X Cygni
Amateur Astronomer Discovers the Cepheid X Cygni and Much More!
![]() |
![]() |
The Cepheid variable X Cygni an |
![]() |
![]() |
The Cepheid variable X Cygni an |
![]() |
Zeta Geminorum is often called the "kneecap" of the constellation Gemini. |
![]() |
![]() |
Top: Delta Cep is the star denoted in the bicep of the King's mighty arm which holds the ruling staff. |
β Lyrae, known as Sheliak to the ancient Arabs and Tsan Tae to the ancient Chinese, was discovered to be a variable star by John Goodricke in 1784, about two years after his successful explanation of the light variations of Algol. In the more than two centuries since its discovery, β Lyrae has played a game of cat and mouse with astronomers attempting to unlock its secrets. Only slowly have some of those secrets been revealed.
Author's note: This article was written prior to the start of the 2009-2011 eclipse. Epsilon Aurigae was the focus of the AAVSO's Citizen Sky project. |
U Monocerotis is an interesting and bright RV Tauri-type variable. Fluctuating between visual magnitude of about 5.1 - 7.1, U Mon is seen to exhibit two periods: a short-term and a long-term period of about 92 and 2475 days, respectively (Percy et al. 1991). The first observations of U Mon date back to the 1870s (Percy et al. 1991), however, the variable has only been monitored continuously by AAVSO observers since 1945.
RV Tauri — The strange prototype of a strange class