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The Sun is the most studied of all stars, and thus constitutes a benchmark for stellar models. However, our vision of the Sun is still incomplete, as illustrated by the current debate on its chemical composition. The problem reaches far…

Differential rotation is a key driver of magnetic activity and dynamo processes in the Sun and other stars, especially as the rate differs across the solar layers, but also in active regions. We aim to accurately quantify the velocity at…

The differential rotation plays a crucial role in the dynamics of the Sun. We study the solar rotation and its correlation with solar activity by applying a modified machine learning algorithm to identify and track coronal bright points…

Solar and Stellar Astrophysics · Physics 2024-07-30 Zahra Shokri , Nasibe Alipour , Hossein Safari

We establish a quantitative relationship between photometric and spectroscopic detections of solar-like oscillations using ab initio, three-dimensional (3D), hydrodynamical numerical simulations of stellar atmospheres. We present a…

Solar and Stellar Astrophysics · Physics 2021-02-17 Yixiao Zhou , Thomas Nordlander , Luca Casagrande , Meridith Joyce , Yaguang Li , Anish M. Amarsi , Henrique Reggiani , Martin Asplund

We report quantitative analysis of the radial gradient of solar angular velocity at depths down to about 15 Mm below the solar surface for latitudes up to 75 degree using the Michelson Doppler Imager (MDI) observations of surface gravity…

Astrophysics · Physics 2015-06-24 T. Corbard , M. J. Thompson

The solar photosphere, chromosphere and corona are known to rotate differentially as a function of latitude. To date, it is unclear if the solar transition region also rotates differentially. In this paper, we investigate differential…

Solar and Stellar Astrophysics · Physics 2021-07-21 Jaidev Sharma , Brajesh Kumar , Anil K Malik , Hari Om Vats

The present work is an effort to investigate possible radial variations in the solar coronal rotation by analyzing the solar radio emission data at 15 different frequencies (275-1755 MHz) for the period starting from July 1994 to May 1999.…

Solar and Stellar Astrophysics · Physics 2021-05-28 Vivek Kumar Singh , Satish Chandra , Sanish Thomas , Som Kumar Sharma , Hari Om Vats

Microturbulence (\xi) is a key parameter introduced in stellar spectroscopy to explain the strength of saturated lines by formally incorporating an additional thermal broadening term in the line opacity profile. Although our Sun can serve…

Solar and Stellar Astrophysics · Physics 2022-01-12 Yoichi Takeda

The properties of the solar wind, as measured in situ throughout the heliosphere, depend both on the characteristics of its coronal source and on the intrinsic processes governing its interplanetary evolution. Recently, radial and Parker…

Here we present a detailed analysis of solar acoustic mode frequencies and their rotational splittings for modes with degree up to 900. They were obtained by applying spherical harmonic decomposition to full-disk solar images observed by…

Astrophysics · Physics 2008-08-22 M. C. Rabello-Soares , S. G. Korzennik , J. Schou

The daily variation of the solar photocenter over some 11 years is derived from the Mount Wilson data reprocessed by Ulrich et al. 2010 to closely match the surface distribution of solar irradiance. The standard deviations of astrometric…

Solar and Stellar Astrophysics · Physics 2015-05-19 V. V. Makarov , D. Parker , R. K. Ulrich

Comparing solar and stellar brightness variations is hampered by the difference in spectral passbands used in observations as well as by the possible difference in the inclination of their rotation axes from the line of sight. We calculate…

Solar and Stellar Astrophysics · Physics 2020-07-01 N. -E. Nèmec , E. Işık , A. I. Shapiro , S. K. Solanki , N. A. Krivova , Y. Unruh

Understanding the global rotational profile of the solar atmosphere and its variation is fundamental to uncovering a comprehensive understanding of the dynamics of the solar magnetic field and the extent of coupling between different layers…

Stellar radial velocities play a fundamental role in the discovery of extrasolar planets and the measurement of their physical parameters as well as in the study of stellar physical properties. We investigate the impact of the solar…

Earth and Planetary Astrophysics · Physics 2016-03-02 A. F. Lanza , P. Molaro , L. Monaco , R. D. Haywood

Aims: We investigate how well modeled solar irradiances agree with measurements from the SORCE satellite, both for total solar irradiance and broken down into spectral regions on timescales of several years. Methods: We use the SATIRE model…

Solar and Stellar Astrophysics · Physics 2015-05-27 Will T. Ball , Yvonne C. Unruh , Natalie A. Krivova , Sami Solanki , Jerald W. Harder

To evaluate site quality and to develop multi-conjugative adaptive optics systems for future large solar telescopes, characterization of contributions to seeing from heights up to at least 12 km above the telescope is needed. We describe a…

Instrumentation and Methods for Astrophysics · Physics 2013-11-25 G. B. Scharmer , T. I. M. van Werkhoven

A discussion of the solar diameter and its variations must be linked to the limb darkening function (LDF). We introduce a new method to perform high resolution astrometry of the solar diameter from the ground, through the observations of…

Solar and Stellar Astrophysics · Physics 2013-02-15 Andrea Raponi

We introduce a new method to perform high resolution astrometry of the solar diameter from the ground, through the observations of eclipses. A discussion of the solar diameter and its variations is linked to the Limb Darkening Function…

Solar and Stellar Astrophysics · Physics 2015-06-03 Andrea Raponi , Costantino Sigismondi , Konrad Guhl , Richard Nugent , Andreas Tegtmeier

We report on an ongoing investigation into a seismic calibration of solar models designed for estimating the main-sequence age and a measure of the chemical abundances of the Sun. Only modes of low degree are employed, so that with…

Astrophysics · Physics 2009-11-13 G. Houdek , D. O. Gough

The data from solar neutrino experiments together with standard solar model predictions are used in order to derive the possible profile of the magnetic field inside the Sun, assuming the existence of a sizeable neutrino magnetic moment and…

Astrophysics · Physics 2009-10-30 Joao Pulido