AAVSO: American Association of Variable Star Observers

Proposal #82

Proposer (3053) Andrew Pearce (apearce6916@gmail.com) obscode: PEX
Assigned To(3663) Dirk Terrell
Date SubmittedFeb. 25, 2018

KK Car is a Mira star with a mean period of approximately 415 days. It does not have a significant observation history with only approximately 500 observations in the AID extended back to 1984. More intense coverage since 2012 has revealed that the star does appear to exhibit humps or standstills in it's light curve on the ascending branch which is something seen on other longer period Mira stars. However some of the visual observations appear discordant and so the true nature of these standstills has yet to be fully defined.

There is little available in the literature regarding KK Car. A Simbad search has revealed no specific references to the star. There does not appear to be any BVRI photometric data available apart from the limited dataset in the AID and only B and V data has been captured in the AID. It has been followed by ASASSN since this system commenced.

Since late January 2018, visually the star appears to have been in a standstill at a constant brightness of around mag 12.6 for a period of approximately 30 days. The unusual aspect of this is that this standstill seems to have occurred on a descending branch of the light curve. This appears to be extremely rare as not other LPV's that show humps have been known to display a hump in this portion of the light curve. These are based on my visual observations. However ASASSN data in this period has not detected a standstill but rather a steady decrease in brightness which is a bit of a mystery!

It is proposed to use the OC61 telescope to secure BVRI photometry at a cadence of approximately 10 days to see if the stars behaviour can be better defined. With a mean period of 415 days, it is proposed to extend the programme for 830 days such that 2 full cycle can be captured to maximise the chances of detecting a hump or standstill.

Target RA (H.HH) Dec (D.DD) Magnitude Telescope Observation Frequency Expiration Date Proprietary Term
KK Car 8.600358 -59.94078 14.0–9.2 No


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