8 research outputs found
Simultaneous optical and X-ray observations of flares and rotational modulation on the RS CVn binary HR 1099 (V711 Tau) from the MUSICOS 1998 campaign
We present simultaneous and continuous observations of the H,
H, He {\sc i} D, Na {\sc i} D,D doublet and the Ca
{\sc ii} H & K lines for the RS CVn system HR 1099. The spectroscopic
observations were obtained during the MUSICOS 1998 campaign involving several
observatories and instruments, both echelle and long-slit spectrographs. During
this campaign, HR 1099 was observed almost continuously for more than 8 orbits
of 2\fd8. Two large optical flares were observed, both showing an increase in
the emission of H, Ca {\sc ii} H & K, H and He {\sc i} D
and a strong filling-in of the Na {\sc i} D,D 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 and
He {\sc i} D 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 G5 V
star was in front. A possible periodicity in the X-ray flare-like events was
also found.Comment: 20 pages, 12 figures, 8 tables, accepted by A&
The supply of multiple ecosystem services requires biodiversity across spatial scales.
The impact of local biodiversity loss on ecosystem functioning is well established, but the role of larger-scale biodiversity dynamics in the delivery of ecosystem services remains poorly understood. Here we address this gap using a comprehensive dataset describing the supply of 16 cultural, regulating and provisioning ecosystem services in 150 European agricultural grassland plots, and detailed multi-scale data on land use and plant diversity. After controlling for land-use and abiotic factors, we show that both plot-level and surrounding plant diversity play an important role in the supply of cultural and aboveground regulating ecosystem services. In contrast, provisioning and belowground regulating ecosystem services are more strongly driven by field-level management and abiotic factors. Structural equation models revealed that surrounding plant diversity promotes ecosystem services both directly, probably by fostering the spill-over of ecosystem service providers from surrounding areas, and indirectly, by maintaining plot-level diversity. By influencing the ecosystem services that local stakeholders prioritized, biodiversity at different scales was also shown to positively influence a wide range of stakeholder groups. These results provide a comprehensive picture of which ecosystem services rely most strongly on biodiversity, and the respective scales of biodiversity that drive these services. This key information is required for the upscaling of biodiversity-ecosystem service relationships, and the informed management of biodiversity within agricultural landscapes