Roberto Piazzesi

High spatial resolution images of the volcanic moon Io at visible and near-infrared wavelengths were obtained by the SHARK-VIS and SHARK-NIR instruments on the Large Binocular Telescope on UT 2025 February 18 and 23. Large-scale changes on Io’s surface are identified in these data and provide vital context for infrared observations from other telescopes and spacecraft. SHARK-VIS imaged part of the plume deposit from a large eruption close to Io’s south pole at Illyrikon that was first observed by NASA’s Juno spacecraft in 2024 December, detecting significant deposit modification. Examples of other significant surface changes detected include at Seth, identifying a new pyroclastic deposit in addition to the new lava flows previously detected in Juno infrared observations; at Amirani, confirming that volcanic activity was now confined to the southern half of the Galileo-epoch lava flow field; new red sulphur-rich deposits at Mixcoatl; and changes in the plume deposits around Prometheus. Plume deposits at Prometheus and at other volcanoes show evidence of complex interplay between different plumes issuing from the same volcano. The combination of SHARK-VIS and Juno JunoCam data moves closer to near-global, near-contemporaneous, visible-wavelength coverage of Io. SHARK-VIS lives up to its promise of a new era of planetary imaging at visible wavelengths and filling the temporal coverage gap between Juno and the arrival of the Europa Clipper and JUICE spacecraft in the Jovian system in 2030 and 2031, respectively.

We report the results from a pilot study to search for black holes and other dark companions in binary systems using direct imaging with SHARK-VIS and the iLocater pathfinder “Lili” on the Large Binocular Telescope. Starting from known single-lined spectroscopic binaries, we select systems with high mass functions that could host dark companions and whose spectroscopic orbits indicate a projected orbital separation ≥30 mas. For this first exploration, we selected four systems (HD 137909, HD 104438, HD 117044, and HD 176695). In each case, we identify a luminous companion and measure the flux ratio and angular separation. However, two of the systems (HD 104438 and HD 176695) are not consistent with simple binary systems and are most likely hierarchical triples. The observed companions rule out a massive compact object for HD 137909, HD 117044, and HD 176695. HD 104438 requires further study because the identified star cannot be responsible for the RV orbit and is likely a dwarf tertiary companion. The SHARK-VIS observation was taken near pericenter, and a second image near apocenter is needed to discriminate between a closely separated luminous secondary and a compact object. When a luminous companion is found, the combination of the RVs and the single SHARK-VIS observation strongly constrains the orbital inclination and the companion mass. Since a single SHARK-VIS observation has a typical on-source observing time of only ∼10 minutes, this a promising method to efficiently identify non-interacting compact object candidates.

Since volcanic activity was first discovered on Io from Voyager images in 1979, changes on Io's surface have been monitored from both spacecraft and ground‐based telescopes. Here, we present the highest spatial resolution images of Io ever obtained from a ground‐based telescope. These images, acquired by the SHARK‐VIS instrument on the Large Binocular Telescope, show evidence of a major resurfacing event on Io's trailing hemisphere. When compared to the most recent spacecraft images, the SHARK‐VIS images show that a plume deposit from a powerful eruption at Pillan Patera has covered part of the long‐lived Pele plume deposit. Although this type of resurfacing event may be common on Io, few have been detected due to the rarity of spacecraft visits and the previously low spatial resolution available from Earth‐based telescopes. The SHARK‐VIS instrument ushers in a new era of high resolution imaging of Io's surface using adaptive optics at visible wavelengths.

MICADO is a workhorse instrument for the ESO ELT, allowing first light capability for diffraction limited imaging and long-slit spectroscopy at near-infrared wavelengths. The PSF Reconstruction (PSF-R) Team of MICADO is currently implementing, for the first time within all ESO telescopes, a software service devoted to the blind reconstruction of the PSF. This tool will work independently of the science data, using adaptive optics telemetry data, both for Single Conjugate (SCAO) and Multi-Conjugate Adaptive Optics (MCAO) allowed by the MORFEO module. The PSF-R service will support the state-of-the-art post-processing scientific analysis of the MICADO imaging and spectroscopic data. We provide here an update of the status of the PSF-R service tool of MICADO, after successfully fulfilling the Final Design Review phase, and discuss recent results obtained on simulated and real data gathered on instruments similar to MICADO.

SHARK-NIR is an instrument which provides direct imaging, coronagraphic imaging, dual band imaging and low resolution spectroscopy in Y, J and H bands, taking advantage of the outstanding performance of the Large Binocular Telescope AO systems. Binocular observations will be provided used in combination with SHARK-VIS (operating in V band) and LMIRCam of LBTI (operating from K to M bands), in a way to exploit coronagraphic simultaneous observations in three different wavelengths. A wide variety of coronagraphic techniques have been implemented in SHARK-NIR, ranging from conventional ones such as the Gaussian Lyot, to others quite robust to misalignments such as the Shaped Pupil, to eventually techniques more demanding in term of stability during the observation, as the Four Quadrant; the latter is giving in theory and simulations outstanding contrast, and it is supported in term of stability by the SHARK-NIR internal fast tip-tilt loop and local NCPA correction, which should ensure the necessary stability allowing this technique to operate at its best. The main science case is of course exoplanets search and characterization and young stellar systems, jets and disks characterization, although the LBT AO extreme performance, allowing to reach excellent correction even at very faint magnitudes, may open to science previously difficult to be achieved, as for example AGN and QSO morphological studies. The institutes participating to the SHARK-NIR consortium which designed and built the instrument are Istituto Nazionale di Astro Fisica (INAF, Italy), the Max Planck Institute for Astronomy (MPIA, Heidelberg, Germany) and University of Arizona/Steward Observatory (UoA/SO, Tucson, Az, USA). We report here about the SHARK-NIR status, that should achieve first light at LBT before the end of 2022.