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Transits of hot Jupiters in X-rays and the ultraviolet have been shown to be both deeper and more variable than the corresponding optical transits. This variability has been attributed to hot Jupiters having extended atmospheres at these…

Earth and Planetary Astrophysics · Physics 2015-06-23 J. Llama , E. L. Shkolnik

Many studies of the solar corona have shown that the observed X-ray luminosity is well correlated with the total unsigned magnetic flux. In this paper we present results from the extensive numerical modeling of active regions observed with…

Astrophysics · Physics 2016-08-30 Harry P. Warren , Amy R. Winebarger

Future generations of precise radial velocity (RV) surveys aim to achieve sensitivity sufficient to detect Earth mass planets orbiting in their stars' habitable zones. A major obstacle to this goal is astrophysical radial velocity noise…

Earth and Planetary Astrophysics · Physics 2016-04-27 Andrew Vanderburg , Peter Plavchan , John Asher Johnson , David R. Ciardi , Jonathan Swift , Stephen R. Kane

In G dwarfs, the surface distribution, coverage and lifetimes of starspots deviate from solar-like patterns as the rotation rate increases. We set up a numerical platform which includes the large-scale rotational and surface flow effects,…

Solar and Stellar Astrophysics · Physics 2018-12-24 Emre Işık , Sami K. Solanki , Natalie A. Krivova , Alexander I. Shapiro

The uncertainties associated with technology- and geography-specific degradation rates make it difficult to calculate the levelized cost of energy (LCOE), and thus the economic viability of solar energy. In this regard, millions of fielded…

Applied Physics · Physics 2018-02-06 Xingshu Sun , Raghu Vamsi Krishna Chavali , Muhammad Ashraful Alam

The data acquisition of solar radiation in a locality is essential for the development of efficient designs of systems, whose operation is based on solar energy. This paper presents a methodology to estimate solar irradiance using an…

The photospheric unsigned magnetic flux has been shown to be highly correlated with radial velocity (RV) variations caused by solar surface activity. This activity indicator is therefore a prime candidate to unlock the potential of RV…

Earth and Planetary Astrophysics · Physics 2024-09-04 F. Lienhard , A. Mortier , H. M. Cegla , A. Collier Cameron , B. Klein , C. A. Watson

We study the variability of solar activity using new photospheric proxies originally developed for the analysis of stellar magnetism with the CoRoT and Kepler photometric observations. These proxies are obtained by tracking the temporal…

Solar and Stellar Astrophysics · Physics 2017-12-13 D. Salabert , R. A. García , A Jiménez , L. Bertello , E. Corsaro , P. L. Pallé

Recent studies indicate that a small number of rogue solar active regions (ARs) may have a significant impact on the end-of-cycle polar field and the long-term behavior of solar activity. The impact of individual ARs can be qualified based…

Solar and Stellar Astrophysics · Physics 2024-05-13 Ruihui Wang , Jie Jiang , Yukun Luo

Parker Solar Probes's (PSP)'s unique orbital path allows us to observe the solar wind closer to the Sun than ever before. Essential to advancing our knowledge of solar wind and energetic particle formation is identifying the sources of PSP…

Solar and Stellar Astrophysics · Physics 2022-08-17 Samantha Wallace , Shaela I. Jones , C. Nick Arge , Nicholeen Viall , Carl J. Henney

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 activity is a potential important limitation to the detection of low mass extrasolar planets with indirect methods (RV, photometry, astrometry). In previous papers, using the Sun as a proxy, we investigated the impact of stellar…

Solar and Stellar Astrophysics · Physics 2015-05-27 A. -M. Lagrange , N. Meunier , M. Desort , F. Malbet

Using solar spectral irradiance measurements from the SORCE spacecraft and the F/F' technique, we have estimated the radial velocity (RV) scatter induced on the Sun by stellar activity as a function of wavelength. Our goal was to evaluate…

Solar and Stellar Astrophysics · Physics 2015-06-23 Robert C. Marchwinski , Suvrath Mahadevan , Paul Robertson , Lawrence Ramsey , Jerald Harder

Time-resolved spectroscopic observations of rapidly oscillating Ap (roAp) stars show a complex picture of propagating magneto-acoustic pulsation waves, with amplitude and phase strongly changing as a function of atmospheric height. We have…

Solar and Stellar Astrophysics · Physics 2015-03-13 O. Kochukhov , E. Khomenko

We present a new empirical model to predict solar energetic particle (SEP) event-integrated and peak intensity spectra between 10 and 130 MeV at 1 AU, based on multi-point spacecraft measurements from the Solar TErrestrial RElations…

Solar and Stellar Astrophysics · Physics 2021-02-24 Alessandro Bruno , Ian G. Richardson

The derivation of radial velocities from large numbers of spectra that typically result from survey work, requires automation. However, except for the classical cases of slowly rotating late-type spectra, existing methods of measuring…

Instrumentation and Methods for Astrophysics · Physics 2014-05-20 M. David , R. Blomme , Y. Frémat , Y. Damerdji , C. Delle Luche , E. Gosset , D. Katz , Y. Viala

Context: Chromospheric activity produces both photometric and spectroscopic variations that can be mistaken as planets. Large spots crossing the stellar disc can produce planet-like periodic variations in the light curve of a star. These…

Solar and Stellar Astrophysics · Physics 2015-05-18 R. Martinez-Arnaiz , J. Maldonado , D. Montes , C. Eiroa , B. Montesinos

Context. The relation between solar surface rotation and sunspot activity still remains open. Sunspot activity has dramatically reduced in solar cycle 24 and several solar activity indices and flux measurements experienced unprecedentedly…

Solar and Stellar Astrophysics · Physics 2015-02-18 L. Zhang , K. Mursula , I. Usoskin

The aim of this work is to provide new insights on the dynamics associated to the resonances which arise as a consequence of the coupling of the effect due to the oblateness of the Earth and the Solar Radiation Pressure (SRP) effect for an…

Earth and Planetary Astrophysics · Physics 2022-12-14 Roberto Paoli

Context. Distinguishing between a signal induced by either stellar activity or a planet is currently the main challenge in radial velocity searches for low-mass exoplanets. Even when the presence of a transiting planet and hence its period…

Earth and Planetary Astrophysics · Physics 2017-05-17 A. Mortier , A. Collier Cameron