Dr. Matthew Kenworthy, "Shadows of Circumplanetary Disks: J1407 and J0600" Shadows of Circumplanetary Disks: J1407 and J0600Planets 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. 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. 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.