Proposal #73

ASAS J143751-6454.9 is an LPV which only has observations from ASAS (available between 2001 and 2009 only). There are no observations in the AAVSO AID or any of the other surveys (based on a check performed through VSX) and there is no literature available which contains other observations apart from ASAS data. It was first brought to the attention of the AAVSO by Sebastian Otero who remarked on the dual maximum nature of this LPV. This was reported in the July 2017 issue of the AAVSO Newsletter. Analysis of the ASAS data (2001–2009) clearly shows a pronounced dual maximum with the secondary minimum being unusually deep. A preliminary period for this star is 539 days, which is quite long for an LPV. LPV's which show prominent dual maxima features in their light curves are relatively rare. Generally the first maxima is fainter than the first (but not always). The average time between the first fainter maxima and the brighter second one is 220 days (ranging from 200 to 231 days in the ASAS data) and then there's a further average duration of 327 days (ranging from 310-351 days) between the brighter second maximum and the next fainter one.

I have shared my ASAS analysis of this star with John Percy who remarked that he light curve clearly does not repeat from cycle to cycle, and the phase curve with a single period has a lot of scatter. Therefore it's more likely that the star is pulsating in (at least) two periods. Stan Walker, Director VSS, believes that the light curve behaviour of this star appears almost unique. Dual maxima LPV's are a rare subset of MIras in general with only 2 known in the northern sky and less than 10 in the southern sky.

I propose to utilise MJUO to undertake BVri photometry of this LPV at a cadence of approximately 30 days over a 1,100 day period. This will cover approximately 2 full cycles for the star. The exact cadence is not important for an LPV such as this and therefore there is a lot of flexibility of when data can be acquired for this star to suit MJUO priorities. It is hoped that the MJUO can observe the star well beyond the faint cut off limit evident in the ASAS data.

I have publicised this star throughout the AAVSO and in particular have targeted some southern visual observers with large telescopes to potentially supplement the CCD photometry undertaken as part of this proposal. The intention would be to analyse the data after this 3 year period and prepare a paper for JAAVSO summarising the results.

I trust I have provided enough information on this proposal. Please let me know if any further information is required.

Regards
Andrew Pearce (PEX)
andrew.pearce@woodside.com.au