المؤلفون: Murabito, Mariarita, Stangalini, Marco, Laming, J. Martin, Baker, Deborah, To, Andy S. H., Long, David M., Brooks, David H., Jafarzadeh, Shahin, Jess, David B., Valori, Gherardo

مصطلحات موضوعية: Astrophysics - Solar and Stellar Astrophysics

الوصف: We investigate the propagation of Alfv\'en waves in the solar chromosphere, distinguishing between upward and downward propagating waves. We find clear evidence for the reflection of waves in the chromosphere and differences in propagation between cases with waves interpreted to be resonant or nonresonant with the overlying coronal structures. This establishes the wave connection to coronal element abundance anomalies through the action of the wave ponderomotive force on the chromospheric plasma, which interacts with chromospheric ions but not neutrals, thereby providing a novel mechanism of ion-neutral separation. This is seen as a "First Ionization Potential Effect" when this plasma is lifted into the corona, with implications elsewhere on the Sun for the origin of the slow speed solar wind and its elemental composition.
Comment: Accepted for publication in Physical review Letters; 7 pages, 3 figures and 3 pages of supplemental material (non present here, it will be available as link in the journal)

الوصول الحر: http://arxiv.org/abs/2404.08305Test

المؤلفون: Long, David M., Baker, Deborah, To, Andy S. H., van Driel-Gesztelyi, Lidia, Brooks, David H., Stangalini, Marco, Murabito, Mariarita, James, Alexander W., Mathioudakis, Mihalis, Testa, Paola

مصطلحات موضوعية: Astrophysics - Solar and Stellar Astrophysics

الوصف: The composition of the solar corona differs from that of the photosphere, with the plasma thought to fractionate in the solar chromosphere according to the First Ionisation Potential (FIP) of the different elements. This produces a FIP bias, wherein elements with a low FIP are preferentially enhanced in the corona compared to their photospheric abundance, but direct observations of this process remain elusive. Here we use a series of spectroscopic observations of Active Region AR 12759 as it transited the solar disc over a period of 6 days from 2-7 April 2020 taken using the Hinode Extreme ultraviolet Imaging Spectrometer (EIS) and Interface Region Imaging Spectrograph (IRIS) instruments to look for signatures of plasma fractionation in the solar chromosphere. Using the Si X/S X and Ca XIV/Ar XIV diagnostics, we find distinct differences between the FIP bias of the leading and following polarities of the active region. The widths of the IRIS Si IV lines exhibited clear differences between the leading and following polarity regions, indicating increased unresolved wave activity in the following polarity region compared to the leading polarity region, with the chromospheric velocities derived using the Mg II lines exhibiting comparable, albeit much weaker, behaviour. These results are consistent with plasma fractionation via resonant/non-resonant waves at different locations in the solar chromosphere following the ponderomotive force model, and indicate that IRIS could be used to further study this fundamental physical process.
Comment: 19 pages, 9 figures, accepted for publication in The Astrophysical Journal

الوصول الحر: http://arxiv.org/abs/2403.06711Test

المؤلفون: Mihailescu, Teodora, Brooks, David H., Laming, J. Martin, Baker, Deborah, Green, Lucie M., James, Alexander W., Long, David M., van Driel-Gesztelyi, Lidia, Stangalini, Marco

مصطلحات موضوعية: Astrophysics - Solar and Stellar Astrophysics

الوصف: The plasma composition of the solar corona is different from that of the solar photosphere. Elements that have a low first ionisation potential (FIP) are preferentially transported to the corona and, therefore, show enhanced abundances in the corona compared to the photosphere. The level of enhancement is measured using the FIP bias parameter. In this work, we use data from the EUV Imaging Spectrometer (EIS) on Hinode to study the plasma composition in an active region following an episode of significant new flux emergence into the pre-existing magnetic environment of the active region. We use two FIP bias diagnostics: Si X 258.375 A/S X 264.233 A (temperature of approximately 1.5 MK) and Ca XIV 193.874 A/Ar XIV 194.396 A (temperature of approximately 4 MK). We observe slightly higher FIP bias values with the Ca/Ar diagnostic than Si/S in the newly emerging loops, and this pattern is much stronger in the preexisting loops (those that had been formed before the flux emergence). This result can be interpreted in the context of the ponderomotive force model, which proposes that the plasma fractionation is generally driven by Alfv\'en waves. Model simulations predict this difference between diagnostics using simple assumptions about the wave properties, particularly that the fractionation is driven by resonant/non-resonant waves in the emerging/preexisting loops. We propose that this results in the different fractionation patterns observed in these two sets of loops.
Comment: Accepted for publication in The Astrophysical Journal

الوصول الحر: http://arxiv.org/abs/2310.13677Test

المؤلفون: Grimani, Catia, Andretta, Vincenzo, Antonucci, Ester, Chioetto, Paolo, Da Deppo, Vania, Fabi, Michele, Gissot, Samuel, Jerse, Giovanna, Messerotti, Mauro, Naletto, Giampiero, Pancrazzi, Maurizio, Persici, Andrea, Plainaki, Christina, Romoli, Marco, Sabbatini, Federico, Spadaro, Daniele, Stangalini, Marco, Telloni, Daniele, Teriaca, Luca, Uslenghi, Michela, Villani, Mattia, Abbo, Lucia, Burtovoi, Aleksandr, Frassati, Federica, Landini, Federico, Nicolini, Giana, Russano, Giuliana, Sasso, Clementina, Susino, Roberto

المصدر: A&A 677, A45 (2023)

مصطلحات موضوعية: Astrophysics - Solar and Stellar Astrophysics, Astrophysics - Instrumentation and Methods for Astrophysics, High Energy Physics - Experiment, Physics - Space Physics

الوصف: Context. Galactic cosmic rays (GCRs) and solar particles with energies greater than tens of MeV penetrate spacecraft and instruments hosted aboard space missions. The Solar Orbiter Metis coronagraph is aimed at observing the solar corona in both visible (VL) and ultraviolet (UV) light. Particle tracks are observed in the Metis images of the corona. An algorithm has been implemented in the Metis processing electronics to detect the VL image pixels crossed by cosmic rays. This algorithm was initially enabled for the VL instrument only, since the process of separating the particle tracks in the UV images has proven to be very challenging. Aims. We study the impact of the overall bulk of particles of galactic and solar origin on the Metis coronagraph images. We discuss the effects of the increasing solar activity after the Solar Orbiter mission launch on the secondary particle production in the spacecraft. Methods. We compared Monte Carlo simulations of GCRs crossing or interacting in the Metis VL CMOS sensor to observations gathered in 2020 and 2022. We also evaluated the impact of solar energetic particle events of different intensities on the Metis images. Results. The study of the role of abundant and rare cosmic rays in firing pixels in the Metis VL images of the corona allows us to estimate the efficiency of the algorithm applied for cosmic-ray track removal from the images and to demonstrate that the instrument performance had remained unchanged during the first two years of the Solar Orbiter operations. The outcome of this work can be used to estimate the Solar Orbiter instrument's deep charging and the order of magnitude for energetic particles crossing the images of Metis and other instruments such as STIX and EUI.
Comment: 8 pages, 6 figures

الوصول الحر: http://arxiv.org/abs/2307.11598Test

المؤلفون: Telloni, Daniele, Romoli, Marco, Velli, Marco, Zank, Gary P., Adhikari, Laxman, Downs, Cooper, Burtovoi, Aleksandr, Susino, Roberto, Spadaro, Daniele, Zhao, Lingling, Liberatore, Alessandro, Shi, Chen, De Leo, Yara, Abbo, Lucia, Frassati, Federica, Jerse, Giovanna, Landini, Federico, Nicolini, Gianalfredo, Pancrazzi, Maurizio, Russano, Giuliana, Sasso, Clementina, Andretta, Vincenzo, Da Deppo, Vania, Fineschi, Silvano, Grimani, Catia, Heinzel, Petr, Moses, John D., Naletto, Giampiero, Stangalini, Marco, Teriaca, Luca, Uslenghi, Michela, Berlicki, Arkadiusz, Bruno, Roberto, Capobianco, Gerardo, Capuano, Giuseppe E., Casini, Chiara, Casti, Marta, Chioetto, Paolo, Corso, Alain J., D'Amicis, Raffaella, Fabi, Michele, Frassetto, Fabio, Giarrusso, Marina, Giordano, Silvio, Guglielmino, Salvo L., Magli, Enrico, Massone, Giuseppe, Messerotti, Mauro, Nisticò, Giuseppe, Pelizzo, Maria G., Reale, Fabio, Romano, Paolo, Schühle, Udo, Solanki, Sami K., Straus, Thomas, Ventura, Rita, Volpicelli, Cosimo A., Zangrilli, Luca, Zimbardo, Gaetano, Zuppella, Paola, Bale, Stuart D., Kasper, Justin C.

مصطلحات موضوعية: Astrophysics - Solar and Stellar Astrophysics, Physics - Space Physics

الوصف: This Letter reports the first observational estimate of the heating rate in the slowly expanding solar corona. The analysis exploits the simultaneous remote and local observations of the same coronal plasma volume with the Solar Orbiter/Metis and the Parker Solar Probe instruments, respectively, and relies on the basic solar wind magnetohydrodynamic equations. As expected, energy losses are a minor fraction of the solar wind energy flux, since most of the energy dissipation that feeds the heating and acceleration of the coronal flow occurs much closer to the Sun than the heights probed in the present study, which range from 6.3 to 13.3 solar radii. The energy deposited to the supersonic wind is then used to explain the observed slight residual wind acceleration and to maintain the plasma in a non-adiabatic state. As derived in the Wentzel-Kramers-Brillouin limit, the present energy transfer rate estimates provide a lower limit, which can be very useful in refining the turbulence-based modeling of coronal heating and subsequent solar wind acceleration.

الوصول الحر: http://arxiv.org/abs/2306.10819Test

المؤلفون: Telloni, Daniele, Zank, Gary P., Adhikari, Laxman, Zhao, Lingling, Susino, Roberto, Antonucci, Ester, Fineschi, Silvano, Stangalini, Marco, Grimani, Catia, Sorriso-Valvo, Luca, Verscharen, Daniel, Marino, Raffaele, Giordano, Silvio, D'Amicis, Raffaella, Perrone, Denise, Carbone, Francesco, Liberatore, Alessandro, Bruno, Roberto, Zimbardo, Gaetano, Romoli, Marco, Andretta, Vincenzo, Da Deppo, Vania, Heinzel, Petr, Moses, John D., Naletto, Giampiero, Nicolini, Gianalfredo, Spadaro, Daniele, Teriaca, Luca, Burtovoi, Aleksandr, De Leo, Yara, Jerse, Giovanna, Landini, Federico, Pancrazzi, Maurizio, Sasso, Clementina, Slemer, Alessandra

المصدر: The Astrophysical Journal, 2023

مصطلحات موضوعية: Astrophysics - Solar and Stellar Astrophysics

الوصف: Evidence for the presence of ion cyclotron waves, driven by turbulence, at the boundaries of the current sheet is reported in this paper. By exploiting the full potential of the joint observations performed by Parker Solar Probe and the Metis coronagraph on board Solar Orbiter, local measurements of the solar wind can be linked with the large-scale structures of the solar corona. The results suggest that the dynamics of the current sheet layers generates turbulence, which in turn creates a sufficiently strong temperature anisotropy to make the solar-wind plasma unstable to anisotropy-driven instabilities such as the Alfv\'en ion-cyclotron, mirror-mode, and firehose instabilities. The study of the polarization state of high-frequency magnetic fluctuations reveals that ion cyclotron waves are indeed present along the current sheet, thus linking the magnetic topology of the remotely imaged coronal source regions with the wave bursts observed in situ. The present results may allow improvement of state-of-the-art models based on the ion cyclotron mechanism, providing new insights into the processes involved in coronal heating.
Comment: 12 pages

الوصول الحر: http://arxiv.org/abs/2302.10545Test

المؤلفون: Stangalini, Marco, Pedichini, Fernando, Pinna, Enrico, Christou, Julian, Hill, John, Puglisi, Alfio, Bailey, Vanessa, Centrone, Mauro, Del Moro, Dario, Esposito, Simone, Fiore, Fabrizio, Giallongo, Emanuele, Hinz, Phil, Vaz, Amali

مرشدي الرسالة: Univ Arizona, LBTO, Univ Arizona, Steward Observ, INAF-OAR, Astronomical Observatory of Rome, National Institute for Astrophysics, Monte Porzio Catone, ItalybADONI Adaptive Optics National Lab of Italy, Italy, ADONI Adaptive Optics National Lab of Italy, ItalycINAF-Arcetri Astrophysical Observatory of Florence, National Institute for Astrophysics, Florence, Italy, University of Arizona, LBTO, Tucson, Arizona United States, KIPAC-Stanford University, Stanford, California, United States, INAF-OAR, Astronomical Observatory of Rome, National Institute for Astrophysics, Monte Porzio Catone, Italy, Universitá di Roma Tor Vergata, Rome, Italy, University of Arizona, CAAO, Steward Observatory, Tucson, Arizona, United States

مصطلحات موضوعية: adaptive optics, atmospheric optics, speckle phenomena

الوصف: Residual speckles in adaptive optics (AO) images represent a well-known limitation on the achievement of the contrast needed for faint source detection. Speckles in AO imagery can be the result of either residual atmospheric aberrations, not corrected by the AO, or slowly evolving aberrations induced by the optical system. We take advantage of the high temporal cadence (1 ms) of the data acquired by the System for Coronagraphy with High-order Adaptive Optics from R to K bands-VIS forerunner experiment at the Large Binocular Telescope to characterize the AO residual speckles at visible wavelengths. An accurate knowledge of the speckle pattern and its dynamics is of paramount importance for the application of methods aimed at their mitigation. By means of both an automatic identification software and information theory, we study the main statistical properties of AO residuals and their dynamics. We therefore provide a speckle characterization that can be incorporated into numerical simulations to increase their realism and to optimize the performances of both real-time and postprocessing techniques aimed at the reduction of the speckle noise. (C) 2017 Society of PhotoOptical Instrumentation Engineers (SPIE).

الإتاحة: http://hdl.handle.net/10150/625223Test
http://arizona.openrepository.com/arizona/handle/10150/625223Test

المؤلفون: Jess, David B., Jafarzadeh, Shahin, Keys, Peter H., Stangalini, Marco, Verth, Gary, Grant, Samuel D. T.

مصطلحات موضوعية: Astrophysics - Solar and Stellar Astrophysics

الوصف: Waves and oscillations have been observed in the Sun's atmosphere for over half a century. While such phenomena have readily been observed across the entire electromagnetic spectrum, spanning radio to gamma-ray sources, the underlying role of waves in the supply of energy to the outermost extremities of the Sun's corona has yet to be uncovered. Of particular interest is the lower solar atmosphere, including the photosphere and chromosphere, since these regions harbor the footpoints of powerful magnetic flux bundles that are able to guide oscillatory motion upwards from the solar surface. As a result, many of the current- and next-generation ground-based and space-borne observing facilities are focusing their attention on these tenuous layers of the lower solar atmosphere in an attempt to study, at the highest spatial and temporal scales possible, the mechanisms responsible for the generation, propagation, and ultimate dissipation of energetic wave phenomena. Here, we present a two-fold review that is designed to overview both the wave analyses techniques the solar physics community currently have at their disposal, as well as highlight scientific advancements made over the last decade. Importantly, while many ground-breaking studies will address and answer key problems in solar physics, the cutting-edge nature of their investigations will naturally pose yet more outstanding observational and/or theoretical questions that require subsequent follow-up work. This is not only to be expected, but should be embraced as a reminder of the era of rapid discovery we currently find ourselves in. We will highlight these open questions and suggest ways in which the solar physics community can address these in the years and decades to come.
Comment: 198 pages, 67 figures, 794 references, accepted for publication as a Living Review in Solar Physics (LRSP)

الوصول الحر: http://arxiv.org/abs/2212.09788Test

المؤلفون: Biondo, Ruggero, Bemporad, Alessandro, Pagano, Paolo, Telloni, Daniele, Reale, Fabio, Romoli, Marco, Andretta, Vincenzo, Antonucci, Ester, Da Deppo, Vania, De Leo, Yara, Fineschi, Silvano, Heinzel, Petr, Moses, Daniel, Naletto, Giampiero, Nicolini, Gianalfredo, Spadaro, Daniele, Stangalini, Marco, Teriaca, Luca, Landini, Federico, Sasso, Clementina, Susino, Roberto, Jerse, Giovanna, Uslenghi, Michela, Pancrazzi, Maurizio

المصدر: A&A 668, A144 (2022)

مصطلحات موضوعية: Astrophysics - Solar and Stellar Astrophysics, Physics - Plasma Physics, Physics - Space Physics

الوصف: As a key feature, NASA's Parker Solar Probe (PSP) and ESA-NASA's Solar Orbiter (SO) missions cooperate to trace solar wind and transients from their sources on the Sun to the inner interplanetary space. The goal of this work is to accurately reconstruct the interplanetary Parker spiral and the connection between coronal features observed remotely by the Metis coronagraph on-board SO and those detected in situ by PSP at the time of the first PSP-SO quadrature of January 2021. We use the Reverse In-situ and MHD Approach (RIMAP), a hybrid analytical-numerical method performing data-driven reconstructions of the Parker spiral. RIMAP solves the MHD equations on the equatorial plane with the PLUTO code, using the measurements collected by PSP between 0.1 and 0.2 AU as boundary conditions. Our reconstruction connects density and wind speed measurements provided by Metis (3-6 solar radii) to those acquired by PSP (21.5 solar radii) along a single streamline. The capability of our MHD model to connect the inner corona observed by Metis and the super Alfv\'enic wind measured by PSP, not only confirms the research pathways provided by multi-spacecraft observations, but also the validity and accuracy of RIMAP reconstructions as a possible test bench to verify models of transient phenomena propagating across the heliosphere, such as coronal mass ejections, solar energetic particles and solar wind switchbacks.
Comment: Astronomy & Astrophysics, Solar Orbiter First Results (Nominal Mission Phase), (in press) DOI: 10.1051/0004-6361/202244535

الوصول الحر: http://arxiv.org/abs/2211.12994Test

المؤلفون: Telloni, Daniele, Zank, Gary P., Stangalini, Marco, Downs, Cooper, Liang, Haoming, Nakanotani, Masaru, Andretta, Vincenzo, Antonucci, Ester, Sorriso-Valvo, Luca, Adhikari, Laxman, Zhao, Lingling, Marino, Raffaele, Susino, Roberto, Grimani, Catia, Fabi, Michele, D'Amicis, Raffaella, Perrone, Denise, Bruno, Roberto, Carbone, Francesco, Mancuso, Salvatore, Romoli, Marco, Da Deppo, Vania, Fineschi, Silvano, Heinzel, Petr, Moses, John D., Naletto, Giampiero, Nicolini, Gianalfredo, Spadaro, Daniele, Teriaca, Luca, Frassati, Federica, Jerse, Giovanna, Landini, Federico, Pancrazzi, Maurizio, Russano, Giuliana, Sasso, Clementina, Berghmans, David, Auchère, Frédéric, Cuadrado, Regina Aznar, Chitta, Lakshmi P., Harra, Louise, Kraaikamp, Emil, Long, David M., Mandal, Sudip, Parenti, Susanna, Pelouze, Gabriel, Peter, Hardi, Rodriguez, Luciano, Schühle, Udo, Schwanitz, Conrad, Smith, Phil J., Verbeeck, Cis, Zhukov, Andrei N.

مصطلحات موضوعية: Astrophysics - Solar and Stellar Astrophysics

الوصف: Switchbacks are sudden, large radial deflections of the solar wind magnetic field, widely revealed in interplanetary space by the Parker Solar Probe. The switchbacks' formation mechanism and sources are still unresolved, although candidate mechanisms include Alfv\'enic turbulence, shear-driven Kelvin-Helmholtz instabilities, interchange reconnection, and geometrical effects related to the Parker spiral. This Letter presents observations from the Metis coronagraph onboard Solar Orbiter of a single large propagating S-shaped vortex, interpreted as first evidence of a switchback in the solar corona. It originated above an active region with the related loop system bounded by open-field regions to the East and West. Observations, modeling, and theory provide strong arguments in favor of the interchange reconnection origin of switchbacks. Metis measurements suggest that the initiation of the switchback may also be an indicator of the origin of slow solar wind.

الوصول الحر: http://arxiv.org/abs/2206.03090Test