4 49 Her

Winzer (1974) discovered that 49 Her (HR 6268 = HD 152308 = V823 Her) was a moderate amplitude photometric variable. He derived a period of 1.0978 days, but noted that the resonance period near 0.918 days was a possible alternative. Good quality differential uvby photometry was obtained with the FCAPT: 56 sets in 1996-97 and 19 sets in 1997-98. A periodogram analysis indicates that the period is close to 0.9366 days. For the best overlap with Winzer's V data rezeroed to the FCAPT y system, the period was lengthened to 0.93663 days. A slight adjustment in the zero epoch was also required. Thus

HJD(light maximum) = 2441453.925 $\pm$ 0.003 + (0.93663 $\pm$ 0.00002) E.

The light curves (Fig. 3) show nearly flat bottomed minima and sharp well defined maxima. The curves for u, v, b, and y are in phase. The minima appear to have two sub-minima with the one near phase 0.37 deeper than the one near phase 0.67. They are of order 0.005 mag fainter than the trend of adjacent values. The amplitudes are 0.055 mag in u, 0.028 mag in v, 0.035 mag in b, and 0.023 mag in y. That the second sub-minimum becomes less easy to see with increasing wavelength indicates that the flux distributions at the two sub-minima are not identical.

Abt & Morrell (1995) find v sin i = 95 km s^-1. With a period of order one day, we must be looking at 49 Her with the rotation pole pointing about 20$^{\circ}$ away from our line of sight. Thus we are seeing differences in the equatorial belt of $\pm$20$^{\circ}$ latitude which are diminished by limb darkening. Light maximum may coincide with the transit of a magnetic pole across the observable stellar photosphere.

  

Figure 3: Photometry of 49 Her plotted according to the ephemeris HJD(light maximum) = 2441453.925 + 0.93663 E. The FCAPT uvby values are shown as + signs while Winzer's V values as rezeroed to the y scale are closed diamonds