000004746 001__ 4746
000004746 005__ 20200131165649.0
000004746 037__ $$aPOSTER-2020-0054
000004746 100__ $$aTrust, O. 
000004746 245__ $$aStarspots and rotation velocities of normal A- and Am-stars
000004746 260__ $$c2019
000004746 269__ $$c2019-08-19
000004746 520__ $$aUsing the “hump and spike” features, we computed the rotation frequencies and amplitudes. The corresponding equatorial rotational velocity (V rot ) and spot size were estimated. On fitting the auto-correlation functions of the light-curves with the appropriate model, we obtained the starspot decay-time scale. The V rot agrees well with the projected rotational velocity (ν sin i) in the literature. Considering a single circular and black spot, we estimate its radius from the amplitude of the “spike”. No evidence for a significant difference in the average “spike” amplitude and spot radius was found for Am/Fm and normal A stars. Indeed, we derived an average value of ∼ 21 ± 2 and ∼ 19 ± 2 ppm for the photometric amplitude and of 1.01 ± 0.13 and 1.16 ± 0.12 R E for the spot radius (where R E is the Earth radius), respectively. We do find a significant difference for the average spot decay-time scale, which amounts to 3.6 ± 0.2 and 1.5 ± 0.2 days for Am/Fm and normal A stars, respectively. In general, spots on normal A stars are similar in size to those on Am/Fm stars, and both are weaker than previously estimated. The existence of the “spikes” in the frequency spectra may not be strongly dependent on the appearance of starspots on the stellar surface. In comparison with G, K and M stars, spots in normal A and Am/Fm stars are weak which may indicate the presence of a weak magnetic field.
000004746 594__ $$aNO
000004746 6531_ $$astars: photometry
000004746 6531_ $$astars: chemically peculiar
000004746 6531_ $$astars: rotation
000004746 6531_ $$astars: starspots
000004746 700__ $$aJurua, E.
000004746 700__ $$aDe Cat, P.
000004746 700__ $$aJoshi, S.
000004746 773__ $$t"Stars and their variability observed from space - Celebrating the 5th anniversary of BRITE-Constellation", Vienna, Austria
000004746 8560_ $$fpeter.decat@observatoire.be
000004746 980__ $$aCPOSTER