The raw coronagraphic performance of current high-contrast imaging instruments is limited by the presence a quasi-static speckle (QSS) background, resulting from instrumental Non-Common Path Errors (NCPEs). Rapid development efficient subtraction techniques in data reduction has enabled final contrasts up to 10-6 be obtained, however it remains preferable eliminate underlying NCPEs at source. In this work we introduce Modal Wavefront Sensor (cMWS), new wavefront sensor suitable for real-time...

ABSTRACT The detection of Earth-like planets with the radial-velocity (RV) method is currently limited by presence stellar activity signatures. On rotational time-scales, spots and plages (or faculae) are known to introduce different RV signals, but their corrections require better proxies. best-known chromospheric proxies in visible Ca ii H&K lines, physical quantities measured profiles need be clarified. We first investigate resolved images Sun order understand spectrum plages, spots,...

Context. Stellar flares cannot be spatially resolved, which complicates ascertaining the physical processes behind particular spectral signatures. Due to their proximity Earth, solar can serve as a stepping stone for understanding stellar counterparts, especially when using Sun-as-a-star instrument and in combination with resolved observations. Aims. We aim understand disk-integrated behaviors of confined X2.2 flare its eruptive X9.3 successor, had energies 2.2 × 10 31 erg 9.3 erg,...

Solar oxygen abundance measurements based on the O I near-infrared triplet have been a much debated subject for several decades, since non-local thermodynamic equilibrium (NLTE) calculations with 3D radiation-hydrodynamics model atmospheres introduced large change to 1D LTE modeling. In this work, we aim test solar line formation across disk using new observations obtained SST/CRISP instrument. The observed data set is spectroscopic mosaic that stretches from center limb. By comparing...

It has so far proven impossible to reproduce all aspects of the solar plage chromosphere in quasi-realistic numerical models. The magnetic field configuration lower atmosphere is one few free parameters such simulations. literature only offers proxy-based estimates strength, as it difficult obtain observational constraints this region. Sufficiently sensitive spectro-polarimetric measurements require a high signal-to-noise ratio, spectral resolution, and cadence, which are at limit current...

Solar flare ribbons are intense brightenings of principally chromospheric material that responsible for a large fraction the emission in solar and stellar flares. We present an on-disc observation ribbon substructures X9.3-class observed by Swedish 1-m Telescope. identify categories seen Ca II 8542 \AA, H$\alpha$, K lines, focusing on their spatial locations (spectro-)polarimetric properties. Color Collapsed Plotting (COCOPLOT) software is used to assist identifying areas interest. five...

Observations of center-to-limb variations (CLV) spectral lines and continua provide a good test for the accuracy models solar stellar atmospheric structure spectral-line formation. They are also widely used to constrain elemental abundances becoming increasingly important in studies exoplanets. However, only few such data sets exist chromospheric lines. We aim create set standard profiles by means mosaics made with CRISP CHROMIS instruments Swedish 1-m Solar Telescope (SST), as well explore...

Context . Transmission spectroscopy is one of the most powerful techniques used to characterize transiting exoplanets, since it allows for abundance atomic and molecular species in planetary atmosphere be measured. However, stellar lines may bias determination such abundances if their center-to-limb variations (CLVs) are not properly accounted for. Aims This paper aims show that three-dimensional (3D) radiation hydrodynamic models assumption non-local ther-modynamic equilibrium (non-LTE)...

Abstract Commercial disco balls provide a safe, effective and instructive way of observing the Sun. We explore optics solar projections with balls, find that while sunspot observations are challenging, disk its changes during eclipses easy fun to observe. ball’s potential for moon other bright astronomical phenomena.

Context. Solar flare ribbons are intense brightenings of primarily chromospheric material that responsible for a large fraction the emission in solar and stellar flares. We present an on-disc observation ribbon substructures X9.3-class observed by Swedish 1-m Telescope. Aims. aim to identify categories seen Ca II 8542 Å, H α , K lines, focusing on their spatial locations (spectro-)polarimetric properties. Methods. used COlor COllapsed Plotting (COCOPLOT) software assist identifying areas...

Non-Common Path Errors (NCPEs) are the dominant factor limiting performance of current astronomical high-contrast imaging instruments. If uncorrected, resulting quasi-static speckle noise floor limits coronagraph to a raw contrast typically 10^−4, value which does not improve with increasing integration time. The coronagraphic Modal Wavefront Sensor (cMWS) is hybrid phase optic uses holographic PSF copies supply focal-plane wavefront sensing information directly from science...

Most modern solar observatories deliver data products formatted as 3D spatio-temporal cubes, that contain additional, higher dimensions with spectral and/or polarimetric information. This multi-dimensional complexity presents a major challenge when browsing for features of interest in several simultaneously. We developed the COlor COllapsed PLOTting (COCOPLOT) software quick-look and context image software, to convey profile or time evolution from all spatial pixels ($x,y$)...

Fan-shaped jets can be observed above light bridges and are driven by reconnection of the vertical umbral field with more horizontal bridges. Because these not fully opaque in chromospheric lines, one cannot study their spectra without highly complex considerations radiative transfer spectral lines from atmosphere behind fan. We get around this taking advantage a unique set observations H$\alpha$ line along Ca II 8542 K obtained Swedish 1-m Solar Telescope where fan-shaped jet was backlit an...

Stellar flares cannot be spatially resolved, which complicates ascertaining the physical processes behind particular spectral signatures. Due to their proximity Earth, solar can serve as a stepping stone for understanding stellar counterparts, especially when using Sun-as-a-star instrument and in combination with resolved observations. We aim understand disk-integrated behaviors of confined X2.2 flare its eruptive X9.3 successor measured by HARPS-N. The behavior multiple photospheric...

An accurate description of the center-to-limb variation (CLV) stellar spectra is becoming an increasingly critical factor in both and exoplanet characterization. In particular, CLV spectral lines extremely challenging as its characterization requires highly detailed knowledge physical conditions. To this end, we present Numerical Empirical Sun-as-a-Star Integrator (NESSI) a tool for translating high-resolution solar observations partial field view into disk-integrated that can be used to...

Context. The emergence of magnetic flux, its transition to complex configurations, and the pre-eruptive state active regions are probed using photospheric magnetograms. Aims. Our aim is pinpoint different evolutionary stages in emerging regions, explore their differences, produce parameters that could advance flare prediction color-coded maps field. Methods. three components field vector combined create color-combined magnetograms (COCOMAGs). From these, areas occupied by color hues...

The emergence of magnetic flux, its transition to complex configurations, and the pre-eruptive state active regions are probed using photospheric magnetograms. We aim pinpoint different evolutionary stages in regions, explore their differences produce parameters that could advance flare prediction, color-coded maps field. three components field vector combined magnetograms (COCOMAGs). From these, areas occupied by colors extracted, creating appropriate time series (color curves). COCOMAGs...

We present synthetic spectra corresponding to a 2.5D magnetohydrodynamic simulation of rotating prominence in the Ca II 8542 Å, H α , K, Mg k, Ly and β lines. The rotation resulted from angular momentum conservation within flux rope where asymmetric heating imposed net prior thermal-instability-driven condensation phase. were created using library built on Lightweaver framework called Promweaver which provides boundary conditions for incorporating limb-darkened irradiation solar disk...

ABSTRACT In our former paper I, we showed on the Sun that different active regions possess unique intensity profiles Ca ii H & K lines. We now extend analysis by showing how those properties can be used real stellar observations, delivering more powerful activity proxies for radial velocity correction. More information extracted rotational time-scale from lines than classical indicators: S-index and $\log (R^{^{\prime }}_{\text{HK}})$. For high-resolution HARPS observations of $\alpha$...

Solar projection using mirrors on a disco ball is fun and unique way to safely observe the Sun, especially during solar eclipse. We share our methods of project eclipse outreach events discuss results best practices from trial runs conducted October 25, 2022, 14, 2023, partial annular eclipses various locations across Europe North America. encourage any location hosting an event April 8, 2024, total display collect feedback visitors about their understanding of, engagement with, projected images

Coronal Mass Ejections (CMEs) remain a focal point of solar and stellar research due to their significant impact on space weather dynamics exoplanet habitability. Unfortunately, it has so far proven difficult measure these events other stars, with only handful confirmed detections.  On the Sun, strong flares (X1-class above) are almost always accompanied by CME. This connection not been found for where regularly detected without CME counterpart. To investigate this discrepancy we...

Context . Transmission spectroscopy is a powerful tool for understanding exoplanet atmospheres. At optical wavelengths, this technique makes it possible to infer the composition and presence of aerosols in atmosphere. However, unocculted stellar activity can result contamination atmospheric transmission spectra by introducing spurious slopes molecular signals. Aims We aim characterise atmosphere transiting WASP-69b, hot Jupiter orbiting an active K star, levels host star. Methods obtained...

Context: Transmission spectroscopy is a powerful tool for understanding exoplanet atmospheres. At optical wavelengths, it makes possible to infer the composition and presence of aerosols in atmosphere. However, unocculted stellar activity can result contamination atmospheric transmission spectra by introducing spurious slopes molecular signals. Aims: We aim characterise atmosphere transiting WASP-69b, hot Jupiter orbiting an active K star, host star's levels. Methods: obtained three nights...

In our former paper I, we showed on the Sun that different active regions possess unique intensity profiles Ca II H & K lines. We now extend analysis by showing how those properties can be used real stellar observations, delivering more powerful activity proxies for radial velocity correction. More information extracted rotational timescale from lines than classical indicators: S-index and log(R'HK). For high-resolution HARPS observations of alpha Cen B, apply a principal independent...

Solar oxygen abundance measurements based on the O I near-infrared triplet have been a much-debated subject for several decades since non-local thermodynamic equilibrium (NLTE) calculations with 3D radiation-hydrodynamics model atmospheres introduced large change to 1D LTE modelling. In this work, we aim test solar line formation across disk using new observations obtained SST/CRISP instrument. The observed dataset is spectroscopic mosaic stretching from center limb. By comparing...