HP Lyrae / HP Lyr
Light curve and phase diagrams of the SRD* type semi regular variable HP Lyrae / HP Lyr
* See below for a discussion about the type of variable this star is.
The following light curve and phase diagrams were constructed from photometry of 93 images. 8 images were taken with the Bradford Robotic Telescope Galaxy Camera between 2014 July 24 and 2015 November 11, and 85 images were taken with the Open University COAST telescope in 2 runs; 2017 July 6 to 2017 December 27, and 2019 June 6 to 2019 September 3. Both telescopes were 14 inch/35 cm Schmidt-Cassegrain telescopes, and all images were taken using a V filter.
* See below for a discussion about the type of variable this star is.
The following light curve and phase diagrams were constructed from photometry of 93 images. 8 images were taken with the Bradford Robotic Telescope Galaxy Camera between 2014 July 24 and 2015 November 11, and 85 images were taken with the Open University COAST telescope in 2 runs; 2017 July 6 to 2017 December 27, and 2019 June 6 to 2019 September 3. Both telescopes were 14 inch/35 cm Schmidt-Cassegrain telescopes, and all images were taken using a V filter.
An enlargement of the middle section is below.
A number of phase diagrams were constructed from these observations.
The best fit period to these observations (Peranso/ANOVA) was 68.3162 days, generating the following phase diagram.
The best fit period to these observations (Peranso/ANOVA) was 68.3162 days, generating the following phase diagram.
The AAVSO VSX value for the period is 68.88 days (accessed 2020 March 21), which generated the following phase diagram.
There has been some discussion over time about which type of variable star this star is. The AAVSO VSX classify it as SRD, with a period of 68.88 days, while the GCVS classify it as an EB eclipsing binary, with a period of 140.75 days (both accessed 2020 March 21). The best fit period for these observations closest to the GCVS period was 138.66 days. Using this period generated the following phase diagram.
Photometry alone could not resolve this issue, but spectroscopy suggests that the system is indeed a semi-regular SRD type rather than an eclipsing binary. See the AAVSO VSX page for some references to papers regarding this star.
[Page updated 2020 March 21]