Uploaded April 2021 | Updated September 2026, 2 weeks ago
Originally broadcast march 27, 2021, this AAVSO webinar features Dr. David Whelan (Austin College) discussing "Classifying Algol C, the Non-Eclipsing Member of the beta Persei System" with Megan Frank and Jessica Junginger, both also of Austin College. 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.
Explore AAVSO and find out how YOU can make a meaningful contribution to science at aavso.org
Originally broadcast march 27, 2021, this AAVSO webinar features Dr. David Whelan (Austin College) discussing "Classifying Algol C, the Non-Eclipsing Member of the beta Persei System" with Megan Frank and Jessica Junginger, both also of Austin College. 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.
Explore AAVSO and find out how YOU can make a meaningful contribution to science at aavso.org
