TypeCepheidThese are the classical Cepheids, or δ Cephei-type variables. Comparatively young objects that have left the main sequence and evolved into the instability strip of the Hertzsprung-Russell (H-R) diagram, they obey the well-known Cepheid period-luminosity relation and belong to the young disk population. DCEP stars are present in open clusters. They display a certain relation between the shapes of their light curves and their periods.AAVSO Alert Notice 529 October 1, 2015Click for lightcurveObserving campaign on 5 variables in CygnusDr. George Wallerstein (University of Washington) has requested AAVSO assistance in monitoring 5 variable stars in Cygnus now through December 2015. He is working to complete the radial velocity curves for these stars, and needs optical light curves for correlation with the spectra he will be obtaining.Dr. Wallerstein writes: "I need to know the time of max or min so I can assign a phase to each spectrum. Most classical cepheids are quite regular so once a time of max or min can be established I can derive the phase of each observation even if my obs are several cycles away from the established max or min. MZ Cyg is a type II cepheid and they are less regular than their type I cousins."" SZ Cyg, X Cyg, VX Cyg, and TX Cyg are all classical Cepheids.V and visual observations are requested. These are long-period Cepheids, so nightly observations are sufficient; many observations made over one night are not necessary.
Hills Observatory: 1 January 2013 to 19 January 2019