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Over the course of its motion through the Galaxy, our solar system has encountered many interstellar environments of varying characteristics. Interstellar medium (ISM) density variations spanning seven orders of magnitude are commonly seen…

Solar and Stellar Astrophysics · Physics 2015-06-16 Katherine Wyman , Seth Redfield

The dust emission polarization spectrum -- how the polarization percentage changes with wavelength -- serves as a probe of dust grain properties in star-forming regions. In this paper, we present 89 $\mu$m - 214 $\mu$m polarization spectrum…

Solar and Stellar Astrophysics · Physics 2025-09-18 Erin G. Cox , Giles Novak , David T. Chuss , Dennis Lee , Marc Berthoud , Kaitlyn Karpovich , Joseph M. Michail , Zhi-Yun Li , Peter C. Ashton

The lack of long and reliable time series of solar spectral irradiance (SSI) measurements makes an accurate quantification of solar contributions to recent climate change difficult. Whereas earlier SSI observations and models provided a…

Recent observations and theoretical investigations of neutron stars indicate that their atmospheres consist not of hydrogen or iron but possibly other elements such as helium. We calculate the ionization and dissociation equilibrium of…

Astrophysics · Physics 2008-11-26 Kaya Mori , Jeremy S. Heyl

We investigate the loss rates of the hydrogen atmospheres of terrestrial planets with a range of masses and orbital distances by assuming a stellar extreme ultraviolet (EUV) luminosity that is 100 times stronger than that of the current…

Earth and Planetary Astrophysics · Physics 2016-04-27 N. V. Erkaev , H. Lammer , P. Odert , K. G. Kislyakova , C. P. Johnstone , M. Güdel , M. L. Khodachenko

We present a further investigation into the increased ionization observed in element charge states in the fast solar wind compared to its coronal hole source regions. Once ions begin to be perpendicularly heated by ion cyclotron waves and…

Astrophysics · Physics 2011-02-11 J. Martin Laming , Susan T. Lepri

In this paper, we show a "proof of concept" of the heating mechanism of the solar chromosphere due to wave dissipation caused by the effects of partial ionization. Numerical modeling of non-linear wave propagation in a magnetic flux tube,…

Solar and Stellar Astrophysics · Physics 2016-03-16 S. Shelyag , E. Khomenko , A. de Vicente , D. Przybylski

Astrophysical ionizing radiation events have been recognized as a potential threat to life on Earth, primarily through depletion of stratospheric ozone and subsequent increase in surface-level solar ultraviolet radiation. Simulations of the…

Earth and Planetary Astrophysics · Physics 2015-03-26 Brian C. Thomas , Patrick J. Neale , Brock R. Snyder

We present our results concerning a systematical analysis of helioseismic implications on solar structure and neutrino production. We find Y$_{ph}=0.238-0.259$, $R_b/R_\odot=0.708-0.714$ and $\rho_b=(0.185-0.199)$ gr/cm$^3$. In the interval…

Astrophysics · Physics 2015-06-24 V. Castellani , S. Degl'Innocenti , W. A. Dziembowski , G. Fiorentini , B. Ricci

Using data collected by the Indian Mars Orbiter Mission in October 2021, we investigated coronal regions of the Sun by analyzing the Doppler spectral width of radio signals to estimate solar wind velocity. A simplified equation is…

Solar and Stellar Astrophysics · Physics 2025-04-02 Keshav Aggarwal , R. K. Choudhary , Abhirup Datta , Roopa M. V. , Bijoy K. Dai

We study the time-dependent modulation effect and derive the local interstellar spectra (LIS) for the cosmic ray (CR) proton, helium, boron and carbon. A two-dimensional modulation model including the variation of the interplanetary…

High Energy Astrophysical Phenomena · Physics 2019-09-25 Bing-Bing Wang , Xiao-Jun Bi , Kung Fang , Su-Jie Lin , Peng-Fei Yin

High-precision pulsar timing requires accurate corrections for dispersive delays of radio waves, parametrized by the dispersion measure (DM), particularly if these delays are variable in time. In a previous paper we studied the Solar-wind…

Solar flares significantly impact the conditions of the Earth's ionosphere. In particular, the sudden increase in X-ray flux during a flare penetrates down to the lowest-lying D-region and dominates ionization at these altitudes (60-100…

Solar and Stellar Astrophysics · Physics 2021-11-17 Laura A. Hayes , Oscar S. D. O'Hara , Sophie A. Murray , Peter T. Gallagher

Since the first \emph{in-situ} measurements of the altitude profile of upper atmospheric density and composition carried out by the Viking lander missions during 1976, similar data were continuously gathered by MAVEN and MOM spacecraft…

Earth and Planetary Astrophysics · Physics 2021-03-03 Kamsali Nagaraja , Praveen Kumar Basuvaraj , S. C. Chakravarty , K. Praveen Kumar

We study the radial evolution of intermittency of density fluctuations in the fast solar wind. The study is performed analyzing the plasma density measurements provided by Helios 2 in the inner heliosphere between $0.3$ and $0.9$ AU. The…

Solar and Stellar Astrophysics · Physics 2014-11-14 R. Bruno , D. Telloni , L. Primavera , E. Pietropaolo , R. D'Amicis , L. Sorriso-Valvo , V. Carbone , F. Malara , P. Veltri

The aim of this paper is to provide geoscientists with the most accurate set of the Earth's astro-climatic parameters and daily insolation quantities, able to describe the Short-Term Orbital Forcing (STOF) as represented by the…

Earth and Planetary Astrophysics · Physics 2017-04-20 Rodolfo G. Cionco , Willie W. -H Soon

The observed variability of the cosmic-ray intensity in the interplanetary space is driven by the evolution of the Sun's magnetic activity over its 11-year quasiperiodical cycle. Investigating the relationship between solar activity indices…

Solar and Stellar Astrophysics · Physics 2022-10-13 Nicola Tomassetti , Bruna Bertucci , Emanuele Fiandrini

3He-rich solar energetic particles (SEPs) are believed to be accelerated in solar flares or jets by a mechanism that depends on the ion charge-to-mass (Q/M) ratio. It implies that the flare plasma characteristics (e.g., temperature) may be…

Solar and Stellar Astrophysics · Physics 2021-03-10 R. Bucik , S. M. Mulay , G. M. Mason , N. V. Nitta , M. I. Desai , M. A. Dayeh

We have developed a modular semi-numerical code that computes the time and spatially dependent ionization of neutral hydrogen (HI), neutral (HeI) and singly ionized helium (HeII) in the intergalactic medium (IGM). The model accounts for…

Cosmology and Nongalactic Astrophysics · Physics 2018-05-02 Anne Hutter

Voyager 1 has explored the solar wind-interstellar medium interaction region between the terminal shock and heliopause following the intensity distribution of galactic cosmic ray protons above 200 MeV energy. Before this component reached…

Solar and Stellar Astrophysics · Physics 2015-09-09 J. J. Quenby , W. R. Webber
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