2007PASP..119.1256A

If magnetic fields cause elemental abundances to change in the stellar photosphere, then all magnetic chemically peculiar (mCP) stars should exhibit signatures of this effect in both their spectra and flux distributions. Given that all stars rotate, these stars should be magnetic, spectrum, and photometric variables, albeit sometimes of low amplitude. We study differential Strömgren observations from the Four College Automated Photoelectric Telescope (FCAPT) of α Psc, HR 5857, and HR 6709, which are small-amplitude mCP stars, and AB Cet, HD 15890, and HR 8240, which were thought to be near-constant mCP stars, to determine the periods and amplitudes of their photometric variability. We construct the photometric amplitude distribution functions of the mCP stars studied by the first author to obtain statistics on their photometric variability in Strömgren photometry. The star α Psc has a period of 0.74552 days, with its largest amplitude in u of 0.030 mag. The largest amplitude (0.035 mag) for HR 5857 is also for u. We confirmed the period of 1.29957 days found by Hatzes using Doppler imaging. For HR 6709 the largest amplitude observed (0.010 mag) is for u photometry. Its period is 1.20352 days. AB Cet might be minimally variable. HD 15980 appears to be minimally variable, with a period of at least 5 yr. HR 8240 is variable with a b amplitude about 0.05 mag and a period that is several years long. Additional observations of these six stars would be useful to confirm their characteristics. Two apparently constant stars studied with FCAPT Strömgren data, HD 11187 and HD 50169, should be checked to see whether they are long-period variables. If additional observations show their variability, then all mCP stars observed photometrically by the first author with the FCAPT will be found to be variable.