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We studied bright umbral dots (UDs) detected in a moderate size sunspot and compared their statistical properties to recent MHD models. The study is based on high resolution data recorded by the New Solar Telescope at the Big Bear Solar…

Solar and Stellar Astrophysics · Physics 2015-06-03 A. Kilcik , V. B. Yurchyshyn , M. Rempel , V. Abramenko , R. Kitai , P. R. Goode , W. Cao , H. Watanabe

We developed an automated method for sunspot detection using digital white-light solar images to achieve a performance similar to that of visual drawing observations in sunspot counting. To identify down to small, isolated spots correctly,…

Solar and Stellar Astrophysics · Physics 2022-12-05 Yoichiro Hanaoka

Magnetic bright points are small-scale magnetic elements ubiquitous across the solar disk, with the prevailing theory suggesting that they form due to the process of convective collapse. Employing a unique full Stokes spectropolarimetric…

Observations of quiet Sun from the Solar Optical Telescope/Spectro-Polarimeter (SOT/SP) aboard the Hinode spacecraft would reveal the magnetic characters of the solar photosphere. By making use of the deep mode observations of three quiet…

Astrophysics · Physics 2008-12-18 Chunlan Jin , Jingxiu Wang , Meng Zhao

High-resolution observations of horizontal motions in the penumbra are needed to complement the concept of penumbrae obtained from spectropolarimetry. Time series of intensity images of a large sunspot in AR 10634 acquired with the Swedish…

Solar and Stellar Astrophysics · Physics 2022-06-01 Michal Sobotka , Klaus G. Puschmann

Umbral dots (UDs) are small-scale convective intrusions in the umbral core of sunspots and pores. Different methods have been used in the past to determine the physical properties of UDs. One of the methods typically used is multi-level…

Solar and Stellar Astrophysics · Physics 2026-05-27 Rohan Eugene Louis , Amit Chaturvedi

The determination of horizontal velocity fields at the solar surface is crucial to understanding the dynamics and magnetism of the convection zone of the sun. These measurements can be done by tracking granules. Tracking granules from…

Astrophysics · Physics 2009-11-13 R. Tkaczuk , M. Rieutord , N. Meunier , T. Roudier

To deepen the analysis of the photometric properties of the umbra of a sunspot, we study proper motions of small features such as umbral dots (UDs) inside a single sunspot observed by the Solar Optical Telescope of Hinode close to the disk…

Solar and Stellar Astrophysics · Physics 2018-07-17 Hadis Goodarzi , Serge Koutchmy , Ali Adjabshirizadeh

Due to the massive increase in astronomical images (such as James Webb and Solar Dynamic Observatory), automatic image description is essential for solar and astronomical. Zernike moments (ZMs) are unique due to the orthogonality and…

Instrumentation and Methods for Astrophysics · Physics 2023-11-07 Hossein Safari , Nasibe Alipour , Hamed Ghaderi , Pardis Garavand

Magnetic bright points in the solar photosphere, visible in both continuum and G-band images, indicate footpoints of kilogauss magnetic flux tubes extending to the corona. The power spectrum of bright-point motion is thus also the power…

Solar and Stellar Astrophysics · Physics 2017-11-29 Samuel J. Van Kooten , Steven R. Cranmer

We report the discovery of a brightness enhancement in the center of a large sunspot umbra at a wavelength of 3 mm using the Atacama Large Millimeter/sub-millimeter Array (ALMA). Sunspots are amongst the most prominent features on the solar…

Solar and Stellar Astrophysics · Physics 2017-05-31 Kazumasa Iwai , Maria Loukitcheva , Masumi Shimojo , Sami K. Solanki , Stephen M. White

Aims: The aim of this paper is to demonstrate that millimeter wave data can be used to distinguish between various atmospheric models of sunspots, whose temperature structure in the upper photosphere and chromosphere has been the source of…

Solar and Stellar Astrophysics · Physics 2015-01-14 Maria A. Loukitcheva , Sami K. Solanki , Stephen M. White

A 50 min time series of one-dimensional slit-spectrograms, taken in quiet sun at disk center, observed at the German Vacuum Tower Telescope (Observatorio del Teide), was used to study the global and spatial variations of different line…

Solar and Stellar Astrophysics · Physics 2013-03-14 K. G. Puschmann , M. Vazquez , J. A. Bonet , B. Ruiz Cobo , A. Hanslmeier

Solar observations in the mid-infrared 8-14 \mu\m band continuum were carried out with cadence of 5 frames per second, in December 2007. Rapid small heated sources, with typical duration of the order of seconds, were found on the bright…

Small-scale magnetic fields can be observed on the Sun in high resolution G-band filtergrams as magnetic bright points (MBPs). We study Hinode/ Solar Optical Telescope (SOT) longitude and latitude scans of the quiet solar surface taken in…

Solar and Stellar Astrophysics · Physics 2012-12-07 D. Utz , A. Hanslmeier , A. Veronig , O. Kühner , R. Muller , J. Jurčák , B. Lemmerer

The contrasts of features in the quiet Sun are studied using filtergrams recorded by the Broad-band Filter Imager on the Hinode/Solar Optical Telescope. In a first step, the scattered light originating in the instrument is modeled using…

Solar and Stellar Astrophysics · Physics 2015-05-13 S. K. Mathew , V. Zakharov , S. K. Solanki

We studied flux emergence events of sub-granular scale in a solar active region. New Solar Telescope (NST) of Big Bear Solar Observatory made it possible to clearly observe the photospheric signature of flux emergence with very high spatial…

Solar and Stellar Astrophysics · Physics 2015-05-28 Eun-Kyung Lim , Vasyl Yurchyshyn , Valentyna Abramenko , Kwangsu Ahn , Wenda Cao , Philip Goode

Short-lived (100s or less), sub-arcsec to a couple of arcsec size features of enhanced brightenings in the narrowband images at the $\mathrm{H_{2V}}$ and $\mathrm{K_{2V}}$ positions of the Ca II H and K lines in the quiet Sun are known as…

Solar and Stellar Astrophysics · Physics 2022-12-21 Harsh Mathur , Jayant Joshi , K. Nagaraju , Luc Rouppe van der Voort , Souvik Bose

The brightness temperature of the radio free-free emission at millimeter range is an effective tool for characterizing the vertical structure of the solar chromosphere. In this paper, we report on the first single-dish observation of a…

Solar and Stellar Astrophysics · Physics 2015-06-24 Kazumasa Iwai , Masumi Shimojo

Since the Solar Dynamics Observatory (SDO) began recording ~ 1 TB of data per day, there has been an increased need to automatically extract features and events for further analysis. Here we compare the overall detection performance,…

Solar and Stellar Astrophysics · Physics 2011-09-05 Cis Verbeeck , Paul A. Higgins , Tufan Colak , Fraser T. Watson , Veronique Delouille , Benjamin Mampaey , Rami Qahwaji