IM Aurigae / IM Aur
Light curves and phase diagrams of the EA type eclipsing binary IM Aurigae / IM Aur. All of these observations were made without filters and have not been transformed.
Light curve and phase diagram of IM Aur obtained from 68 images taken with the Bradford Robotic Telescope Cluster Camera (BRT) between 2013 October 20 and 2016 October 1.
The lack of data for the rise out of the primary minimum is (I presume) an artefact of the BRT scheduler 'phasing' or 'beating' with the almost 1.25d period of the star.
The lack of data for the rise out of the primary minimum is (I presume) an artefact of the BRT scheduler 'phasing' or 'beating' with the almost 1.25d period of the star.
A primary minimum was observed with the 2" Titan from Somerby Observatory on 2016 November 1.
The secondary minimum of IM Aur observed from Somerby Observatory with the 2" Titan on 27 December 2017. The 1856 images used were unfiltered.
A primary minimum was observed from Somerby Observatory with the 2" Titan on 14 December 2022. The time of minimum was calculated, as shown below.
Coming out of a secondary minimum observed from Somerby Observatory with the 2" Titan on 2022 December 21.
Coming out of a secondary minimum observed from Somerby Observatory with the 2" Titan on 2022 December 26.
A secondary minimum observed from Somerby Observatory with the 2" Titan on 2023 January 16. The gaps are due to passing cloud.
It was noticed that the maximum magnitude after the secondary minima on 2017 December 27, 2022 December 21 and 2022 December 26 were not the same. That of 2017 was closer to mag 7.94 than the 7.98 of the other 2, or of the maximum after the primary minimum of 2022 December 24. These are shown below, together with the check star at mag 8.4 shown in red. This is consistent for all sets of results, which suggests that the difference in maximum magnitude of IM Aur is possibly not an observational or processing artefact. That said, these small amplitude light curves are pushing my equipment to the limit, and this is not helped by the less than ideal weather conditions (passing cloud and winter mist) that we seem to be experiencing a lot of at the moment. I will be giving this system a rest for a while in the hope that conditions improve sometime.
It has been suggested that this system is complicated by the presence of a third body, which not only affects the o-c results but the shapes, and hence observed brightnesses, of the two main components, or conversely that there might be mass transfer between the two components (see below).
Whatever the case, the above observations suggest the importance of observing eclipsing binaries outside eclipse, as there is much more information to be gleaned from these systems than from their times of minima alone. As ever, more observations needed.
Whatever the case, the above observations suggest the importance of observing eclipsing binaries outside eclipse, as there is much more information to be gleaned from these systems than from their times of minima alone. As ever, more observations needed.
The catalogued period for this system is given as 1.2472863d (GCVS), 1.24728553d (AAVSO VSX) and 1.2472857d (Kreiner). (Accessed 2022 December 17). There is significant o-c activity with this system (Kreiner). The following articles discuss this system in some detail; Bruhweiler et al 1986 and Borkovits et al 2002.
[Page updated 2023 January 23]