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In this work, we study and quantify properties of strong-field small-scale convection and compare observed properties with those predicted by numerical simulations. We analyze spectropolarimetric 630.25 nm data from a unipolar ephemeral…

Solar and Stellar Astrophysics · Physics 2015-05-19 G. Narayan , G. B. Scharmer

Swirl-shaped flow structures have been observed throughout the solar atmosphere, in both emission and absorption, at different altitudes and locations, and are believed to be associated with magnetic structures. However, the distribution…

Solar and Stellar Astrophysics · Physics 2024-12-06 Quan Xie , Jiajia Liu , Chris J. Nelson , Robert Erdélyi , Yuming Wang

Recent wide-area surveys have enabled us to study the Milky Way with unprecedented detail. Its inner regions, hidden behind dust and gas, have been partially unveiled with the arrival of near-IR photometric and spectroscopic datasets. Among…

In this work we investigate the dynamic behavior of inter-network regions of the solar chromosphere. We observed the chromosphere of the quiet Sun using a narrow-band Lyot filter centered at the Ca II K 2v emission peak with a bandpass of…

Astrophysics · Physics 2009-11-11 F. Wöger , S. Wedemeyer-Böhm , W. Schmidt , O. von der Lühe

We conducted a deep survey of resolved sub-systems among wide binaries with solar-type components within 67 pc from the Sun. Images of 61 stars in the K and H bands were obtained with the NICI adaptive-optics instrument on the 8-m…

Solar and Stellar Astrophysics · Physics 2015-05-19 Andrei Tokovinin , Markus Hartung , Thomas L Hayward

We used photospheric intensity images and magnetic field measurements from the New Solar Telescope in Big Bear and Helioseismic Magnetic Imager on board Solar Dynamics Observatory (SDO) to study the the effect that the new small-scale…

Solar and Stellar Astrophysics · Physics 2012-07-30 V. Yurchyshyn , K. Ahn , V. Abramenko , P. Goode , W. Cao

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

Continued progress in observational stellar astrophysics requires a deep understanding of the underlying convection dynamics. We present results of realistic 3D radiative hydrodynamic simulations of the outer layers of a moderate mass star…

Solar and Stellar Astrophysics · Physics 2016-04-27 Irina N. Kitiashvili , Alexander G. Kosovichev , Nagi N. Mansour , Alan A. Wray

The global scales of solar convection are studied through three-dimensional simulations of compressible convection carried out in spherical shells of rotating fluid which extend from the base of the convection zone to within 15 Mm of the…

Astrophysics · Physics 2009-11-13 Mark S. Miesch , Allan Sacha Brun , Marc L. Derosa , Juri Toomre

Granulation is the observable signature of convection in envelopes of low-mass stars, forming the background in stellar power spectra. While well-studied in evolved giants, granulation on the MS has received less attention. We here study…

Solar and Stellar Astrophysics · Physics 2026-03-18 Jens R. Larsen , Mia S. Lundkvist , Martin B. Nielsen , Guy R. Davies , Yixiao Zhou , Mikkel N. Lund

We analysed line-of-sight magnetic fields and magnetic power spectra of an undisturbed photosphere using magnetograms acquired by the Helioseismic and Magnetic Imager (HMI) on-board the Solar Dynamic Observatory (SDO) and the Near InfraRed…

Solar and Stellar Astrophysics · Physics 2020-08-17 Valentina I. Abramenko , Vasyl B. Yurchyshyn

The Sun provides us with the only spatially well-resolved astrophysical example of turbulent thermal convection. While various aspects of solar photospheric turbulence, such as granulation (one-Megameter horizontal scale), are well…

Solar and Stellar Astrophysics · Physics 2017-03-14 F. Rincon , T. Roudier , A. A. Schekochihin , M. Rieutord

It is now well established that the quiet Sun contains in total more magnetic flux than active regions and represents an important reservoir of magnetic energy. But the nature and evolution of these fields remain largely unknown. We…

Solar and Stellar Astrophysics · Physics 2021-07-07 Marianne Faurobert , Gilbert Ricort

Magnetic Bright Points (MBPs) are among the smallest observable objects on the solar photosphere. A combination of G-band observations and numerical simulations is used to determine their area distribution. An automatic detection algorithm,…

Solar and Stellar Astrophysics · Physics 2015-05-19 P. J. Crockett , M. Mathioudakis , D. B. Jess , S. Shelyag , F. P. Keenan , D. J. Christian

We present a visual determination of the number of bright points (BPs) existing in the quiet Sun, which are structures though to trace intense kG magnetic concentrations. The measurement is based on a 0.1 arcsec angular resolution G-band…

Solar and Stellar Astrophysics · Physics 2015-03-16 J. Sanchez Almeida , J. A. Bonet , B. Viticchie , D. Del Moro

For the past 150 years, the prevailing view of the local Interstellar Medium (ISM) was based on a peculiarity known as the Gould's Belt, an expanding ring of young stars, gas, and dust, tilted about 20$^\circ$ to the Galactic plane. Still,…

We investigate the structural properties of nuclear star clusters in late-type spiral galaxies. More specifically, we fit analytical models to HST images of 39 nuclear clusters in order to determine their effective radii after correction…

Context. Investigations of the magnetism of the quiet Sun are hindered by extremely weak polarization signals in Fraunhofer spectral lines. Photon noise, straylight, and the systematically different sensitivity of the Zeeman effect to…

The granulation pattern that we observe on the surface of the Sun is due to hot plasma from the interior rising to the photosphere where it cools down, and descends back into the interior at the edges of granules. This is the visible…

A detailed imaging analysis of the globular cluster (GC) system of the Sombrero galaxy (NGC 4594) has been accomplished using a six-image mosaic from the Hubble Space Telescope Advanced Camera for Surveys. The quality of the data is such…

Astrophysics · Physics 2008-11-26 L. R. Spitler , S. S. Larsen , J. Strader , J. P. Brodie , D. A. Forbes , M. A. Beasley