Dr. Barbara Harris, "How to Do Variable Star Photometry With Your DSLR" Many astronomers have a DSLR and use it for general photography and astrophotography. I would like to encourage you to use your DSLR to contribute to science by measuring the brightness of variable stars.
Dr. Steve Howell, "Using AAVSO photometry to understand and characterize variable giant stars" During a multi-year campaign, the AAVSO provided multi-color photometry to complement optical spectroscopy in an attempt to understand a number of long-standing misunderstood complexities and characteristics in a set of variable giant and supergiant stars. This talk will review the observations and how they have been fit together to formulate new insights into such stars. A few particularly interesting examples will be highlighted.
Dr. Juan Echevarría, "Spectroscopic and photometric observations of the intermediate polar DW Cnc" Spectroscopy and photometric observations of the DW Cnc interactive binary will be shown during a low state and the beginning of a return to a high state: we will see that the signal from the spin of the white dwarf (38 min.), as well as the beat period signal (69 min.), were both absent, and mostly the power spectra showed the orbital period frequency (86 min.). On the way to the high state, we will start to see the former signals, but they are still not of the strength of the observations made around 1999-2003 by Patterson et al. (2004) and Rodriguez-Gil et al. (2004).
Dr. David Whelan, "Classifying Algol C, the Non-Eclipsing Member of the beta Persei System" For nearly a century it has been known that there are at least three stars in the Algol system: two (A and B ) in a close eclipsing binary, and a third (C) orbiting the binary at a much greater distance. But tension has existed as to Algol C's precise spectral type. Some scientists claim that it is a normal A- or F-type star, while others state that it must be an Am star. Using low-resolution spectra suitable for spectral classification, we have observed the Algol system at numerous phase angles, including primary and secondary eclipse, and have scaled and subtracted two of our spectra to create a spectrum for Algol C that allows us to recommend for it a precise spectral type. We will discuss our method, which is accessible to anyone with a suitable spectrograph. We will analyze our result to determine whether it can be deemed "correct." And if we are correct, then we will have definitively answered one of the many long-standing questions of astrophysical importance that lie hidden in plain sight, among the brightest stars in the sky.
Lauren Herrington, "Spectrography on a Budget" Spectrography has long been seen as a difficult and expensive pursuit, but it really doesn't have to be! The march of technological progress has brought about low-read-noise CMOS cameras, powerful computers, and inexpensive diffraction gratings, all of which help make it possible to record high quality stellar spectra without using a tracking mount at all.
I will reveal how you can use the "drift scanning method" to record scientifically useful spectra of tens of thousands of stars using nothing but a camera, diffraction grating, and an untracked telescope. I will also discuss how to optimize your resolution, so that you can use your slitless grating to record fine details, such as the blueshifted absorption lines originating in the torrential stellar wind of P Cygni. Lastly, I will demonstrate how to process and calibrate your spectra, and how to submit your processed spectra to the AAVSO's database.
No prior knowledge is necessary, but attendees will likely find it beneficial to know ahead of time what the terms "spectrum," "absorption," and "emission" mean as they relate to astronomy, and how to operate a simple telescope. Recommended pre-How-to Hour reading: http://spiff.rit.edu/classes/phys301/lectures/spec_lines/spec_lines.html.
AAVSO's Short Period Pulsator (SPP) Observing Section, "SPP Observing Section Webinar" The webinar begins with an introduction by SPP observing section leader Eric Hintz (5 minutes), and is followed by Jarrod Hansen discussing using short period variables to teach research to undergraduate students (25 minutes). Marcelo Bighetti will then speak on development of a high school competition based on short period pulsating stars (25 minutes). Hintz will wrap up the presentation by discussing testing automated variable star period determinations for SPP stars (40 minutes).
Using short period variables to teach research to undergraduate students: Over many years, SPP variables have been used as one of the targets for an observational astronomy class at Brigham Young University. The final goal of this class is to generate publication-quality papers from data taken in class and from online archives. As the class has evolved, the expectation levels have gone up. The current state of what the students can do with SPP variables will be discussed.
Development of a high school competition based on short period pulsating stars: SPP stars and other variables provide ideal targets for young observers. A short study showed that many junior high and high school-age students think astronomers basically run star parties. There is a need to change this perception, and SPP variables provide an ideal tool. An idea for high school competition using data on SPP stars will be presented. This is still in the early development phase, but we hope to have a test program with a small group of schools next school year. Once piloted, plans include having AAVSO observers help school groups get even larger data sets.
Testing automated variable star period determinations for SPP stars: Observers can contribute even if they only have a couple hours in a night to work. We have used SPP variables for many years to teach research methods to our astronomy majors at BYU. The students can see clear variations in a single night and can most likely get entire cycles of the light curve. In the current epoch of astronomy there are a large number of programs that find new variable stars, such as TESS, KELT, ATLAS, ASSN, and in the future, LSST. We have searched these databases for potential new targets for extensive study using our group of 6 robotic campus telescopes. However, the number of potential variables is far more than even 6 telescopes can handle. We hope to make a list of targets available to AAVSO observers that covers both hemispheres, over the entire year, and over a range of magnitudes. The majority of these objects do not appear in previous variable star catalogs, and most don't have an entry in SIMBAD. This is a chance to help establish the true nature of these objects, even if you only have a few hours.
Dr. Boris Gänsicke, "The end of the worlds" We now know that it is totally normal for stars to have planets, and the variety and complexity of observed exo-planetary systems is continuously growing. One question that then arises: what is the ultimate fate of these planetary systems? And what is the fate of our solar system? Once the planet host stars run out of fuel, they will become red giants, shedding a fraction of their mass, and leaving their burnt-out, Earth-sized cores behind (white dwarfs). Recent years have seen a rapidly growing number of observations that show that many planets or their remains survive the metamorphosis of their host stars, and now orbit the slowly cooling embers of stellar evolution. I will review how we can identify such evolved planetary systems via the detection of planetary debris contaminating the atmospheres of white dwarfs--debris causing rapidly evolving photometric transits, and discuss the detections of giant planets on close orbits around white dwarfs.
Bob Buchheim, "How to start with CCD photometry" CCD astro-imaging can make beautiful pictures and very accurate measurements of the objects in your field. This workshop is aimed at the person who is curious about the “measurement” aspect of CCD imaging. I will introduce the concept of stellar photometry, some differences in imaging techniques when your goal is “measurement” vs. “beauty,” and suggestions for your first few variable star activities. No experience in CCD imaging is required to join this session, but a little bit of knowledge will be helpful. The goal is to help you experience variable star measurement for yourself, so you can decide if it is an activity that you enjoy.
Dr. Christian Knigge, "Cataclysmic Variables as Universal Accretion Laboratories" Cataclysmic variables (CVs) are numerous, bright, and nearby, making them excellent laboratories for the study of accretion physics. Since their accretion flows are unaffected by relativistic effects or ultra-strong magnetic fields, they provide a crucial "control" group for efforts to understand more complex/compact systems, such as accreting neutron stars (NSs) and black holes (BHs). I will review recent work on CVs, which has revealed that these superficially simple systems actually exhibit the full range of accretion-related phenomenology seen in accreting NSs and BHs. Given this rich set of shared behavior, it is reasonable to hope that much of accretion physics is, in fact, universal.
François Cochard, ""Spectroscopy: which hardware for which observations?" We'll look into what kind of hardware is required to start in spectroscopy, and the kind of observations we can make with it. There are a lot of things that we can do in spectro---but some are easier and some less so. This presentation will mainly be dedicated to newcomers to spectroscopy, and you can attend even with no experience---just curiosity!
Trevor Dorn-Wallenstein, "Solving the Red Supergiant Problem with a New Class of Pulsators" Massive stars drive the radiative, chemical, and kinematic evolution of their host galaxies. Despite the importance of these stars, the physical factors that govern their progression through the exotic evolved states that we observe them in are poorly understood, and every new observational advance seems to raise more questions than it answers. In particular, there is a mismatch between the masses of stars we expect to explode as supernovae, and the red supergiant stars we have witnessed undergoing this cataclysmic event—a discrepancy known as the red supergiant problem. One potential solution? If the most massive and luminous red supergiants shed enough of their envelopes before the ends of their lives, they explode as yellow or blue supergiants instead. While finding genuine post-red supergiants is difficult, discovering the lowest mass star that undergoes this phenomenon would place stringent constraints on the evolution and final fates of massive stars. In this talk, I will highlight the discovery of a new class of pulsators called “fast yellow pulsating supergiants” (FYPS) that may be genuine post-red supergiant objects. I will discuss the context surrounding this discovery, as well as the scientific avenues that FYPS may let us explore. Finally, I will demonstrate how observations from AAVSO observers can enable similar discoveries.
Dr. Burçin Mutlu-Pakdil, "The Faintest and Smallest Galaxies" around the Milky Way are the most ancient, most metal-poor, and most dark-matter-dominated systems known. These extreme objects offer unique access to small scales where the stellar and dark matter content can be studied simultaneously and hold the promise of major breakthroughs in understanding the nature of dark matter, and a more complete picture of galaxy formation. Thus, their discovery and characterization are among the most important goals in the field. I will share our ongoing observational efforts to detect these faint systems around the Milky Way and beyond, and upcoming advances in the era of deep and wide imaging instrumentation.
Richard Berry, "Your First Observatory: Keep It Simple!" Your first observatory should be inexpensive, simple, and easy to use. Its purpose: to be the place you call your own, offering minimal set-up time and maximal convenience. For example, a simple L-shaped fence can shelter you from wind and stray light, while a small concrete pad with an electric outlet can make set up fast and the alignment accurate. After getting started with a simple observatory, you can build on the experience as you plan a fancier shelter, roll-off roof, or domed observatory.
Dr. Dan Milisavljevic of the Supernova Early Warning System (SNEWS) Team, "Observing the Next Galactic Supernova: Will you be ready?" The catastrophic deaths of massive stars--supernova explosions--are among the most powerful and important events in the cosmos. Supernovae strongly shape the structure and chemistry of their host galaxies; they produce a variety of exotic objects including neutron stars, black holes, and gamma-ray bursts; and, perhaps most importantly, supernova debris ejected into interstellar space is chock full of the heavy elements that make planets and life possible. Dr. Milisavljevic will provide a vivid description of historical supernovae that occurred in our own Milky Way galaxy, and outline plans for a coordinated global response to the next "Big One." Particular emphasis will be drawn to the special role that AAVSO members will have in responding to an alert from the Supernova Early Warning System (SNEWS), which is a network of neutrino detectors around the world designed to rapidly provide the first announcement when the next once-in-a-century Galactic supernova occurs.
Tom Calderwood, "A Romp with Betelgeuse" The dramatic fade-out of alpha Orion in 2019-2020 was of major interest to professional and amateur astronomers alike, and scientists are still trying to sort out what happened. We will review the research results for this extraordinary event and highlight AAVSO's photometry of the red star in the giant's left shoulder.
Dr. Gibor Basri, "Information and Illusions in Starspot Light Curves" Brightness variations of stars have been known for centuries. Some of them are due to the passage of starspots over the visible hemisphere as stars rotate. In the past 15 years, we have been able to gather vastly better, longer, and more numerous light curves from space--especially from the Kepler mission. Starspots have various sizes, grow and decay with various timescales, and appear at various locations over time; their composite light curve also depends on the stellar inclination. Stars like the Sun show such chaotic light curves that it is hard to infer even the rotation periods. In (more variable) stars that show clear periods, most light curves are deceptively simple, with one or two dips per stellar rotation. This simplicity is mostly illusory; the true spot distributions can be quite complicated. That presents problems to making astrophysical conclusions about the starspots. I’ll discuss what we are learning and how stellar variability changes as a function of stellar mass and age.
(Stay tuned for more!)
Dr. Nancy Morrison, "How To Write an Astronomical Research Paper" The presentation will be designed so that writers at all levels can take away valuable principles. It will include discussion and examples of how to: know and write for your audience, write an abstract, organize a research report by section, organize your ideas within each section, cover elementary concepts, support your points with citations, make a literature search with the ADS and with SIMBAD, support your points with figures and tables, design figures, write table and figure captions, construct a citation list, and revise your manuscript. A revision exercise will be provided as "homework."
I have been asked to participate in a UN sponsored meeting, led by the IAU and Spain, called Dark and Quiet Skies (D&QS). This is a UN effort to have some international agreements on light pollution, satellite proliferation, Observatory protections, radio spectrum and more.
Dr. Mario Motta, "'Dark and Quiet Skies,' a UN effort at light pollution control and more" I was asked to be part of this meeting, along with other researchers, to expand on my previous American Medical Association (AMA) reports on light pollution regarding human health effects. I am currently a Trustee of the AMA (the governing board of the AMA), and the AMA has been supportive in allowing me to officially represent them in this endeavor. This is because the AMA has an existing policy on LED lighting, of which I was primary author for in 2016. It has been a 6-month effort to produce the “final document” that was ratified at an October 2020 meeting (online due to Covid), and has been submitted for review by the UN. This is a work of the whole committee, though I was the primary author on sections regarding human health effects. There are four other reports (e.g. on satellite proliferation, observatory protection, etc.), which expand this encompassing document. We hope it leads to eventual UN approval by the general assembly. There is a follow-up meeting in October of 2021.
Stay tuned for more!
Past 2021 webinars
Dr. Matthew Kenworthy, "Shadows of Circumplanetary Disks: J1407 and J0600" Planets form in the disks surrounding very young stars, and the planets themselves will have a smaller disk around them in which moons will form. These circumplanetary disks are hundreds of times larger than Saturn's rings and when they transit in front of their parent stars, the transits can last hundreds of days, with individual ring structures causing fluctuations on timescales of one day or less. The AAVSO has proved crucial in monitoring several stars in which we believe we are seeing circumplanetary disk transits. From the star J1407 and its eclipses in 2007, through to the current monitoring campaign of J0600, I'll show what we can discover through multiband light curves and what we hope to see in the next few years.
Dr. Hans Moritz Günther, "Variability in young stars: From the AAVSO to X-rays" While our Sun is almost 5 billion years old, stars still form in the the dark clouds of our Milky Way. When we observe those regions we can learn how star and planet formation works, so that we also understand the formation of our own solar system and the Earth better. I will show how we can use variability on many different time scales from hours to centuries to understand how young stars work. How do they accrete mass? How do their proto-planetary disks evolve? Do proto-planets ever crah into the stars? I will look at several specific stars such as RW Aur and T Tau, the star that named the group of T Tauri stars, and describe our observations including X-rays, UV, and optical data. In most cases, no one observation alone can tell us what's happening on the star; only when we combine observations from the Chandra X-ray observatory, the Hubble Space Telescope, and AAVSO data we can learn about the physics of star formation. For a few examples, I will explain how observations on space telescopes are allocated and planned, and why the generous and flexible support by AAVSO observers is so crucial to our observing programs. Star formation is a very active area of research with many open questions to solve and certainly one of the areas in astronomy that delivers extremely beautiful images of the Milky Way that surrounds us.
Melanie Crowson, "Study of and Reclassification Evidence For Four Candidate RR Lyraes - TY Cam, V0363 Dra, NSV 13109, V1386 Aql" RR Lyrae stars have been an important aspect of studying stellar evolution since their discovery in the early 20th century and are now frequently used for distance measurements in the universe. The purpose of this research is to examine four RR Lyraes, two confirmed and two candidates, in an attempt to determine their periodicities and assess their classifications. RR Lyraes TY Cam, and V0363 Dra, as well as candidates NSV 13109 and V1386 Aql were chosen for this project, and were all studied using the American Public University’s (APU) 24 inch CDK telescope and the NKAF observatory, along with the ASAS-SN and SuperWASP archives. This study determined the most likely periods of TY Cam and V0363 Dra, and sided with the reclassification suggestion by ASAS-SN for NSV 13109 as an L class, irregular variable. For V1386 Aql it was found that much inaccurate data has been collected on this star due to its proximity to a brighter companion; however it appears to be a promising variable candidate, but requires more precision photometry to solidify its classification. Future research by APU will include such observations on this challenging, potential variable.
Dr. Sarah Antier,"Kilonova-catcher project at GRANDMA and how AAVSO observers can help" Diverse messengers - photons and gravitational waves - provide a new picture of the collision of two neutron stars. In this talk, I will first review briefly how coherent analysis of the messengers can not only better constrain the astrophysical scenarios at play, but also further knowledge on the cosmology and fundamental physics side. In a second part, I will present the Global Rapid Advanced Network Devoted to the Multi-messenger Addicts, which aims to identify and characterize the optical counterparts of gravitational-wave sources. As a third part, I will describe how you can, as an amateur astronomer, join the project and participate in the observations of neutron star mergers.
Dennis Conti, AAVSO Exoplanet Observing Section, "Using AstroImageJ for Exoplanet Analysis" This webinar will include a step-by-step walkthrough of using the AstroImageJ freeware for the reduction, differential photometry, modeling, and overall analysis of exoplanet observations.
Dr. Luisa Rebull, "Stellar Rotation in Young Clusters using K2 and TESS" K2 has provided a phenomenal opportunity to study properties of stars in clusters, particularly young low-mass stars, far beyond the expectations of the original Kepler mission. The high-precision photometry provided by K2 allows us to probe stellar variability to lower masses and lower amplitudes than has ever been done before. Younger stars are generally more rapidly rotating and have larger star spots than older stars of similar masses, so spots rotating into and out of view reveal the (surface) rotation rate of these stars. K2 has monitored stars from several clusters, most notably Rho Oph (~1 Myr), Taurus (~5 Myr), USco (~20 Myr), the Pleiades (~125 Myr), and Praesepe (~700 Myr). The light curves have yielded thousands of rotation rates, and revealed far greater diversity in light curves than was anticipated. Now that we have TESS data as well, we can add the Upper Centaurus-Lupus (UCL) and Lower Centaurus-Crux (LCC) young moving groups (~15 Myr). In this talk, I will review the K2 results and present early results from UCL/LCC.
Dr. Margarita Karovska, "Why is it important to observe/monitor LPVs?" Long Period Variables (LPVs) are evolved stars (cool giants and supergiants) that show significant variations (including photometric, spectral, and variations of other physical characteristics) on time scales ranging from days to many years, even centuries (as shown for example by the AAVSO long term monitoring of their light curves). Some of these stars show regular periodic brightness changes due to pulsation, in some cases few magnitudes over hundreds of days (e.g., Miras). Longer secondary periods have also been observed, on the order of thousands of days, with the causes still not clearly identified. Among the LPVs there are stars that show irregular variations, and the causes of this variability have not yet been determined. A number of LPVs have a companion star, including an evolved compact white dwarf accreting mass from the powerful wind of the cool giant or supergiant.
Based on many years of multi-mission, multi-wavelength studies of these incredibly interesting sources, including high-angular resolution studies using ground- and space-based observations, I can summarize the results with three words: fascinating, unexpected, and surprising! The seemingly regular behaviour of many LPVs is anything but that--when studied on a longer time scale of years!
I will highlight some recent results with emphasis on the critical role of the AAVSO long term LPV observing/monitoring in enabling these discoveries and on the potential for many future discoveries.