Context. The population of comets hosted by the Oort cloud is heterogeneous. Most studies in this area have focused on highly active objects, those with small perihelion distances or examples of objects with peculiar physical properties and/or unusual chemical compositions. This may have produced a biased sample of Oort cloud comets in which the

Aims: Our aim is to demonstrate the limitations of using a single-component model to study the magnetic field of an active region filament. To do this, we analyzed the polarimetric signals of the He I 10830 Å multiplet, which were acquired with the infrared spectrograph GRIS of the GREGOR telescope (Tenerife, Spain). Methods: After a first analysis

Aims: The determination of the magnetic filed vector in solar filaments is made possible by interpreting the Hanle and Zeeman effects in suitable chromospheric spectral lines like those of the He I multiplet at 10 830 Å. We study the vector magnetic field of an active region filament (NOAA 12087). Methods: Spectropolarimetric data of this active

This WP describes the future science opportunities using CMB spectral distortions of the cosmic microwave background as a probe of fundamental physics.

This white paper briefly summarizes stellar science opportunities enabled by ultra-high resolution (sub-100 μarc-sec) astronomical imaging in the visible (U/V) wavebands. We describe the science impact of imaging of several thousand bright (m < 6), hot (O/B/A) stars using a modern implementation of Stellar Intensity Interferometry (SII).

Microlensing in strong-lens systems with quasars provides a unique detailed view of the internal structure of active black holes to the scale of nano- arcseconds. The case is made for the potential of this approach to revolutionize our understanding of quasar physics and its role in broader questions, with a coherent community strategy.