and the launching of massive groups of satellites by private commercial space companies. In this talk, we outline the efforts currently underway to (re-)engage professional and amateur astronomers in quantifying the effects due to both these causes, as well as in outreach efforts made recently towards engaging the media and policy-makers. Finally, we describe the resources available for amateur astronomers and casual stargazers to contribute towards protecting the night sky, starting with collecting and analyzing original measurements.
Abrupt Pulsation Resumptions in Deneb: An Update
By Joyce Guzik
Los Alamos National Laboratory, Los Alamos, New Mexico
Co-Authors: Brian Kloppenborg, Noel D. Richardson, Jason Jackiewicz, Nancy Morrison, Tom Calderwood, Andrzej Pigulski
Deneb, the prototype alpha Cygni variable, is a bright A2 Ia supergiant that shows irregular variability, presumed to be pulsations, with a 12-day quasi-period. Analyses of radial velocity and photometry data from 1930 to the present (Abt et al. 2023; Guzik et al. 2023, 2024) suggested that 12-day variations begin abruptly at an arbitrary phase, damp out after several cycles, and resume at intervals of around 75 days.
These analyses raised several questions, among them: How precise and regular is the time interval of around 75 days between resumption of the 12-day pulsations? Do these resumptions in fact occur abruptly and at an arbitrary phase?
At the AAVSO 112th Annual Meeting, we discussed photometry and radial velocity data from Richardson et al. (2011), photometry from the American Association of Variable Star Observers database (Kloppenborg, AAVSO, 2023), and photometry by the TESS spacecraft.
For the above-mentioned data sets, either the sampling was too sparse or the time series were too short to answer these questions. However, we have identified additional data and have begun new observing programs. Here we present analysis of an 8.6-year photometric data set from the Solar Mass Ejection Imager (Kloppenborg 2023), BRITE Constellation (Weiss et al. 2014) light curves, radial velocity data extending the end point of the time series of Richardson et al. (2011), radial velocities from Eaton (2020), and new photometry by the AAVSO PEP section. We also discuss results of Cotton et al. (2024) showing a large excursion in Deneb’s polarization just after a pulsation resumption seen in the TESS data. We hope that these studies will answer the questions raised and lead to a better understanding of the origin of the variability and the evolutionary state of Deneb.
References
Abt, H.A., Guzik, J.A., and Jackiewicz, J. 2023, The Abrupt Resumptions of Pulsations in α Cygni (Deneb), PASP 135, 1054, 124201
Cotton, D. V., et al., 2024, Deneb is a large-amplitude polarimetric variable, ApJ Letters 967, L43
Eaton, J.A., 2020, 35,000 Radial Velocities for 348 Stars from the Tennessee State University Automatic Spectroscopic Telescope, JAAVSO 48, 91
Guzik, J.A., Abt, H., Jackiewicz, J., and Kloppenborg, B.K. 2023, Abrupt Periodic Pulsation Resumptions in Deneb, Proceedings of the 112th Annual Meeting of the AAVSO [PDF]
Guzik, J.A., Kloppenborg, B., and Jackiewicz, J. 2024, Deneb and the alpha Cygni Variables, Society for Astronomical Sciences Symposium on Telescope Sciences 2024 proceedings [PDF], eds.J.C. Martin, R.K. Buchheim, R.M. Gill, W. Green, and J. Menke
Guzik et al., 2024, Deneb’s Variability as Viewed by BRITE Constellation and the Solar Mass Ejection Imager, The BRITE Side of Stars, Vienna, Austria, August 2024
Jackson, B.V., et al. 2004, The Solar Mass Ejection Imager (SMEI) Mission, Sol. Phys. 225, 177
Kloppenborg, B.K. 2023, Observations from the AAVSO International Database, https://www.aavso.org
Richardson, N.D., Morrison, N.D., Kryukova, E.E., and Adelman, S.J. 2011, A five-year spectroscopic and photometric campaign on the prototypical alpha Cygni variable and A-type supergiant star Deneb, AJ 141, 17
Weiss, W., et al. 2014, BRITE-Constellation: Nanosatellites for Precision Photometry of Bright Stars, PASP 126, 573
Possible Wavelength Dependence in Times of Maximum Light for Pulsating Variable Stars
By Mike Joner
Physics and Astronomy, Brigham Young University, Provo, Utah
Co-Authors: Peter Jensen, Oliver Hancock, Michael Holland, Tyler Jensen, and Denzil
Watts
The analysis of O-C diagrams often includes a mix of data from many sources with observations secured using a wide variety of different filters and instrumental systems. While many observations are made using a standard V filter, it is common to see these results mixed with observations obtained through other Johnson/Cousins, Sloan, Stromgren, and in some cases simply a blocking, clear, or no filter at all. There are many archival observations where the magnitudes observed are dependent on responses of various photographic emulsions. In this investigation, we examine the possible dependency of maximum light determinations with wavelength and check to see if this is a possible source of error in O-C analysis.
Rather than searching for a wavelength dependency through theoretical modeling, we have chosen to compare times of maximum light rigorously determined from BVRI observations secured using a single instrumental system. We use this empirical approach to compare times of maximum light observed through each of these filters for three pulsating variable stars with periods less than 200 minutes. We present results from observations of V2455 Cygni, DY Pegasi, and XX Cygni obtained at the Brigham Young University West Mountain Observatory by undergraduate student observers during 2024.
We acknowledge the Brigham Young University Department of Physics and Astronomy for continued support of the research facilities at the West Mountain Observatory. We also thank the College of Computational, Mathematical, and Physical Sciences for continued funding of undergraduate research experiences.
NASA’s Imaging X-Ray Polarimetry Explorer (IXPE)
By Philip Kaaret
NASA Marshall Space Flight Center
IXPE is NASA’s first mission to study the polarization of X-rays from celestial objects. IXPE investigates some of the most extreme objects in the universe including black holes and their jets, supernova remnants, and neutron stars. I will describe the IXPE mission and some of the scientific advances it has made since launch in late 2021. I will highlight how some IXPE observations are enhanced by contemporaneous optical polarimetry and how AAVSO members could contribute.
Transient Stars in Cosmic Microwave Background Surveys
By Tom Maccarone
Physics & Astronomy, Texas Tech University, Lubbock, Texas
Co-Author: Gil Holder
The cosmic microwave background is spatially extremely smooth and varies only on timescales of billions of years. However, in recent years, attempts to measure the small angular scale spatial variations of the microwave background have led to large numbers of repeated measurements of the same parts of the sky with reasonably good sensitivity and angular resolution. In the process of making these measurements, transient sources have been discovered, mostly from flares of red dwarf stars and tidally locked binary stars. In a few cases, TESS has fortuitously been looking at the locations of these objects, and, in some cases, they have shown optical flares of brightnesses easily achievable with telescopes under half a meter in size, while, in other cases, no flaring was seen. Some of these objects have shown relatively frequent flares, making them ideal targets for pointed observations that can provide more information and help produce unique data sets to understand the most extreme magnetically powered flares in stars. Because these flares are often faster than the cadences of sky surveys like ASAS-SN, often occur when TESS isn’t looking, and are best observed in filters like U band and H-alpha, which are not part of current sky surveys, they represent an ideal niche for AAVSO members with access to the Southern Sky to participate in cutting edge science.
References
S. Guns et al., 2021 ApJ 916, 98
C. Tandoi et al., 2024 ApJ 972, 6
Empowering African Youth in Astronomy: The Impact of Pan-African Citizen Science e-Lab
By Miracle Marcel
Pan-African Citizen Science e-Lab, Enugu, Nigeria
Co-Authors: All PACS e-Lab’s contributors mentioned in the paper
In Africa, many, especially young people from various nationalities, aspire to engage in space science and astronomy, yet opportunities are limited. I was one of these eager individuals. After earning my degree in physics and astronomy in Nigeria, I sought advanced projects in the global North, particularly in citizen science. In December 2020, I founded the Pan-African Citizen Science e-Lab (PACS e-Lab), an online platform that brings these projects to Africans in the global South.
Our initiatives include:
- Asteroid Hunting: Participants search for new asteroids using data from telescopes like Pan-STARRS and the Catalina Sky Survey, in collaboration with the International Astronomical Search Collaboration (IASC). PACS e-Lab is IASC’s largest African partner, with over 30 provisional discoveries since 2020.
- Exoplanet Research: We observe exoplanets discovered by missions like TESS and Kepler to refine their Mid Transit Time, aiding future missions. PACS e-Lab is the largest African collaborator with NASA’s Exoplanet Watch, training participants in star observation, photometry, and data reporting.
- Astronomy Research Writing: Participants conduct research on celestial objects, using data from the Las Cumbres Observatory. They are trained in data processing and research paper writing for publication.
- Astro Photo Visual Development: This program teaches amateur astronomers to process deep space images using data from telescopes like Hubble and James Webb, utilizing software like Photoshop and GIMP.
In just three years, PACS e-Lab has reached over 40 African countries, with plans to expand across the continent. Attending the AAVSO’s 113th Annual Meeting will allow me to showcase our work and its impact on African astronomy education, contributing to the Sustainable Development Goals, while also fostering valuable networks for further outreach.
Acknowledgment: Miracle Chibuzor Marcel, Founder & Director of PACS e-Lab, acknowledges support from ATLAR Innovation in Portugal.
A More Precise Measurement of the Rate of Change of the Period of δ Scuti Variable DY Her
By Abigale Moen
Department of Physics and Astronomy, Minnesota State University, Moorhead, Minnesota
Co-Author: Dr. Matthew Craig
This study continues the period change observations of the high amplitude δ Scuti variable star, DY Her, from last year. DY Her has a period of .1486309 days and has been observed to have a slow overall period change from data gathered over several decades. Historical O-C data on DY Her has been obtained and analyzed alongside recent O-C observations using light curve data from the Paul P. Feder Observatory and observations of DY Her obtained from AAVSO from the past 21 years. This year, an additional year of AAVSO observations and one additional night of data from the Feder Observatory were added to the dataset, and the historical data were incorporated into our fits. Analysis of the O-C curve returned a period rate of change (1/P)*(dP/dt) of (–3.12±0.09) x 10-8 yr-1, which is consistent with, but more precise than, the recent values reported in the literature in Derekas et al. (2009), –2.9 x 10-8 yr-1, and in Derekas et al. (2003), (–2.8±0.4) x 10-8 yr-1.
Comparative Analysis of Variable Stars from the Kepler Space Telescope and the Oukaimeden Observatory and TESS
By Amrar Mohamed
Co-Authors: Fes Boulemane, Abdelmajid Benhida, Katrien Kalonberg, Youssef el Jarir,
Zouhair Benkhaldoun, Sefyani Fouad, Khadija Chafaoui
Abstract pending.
Asteroseismic Analysis of GD358 and other White Dwarfs
By Nova Moore
Los Alamos National Laboratory, Los Alamos, New Mexico
Co-Authors: Paul Bradley, Aaron LaCluzye
We used the 0.4-meter reflecting telescope at the Brooks Astronomical Observatory of Central Michigan University to collect time-series photometry of the pulsating helium atmosphere white dwarf GD 358 and other white dwarfs as candidates for pulsation. Our goal was to assess whether such a facility is useful for detecting pulsations in and performing asteroseismology of pulsating white dwarfs. We easily detected pulsations in GD 358 and ascertained the time dependent behavior of several of the higher amplitude modes. We find evidence of pulsations in the stars PHL 970 and SDSS J112304.64+070346.1 and no evidence of pulsations (above the noise level) in the stars GD 93, KUV 07540+4015, KUV 09538+3405, LP 207-7, LP 313-16, FBS 0808+435, CBS 92, and HZ 10.
Analysis of RR Lyrae Stars in the Globular Cluster NGC 3201
By Nicholas Peh
Stanford Online High School, Kuala Lumpur, Malaysia
Co-Authors: Maiya Qiu, Eden Li, Kalee Tock
We selected the RR Lyrae stars V6, V26, V51, and V66 in the globular cluster NGC 3201 for analysis in B, V, rp, and ip filters. These four stars are Blazhko candidates due to their modulating period or amplitude. We found evidence supporting the Blazhko candidacy of V6, V51, and V66 by comparing past literature and archival data with our images. V26 does not appear to have modulating periods between studies from 2002, 2003, and 2021 to 2024. Light curves were fitted using point spread function photometry (psx), which was found to produce significantly cleaner light curves compared to those created by source extractor photometry. We have updated periods for V66 from 0.6675 days in 2021 to 0.6667 days in 2024. We also present the amplitudes of the target stars and situate them in their stellar environments using a Color Magnitude Diagram (CMD) of the NGC 3201 cluster. Isochrone fits used the software Astromancer, whose metallicity output was converted from [M/H] to [Fe/H] for comparison with past literature. The resulting metallicity was lower than expected and implies that the cluster is straddling the cutoff between Oosterhoff dichotomy Type I and Type II.
Long Secondary Periods in Red Giants: AAVSO Observations and the Eclipse Hypothesis
By John Percy
Department of Astronomy & Astrophysics, and Dunlap Institute University of Toronto, Toronto, Ontario, Canada
Co-Author: Melanie Szpigiel
Red giant stars are unstable to low-order pulsation modes. At least a third of them also show a “long secondary period” (LSP), 5 to 10 times longer than the pulsation period, depending on whether the pulsation is in the fundamental mode or the first overtone. The cause of the LSPs was unknown for almost a century. Recently, Soszyński et al. (2021) have presented strong evidence that they are due to eclipses of the red giant by dust-enshrouded companions, perhaps with dust tails and/or circumstellar discs, which were originally planets, but which have subsequently accreted gas and dust from the star and become brown dwarfs or low-mass stars. In the present paper, we have used the unique decades-long AAVSO database of visual and photoelectric observations, and a sample of 11 stars with dense, sustained coverage to study two aspects of this eclipse model: (1) the relationship between the eclipse light curve or phase curve and the eclipse geometry, and (2) the long-term changes in the eclipses over the many decades of the observations.
First, we use careful light curve and phase curve analysis (using the routine within VSTAR) to study and describe the shapes of the light and phase curves. For instance: we find, among other results that the stars with the larger-amplitude LSPs (such as Y Lyn) show a faster eclipse ingress and a slower eclipse egress, consistent with an eclipse model in which the companion has a dusty “tail”.
Second: to study the long-term changes, we inspect the long-term light curves; we use the wavelet routine within VSTAR to track the amplitude; and we separately analyze sub-sections of the data. Because the pulsational variability is a form of “noise” when studying the LSPs, it can also be helpful to average the observations in bins equal to the pulsation period. We find, among other things that the LSP amplitude changes by typically a factor of 5 on a time scale of tens of thousands of days (i.e., tens of orbits), indicating that the dust forms and disperses on that time scale. At times, the amplitude decreases almost to zero, indicating that the companion must be small and that the dust can disperse almost completely.
Acknowledgements: We thank the AAVSO observers for making the observations over many decades, and the AAVSO staff for making them publicly available. This project would not have been possible without that data. We also thank the AAVSO for creating VSTAR and making it available. This project was financially supported by the University of Toronto Work-Study Program and by the Dunlap Institute.
Wideband Photometry of the Semi-Regular Variable Star RZ Arietis
By Richard Willis Schmude Jr.
Gordon State College, Barnesville, Georgia
Co-Author: Qasim Ahmed
RZ Ari is a bright, pulsating red giant star with a spectral class of M6 III. It is classified as a semiregular variable. Reported periods of brightness change range from 37.7 days to 56.5 days (Percy et al. 2008, PASP 12, p. 523) and 49.9 and 45.8 days (Tabur et al., 2009, MNRAS 400). This range of periods makes this an interesting star to study. During the past year, brightness measurements of RZ Ari were made using a single-channel SSP-5 photometer manufactured by Optec, Inc. and an 8-cm refracting telescope. All measurements were made near or within Barnesville GA at an altitude near 260 m. To gain a better understanding of the context of our observations, results from the AAVSO database were examined. This database contains over 900 V-filter brightness observations of RZ Ari made between 1983 and 2024. The mean color-corrected V-filter brightness based on our 49 measurements (Nov. 2023 to Sept. 2024) is magnitude 5.9, whereas the corresponding mean for the AAVSO database is magnitude 5.8. The difference is evidence that RZ Ari may undergo long-term brightness changes over a period of years or decades. In fact, one new study of this star’s magnetic environment is consistent with a rotational period between 530 and 704 days (Konstantinova-Antova et al., 2023, A & A, 681, A36). The mean V – R value (in magnitudes) varies as V – R = 0.20 V + 0.04. This is based on measurements in the AAVSO database made between 2016 and 2024. One of the authors (R. Schmude, Jr.) also searched the AAVSO database for well-measured periods of this star. Measurements were analyzed for each apparition from 1983 to 2024. (An apparition for RZ Ari starts in July and lasts for the next nine months.). There are many gaps in the data, which prevent us from measuring most of the periods between 1983 and 2023. Nevertheless, twelve periods were measured using the AAVSO data, and two more were measured using data taken by the author and his students. The mean period for RZ Ari based on these 14 measurements is 57 days with a standard deviation of 10 days. Periods ranged from 45 to 76 days. Our results are consistent with the previously reported periods; however, the data shows that the period may fluctuate from one cycle to the next. Evidence for this will be presented. Longer periods (over a year) should also be examined as we learn more about the rotational period and magnetic environment of this star.
Independent Discoveries by Two British Amateur Astronomers of the 1946 Eruption of T CrB
By Jeremy Shears
British Astronomical Association Variable Star Section, Chester, United Kingdom
Amateur astronomers were the first to detect the last two eruptions of the recurrent nova, T CrB: John Birmingham, in Ireland, in 1866; A.S. Kamenchuk, in the Soviet Far East, and H.F. N. Knight, in England, in 1946. In the days following the 1946 eruption, reports appeared in the British press of a further independent discovery a few hours before Frank Knight’s. The discoverer in this case was a 15-year-old schoolboy, Michael Woodman, observing in Wales. This talk examines the circumstances surrounding Knight’s and Woodman’s discoveries, based on correspondence between Knight and W.M. Lindley, then Director of the British Astronomical Association Variable Star Section, contemporary reports and the recollections of Michael Woodman.
Astrometric Measurements of Binary Star Systems using Speckle Interferometry
By Dinesh Shetty
Ferris State University, Physical Sciences Department, Big Rapids, Michigan
Co-Authors: Francisco Vasquez, Pat Boyce, Grady Boyce, and Mark Harris
Astrometric measurements of the physical systems WDS 14153+0308, WDS 18031-0811, WDS 18540+3723, WDS 20182+2912, 20210+4437, and WDS 2155+1053 were performed using speckle interferometry. The measurements were done using the 17" Boyce Astro Research Observatory’s Plane Wave CDK telescope. The orbital plots and the elements for many of these systems were published in the Washington Double Star catalog [1] about two decades ago. The measurements yielded a mean separation distance and mean separation angle of, 1.136″ ± 0.008″ and 28.288° ± 0.147°, respectively, for WDS 2155+1053, and a mean separation distance and angle of, 0.930"± 0.003" and 28.92° ± 0.21°, for WDS 20210+4437. The measurement for WDS 2155+1053 agrees well with the published sixth orbital catalog. Other systems show minor changes in their published orbit. However, the measurement for WDS 20210+4437 shows a significant departure indicating a refinement of the current orbital solution.
[1] Washington Double Star Catalog (2023), United States Naval Observatory.
Detecting Errors in Submitted Observations
By Mark Spearman
Factory Physics, Inc., Texas
The integrity of AAVSO photometric data is of utmost importance in order to provide useful information to researchers. However, with the rise of automated systems, there appears to be an increase in the dissimilation of bad data. Moreover, the means of detecting erroneous data and either correcting them or removing them is not straightforward.
The purpose of this talk is to provide an indication of the magnitude of the problem and to offer means of automatically highlighting outliers that could be erroneous.
Posters
A Study of the High Amplitude Delta Scuti Star BP Peg
By Amelia Abst
Co-Authors: R. M. Blake, M. Guth, H. Wildharber
As part of a program to monitor high amplitude Delta Scuti stars, (HADS), we obtained times of maximum light for the HADS BP Peg over three observing seasons. Wong et al (2014) modeled BP Peg as a binary star with a period. Using data from the AAVSO archive and new observations obtained with the UNA observatory we measure new times of maximum light and use the binary ephemeris to determine if the O-C values match that of the model. We conclude that the binary model is able to account for the O-C values. We suggest that spectroscopic observations begin to allow an improved orbital determination.
A Tool to Predict Binary Eclipses Observable from Your Location
By Gabriel Grant
Physics Department, Minnesota State University, Moorhead, Minnesota
Co-Author: Dr. Matthew Craig
We had an initial, open-ended goal of observing eclipsing binary star systems. The AAVSO Target Tool was challenging to use for choosing targets. The target tool did not consider whether an eclipse was observable on a particular night or at our location; it simply lists stars that are visible.
We wrote an open-source program in Python to do this calculation and will also make this available as a web app. We generate predictions for the eclipsing binary stars listed in the Otero+ spreadsheet using period and eclipse duration looked up from VSX. The tool uses the observer location and observer-specified constraints on elevation and sky darkness to generate a list of upcoming full or partial transits observable from their location.
An observation of object V2480 Cyg was taken with the Paul P. Feder Observatory using the times that were calculated from the program. The observed time was roughly a couple hours off the prediction. This could be a result of either the period or the epoch reported in VSX being incorrect, or both. Fortunately, there was TESS data that we used to compare the period times. The periods between TESS and VSX agree only to the first three decimal places. We will present an updated ephemeris in our poster.
Improved Variability Data for the Brightest Solar-type Stars with TESS
By Lauren Herrington
Department of Earth, Atmospheric and Planetary Sciences, Massachusetts Institute of Technology
Co-Author: Sara Seager
Magnetic features rotating across the surface of a star cause low-amplitude photometric variations on timescales of days to weeks, enabling direct measurement of a star’s rotation period. These variations typically measure much less than 0.1 magnitudes in amplitude, making them difficult to detect from the ground; but with the improved precision offered by the Transiting Exoplanet Survey Satellite (TESS), rotational modulation can be observed in hundreds of bright stars. However, TESS’ systematics interfere with automated methods of detecting variability, causing spurious detections and erroneous periods[1]. Therefore, we used direct visual examination to characterize the TESS light curves of 1,099 of the brightest G and K stars, searching for signs of rotation. The resulting catalog has a very low false positive rate, and contains estimated periods, photometric amplitudes, and assorted variability data for over 350 stars. Most of the stars which we found to be variable are dominated by rotational variation, but a subset display other types of variability, such as binary ellipsoidal variation or flares. This data is being assessed for incorporation in VSX, and will be used to inform target selection for the Copernicus Constellation, a proposed satellite constellation designed to discover Earth-like exoplanets transiting nearby Sun-like stars. Copernicus’ critical Phase 1 mission relies on targeting only the fastest-rotating stars, in order to resolve asteroseismic mode splits and identify stars with inclinations favorable to exoplanetary transits. The rotation periods obtained in this study will allow us to optimize Copernicus’ asteroseismic search, extending the amount of mission time available for the Phase 2 transit search.[2]
[1] Douglas, S. T., Agüeros, M. A., Covey, K. R., & Kraus, A. (2017). Poking the beehive from space: K2 rotation periods for Praesepe. The Astrophysical Journal, 842(2), 83.
[2] Herrington, L., & Seager, S. (2024). Rotation Rates of Bright Solar-type Stars with TESS. TESS Science Conference 3 (TSC3), Massachusetts Institute of Technology,
Cambridge, MA, USA. Zenodo.
Spectroscopic Changes of Pleione
By Caleb Kettering
University of North Alabama
Co-Author: R. M. Blake
The Be star Pleione is known to undergo short and long-term changes in its spectrum. Using the Be Star Database we have measured the equivalent widths and B/R ratios of Pleione for the 2022/2023 observing season. We see changes in the H-alpha equivalent width, with a period of increase in line strength followed by a decrease. Accompanying this is a change in the B/R ratio, where the red portion of the H-alpha spectrum changes from being the stronger component to the weaker. Such changes have been reported previously. In between these rapid changes is a slow decrease in H-alpha equivalent width. The rapid changes seem to be superimposed on a long-term decrease in H-alpha emission. We plan to study the hydrogen line ratios and brightness variations of Pleione.
Sunspottery: A Century of Supposed Solar Effects on Human Behavior in the Popular Imagination, 1878-1978
By Dr. Kristine Larsen
Earth and Space Sciences, Central Connecticut State University, New Britain, Connecticut
In 1883, J.A.W. Oliver’s Sunspottery critically evaluated myriad claims concerning the sun’s influence on our planet. He recounts a public lecture in which an explanation of English economist (William) Stanley Jevons’ 1878 paper “Commercial Crises and Sun-spots” was met with laughter by the audience. While Oliver, Richard Proctor and others debunked claimed connections between economics and sunspots in the 1880s, nearly a century later some economists continued to raise the specter of a possible correlation. Similarly, Russian scientist Alexander L. Tchijevsky aligned sunspot records with significant events in human history, including wars, revolutions, and riots, and claimed that the majority occurred near the time of solar maximum. His claims were brought to an American audience through a talk delivered in his stead at the 1926 annual meeting of the American Meteorological Society. Tchijevsky’s work can be identified in several works of science fiction/horror. Newspaper reporter Mike Hamilton notes a disturbing pattern of suicides and violent murders in Clifford D. Simak’s “Sunspot Purge” (1940). We also see echoes of Tchijevsky’s claims in Robert Heinlein’s The Year of the Jackpot (1952) and the 1975 Italian film Macchie Solari (Sunspots, dir. Armando Crispino). Given the current public interest in the solar cycle, fueled in part by the May 2024 auroral outbreaks, as well as the persistence of erroneous fear-mongering surrounding the “Carrington Event”, a close analysis of the connection between science, pseudoscience, and popular media in fueling persistent myths surrounding a solar activity/human behavior connection is timely.
References
Giegengack, R. 2015, Proc. Amer. Phil. Soc. 159, 421.
Jevons, W.S. 1878, Nature 19, 33.
Montgomery, P.M. 2003, Universal Economics Newsletter, 18 Jul., 1.
Oliver, J.A.W. 1883, Sunspottery: Or, What Do We Owe to the Sun?, Simpkin, Marshall and Co.
Proctor, R.A. 1880, Scribner’s Monthly, 20.2, 170.
Tchijevsky, A.L. 1971, Cycles, 21.".
Candidate Exoplanet Observations
By Jacob Mailhot
MSUM Physics, Moorhead, Minnesota
Co-Authors: Hannah Crumby, Dr. Matthew Craig
We report five observations of transits candidate exoplanets identified through the tool available to members of the TESS Follow-up Observers Program SG01. In three of the observations, we observed partial or full transits. In each case, we calculated relative flux of the exoplanet candidate using stellar plot and EXOTIC. Both were used to confirm that we had seen a transit and to check parameters of the transit for consistency. We reported one of the transits to the TESS project.
Astronomical Photometric Analysis with Cell Phone Cameras
By Anusha Mehta
Department of Physics and Meteorology, United States Air Force Academy
Co-Author: Lt. Col. Benjamin Roth
We present a hands-on approach to teaching basic photometry, one of the foundational aspects of observational astronomy, using only a smartphone camera and open-source software. By manipulating the basic magnitude equation, solving for the calibration constant, and using images to determine this constant, students gain an appreciation for working with astronomical data. The lab provides guidance on the use of SAOImageDS9 software, accessing and analyzing open star catalogs, plate solving an astronomical image captured by the student, and the application of aperture photometry. Students calculate the apparent magnitudes of stars, a measure of their brightness, achieving an uncertainty of less than ten percent. This methodology bridges the gap between theoretical concepts and practical applications, demonstrating the use of open-source and easily available technology in astronomical observations. We report this method as a more accessible and practical approach to learning astronomical photometry for those new to astronomy.
PA Number: USAFA-DF-2024-629
The views expressed in this article, book, or presentation are those of the author and do not necessarily reflect the official policy or position of the United States Air Force Academy, the Air Force, the Department of Defense, or the U.S. Government.
Period Analysis of Eclipsing Cataclysmic Variable Stars
By David Moffett
Department of Physics, Furman University
Co-Authors: Menna Ellaqany, Valeria Garcia, Mridul Agrawal, and Emily Hatten
We have studied the orbital dynamics of select eclipsing cataclysmic variable (CV) stars by analyzing photometric time series from the TESS space observatory, specifically 2-minute cadence data from the Mikulski Archive for Space Telescopes (MAST). The Python code we developed uses a periodogram to determine the average orbital period of the system, then fits an inverse Gaussian curve to each eclipse in the light curve to find the observed (O) eclipse epochs. Then, we calculate the computed/predicted (C) eclipse epochs and finally construct an O-C diagram for the eclipsing CV in question. Analyzing the O-C diagrams of our target CVs, we have constrained values for their period derivatives—the rate at which the orbital period changes with time.
We focused on a few sources from each class of non-magnetic, eclipsing CVs. The CVs we studied include dwarf novae (DN) variables, which encompass SU UMa type (with superoutburst/superhumps), Z Cam type (standstill outbursts), and U Gem DN subclasses. We include in our study classical novae variables, nova-like variables (including the VY Scl and UX UMa subclasses), and recurrent novae variable stars. This project aims to both introduce time series analysis techniques to undergraduate research students and contribute to the understanding of eclipsing CV orbital evolution.
MESA Modeling of Blue Supergiants and Alpha Cygni Variables
By Ava "Nova" Moore
Los Alamos National Laboratory, Los Alamos, New Mexico
Co-Author: Joyce Guzik
Alpha Cygni variables are a subset of supergiant stars with spectral types A and B that show variations in their luminosity and radial velocities (Saio et al., 2013). How these stars proceed through their evolution depends on their helium core mass, as well as poorly understood phenomena such as mixing, overshooting, and wind mass loss (Saio et al., 2013). For our research, a study of the parameters that affect a star’s evolution through the red supergiant phase and determine whether a star returns to the blue supergiant region is performed using the MESA (Module for Experiments in Stellar Astrophysics) code for models with mass fraction of elements heavier than hydrogen and helium Z = 0.015. Then, pulsation analysis is done on each model using the GYRE stellar oscillation code. Our goal is to determine which models show radial or nonradial pulsations and compare predicted periods to those observed in Alpha Cygni stars, and therefore whether pulsations can help to explain the variability in these stars. We also look to see if these models have similar mechanisms for their variability, which will aid in determining whether the group of Alpha Cygni variables are a homogenous class or not.
Evolution of RCB stars, and a General Law for the Shape of Isolated Dips
By Dr. Brad Schaefer
Dept of Physics and Astronomy, Louisiana State University, Baton Rouge, Louisiana
Professional astronomers can never get the long runs of telescope time needed to produce running light curves of R CrB stars, whereas the small telescope amateurs around the world have wonderfully filled this need. I have used the vast number of visual and V magnitudes in the AAVSO International Database for 14 R CrB stars. (1) Ordinary cool R CrB stars might show secular evolution on a century timescale, for example when the star enters or leaves the R CrB region on the HR diagram. With 323,464 magnitudes for ten ordinary cool R CrB stars, I extracted only magnitudes far away from any dip. These light curves show the stars at maximum light, and I sought linear trends or any type of significant variability. No variability was found, with typical uncertainties of +-0.10 mag/century. (2) I examined the at-maximum light curves for four ‘Hot R CrB stars,’ with these showing dust dips and a positioning to the left of the R CrB region on the HR diagram. All four stars are seen to be fading from ~1930 to present, at rates of 2.4, 1.2, 1.2, and 0.6 mag/century. Wow, we are seeing ‘fast’ evolution on individual stars in real-time. The secular declines are cause by the stars evolving to hotter temperature at constant luminosity, such that the bolometric correction to the optical band makes for an apparent dimming. (3) I have used the AAVSO data to extract light curves of many individual isolated dips. These isolated dips all show a universal profile. I use ordinary theory of the dust formation and dispersal to derive this exact empirical profile, with the general equation mobs = m0 + D[1 + (t − t0)/T0]−2, where m0 and T0 are constants for each R CrB star, while D and t0 are the magnitude- scale and time-shift parameters for each individual dip. Importantly, both theory and observation have the dip minima being flat-bottomed, and this demonstrates that the initial dust formation occurs in zero-velocity gas that is in the outer atmosphere of the RCB star.
Time Series Analysis of Mira SED Fits
By Atticus Stewart
New Mexico Institute of Mining and Technology and Lowell Observatory
Co-Authors: Zachary Goodrich, Dana K. Baylis-Aguirre, Michelle J. Creech-Eakman, and Gerard T. van Belle
The conditions in Mira variable atmospheres make them wonderful laboratories to study a variety of stellar physics such as molecule+grain formation, dust production, shock chemistry, stellar winds, mass-loss, opacity driven pulsation, and shocks. Mira stars are asymptotic giant branch (AGB) stars that pulsate every 100-500 days and release lots of dust from their atmospheres that chemically enrich their surrounding environments. They also have very long pulsation periods, with all of the stars having periods longer than 100 days. Miras can be found all over the galaxy.
We are currently curating a Reference Set of 106 Mira variables all over the galaxy based upon over a decade of synoptic observations made with the Palomar Testbed Interferometer (PTI). The Miras included in this dataset set include M-types (oxygen-rich), S-types (intermediate), and C-types (carbon-rich) and span a wide range of pulsation periods. PTI measured k-band angular sizes that when combined with a distance allow us to directly determine fundamental stellar parameters such as effective temperature, radial size, bolometric flux etc.
We will show preliminary time-series analysis of spectral energy distribution (SED) fits for selected Miras in the Reference Set. Data for our SED fits will be coming from the Lowell observatory using robotic data collection. Each night the 20-inch telescope will take narrow-band photometry of our stars and send the data to us. We will use sedFit to produce phase-dependent SED fits to study how much energy is coming out of the atmosphere through the pulsation cycle. We will be looking for patterns such as stars with the same chemistry, or with similar periods. We will be adding this data to our recently constructed Reference Set website for community access.
ROTUZ: Robotic Optical Telescope of University of Zielna Góra
By Magdalena Szkudlarek and Michał Żejmo
Janusz Gil Institute of Astronomy, University of Zielona Góra, Poland
The ROTUZ (Robotic Optical Telescope of University of Zielona Góra) system is an innovative solution in the field of automated astronomical observations, located at an observatory in Chile. This project, conducted by the Institute of Astronomy at the University of Zielona Góra in Poland, utilizes two telescopes with diameters of 50 cm (CDK 20) and 28 cm (RASA 11), enabling observations across a wide range of optical wavelengths. Thanks to full automation and its location in one of the darkest places on Earth, ROTUZ plays an important role in asteroid and space debris monitoring, as well as in observing astrophysical phenomena such as exoplanet transits.
The ROTUZ system is operated remotely, allowing efficient operation without the need for a constant on-site presence of astronomers. The telescopes are used both for conducting research projects and for educational purposes, supporting students in learning observational methods and data analysis in astronomy. ROTUZ also serves as a platform for international collaboration, providing access to high-quality astronomical data for scientists worldwide.
The aim of the ROTUZ system is to continue research on dynamic processes in the Universe while promoting astronomy by engaging both the academic and outreach communities in astronomical observations.
Revisiting RR Lyrae Periodicity in EY UMa: TESS Data and Ground-Based Observations
By Emily Watson
Minnesota State University, Moorhead, Minnesota
Co-Author: Dr. Matthew Craig
The purpose of this project was to build on last year’s project of determining the primary and Blazhko period of the RR Lyrae star EY UMa. This year, data from the TESS satellite, accessed by the Python package Eleanor, was used to try to resolve a conflict we reported last year between the short and long term periods determined from our data and those determined from the CRTS. Unfortunately, we have been unable to reconcile the different conclusions from our data sources. Along with an updated summary of our results, this talk will demonstrate how to access TESS data using Eleanor and use it for variable star analysis. Our analysis will include the TESS data and ground-based data collected by AAVSO member Geoff Stone and at the Paul P. Feder Observatory.
The Continued Search for Variable Stars
By Tanner Weyer
Department of Physics and Astronomy, Minnesota State University, Moorhead, Minnesota
Co-Author: Dr. Matthew Craig
Over the course of 2022, 2023 and 2024 we utilized the Paul P. Feder observatory in conjunction with data from several other sources to search for variable stars in a field located in the Constellation Boötes. The field had no known variables but using data from the Feder Observatory, AAVSO member Geoff Stone, and NASA’s TESS satellite, we have found several variable stars and have initial period estimates for them. During 2023 we selected eight promising stars based on data from our Feder Observatory, then during 2024 we obtained data from our observatory and NASA’s TESS Quick Look Pipeline (QLP) to complement our ground-based observations. Of the eight stars initially selected from our data as potential variable, 3 of them are variable according to TESS’s data. Utilizing a Lomb-Scargle periodogram we were able to estimate the period of these stars. All of the stars found thus far exhibit periods on the order of several days and magnitude changes of several millimagnitude. We are working to classify the stars.