112 Annual Meeting Abstracts

Paula Szkody

University of Washington

Cataclysmic variables are a major target for many AAVSO observers, which has led to a long term database that is of tremendous value in attempting to understand all the idiosyncrasies of these systems. I will highlight some of the work and results obtained by collaborations with AAVSO directors and members throughout the past 40 years and present some results from our current Large Treasury HST program on CVs.

Catherine Espaillat

Boston University

Planets form out of the building blocks and raw materials that were present in their planetary nurseries, known as protoplanetary disks. In order to catch planet formation in action, we search for the telltale footprints that actively forming planets leave behind on these protoplanetary disks. We employ both computer simulations and astronomical observations in our research, working with multi-wavelength data spanning the X-ray to radio wavelengths.

Gail Schaefer

Center for High Angular Resolution Astronomy

The CHARA Array combines the light of six 1-meter telescopes at optical and near infrared wavelengths to achieve an angular resolution equivalent to a 300 meter telescope. The Array is located at Mount Wilson Observatory and operated by Georgia State University. With milli-arcsecond resolution, the CHARA Array can measure the sizes of stars, image stellar surfaces, resolve the inner structure of circumstellar disks, map the orbits of close binary companions, and peer into the early structure of nova explosions. I will give an overview of the CHARA Array, highlight recent science results, and discuss a new collaboration with AAVSO to provide photometric observations on CHARA targets.

Scott G. Call¹, Eric G. Hintz¹, Steve Ardern², Victoria Scowcroft², Tim Morrell¹

¹Brigham Young University

²University of Bath

Cepheid variables play a crucial role in the bottom rung of the distance ladder, which defines distance measurements in astronomy. Therefore, any uncertainties in Cepheid measurements have the potential to propagate upwards in the distance ladder, affecting higher-level measurements such as the Hubble constant.

Metallicity is expected to affect the sensitivity of the period-luminosity relation. Recently, carbon monoxide (CO) has been observed in a few classical Cepheids. The CO forms in these atmospheres near minimum light and subsequently is destroyed as temperatures rise. This behavior leads to changes in the near and mid-infrared wavelengths corresponding to CO and will influence the period-luminosity relation.

We conducted observations of the classical Cepheid, CP Cep, utilizing the ARC 3.5m telescope at Apache Point Observatory and the near-infrared spectrograph, TripleSpec. The initial observations detected strong CO absorption bands, while follow-up observations on the subsequent night revealed a reduction in CO absorption, suggesting the destruction of CO molecules. Exploring how metallicity factors into period-luminosity relations for Cepheids may enhance the precision of distance measurements and mitigate the discrepancy of Hubble constant measurements.

Matt Craig

Department of Physics and Astronomy, Minnesota State University Moorhead

The increasing frequency and extent of forest fires in North America has led to increasingly frequent smoke cover on nights would otherwise have been clear. This very brief talk aims to illustrate the extent of the problem by sharing an animation of the satellite-determined extent of smoke over North America from April 1, 2023 through September 2023. Much of the continental US had at least light smoke cover for a substantial portion of the summer, and there are locations which had smoke cover the entire summer. The reddening this causes is apparent to the eye on a sunny day; the effects of this reddening on starlight should be investigated systematically.

Philip Masding

British Astronomical Association

Pulsating stars have been studied using non-linear hydrodynamic codes since the pioneering work of Robert Christy in the 1960’s. Modern codes include improvements such as allowing for convection but there is a penalty in terms of computation speed and for some stars convection is not significant. In this work a new version of the Christy program has been developed which can run hundreds of star models to convergence in a day or two of computer time. This allows overall patterns of behaviour to be studied and suitable models for individual case stars to be identified for more detailed follow up.

An initial program determines the necessary depth of the envelope and its mass distribution amongst the required number of zones. It then uses an iterative technique to solve for hydrodynamic equilibrium. The dynamic equations are then solved by a C++ program for maximum speed.

Two stars, SZ Lyn and RR Lyr, were used as test cases for the model. Light curve and radial velocity data were obtained for these stars using amateur equipment. Note that for stars of magnitude 10 or brighter radial velocity can be determined to +/-2km/s using a 0.28m telescope and a LHIRES spectrograph (resolving power 7000).

A run of 1200 different parameter sets (mass, radius, effective temperature and hydrogen fraction) showed the period—mean-density relationship and also illustrated how some models pulsate in the fundamental mode and others in the first overtone. These results were then used to identify the best parameters to fit the RR Lyr data. A similar search for SZ Lyn was simplified using the period-mean-density relationship because the required period means radius and mass are not independent. The model results show a good fit to the data for both stars in terms of the amplitude, period and key features of the light and velocity curves. Further work looked at double-mode pulsation and identified a number of candidates amongst the parameter sets used. Results showed that although often double-mode pulsation can persist for several thousand cycles the model usually settled in one mode or the other; however a single case showed steady dual-mode pulsation after 22000 cycles.

Abigale Moen, Dr. Matthew Craig, Emily Watson, and Tanner Weyer

Department of Physics and Astronomy, Minnesota State University Moorhead

This study observes period changes of DY Her, a high amplitude δ Scuti variable star with a period of 0.148631353 days. DY Her has been observed to have a slow overall period change from data gathered over several decades. Using light curve data taken over multiple nights at Paul P. Feder Observatory and observations of DY Her obtained from AAVSO from the past 20 years, the observed and calculated maxima were found, and an O-C graph was created to observe the period changes. A predicted O-C curve from past work was plotted alongside the O-C data in this study to see if the more recent data on DY Her’s period changes remain consistent with prior data on the star. The new O-C observations agree with previous analysis of the period changes and show that the period of DY Her is slowly decreasing.

Emily Watson, Dr. Matthew Craig, Tanner Weyer, and Abigale Moen

Department of Physics and Astronomy, Minnesota State University Moorhead

This study involved looking at an RR Lyrae star in Ursa Major, EY UMa. This star has long-term variability due to the Blazhko effect as well as the short-term variability characteristic of RR Lyrae stars. This project aims to better measure the short-term period of EY UMa and the longer-term period of the Blazhko effect. The Paul P. Feder Observatory has taken data on EY UMa almost every year since 2012.  A Lomb-Scargle periodogram was used to measure the period. Based on preliminary analysis of a subset of the data, the short-term period is 0.549 days and the Blazhko period is approximately 93.2 days. The calculated value of the short-term period is in line with the period given in VSX. Updated values based on analysis of more data will confirm the accuracy of the periods calculated thus far. Measurements from surveys such as the Catalina Real-Time Transient Survey will also be utilized as analysis continues.

John Percy, Mayank Shenoy, and Sandra Zhitkova

Department of Astronomy & Astrophysics and Dunlap Institute of Astronomy & Astrophysics, University of Toronto

Red giant stars are unstable to radial pulsation, most commonly in the fundamental and/or first overtone mode. At least a third also have a long secondary period (LSP), 5 to 10 times the pulsation period. Its cause was unknown for decades but, in 2021, there was a publication with strong evidence that the LSP was due to eclipses of the red giant by a dust-enshrouded companion which was originally a planet, but accreted matter from the red giant wind and became a brown dwarf or low-mass star. Still, several questions remain, and some of these are among the motivations for the present work. One question is the nature and cause of “LSP stars” -- an unofficial class of red giant variables, introduced in the All-Sky Automated Survey for Supernovae (ASAS-SN) variable star catalog. In these, the LSP variability is dominant; it has a significantly larger amplitude than the pulsation.

In one part of the present study, we “set the scene” by using AAVSO data and VSTAR software to analyze the variability of 102 red giants (and 10 red supergiants) in the AAVSO Binocular Observing Program (ABOP), including pulsation and LSP periods and amplitudes. At least 24 stars pulsated in two or more modes, and at least 58 had LSPs. In the other part of this study, we determined the periods and amplitudes of a sample of 35 of the 185 LSP stars in the ASAS-SN catalog, using ASAS-SN data, and VSTAR. These stars have short pulsation periods and small pulsation amplitudes, typical of a low-luminosity red giant. But such stars would not be expected to have strong winds, so how were they able to accrete enough matter to convert a planet into a brown dwarf or low-mass star? Indeed, several stars in the ABOP are LSP stars in the sense that their catalog period is actually their long secondary period and not their pulsation period.

We will present an overview of our results and their limitations and mention several questions remaining. Some of these questions involve the amplitudes of pulsation and LSP, which have not been determined and/or extensively discussed in previous studies. AAVSO observations can continue to help.

Acknowledgements: We thank the AAVSO observers and staff, and the compilers of the ASAS-SN database and catalog for providing the data on which this study is based. Authors Shenoy and Zhitkova are astronomy majors at the University of Toronto, supported by the highly selective U of T Work-Study Program.

Arne Henden, Bert Pablo, Brian Kloppenborg, Ed Wiley, Ken Menzies, George Silvis, Matt Craig¹, Mark Munkacsy, Tom Calderwood, Gordon Myers

¹Department of Physics and Astronomy, Minnesota State University Moorhead

When looking at light curves in the AAVSO Light Curve Generator, it isn't unusual to find observations that seem inconsistent with other observations of the same variable made at about the same time. Some AAVSO members have questioned whether these easily found inconsistencies affect the AAVSO's reputation within the research community and whether anything can (or should) be done to improve the quality of data within the AAVSO International Database.

About a year ago, the AAVSO commissioned a Data Quality Task Force to explore the seriousness of these inconsistencies, to discover the types of problems or mistakes causing these inconsistencies, and to make recommendations for how those issues can be resolved. The Data Quality Task Force has completed its work. The Task Force (composed of 10 active members of the AAVSO) analyzed samples of CCD and CMOS data from the AAVSO International Database, and found discrepant data, missing data fields, and data values inconsistent with AAVSO reporting instructions. Different issues had very different rates of occurrence; about 90% of the sample was not color-transformed (as requested in the AAVSO photometry guides), while typical problem rates for missing data fields were in the range of 5-10%. However, only a few researchers have complained about AAVSO data quality. Nevertheless, the Task Force recommends a strategy built upon six straightforward ways for observers to improve the quality of their submissions:

• Measure and monitor: No formal program to measure the quality of AAVSO observations exists today. The AAVSO should invest in a quality measurement program.
• Quality checks at submission: Software that accepts CCD and CMOS data (WebOBS) should be improved, allowing mistakes to be found and corrected before the observation is accepted.
• Strong observer feedback: The AAVSO should provide feedback directly to our observers, identifying mistakes and providing observer-specific quality metrics.
• Education to build knowledge: The AAVSO should redouble efforts to help the observing community learn more about photometry and best practices.
• Emphasize quality over quantity: The AAVSO should restructure its awards and recognition to emphasize data quality while also acknowledging quantity.
• Better-informed end users: Researchers who pull data from the AAVSO database need better information packages to explain the details of the data and set clear expectations for what is being provided.

The 27 detailed, prioritized recommendations that address these six strategic elements are contained in the Task Force's final report. These recommendations establish a framework for a series of technical (and, to some degree, cultural) changes that will affect most AAVSO observers, and further strengthen the AAVSO's reputation within the variable star community.

David J. Corliss

The extreme dimming events observed in Betelgeuse in 2019-20 and RW Cephei in 2022 occurred suddenly following long periods of stable behavior. After these events, the stars have increased in brightness but have not returned to earlier behavior. Unobserved Components Models (UCM) provide a statistical method for analyzing changes in baseline characteristics such as these. UCM separates a light curve into periodic, baseline level, regression trend, and irregular components. This enables qualification and comparison of a star's behavior before, during, and after events such as those recently seen in Betelgeuse and RW Cephei. This analysis finds Betelgeuse has brightened since the dimming event, with a shorter period and an upward trend in brightness exceeding the previous baseline level. As of May 2023, Betelgeuse is found to have a V of 0.2 and a period of about 310 - 360 days, lower than the period of 400 - 425 days before the dimming event. The irregular variable RW Cephei is found to have a historical baseline magnitude of 7.01 ± 0.12. RW Cephei also has increased in brightness since its dimming event, from 7.75 at its faintest in early 2023 to 7.38 two months later. Source code for UCM analysis of variable stars is given in Python, R, and SAS.

Joyce A. Guzik¹, Helmut A. Abt², and Jason Jackiewicz³

¹Los Alamos National Laboratory

²Kitt Peak National Observatory

³New Mexico State University

Deneb (alpha Cygni) is a bright (V magnitude 1.25) blue-white supergiant (spectral type A2Ia) which shows variability in both radial velocity and photometric measurements.

Abt et al. (2023, PASP, submitted) review radial velocity measurements made by Paddock (1935) taken frequently at twilight from the Lick observatory 36’’ telescope spectrograph during 1927-1935. They find resumptions of pulsations with a dominant quasi-period of around 12 days that seem to occur every ~70 days, and damp out after a few cycles. These resumptions happen at arbitrary phase. Perhaps another event like this was captured in a shorter series of radial velocity measurements by Abt in 1956 (Abt 1957).

We have examined subsequent radial velocity and photometry data of Parthasarathy and Lambert (1987) and Richardson et al. (2011), along with photometric measurements by the TESS spacecraft (Ricker et al. 2014, 2015), the Hipparcos satellite (van Leeuwen et al. 1997), and V-magnitude observations by ten different observers between June 2021 and June 2023 reported in the AAVSO International Database (AID, Kloppenborg 2023). We will show evidence for resumptions of larger-amplitude pulsations in these data, and comment on the interval between resumptions.

We would like to answer many questions about Deneb. Some of these are:

1. Can we confirm that pulsation resumptions occur at around 70-day intervals, and how precise are these intervals?
2. Do these resumptions occur at an arbitrary phase in the 12-day dominant period?
3. Do they occur at the same time in light curve and radial velocity data?
4. Are there additional radial and non-radial pulsation modes with well-defined periods and amplitudes (see, e.g., Lucy 1976)?

The available TESS time series is too short/discontinuous and the AAVSO ground based photometry data points are a little too infrequent to answer these questions definitively. However, several additional 27-day sectors of TESS data, preferably contiguous, as well as AAVSO time series data with around one data point per night for several consecutive 70-day intervals may be possible to obtain. Targeting other alpha Cygni-type variables would also be useful. We are interested particularly in 6 Cas, which is a member of the same OB association and has a similar spectral type, mass, and age as Deneb.

These data, along with stellar evolution and pulsation modeling, will help to answer the questions of the causes of Deneb’s variability and of the periodic resumption of larger-amplitude pulsations.

References

Abt, H.A. 1957, ApJ, 126, 138
Kloppenborg, B.K. 2023, Observations from the AAVSO International Database, https://www.aavso.org
Lucy, L.B. 1976, ApJ, 206, 499
Paddock, G.F. 1935, Lick Obs. Bull., 17, No. 472, 99
Parthasarathy, M. and Lambert, D.L. 1987, J. Astrophys. Astron. 8, 51
Richardson, N.D., Morrison, N.D., Kryukova, E.E., and Adelman, S.J. 2011, AJ, 141, 17
Ricker, G.R., et al. 2014, Transiting Exoplanet Survey Satellite (TESS) (2014SPIE.9143E..20R)
Ricker, G.R., et al. 2015, Journal of Astronomical Telescopes, Instruments, and Systems, Volume 1, id. 014003
van Leeuwen, F., et al. 1997, Astron. Astrophys. 323, L61–L64

Robert K. Buchheim

AAVSO; Lost Gold Observatory

EQ Peg is a well-known red dwarf flare-star. It was a target of an ongoing project to characterize stellar flares with simultaneous spectroscopy and photometry. We report spectro-photometric analysis of a large flare on EQ Peg. Time-series B-band photometry is combined with time-series spectroscopy to characterize the brightness profile and the development of spectral features spanning 4.8 hours of overlapping photometric and spectroscopic observations. At its peak, the flare increased the star’s brightness by 1.2 magnitudes in B-band (more than doubling its luminosity); the flare showed a typical “fast rise, exponential decay” shape, with FWHM ≈ 1.7 minutes. The energy released by the flare in B-band was ≈ 3.2 X 1032 erg, putting it near the lower bound of “superflare” energy (>1033 erg, bolometric). Time-series spectroscopy shows that the Balmer emission lines remain strong for a much longer time (FWHM ≈ 22 to 28 min, depending on the line), taking about 3.5 hours to return to their pre-flare strength. The flare spectrum continuum slope indicates a peak temperature of ≈ 14,000K.

Gary Walker

Maria Mitchell Observatory

V1478 Cyg, a.k.a. MWC349, is an enigmatic emission line (Type Be) binary system with a long history of observation. We present over 25,000 observations taken from Sierra Remote Observatory in Auberry, California, Pixelskies Observatory in Castelajar, Spain and Maria Mitchell Observatory over the past few years. Observations in BVRI & Ha with bandwidths of 30, 45, 100 and 300 Angstroms on nearly a nightly basis were obtained. Careful observation in 2017 showed an unusual outburst for 7 clear nights during 10 nights of observation in in all 8 filters. A total of 2,600 observations in outburst were recorded. Attempts to corroborate the outburst yielded only two data points from ASAS-SN and they showed no outburst. This suggests a very interesting scenario that fits this data, with a microlensing event of a suspected exoplanet with approximately a 24-hour period around a very faint star or a dark matter object, potentially a Massive Compact Halo Object (MACHO).

Michael Poxon

AAVSO YSO section

The Cepheus Flare region between around 100 – 120 degrees galactic longitude and latitude up to +20 degrees comprises a huge and complex area of (especially) high-mass star formation, including several OB associations. The presentation will look at this region as part of a long-term dynamic system of past supernova events and the ensuing bursts of star-forming, with special relevance to the many diverse Young Stellar Objects present, which provide excellent opportunities for amateur study with even modest instruments.

The aim is to encourage AAVSO members (including imagers!) to observe more of these stars such as V373 and BG Cep and their environments in order to further our understanding of ongoing star-formation processes.

L. A. Sgro^1,2, T. M. Esposito^1,2,3, F. Marchis^1,2, D. O. Peluso¹, A. Graykowski¹, R. A. Lambert¹, Ian Weaver¹

¹SETI Institute, Carl Sagan Center

²Unistellar

³Astronomy Department, University of California

The Unistellar Citizen Science Network, a collaboration of professional and citizen observers around the world, is shaping the way amateur astronomers interact with science. Conversely, it is changing the way astronomical science is performed, particularly in the realm of exoplanet transits.

The network consists of citizen scientists who operate mobile and easy-to-use 4.5-in imaging telescopes, called Enhanced Vision Telescopes or eVscopes, produced by Unistellar. In 2019, the SETI Institute and Unistellar solidified a partnership to develop the network’s scientific applications, such as the Exoplanet Transits program. With this NASA-funded program, observers can investigate known planets and gas-giant candidates discovered by the Transiting Exoplanet Survey Satellite (TESS). For these candidates, only one or two transits have been observed by TESS, and additional follow-up is required to confirm the planet and determine a period. However, single- or duo-transit candidates and long-duration (> ~10 hours) transits pose challenges: 1) without multiple transits, the period is not well-constrained, necessitating searches over multiple nights, and 2) long-duration transits require observations from multiple locations due to the rising sun. This is where the Unistellar network has already been invaluable with its global spread of participants.

In 2021, 31 citizen astronomers observed a 16-hour transit by Kepler-167e and results were published in the Astrophysical Journal Letters in 2022, detailing how their observations confirmed a period of 1071 days¹. This campaign set a record for the longest period exoplanet to have its transit detected from the ground, and all observers received co-author status for their observations. Several other transit hunts over the course of multiple nights have been successful in confirming TESS planet candidates and determining their periods. Most recently, observers who include high school participants in the educational Chabot Space & Science Center “Galaxy Explorers” program, aimed to observe a transit of TIC 13927066b². We will discuss these results and their methodology, the educational merits of our program, and the greater impact of citizen science.

References

¹Perrocheau, Amaury, et al. "A 16 hr Transit of Kepler-167 e Observed by the Ground-based Unistellar Telescope Network." The Astrophysical Journal Letters 940.2 (2022): L39.
²Peluso, et al. In Prep.

Tanner Weyer, Dr. Matthew Craig, Emily Watson, Abigale Moen, Mara DeRung

Department of Physics and Astronomy, Minnesota State University Moorhead

During the spring of 2022 the Paul P. Feder observatory was performing ground-based follow-up observations of a potential exoplanet for NASA’s TESS mission and realized the field had no variable stars in VSX. Searches of data from several all-sky surveys also found no variables. We observed the field on 7 nights in May and June of 2023. We will describe our progress in identifying potential variable stars in the field, including an overview of the calibration and photometry issues we encountered. We also discuss the difficulty of interpreting the data even when we combine it with data from all-sky surveys.

Hafsa Jamil^1,2, Oliver Hancock¹, and Michael Joner¹

¹ Brigham Young University, Department of Physics and Astronomy

² Rutgers, the State University of New Jersey, Department of Physics and Astronomy

Exoplanets have been studied by astronomers for numerous reasons, either to find habitable planets or to gain a broader understanding of the properties of planets. This paper will focus on experiences and skills acquired during a 10-week Research Experience for Undergraduates program at Brigham Young University (BYU) during the summer of 2023. New skills gained in this program included operating the different telescopes at the BYU West Mountain Observatory (WMO), learning about astronomical photometry (specifically transit photometry), planning observing sessions, selecting appropriate targets for different nights, processing the raw data frames, and using software such as AstroImageJ (AIJ) to graph and evaluate transit candidates. Practice analysis was done using archival data of observed transits from previous projects at WMO. Potential exoplanet candidates were selected using TESS Input Catalog (TIC) from the Transiting Exoplanet Survey Satellite (TESS). Targets were selected based on the information on the TESS website, where it displays features of the potential targets such as transit depth, elevation, time of night, transit time, etcetera. These factors are important as they have to be viable for the team to observe them at WMO. Candidates identified were observed with either the 0.32-m or the 0.91-m telescopes at WMO. Results are presented of observations that have been made and evaluated as a result from this REU experience.

Overall results are still ongoing, as more exoplanet candidates are being gathered. Of the current candidates collected, results were found that there was a dip in both filters of the transit curves of one TIC candidate. There was a TIC candidate that did not transit in the graph at all, so it was ruled out. This also applied to another TIC candidate which only transited in one filter. For the one TIC target that did transit in both filters, further analysis will be conducted to determine if it is an exoplanet. The anticipated analysis will help to identify false positives among the candidates and confirm the validity of the targets. When doing analysis on a transit curve, the candidate may either be an exoplanet or a pair of eclipsing binary stars, as both will portray a dip in the transit light curve graph. To identify these false positives, factors to consider are the light curve shape, or if the target star did not have a transit dip, yet the star next to it did. Once this analysis is made, it can be concluded whether or not the targets collected are actual planets. This will not only make the transit method more viable for finding exoplanets, but it will also display how time series photometry can be applied to this type of research in the future.

Acknowledgements are owed to Brigham Young University’s Department of Physics and Astronomy for supporting West Mountain Observatory and making it available for this research. This research was also funded by the NSF grant #2051129.

Arushi Nath

Affiliation: MonitorMyPlanet.com

Hundreds of near-earth asteroids are discovered every month, outpacing current abilities to analyze them. Knowledge of an asteroid's physical properties is essential to deflect it. I took images from robotic telescopes from the Burke Gaffney Observatory, the Faulkes Telescope Project, AAVSOnet, iTelescope, Open University, and the Canadian Space Agency’s NEOSSat telescope in space. I then developed open-source algorithms that combined images from robotic telescopes, open data, and school math to determine asteroids' size, rotation period, strength, and mutual orbital period in the case of binary asteroids.

I took over 55 hours of observations of the Didymos binary asteroid spread before, during and after the NASA DART Mission impact. My algorithm determined its size to be 820 metres, with a 2.26-hour rotation period and rubble-pile strength. Post-impact, I measured a 35-minute decrease in the mutual orbital period of Dimorphos around Didymos. The brightness of the Didymos system increased by 1.2 magnitudes because of sunlight reflected from the ejecta, and I measured the ejecta tail to be 20,000 km long. My results matched with external sources.

I have made my algorithm open source as a 4-part training module so that youth and citizen scientists can accelerate the pace of analysis of near-earth asteroids and become planetary defenders. I have delivered webinars at iTelescope, the Royal Astronomical Society of Canada, the 2023 Planetary Defense Conference, the 2023 NASA Exploration Science Forum and the NASA Youth Space Apps hackathon. I have published my initial findings in the Royal Astronomical Society of Canada Journal. This project won me the "Best of the Canada Wide Science Fair Award (Innovation) 2023" among almost 400 finalists. I represented Team Canada at the European Union Contest for Young Scientists held in Belgium in September of 2023, where my project won the second grand award among over 130 participants from 36 countries.

Kenneth Beckmann

Astronomical and biblical historians have long searched ancient texts to identify and explain a mysterious Star which was mentioned in the Gospel of Matthew (Matthew 2:1-12, 16-18), i.e., the Star of Bethlehem. The purpose of this paper is to provide an in-depth study and understanding of three observations left by the author making it possible for the modern historian to unlock the secrets of the Stars of Bethlehem, the identity of a priesthood known as the Magi, their observations of wandering stars at an ancient observatory in central Turkey and afterwards their travels on tributaries of the Silk Road to Jerusalem and later Bethlehem.

The Legend of the Star of Bethlehem has long been imagined as a non-historical, largely fictional literary form known as a Midrash. The description of the Star appears so vague that it seems nigh impossible to definitively identify any of multiple transients over a period of one hundred years, from the time when the Star appeared to a time when the author wrote the Midrash. Recent unearthed evidence and hypothesis suggests otherwise.

The ancient Greek word, “Anatolia” ἀνατολῇ (anatolē) translates as “the East.” Anatolia was mentioned in Matthew 2:1. The author utilized this word to describe both the homeland of the Magi and the type of astronomical observations which were conducted at a remote ancient observatory. While history has long suggested the Greek word is a description for the Magi’s homeland in Babylon or Sinai, a careful study of the text suggests that the author spoke about a specific priesthood of Magi that were commissioned during the reign of the sovereign, Antiochus I (70 BCE to 30 BCE) in the Kingdom of Commagene, roughly 60 miles northwest of the ancient city of Edessa, Mesopotamia (modern Urfa or Şanlıurfa, Turkey). In ancient times, the Greek word “Anatolia” (the East) referred to a sub-region of central Turkey less than one hundred miles south of the Black Sea.

At the ancient astronomical observatory of Nemrut Dağ in Anatolia, the Magi studied the movement of the wandering stars (Sun, Moon, Mercury, Venus, Mars, Jupiter and Saturn) as they traveled the Ecliptic through the twelve Zodiacal constellations. The author also utilized the same Greek word “Anatolia” to describe the type of astronomical observations (helical) the Magi conducted at the ancient observatory (“For we saw of Him the Star in the East.” Matthew 2:2b)

A careful study of two additional observations the author left in Matthew 2:7 (“Then, Herod secretly having called the Magi, inquired exactly of them the time of the appearing Star”) and Matt. 2:9-10 (“And having heard the King, they went away and behold, the Star which they saw in the East went before them until having arrived it stood over where was the Child. Having seen now the star, they rejoiced with joy great exceedingly”) shows that the text employed a form of the same Greek word to describe not one but multiple Stars.

In Matthew 2:16b, the author also left a cipher which identified a unique candidate for the observations in Matthew 2:7 and Matthew 2:9-10 that unequivocally revealed a Star which was recorded in a catalogue of comets observed by ancient Chinese astronomers.

The presentation provides a holistic historical understanding of the text, the Stars’ identities, the priesthood of Magi who traveled from central Turkey first to Jerusalem and later Bethlehem and the purpose for the Midrash in the author’s work. The final observation (Matthew 2:9-10) described the Magi, who, after reaching Jerusalem around the middle of April 5 BC, twelve days later, made a nocturnal journey to Bethlehem and arrived early morning at the beginning of May shortly before sunrise. There, they viewed the Star hanging in the heavens over the village. The final observation (Matthew 2:9-10) described an eyewitness account of the Star viewed on or around May 2nd, 5 BCE which can be corroborated by a simulation of the Star’s approximate position using a modern online computer planetarium program.

Such in-depth studies of this Midrash and other ancient writings which built upon the Legend of the Star over succeeding generations can provide a treasure trove of historical and celestial informational gems about the identities of celestial transients which may have otherwise been lost to legends and myths.

Diz, H.R.^1,2, Beamson, G., Gebhard, G., Martin, J., de Elias, J., Desrosiers, J.B., Larsson, M., de Hilster, N., Lopez, S. D., Cookson, S., Piehler, G.

¹AAVSO

²British Astronomical Association

A team of amateur astronomers has begun a study of the spectroscopic changes in Be stars that exhibit rapid variability.  Rapid variability in Be stars has been reported by Percy (1987) and others. Rapid is here defined as variability on the scale of minutes to hours. Classical Be stars are non-supergiant variable stars of spectral class B that have Balmer emission lines in their spectrum; they are early main-sequence stars that are hot and rotating rapidly (Porter and Rivinus, 2003). These stars characteristically have a circumstellar decretion disk of material (mostly hydrogen) which has escaped from the surface of the star in a manner not yet fully understood.

Because we are amateurs in Europe and North America using medium sized telescopes, equipped in some cases with homemade spectroscopes, we have selected as candidates for this study a set of ‘bright’ Be stars (magnitude <7) from among those Be stars reported by Percy (1987) as being probable or possible rapid variables. The primary repository of Be star spectra is the BeSS database, where thousands of profiles have been uploaded over many years of observing. However, except for the most highly studied stars, there is for a given star sometimes one spectrum per night, but more often only a few spectra per week, or in some cases, a few per month or year.

Documenting rapid variability requires frequent, sequential exposures of ten minutes or so, over as long a period of time as possible in order to detect very short term variations in spectral line features. During the first phase of the project, each team member was assigned a star from the list of candidates. Each team member then began an intensive series of spectroscopic observations to look for rapid variability. If rapid variability is observed, that star will be included in the next phase of the project. For each such star a more extensive set of observations is planned, in that the entire team will target the same star on the same night. Since team members are located in time zones ranging from UTC+1 to UTC-6, observations made in the East on that night will be followed by those of team members to the west, thus virtually extending the night, and resulting in a lengthy time series of observations.  This will be repeated on additional nights until an acceptable set of observations is acquired. Then, the team will target the next star on the list until all of our finalist stars have been adequately observed. Our final step will be to use variation in line features to estimate periodicity, if it exists, and to infer what we can about each star’s disk behavior (as revealed by the H-alpha line at 6562.8 Å), and about the photosphere’s behavior (as revealed by the helium line at 6678.2 Å).

The team began making observations at the beginning of September, 2023, and will conclude in the spring of 2024. We will report preliminary results at the AAVSO Annual Meeting in November 2023. Upon completion of data analysis, we will report our findings in a peer-reviewed journal.

A. Graykowski¹, R. A. Lambert¹, F. Marchis^1,2, T. M. Esposito^1,2,3, L. A. Sgro^1,2, Ian Weaver¹, D. O’C. Peluso^1,4, P. A. Dalba⁵

¹SETI Institute, Carl Sagan Center

²Unistellar

³Astronomy Department, University of California, Berkeley

⁴Centre for Astrophysics, University of Southern Queensland

⁵Apple Inc

Unistellar is partnered with the SETI Institute to establish joint research and education programs aimed at developing a citizen scientist network of Unistellar astronomers. Every aspect of Unistellar’s citizen science programs, from observation to analysis to publication, is shared with citizen astronomers with the intention to provide peer-review research level education to participants. We will discuss the education program and the five citizen science programs: Exoplanets, asteroids, planetary defense, transients, and comets. We will focus on the results from the comet program, which has grown significantly over the last year. This network of small telescopes (114 mm diameter) has allowed for the consistent monitoring of cometary activity, which is crucial to predict a comet’s variable brightness and capture unexpected outbursts. Outbursts are ephemeral events, and therefore necessitate quick identification and follow-up. This requires both long-term monitoring and flexibility to quickly turn telescopes to the sky. The Unistellar network has monitored over 10 comets in the last year, with ~1-5 comets observed each day. We measure the magnitude of these comets using aperture photometry over several months of observations. We will present their resulting secular light curves and discuss how these aid in the predication of cometary activity. We will also present observations of comets 29P/Schwassmann-Wachmann and 12P/Pons-Brooks in outburst. We measure the change in magnitude before and after the outbursts and the rates at which the comets fade back to their intrinsic magnitudes to estimate the mass lost in the event and characterize the potential outbursting mechanisms. Comet 12P was a particularly faint comet pre-outburst, approaching the Unistellar eVscope limit, measuring ~17 magnitude. We compare these analyses to Unistellar observations of the NASA DART spacecraft impact into Dimorphos. The Unistellar network observed the asteroid before, during and after the impact, clearly displaying a quick brightening due to the ejecta. Using aperture photometry, we measured this brightening and eventual fading over time to estimate a mass of ~10 million kg lost to the ejecta1. The result of this man-made impact can be compared to other potential outbursting mechanisms such as rotational instability, pressure build-up, and natural impacts in both active asteroids and comets. Comets’ and asteroids’ dynamic activity give insight to their composition and evolution from their primitive sources regions in the solar system, and the Unistellar network is the perfect tool to monitor their variable activity over time.

References

¹Graykowski, A., Lambert, R.A., Marchis, F. et al. Light curves and colours of the ejecta from Dimorphos after the DART impact. Nature 616, 461–464 (2023). https://doi.org/10.1038/s41586-023-05852-9

Kristine Larsen

Central Connecticut State University

Astronomical objects of many types have provided fruitful fodder for works of science fiction for centuries. Variable stars are no exception. From the fictional eclipsing binary Walaz in the Edmond Hamilton 1934 short story “Thundering Worlds” to the use of pulsating variables as signposts on an interstellar highway in George O. Smith’s 1953 pulp novel Troubled Star, variable stars of various flavors have starred in popular media. Not surprisingly, cataclysmic variables, in particular novae and supernovae, have been a favorite plot hammer in the novelist’s (and screen writer’s) toolkit. Exploding stars have been featured in science fiction for well over a century, long before the existence of both novae and supernovae as separate classes of objects was known. Indeed, even in the 21st century “nova” is often used ubiquitously in popular media as a catch-all term for stellar outbursts, even when a supernova – or a super-flare – is clearly meant. While the names and locations in the sky of most of these fictional variables remain vague in fiction, occasionally a specific constellation will be named, as in the case of the film 2:22 (2017), in which a nova is specifically said to occur in Aries, or Nova (2013), in which a supernova is seen in Orion. On rare occasions, a historical nova or supernova is specifically invoked in fiction, to give real-world gravitas to the imaginary scenario, for example, GK Persei (Nova Persei 1901) in H.P. Lovecraft’s 1919 short story “Beyond the Wall of Sleep.” This poster reviews the use of novae and supernovae as plot devices in works of science fiction, demonstrating a curious association of such objects with the constellation Aquila, despite the fact that there are several constellations that have hosted more known novae. A study of coverage of observed novae in Aquila in the 20th century reveals possible explanations for the frequency of spectacular Novae Aquilae in science fiction. Therefore, an analysis of astronomical history in tandem with examples of astronomical references in popular culture reveal the influence that one has upon the other and can solve the mystery of how astronomical events can be easily conflated by authors, even in works of “hard” science fiction.