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Heat transport in the solar corona and wind is still a major unsolved astrophysical problem. Because of the key role played by electrons, the electron density and temperature(s) are important prerequisites for understanding these plasmas.…

Searches for small exoplanets around solar-type stars are limited by stellar physical variability. While chromospheric variability is well studied, observing, modeling. and understanding the much smaller fluctuations in photospheric…

Solar and Stellar Astrophysics · Physics 2024-07-03 Dainis Dravins , Hans-Günter Ludwig

Context. The Si IV lines at 1394 \r{A} and 1403 \r{A} form in the solar atmosphere at a temperature of $\sim10^{4.8}$ K. They are usually considered optically thin, but their opacity can be enhanced during solar flares. Traditionally, the…

Solar and Stellar Astrophysics · Physics 2023-07-19 Hao-Cheng Yu , J. Hong , M. D. Ding

Normal thermal fluctuations of the cell membrane have been studied extensively using high resolution microscopy and focused light, particularly at the peripheral regions of a cell. We use a single probe particle attached non-specifically to…

Biological Physics · Physics 2020-04-16 Rahul Vaippully , Vaibavi Ramanujan , Manoj Gopalakrishnan , Saumendra Bajpai , Basudev Roy

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

We present HST/STIS long-slit spectroscopy of NGC 1976. Our goal is to measure the intrinsic line ratio [O III] 4364/5008 and thereby evaluate the electron temperature (T_e) and the fractional mean-square T_e variation (t_A^2) across the…

We present a comparative spectral analysis to explore the ability of a cooler Sun model to accurately capture the spectral line shape changes caused by Sunspots. In the search for small Earth-like planets, the effects of stellar surface…

Solar and Stellar Astrophysics · Physics 2025-08-13 Claire Komori , John M. Brewer , Lily L. Zhao

Observation of the strengths and profiles of the hydrogen Balmer absorption series is an established technique for determining the effective temperature and surface gravity of hot H-rich white dwarf stars. In principle, the Lyman series…

Astrophysics · Physics 2009-11-07 M. A. Barstow , S. A. Good , M. R. Burleigh , I. Hubeny , J. B. Holberg , A. J. Levan

Ground-based thermal infrared observations face substantial challenges in correcting the predominant background emitted as thermal radiation from the atmosphere and the telescope itself. With the upcoming 40\,m class ELTs, unprecedented…

Instrumentation and Methods for Astrophysics · Physics 2024-08-29 J. R. Sauter , W. Brandner , J. Heidt , F. Cantalloube

Delta-T shot noise is activated in temperature-biased electronic junctions, down to the atomic scale. It is characterized by a quadratic dependence on the temperature difference and a nonlinear relationship with the transmission…

Mesoscale and Nanoscale Physics · Physics 2025-04-08 Matthew Gerry , Jonathan J. Wang , Joanna Li , Ofir Shein-Lumbroso , Oren Tal , Dvira Segal

With an aim to examine whether the predicted solar gravitational redshift can be observationally confirmed under the influence of the convective Doppler shift due to granular motions, we attempted measuring the absolute spectral line-shifts…

Solar and Stellar Astrophysics · Physics 2015-06-05 Yoichi Takeda , Satoru Ueno

Temporal variations of the structure and the rotation rate of the solar tachocline region are studied using helioseismic data from the Global Oscillation Network Group (GONG) and the Michelson Doppler Imager (MDI) obtained during the period…

Astrophysics · Physics 2009-11-06 Sarbani Basu , H. M. Antia

Kepler short-cadence photometry of 2347 stars with effective temperatures in the range 6000-10000 K was used to search for the presence of solar-like oscillations. The aim is to establish the location of the hot end of the stochastic…

Solar and Stellar Astrophysics · Physics 2020-08-17 L. A. Balona

ALMA observations of the Sun at mm-$\lambda$ offer a unique opportunity to investigate the temperature structure of the solar chromosphere. In this article we expand our previous work on modeling the chromospheric temperature of the quiet…

Solar and Stellar Astrophysics · Physics 2020-08-19 C. E. Alissandrakis , A. Nindos , T. S. Bastian , S. Patsourakos

The temperature and magnetic field dependence of lattice and carrier excitations in MnSi is studied in detail using inelastic light scattering. The pure symmetry components of the electronic response are derived from the polarization…

Strongly Correlated Electrons · Physics 2014-07-23 H. -M. Eiter , P. Jaschke , R. Hackl , A. Bauer , M. Gangl , C. Pfleiderer

Convective motions in the solar atmosphere cause spectral lines to become asymmetric and shifted in wavelength. For photospheric lines, this differential Doppler shift varies from the solar disk center to the limb. Precise and comprehensive…

Solar and Stellar Astrophysics · Physics 2019-04-10 Johannes Löhner-Böttcher , Wolfgang Schmidt , Rolf Schlichenmaier , Tilo Steinmetz , Ronald Holzwarth

The astrophysically very interesting Li I 671 nm line has been observed with high spatial resolution in solar granulation with the intention to diagnose departures from local thermodynamic equilibrium (LTE) in the line formation. The…

Astrophysics · Physics 2007-05-23 Dan Kiselman

Observations of the Sun in the visible spectral range belong to standard measurements obtained by instruments both on the ground and in the space. Nowadays, both nearly continuous full-disc observations with medium resolution and dedicated…

Solar and Stellar Astrophysics · Physics 2020-06-30 Michal Švanda , Jan Jurčák , David Korda , Jana Kašparová

The development of safe and robust autonomous driving functions is heavily dependent on large-scale, high-quality sensor data. However, real-world data acquisition requires extensive human labor and is strongly limited by factors such as…

Computer Vision and Pattern Recognition · Computer Science 2025-08-27 Samed Doğan , Maximilian Hoh , Nico Leuze , Nicolas Rodriguez Peña , Alfred Schöttl

Oscillation properties are usually measured by fitting symmetric Lorentzian profiles to the power spectra of Sun-like stars. However the line profiles of solar oscillations have been observed to be asymmetrical for the Sun. The physical…

Solar and Stellar Astrophysics · Physics 2018-05-02 O. Benomar , Mjo. Goupil , K. Belkacem , T. Appourchaux , M. B. Nielsen , M. Bazot , L. Gizon , S. Hanasoge , K. R. Sreenivasan , B. Marchand