Interferometry of chemically peculiar stars: theoretical predictions versus modern observing facilities

Abstract

By means of numerical experiments we explore the application of\ninterferometry to the detection and characterization of abundance spots in\nchemically peculiar (CP) stars using the brightest star eps~Uma as a case\nstudy. We find that the best spectral regions to search for spots and stellar\nrotation signatures are in the visual domain. The spots can clearly be detected\nalready at a first visibility lobe and their signatures can be uniquely\ndisentangled from that of rotation. The spots and rotation signatures can also\nbe detected in NIR at low spectral resolution but baselines longer than 180~m\nare needed for all potential CP candidates. According to our simulations, an\ninstrument like VEGA (or its successor e.g., FRIEND) should be able to detect,\nin the visual, the effect of spots and spots+rotation, provided that the\ninstrument is able to measure $V^2\\approx10^{-3}$, and/or closure phase. In\ninfrared, an instrument like AMBER but with longer baselines than the ones\navailable so far would be able to measure rotation and spots. Our study\nprovides necessary details about strategies of spot detection and the\nrequirements for modern and planned interferometric facilities essential for CP\nstar research.\n