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Doppler Imaging and Flare Activity on HR1099

In collaborative work with David García Alvarez (an Observatory PhD student now at Harvard) and John Butler, an extensive study of the RS CVn binary HR1099 was completed leading to two papers; the first on Doppler imaging and the second on flare activity.

Spectra for the Doppler imaging were taken at two different sites, Kitt Peak National Observatory (KPNO), Arizona, and Mount Stromlo Observatory (MSO), Australia, during the 1998 MUltiSIte COntinuous Spectroscopic (MUSICOS) campaign. Contemporaneous photometry from the Wolfgang-Amadeus Automatic Photoelectric Telescope (APT) at the Fairborn Observatory, Tucson, Arizona, was used to constrain the Doppler images. The resulting maximum entropy reconstructions based on the least-squares deconvolved profiles, derived from $\sim$2000 photospheric absorption lines, reveal the presence of starspots at medium-high latitudes. We have obtained maps for both components of the binary system for the first time. The predominant structure in the primary component is an off-centred polar spot, confirming previous work on the same target by using independent codes. The result is verified by using both data sets independently. The lower spectral resolution data set gives a less detailed map for the MSO data set. The images obtained for the secondary component show a low-latitude spot around orbital phase 0.7. This spot seems to mirror the structure seen on the primary. It might suggest that tidal forces may influence the spot distribution on this binary system.

In the flare paper, simultaneous and continuous observations in H$\alpha$, H$\beta$, HeI D₃, the NaI D₁D₂ doublet and the CaII H & K lines were obtained. As above, the spectroscopic observations were obtained during the MUSICOS 1998 campaign involving several observatories and instruments, both echelle and long-slit spectrographs. During this campaign, HR1099 was observed almost continuously for more than 8 orbits of 2.8 days. Two large optical flares were observed, both showing an increase in the emission of H$\alpha$, CaII H & K, H$\beta$ and HeI D₃ and a strong filling-in of the NaI D₁,D₂ doublet.

Contemporary photometric observations were carried out with the robotic telescopes APT-80 of Catania and Phoenix-25 of Fairborn Observatories. Maps of the distribution of the spotted regions on the photosphere of the binary components were derived using the Maximum Entropy and Tikhonov photometric regularization criteria. Rotational modulation was observed in H$\alpha$ and HeI D₃ in anti-correlation with the photometric light curves. Both flares occurred at the same binary phase (0.85), suggesting that these events took place in the same active region. Simultaneous X-ray observations, performed by ASM on board RXTE, show several flare-like events, some of which correlate well with the observed optical flares. Rotational modulation in the X-ray light curve has been detected with minimum flux when the less active G5V star was in front. A possible periodicity in the X-ray flare-like events was also found.