This lab analyzed variable stars from the American Association of Variable Star Observers’ International Variable Star Index, which had magnitudes between 9 and 12.5. The stars were also classified as potential RR Lyrae variable stars. The goal of the lab was to determine if the classification was correct. In order to do this, we used tables containing photometric measurements, with data collected by ASAS and ASAS-SN. The tables were then analyzed in Google Colab to determine the light curves, the period, the epoch, and the minimum and maximum magnitude . The light curve are used to determine how the brightness of the changer over time. If the star was an RR Lyrae, the rise was also calculated. If it was an eclipsing binary system with well-defined eclipse duration, an EA, the length of phase the stars spend eclipsed was estimated from the light curve. With these values, we were able compare our period to the one in the AAVSO VSX Bright “RR Lyrae” variables spreadsheet along with comparing our light curves with the ones in the variable star atlas. A big difference in periods could indicate the need for a revision. In order to properly determine the variable type, we also had to consider the light contamination from nearby stars as their light would have blended with the data of the target star. All the star that I analyzed did not contain any light contamination.

For this post, I will discuss two stars I have analyzed.

V1059 Cas is a variable star located in the Cassiopeia constellation, which is also an asterism. It is located in the northern sky and is named after the vain Queen Cassiopeia, from Greek Mythology. The constellation was one of the 48 constellations listed by Ptolemy, a Greek astronomer,  in the 2nd-century. A variable star is a star that has fluctuations in its brightness.

V1059 Cas was classified as an RRAB. In my analyzing, the period I was able to determine was 0.6495991 days, which resulted with a period difference of 8.09E-05 with the given period from the AAVSO VSX spreadsheet. From this and the light curve, which matched an RRAB, I stated that the star did not need to be revised. The epoch was 2455941.156, rise was 42, maximum magnitude: 10.32 and minimum magnitude: 10.56.

V1059 Cas was part of a study done by Kinemuchi K. et al (2006) analyzed RR Lyrae stars in the northern. This study analyzed many aspects of the stars, For example, the distances to the RRAB stars were determine with the use of an “adopted luminosity-metallicity relation with corrections for interstellar extinction”.

The second star was ASAS J203832-1856.5, located in the Capricornus constellation. It is located in the southern sky and was also one of the 48 constellations listed by Ptolemy. The name of the constellation is Latin for “horned goat” or “goat horn” or “having horns like a goat’s”.

This star was classified as an RRC. In my analyzing, I determined a period of 0.4502572 days, which resulted in a period difference of -2.25E-01. This is a huge difference and was the first indication that the star was wrongly classified. The resulting light curve matched the one of an EW. From, this I was able to state that the star is more likely an EW than an RRC. The epoch was 2458677.631, maximum magnitude: 10.79 and minimum magnitude: 10.97. Due to it being an EW variable star there wasn’t a rise or an eclipse duration due to it being an EW.

Overall, this was a very interesting and challenging project, which I deeply enjoyed.