M. van Noort

Max Planck Institute for Solar System Research

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S. K. Solanki

Max Planck Institute for Solar System Research

A. Lagg

Max Planck Institute for Solar System Research

L. Rouppe van der Voort

University of Oslo

T. L. Riethmüller

Max Planck Institute for Solar System Research

J. C. del Toro Iniesta

Instituto de Astrofísica de Andalucía

A. Gandorfer

Max Planck Institute for Solar System Research

J. Hirzberger

Max Planck Institute for Solar System Research

L. Gizon

Max Planck Institute for Solar System Research

D. Orozco Suárez

Instituto de Astrofísica de Andalucía

J. Blanco Rodríguez

Parc Científic de la Universitat de València

Cooperative Institutions

Instituto de Astrofísica de Canarias

105

Max Planck Institute for Solar System Research

Universidad de La Laguna

Max Planck Society

Centre National de la Recherche Scientifique

Institut für Sonnenphysik

Consejo Superior de Investigaciones Científicas

National Institute for Astrophysics

National Solar Observatory

High Altitude Observatory

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Large-amplitude transverse MHD waves prevailing in the H$\alpha$ chromosphere of a solar quiet region revealed by MiHI integrated field spectral observations

arXiv (Cornell University) (2024)

Jongchul Chae M. van Noort M. S. Madjarska Kyeo-Re Lee Juhyung Kang

The investigation of plasma motions in the solar chromosphere is crucial for understanding the transport of mechanical energy from the interior of the Sun to the outer atmosphere and into interplanetary space. We report the finding of large-amplitude oscillatory transverse motions prevailing in the non-spicular Halpha chromosphere of a small quiet region near the solar disk center. The observation was carried out on 2018 August 25 with the Microlensed Hyperspectral Imager (MiHI) installed as an extension to the spectrograph at the Swedish Solar Telescope (SST). MiHi produced high-resolution Stokes spectra of the Halpha line over a two-dimensional array of points (sampled every 0.066 arcsec on the image plane) every 1.33 s for about 17 min. We extracted the Dopple-shift-insensitive intensity data of the line core by applying a bisector fit to Stoke I line profiles. From our time-distance analysis of the intensity data, we find a variety of transverse motions with velocity amplitudes of up to 40 km/s in fan fibrils and tiny filaments. In particular, in the fan fibrils, large-amplitude transverse MHD waves were seen to occur with a mean velocity amplitude of 25 km/s and a mean period of 5.8 min, propagating at a speed of 40 km/s. These waves are nonlinear and display group behavior. We estimate the wave energy flux in the upper chromosphere at 3 x 10^6 erg cm^-2 s^-1. Our results contribute to the advancement of our understanding of the properties of transverse MHD waves in the solar chromosphere.

Chromosphere

QUIET

10.1051/0004-6361/202449772

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Slender Ca ii H Fibrils Mapping Magnetic Fields in the Low Solar Chromosphere

The Astrophysical Journal Supplement Series (2017)

S. Jafarzadeh R. J. Rutten S. K. Solanki T. Wiegelmann T. L. Riethmüller

A dense forest of slender bright fibrils near a small solar active region is seen in high-quality narrowband Ca II H images from the SuFI instrument onboard the Sunrise balloon-borne solar observatory. The orientation of these slender Ca II H fibrils (SCF) overlaps with the magnetic field configuration in the low solar chromosphere derived by magnetostatic extrapolation of the photospheric field observed with Sunrise/IMaX and SDO/HMI. In addition, many observed SCFs are qualitatively aligned with small-scale loops computed from a novel inversion approach based on best-fit numerical MHD simulation. Such loops are organized in canopy-like arches over quiet areas that differ in height depending on the field strength near their roots.

Chromosphere

10.3847/1538-4365/229/1/11

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Citations (38)

High resolution Zeeman experiments on singlet, triplet, and quartet states of metalloporphines

The Journal of Physical Chemistry (1976)

Gerard W. Canters G. R. Jansen M. van Noort J.H. van der Waals

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTHigh resolution Zeeman experiments on singlet, triplet, and quartet states of metalloporphinesG. W. Canters, G. Jansen, M. Noort, and J. H. Van der WaalsCite this: J. Phys. Chem. 1976, 80, 20, 2253–2259Publication Date (Print):September 1, 1976Publication History Published online1 May 2002Published inissue 1 September 1976https://pubs.acs.org/doi/10.1021/j100561a024https://doi.org/10.1021/j100561a024research-articleACS PublicationsRequest reuse permissionsArticle Views126Altmetric-Citations58LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InRedditEmail Other access options Get e-Alerts

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10.1021/j100561a024

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Citations (61)

Rapid Temporal Variability of Faculae: High‐Resolution Observations and Modeling

The Astrophysical Journal (2006)

Bart De Pontieu M. Carlsson R. F. Stein L. Rouppe van der Voort M. G. Löfdahl

We present high-resolution G-band observations (obtained with the Swedish 1 m Solar Telescope) of the rapid temporal variability of faculae, which occurs on granular timescales. By combining these observations with magnetoconvection simulations of a plage region, we show that much of this variability is not intrinsic to the magnetic field concentrations that are associated with faculae, but rather a phenomenon associated with the normal evolution and splitting of granules. We also show examples of facular variability caused by changes in the magnetic field, with movies of dynamic behavior of the striations that dominate much of the facular appearance at 01 resolution. Examples of these dynamics include merging, splitting, rapid motion, apparent fluting, and possibly swaying.

Solar telescope

Plage

Temporal resolution

10.1086/505074

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Citations (42)

Internetwork magnetic field as revealed by two-dimensional inversions

Astronomy and Astrophysics (2016)

S. Danilović M. van Noort M. Rempel

Context. Properties of magnetic field in the internetwork regions are still fairly unknown because of rather weak spectropolarimetric signals.

10.1051/0004-6361/201527842

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Citations (42)

Stark effect on the S1 ← S0 transition of the two tautomeric forms of chlorin studied by photochemical hole-burning in n-hexane and n-octane single crystals at 1.2 K

Chemical Physics Letters (1983)

A.I.M. Dicker Lawrence W. Johnson M. van Noort J.H. van der Waals

Chlorin

Hexane

10.1016/0009-2614(83)87201-7

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Physical properties of a sunspot chromosphere with umbral flashes

Astronomy and Astrophysics (2013)

J. de la Cruz Rodríguez L. Rouppe van der Voort H. Socas‐Navarro M. van Noort

We present new high-resolution spectro-polarimetric Ca II 8542 observations of umbral flashes in sunspots. At nearly 0.18", and spanning about one hour of continuous observation, this is the most detailed dataset published thus far. Our study involves both LTE and non-LTE inversions (but includes also a weak field analysis as a sanity check) to quantify temperatures, mass flows and the full magnetic field vector geometry. We confirm earlier reports that UFs have very fine structure with hot and cool material intermixed at sub-arcsecond scales. The shock front is roughly 1000 K hotter than the surrounding material. We do not observe significant fluctuations of the field in the umbra. In the penumbra, however, the passage of the running penumbral waves alter the magnetic field strength by some 200 G (peak-to-peak amplitude) but it does not change the field orientation (at least not significantly within our sensitivity of a few degrees). We find a trend of decreasing high-frequency modulation power for more inclined magnetic fields for the line-of-sight velocity and magnetic field strength. In the outer penumbra we find an absence of high frequency power while there is increasingly more power at high frequencies towards the umbra.

Sunspot

Field strength

Chromosphere

10.1051/0004-6361/201321629

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Citations (71)

Transverse Oscillations in Slender Ca ii H Fibrils Observed with Sunrise/SuFI

The Astrophysical Journal Supplement Series (2017)

S. Jafarzadeh S. K. Solanki R. Gafeira M. van Noort P. Barthol

We present observations of transverse oscillations in slender Ca II H fibrils (SCFs) in the lower solar chromosphere. We use a 1 hr long time series of high- (spatial and temporal-) resolution seeing-free observations in a 0.11 nm wide passband covering the line core of Ca II H 396.9 nm from the second flight of the Sunrise balloon-borne solar observatory. The entire field of view, spanning the polarity inversion line of an active region close to the solar disk center, is covered with bright, thin, and very dynamic fine structures. Our analysis reveals the prevalence of transverse waves in SCFs with median amplitudes and periods on the order of 2.4+-0.8 km/s and 83+-29 s, respectively (with standard deviations given as uncertainties). We find that the transverse waves often propagate along (parts of) the SCFs with median phase speeds of 9+-14 km/s. While the propagation is only in one direction along the axis in some of the SCFs, propagating waves in both directions, as well as standing waves are also observed. The transverse oscillations are likely Alfvenic and are thought to be representative of magnetohydrodynamic kink waves. The wave propagation suggests that the rapid high-frequency transverse waves, often produced in the lower photosphere, can penetrate into the chromosphere with an estimated energy flux of ~ 15 kW/m^2. Characteristics of these waves differ from those reported for other fibrillar structures, which, however, were observed mainly in the upper solar chromosphere.

Chromosphere

Sunrise

Photosphere

Sunspot

Field line

Transverse wave

10.3847/1538-4365/229/1/9

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Citations (29)

Image restoration of solar spectra

Astronomy and Astrophysics (2017)

M. van Noort

When recording spectra from the ground, atmospheric turbulence causes degradation of the spatial resolution. We present a data reduction method that restores the spatial resolution of the spectra to their undegraded state. By assuming that the point spread function (PSF) estimated from a strictly synchronized, broadband slit-jaw camera is the same as the PSF that spatially degraded the spectra, we can quantify what linear combination of undegraded spectra is present in each degraded data point. The set of equations obtained in this way is found to be generally well-conditioned and sufficiently diagonal to be solved using an iterative linear solver. The resulting solution has regained a spatial resolution comparable to that of the restored slit-jaw images.

Point spread function

Optical transfer function

10.1051/0004-6361/201731339

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Citations (14)

Status of work-package 4.2: spectropolarimetry using a microlens-fed spectrograph

M. van Noort H.-P. Doerr

Microlens

Source

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