Uploaded May 2024 | Updated September 2026, 2 weeks ago
Originally broadcast on April 13, 2024.
While all cataclysmic variables contain the same basic component stars (a white dwarf and a close companion), they vary widely depending on individual properties like magnetic fields, accretion state, evolution state and companion type.
In this webinar, Prof. Paula Szkody described the photometric and spectroscopic behavior of various types of cataclysmic variables, detailing those which are well understood, and describing the observations which are still needed to complete our understanding of these fascinating systems.
After her presentation, Prof. Szkody stayed online for an extended Q&A session, answering many thought-provoking questions from the audience.
*Timestamps:*
00:00 Opening announcements
02:23 Introducing Prof. Paula Szkody
03:58 Presentation - A Grand Tour of Capricious Cataclysmic Variables
50:28 Q&A with Prof. Szkody
01:22:46 Closing announcements
*Prof. Paula Szkody* uses a multiwavelength approach to study close binary stars with active mass transfer (Cataclysmic Variables). Her current research involves ultraviolet observations with the Hubble Space Telescope as well as APO and ground-based optical facilities around the world. She is currently finding the faintest, lowest mass transfer CVs leading to insights into the nature of mass transfer and accretion onto magnetic and non-magnetic white dwarfs, accretion disks and their X-ray-emitting boundary layers, stellar coronae, and the effects of irradiation on the upper atmospheres of late-type secondary stars.
Her work involves observations of all types of close binary systems involving mass transfer onto a white dwarf. This includes novae, dwarf novae, and novalikes which are all termed Cataclysmic Variables (CVs). The magnetism of the white dwarf determines if the mass flow from the low mass companion will be through an accretion disk, a curtain or a funnel onto the magnetic poles. The structure of the accretion flow as well as the underlying stars is determined from multiwavelength observations from X-ray through ultraviolet and optical to the infrared. Many of these objects are being discovered through ground-based surveys (SDSS, CRTS, iPTF) and followup takes place from space and ground to determine their specific types and how they fit into population models of close binary formation.
*✩ Interested in attending a live AAVSO webinar on Zoom?* Visit aavso.org/webinars to view our schedule and register for upcoming events.
Originally broadcast on April 13, 2024.
While all cataclysmic variables contain the same basic component stars (a white dwarf and a close companion), they vary widely depending on individual properties like magnetic fields, accretion state, evolution state and companion type.
In this webinar, Prof. Paula Szkody described the photometric and spectroscopic behavior of various types of cataclysmic variables, detailing those which are well understood, and describing the observations which are still needed to complete our understanding of these fascinating systems.
After her presentation, Prof. Szkody stayed online for an extended Q&A session, answering many thought-provoking questions from the audience.
*Timestamps:*
00:00 Opening announcements
02:23 Introducing Prof. Paula Szkody
03:58 Presentation - A Grand Tour of Capricious Cataclysmic Variables
50:28 Q&A with Prof. Szkody
01:22:46 Closing announcements
*Prof. Paula Szkody* uses a multiwavelength approach to study close binary stars with active mass transfer (Cataclysmic Variables). Her current research involves ultraviolet observations with the Hubble Space Telescope as well as APO and ground-based optical facilities around the world. She is currently finding the faintest, lowest mass transfer CVs leading to insights into the nature of mass transfer and accretion onto magnetic and non-magnetic white dwarfs, accretion disks and their X-ray-emitting boundary layers, stellar coronae, and the effects of irradiation on the upper atmospheres of late-type secondary stars.
Her work involves observations of all types of close binary systems involving mass transfer onto a white dwarf. This includes novae, dwarf novae, and novalikes which are all termed Cataclysmic Variables (CVs). The magnetism of the white dwarf determines if the mass flow from the low mass companion will be through an accretion disk, a curtain or a funnel onto the magnetic poles. The structure of the accretion flow as well as the underlying stars is determined from multiwavelength observations from X-ray through ultraviolet and optical to the infrared. Many of these objects are being discovered through ground-based surveys (SDSS, CRTS, iPTF) and followup takes place from space and ground to determine their specific types and how they fit into population models of close binary formation.
*✩ Interested in attending a live AAVSO webinar on Zoom?* Visit aavso.org/webinars to view our schedule and register for upcoming events.
![AAVSO How to [Understand Star Photometry]](https://i.ytimg.com/vi/ufbFaUywEBg/mqdefault.jpg "AAVSO How to [Understand Star Photometry]
Originally broadcast March 5, 2022. Instructor: Richard Berry. Berry is well experienced in stellar photometry and was a programmer for the science-oriented software Astronomical Image Processing for Windows (AIP4Win).
Photometry seems like magic: you click on a star image and a magnitude pops up! But a lot happens between the moment you click and the moment that magnitude pops up on the computer screen. Berry explores with you in non-technical terms what the computer has to do to turn your pixels into meaningful information. This talk complements Bob Buchheims Introduction to Photometry 2021 webinar (https://www.youtube.com/watch?v=gcE7c4CggFM). Berry describes how to do photometry by presenting the inside picture of how photometry works and why it works so well. He demonstrates using AIP4Win software (join aip4win@groups.io to download this freeware package), but all stellar photometry software works pretty much the same way.
Interested in AAVSOs Instrumentation & Equipment Section led by Rich Berry? aavso.org/instrumentation-section
Interested in our other How-to Hours and webinars? aavso.org/programs-events
Visit us and learn how to make a meaningful contribution to science at aavso.org")
![AAVSO How to [Think About Transformation]](https://i.ytimg.com/vi/urgkBDkiUEE/mqdefault.jpg "AAVSO How to [Think About Transformation]
with instructor Tom Calderwood. Originally broadcast June 4, 2022. Astronomers have spent decades defining photometric systems. Systems like Johnson-Cousins define a standard scale on which photometry from different observers can be directly compared. However, simply using a Johnson or Cousins filter does *not* put your magnitudes on the standard system. Your data require adjustment, and this step is known as transformation. In this discussion, Tom explains why transformations are necessary, and sketch out the basics of how their parameters are determined.
Tom Calderwood is head of the AAVSO Photoelectric Photometry Observing Section. He observes from Central Oregon, and is the author of The Great Dimming of Betelgeuse in the March 2021 issue of Sky & Telescope. A graduate of MIT in mathematics, he is a retired software engineer who worked on parallel processing computers, communication networks, video games, and the data system for the Chandra X-ray Observatory.
Interested in attending a free live How to [...] session? aavso.org/2022-how-to-hours
Want to learn more about photoelectric photometry (PEP)? AAVSO has an observing section full of people dedicated to it: https://www.aavso.org/aavso-photoelectric-photometry-pep-section
Check out all AAVSO has to offer you at aavso.org")
