Related papers: Sunspot umbra atmosphere from full Stokes inversio…
Sunspots are a canonical marker of the Sun's internal magnetic field which flips polarity every ~22-years. The principal variation of sunspots, an ~11-year variation in number, modulates the amount of magnetic field that pierces the solar…
Given its unchallenged capabilities in terms of sensitivity and spatial resolution, the combination of imaging spectropolarimetry and numeric Stokes inversion represents the dominant technique currently used to remotely sense the physical…
Chromospheric observations of sunspot umbrae offer an exceptional view of magneto-acoustic shock phenomena and the impact they have on the surrounding magnetically-dominated plasma. We employ simultaneous slit-based spectro-polarimetry and…
Wavelet analysis of different solar activity indices, sunspot numbers, sunspot areas, flare index, magnetic fields, etc., allows us to investigate the time evolution of some specific features of the solar activity and the underlying dynamo…
Some models for the topology of the magnetic field in sunspot penumbrae predict the existence of field-free or dynamically weak-field regions in the deep Photosphere. To confirm or rule out the existence of weak-field regions in the deepest…
Solar pores are strongly magnetized regions lacking a photospheric penumbra and characterized by predominantly vertical magnetic fields. We present a multi-line study of flashes in a solar pore using high-resolution observations from the…
We model the deepest observable layers of dark sunspot umbral atmospheres in terms of an empirical model which equally describes observed near infrared continuum intensities and line profiles. We use the umbral continuum intensity at 1.67…
The peculiar behaviour of the solar cycle 23 and its prolonged minima has been one of the most studied problems over the last few years. In the present paper, we study the asymmetries in active region magnetic flux in the northern and…
Context. The solar chromosphere and the lower transition region is believed to play a crucial role in the heating of the solar corona. Models that describe the chromosphere (and the lower transition region), accounting for its highly…
Aims. To understand the morphology of the chromosphere in sunspot umbra. We investigate if the horizontal structures observed in the spectral core of the Ca II H line are ephemeral visuals caused by the shock dynamics of more stable…
In sunspot umbrae, convection is largely suppressed by the strong magnetic field. Previous measurements reported on negligible convective flows in umbral cores. Based on this, numerous studies have taken the umbra as zero reference to…
This article reviews some of the leading results obtained in solar dynamo physics by using temporal oscillator models as a tool to interpret observational data and dynamo model predictions. We discuss how solar observational data such as…
Spatial distributions of the dominant oscillation frequency obtained for four sunspots show a feature shared by all the analysed levels of the solar atmosphere in these sunspots. This feature located in the inner penumbrae indicates that…
The effects of acoustic wave absorption, mode conversion and transmission by a sunspot on the helioseismic inferences are widely discussed, but yet accounting for them has proved difficult for lack of a consistent framework within…
The first significant sunquake event of Solar Cycle 25 was observed during the X1.5 flare of May 10, 2022, by the Helioseismic and Magnetic Imager (HMI) onboard the Solar Dynamics Observatory. We perform a detailed spectro-polarimetric…
Solar active regions show a wide variety of oscillatory phenomena. The presence of the magnetic field leads to the appearance of several wave modes, whose behavior is determined by the sunspot thermal and magnetic structure. We aim to study…
Sunspots are the most important indicator of the magnetic activity on the solar surface during a cycle. Every sunspot group is formed and shaped by the magnetic field of the Sun. Hence, the magnetic field intensity shows itself as the size…
Determining the magnetic field of solar spicules is vital for developing adequate models of these plasma jets, which are thought to play a key role in the thermal, dynamic, and magnetic structure of the chromosphere. Here we report on…
Comparison of photographic observations and vector-magnetograph measurements demonstrate, that the outer boundary of the sunspot penumbra --even in complex sunspot groups-- closely follows the 0.075T isogauss line of the total value of the…
The spectral window, containing Fraunhofer lines formed in the solar photosphere, around the magnetically sensitive Cr I lines at 5780.9, 5781.1, 5781.7, 5783.0, and 5783.8 \r{A}, with Land\'e g-factors between 1.6 and 2.5, is explored. The…