Doppler Imaging of Chemical Abundance Spots

Chemical abundance maps for α2 Canum Venaticorum reconstructed self-consistently with the stellar magnetic field geometry.
Kochukhov et al., 2002, A&A, 389, 420
Chemical abundance maps for 53 Camelopardalis reconstructed self-consistently with the stellar magnetic field geometry.
Kochukhov et al., 2004, A&A, 414, 613
Distribution of mercury abundance ("Hg") and isotope composition ("q", higher values correspond to prevalence of heavier mercury isotopes) over the surface of the rapidly rotating Hg-Mn star α Andromedae. This is the first modeling of an inhomogeneous distribution of chemical composition for a non-magnetic chemically peculiar star. The discovery of mercury spots on the surface of α Andromedae demonstrated that magnetic field is not the only effect responsible for creating and supporting surface structures in peculiar stars.
Adelman, Gulliver, Kochukhov, Ryabchikova, 2002, ApJ, 575, 449
Results of the long-term monitoring of the structure of mercury clouds in α Andromedae. We have observed this star during seven years and reconstructed a series of mercury abundance maps. The plots below show the Hammer-Aitoff projection of the Hg surface distribution for years 1998, 2002 and 2004. The lower row shows respective difference maps. For the first time in any star, we have detected slow variation of chemical structures - a remarkable phenomenon akin to weather in terrestrial and giant planet atmospheres.
Kochukhov et al., 2007, Nature Physics, 3, 526
Surface distributions of Ca, Fe, Ba and Nd abundance over the surface of the southern late A pulsating chemically peculiar star HR 3831. Contours of equal abundance are plotted with a step of 1.0 dex and highlight complex abundance structures in HR 3831. The double green line shows the stellar rotation equator, while dashed line, cross and circle shows approximate position of the magnetic equator, positive and negative poles of the dominant dipolar component of the stellar magnetic field. These four chemical composition maps were produced using exceedingly high-quality stellar spectra (observations at 36 rotation phases with the spectral resolving power of 123,000 and signal-to-noise ratio in excess of 700) and thus constitute the most precise stellar chemical abundance maps ever obtained.
Kochukhov et al., 2004, A&A, 424, 935
Other chemical abundance distributions of HR 3831 reconstructed with observational data of moderately high quality. Note the high-contrast maps of lithium (concentrated in two small spots at the magnetic poles) and oxygen (forms a ring of enhanced abundance precisely at the magnetic equator).
Kochukhov et al., 2004, A&A, 424, 935
More chemical abundance maps for HR 3831. Alltogether we reconstructed surface distributions of 17 chemical species for HR 3831, which is considerably more than 3-4 abundance maps typically available for other peculiar stars and thus represents the most comprehensive observation of the results of radiative diffusion in an Ap star.
Kochukhov et al., 2004, A&A, 424, 935
Chemical abundance maps for young magnetic Bp star HD 72106. With an age of about 9 Myr this object already shows typical CP-star surface chemical spot pattern, indicating efficiency and short timescale of the underlying process of the diffusive separation of chemical elements.
Folsom, Wade, Kochukhov, et al., 2008, MNRAS, 391, 901