Pulsating star, δ Scuti, RR Lyrae, light curve, period-luminosity relationships


Pulsating stars are used as standard candles which are helpful in determining distances to stellar objects along with the relationship between their period and apparent luminosity. The focus of this study was the variable star, V1719 Cygni, which is often classified as a Delta (δ) Scuti star, but there exists debate that it should be classified as a RR Lyrae star due to its abnormal light curve and similar characteristics between the two variable star categories. Observational data was taken in 2019 using the Las Cumbres Observatory international telescope network. The resulting data were calibrated using comparison stars in the field of known magnitude. We performed aperture photometry in the V-, B-, i- and z- photometric bands. The period was then found using the string method which determines the most probable period. The average period was found to be 0.269 days with an error of 0.0005. The distance was calculated using the previously established period-luminosity relation for both δ Scuti and RR Lyrae stars to determine which classification fits our data best. The distance calculation was more closely aligned with previous results when using the δ Scuti relationship as compared to the RR Lyrae relationship. Based on these results, we conclude that V1719 Cygni should be classified as a high-amplitude δ Scuti variable star. It is important to note that period-luminosity relationships have not been established in all photometric bands, but the period measurements obtained in the B-, i-, and z- bands will help to establish that relationship.