Astrophysics - Solar and Stellar Astrophysics

Three Years of SPHERE: The Latest View of the Morphology and Evolution of Protoplanetary Discs

Spatially resolving the immediate surroundings of young stars is a key challenge for the planet formation community. SPHERE on the VLT represents an important step forward by increasing the opportunities offered by optical or near-infrared imaging …

BP Piscium: its flaring disc imaged with SPHERE/ZIMPOL$^★$

Whether BP Piscium (BP Psc) is either a pre-main sequence T Tauri star at d ensuremath≈ 80 pc, or a post-main sequence G giant at d ensuremath≈ 300 pc is still not clear. As a first-ascent giant, it is the first to be observed with a molecular and …

Multiple rings in the transition disk and companion candidates around RX J1615.3-3255. High contrast imaging with VLT/SPHERE

Context. The effects of a planet sculpting the disk from which it formed are most likely to be found in disks that are in transition between being classical protoplanetary and debris disks. Recent direct imaging of transition disks has revealed …

Magnetic field topology and chemical spot distributions in the extreme Ap star HD 75049

Context. Intermediate-mass, magnetic chemically peculiar (Ap) stars provide a unique opportunity to study the topology of stellar magnetic fields in detail and to investigate magnetically driven processes of spot formation. Aims: Here we aim to …

Surprising detection of an equatorial dust lane on the AGB star IRC+10216

Aims: Understanding the formation of planetary nebulae remains elusive because in the preceding asymptotic giant branch (AGB) phase these stars are heavily enshrouded in an optically thick dusty envelope. Methods: To further understand the morphology …

Imaging the circumstellar environment of the young T Tauri star SU Aurigae

The circumstellar environments of classical T Tauri stars are challenging to directly image because of their high star-to-disk contrast ratio. One method to overcome this is by using imaging polarimetry where scattered and consequently polarised …

Three-dimensional magnetic and abundance mapping of the cool Ap star HD 24712 . I. Spectropolarimetric observations in all four Stokes parameters

Context. High-resolution spectropolarimetric observations provide simultaneous information about stellar magnetic field topologies and three-dimensional distributions of chemical elements. High- quality spectra in the Stokes IQUV parameters are …

Are there tangled magnetic fields on HgMn stars?

Context. Several recent spectrophotometric studies failed to detect significant global magnetic fields in late-B HgMn chemically peculiar stars, but some investigations have suggested the presence of strong unstructured or tangled fields in these …

The color dependent morphology of the post-AGB star HD 161796

Context. Many protoplanetary nebulae show strong asymmetries in their surrounding shells, pointing to asymmetries during the mass loss phase. Questions concerning the origin and the onset of deviations from spherical symmetry are important for our …

Magnetically Controlled Accretion on the Classical T Tauri Stars GQ Lupi and TW Hydrae

We present high spectral resolution (R ensuremath≈ 108, 000) Stokes V polarimetry of the classical T Tauri stars (CTTSs) GQ Lup and TW Hya obtained with the polarimetric upgrade to the HARPS spectrometer on the ESO 3.6 m telescope. We present data on …