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Following the tracks of Malbet, Yu, & Shao (1995} on dark hole algorithms, we present analytical methods to measure and correct the speckle noise behind an ideal coronagraph. We show that, in a low aberration regime, wavefront sensing can…

Astrophysics · Physics 2009-11-11 Pascal Borde , Wesley Traub

By extrapolating from observationally derived surface magnetograms of low-mass stars we construct models of their coronal magnetic fields and compare the 3D field geometry with axial multipoles. AB Dor, which has a radiative core, has a…

Astrophysics · Physics 2009-11-13 S. G. Gregory , M. Jardine , C. Argiroffi , J. -F. Donati

The raw coronagraphic performance of current high-contrast imaging instruments is limited by the presence of a quasi-static speckle (QSS) background, resulting from instrumental non-common path errors (NCPEs). Rapid development of efficient…

Instrumentation and Methods for Astrophysics · Physics 2017-01-18 Michael J. Wilby , Christoph U. Keller , Frans Snik , Visa Korkiakoski , Alexander G. M. Pietrow

In recent years, space weather research has focused on developing modelling techniques to predict the arrival time and properties of coronal mass ejections (CMEs) at the Earth. The aim of this paper is to propose a new modelling technique…

Solar and Stellar Astrophysics · Physics 2018-02-22 P. Pagano , D. H. Mackay , A. R. Yeates

We carry out a study of the global three-dimensional (3D) structure of the electron density and temperature of the quiescent inner solar corona ($r<1.25 R_\odot$) by means of tomographic reconstructions and magnetohydrodynamic simulations.…

Solar and Stellar Astrophysics · Physics 2020-06-17 D. G. Lloveras , A. M. Vásquez , F. A. Nuevo , C. Mac Cormack , N. Sachdeva , W. Manchester , B. Van der Holst , R. A. Frazin

We present a method for tracking and predicting the propagation and evolution of coronal mass ejections (CMEs) using the imagers on the STEREO and SOHO satellites. By empirically modeling the material between the inner core and leading edge…

Solar and Stellar Astrophysics · Physics 2012-02-28 Samuel Schreiner , Cynthia Cattell , Kris Kersten , Adam Hupach

Solar coronal dimmings have been observed extensively in the past two decades and are believed to have close association with coronal mass ejections (CMEs). Recent study found that coronal dimming is the only signature that could…

Future high-contrast imaging spectroscopy with a large segmented telescope will be able to detect atmospheric molecules of Earth-like planets around G- or K-type main-sequence stars. Increasing the number of target planets will require a…

Instrumentation and Methods for Astrophysics · Physics 2022-05-25 Satoshi Itoh , Taro Matsuo

The possibilities of organizing an observation service for solar activity in order to provide space weather forecasting are considered. The most promising at this stage is the creation of a ground-based observation network. Such a network…

Solar and Stellar Astrophysics · Physics 2023-03-06 A. G. Tlatov , A. A. Pevtsov

Coronal hole boundaries are the interfaces between closed and open magnetic field regions in the solar atmosphere. Many fundamental processes take place at these regions, including magnetic reconnection that is responsible for solar wind…

Magnetic field couples the solar interior to the solar atmosphere, known as the corona. The coronal magnetic field is one of the crucial parameters which determines the coronal structures and regulates the space weather phenomena like…

Solar and Stellar Astrophysics · Physics 2022-07-26 Devojyoti Kansabanik , Divya Oberoi , Surajit Mondal

High-contrast imaging from space must overcome two major noise sources to successfully detect a terrestrial planet angularly close to its parent star: photon noise from diffracted star light, and speckle noise from star light scattered by…

Astrophysics · Physics 2009-11-13 Pascal J. Borde , Wesley A. Traub

Presently, many models of the coronal magnetic field rely on photospheric vector magnetograms but these data have been shown to be problematic as the sole boundary information for nonlinear force-free field (NLFFF) extrapolations. Magnetic…

Solar and Stellar Astrophysics · Physics 2021-06-29 A. Malanushenko , C. J. Schrijver , M. L. DeRosa , M. S. Wheatland , S. A. Gilchrist

The 8 April 2024 total solar eclipse (TSE) provides a unique opportunity to study the solar corona. This work presents our prediction of the solar corona at the time of the eclipse based on magnetohydrodynamic (MHD) modeling performed with…

Context. Convective regions in stellar models are always associated with uncertainties, for example due to extra-mixing or the possible inaccurate position of the transition from convective to radiative transport of energy. These have a…

Solar and Stellar Astrophysics · Physics 2018-02-07 G. Buldgen , D. R. Reese , M. A. Dupret

Several concepts now exist for small, space-based missions to directly characterize exoplanets in reflected light. Here, we develop an instrument noise model suitable for studying the spectral characterization potential of a…

Earth and Planetary Astrophysics · Physics 2016-01-21 Tyler D. Robinson , Karl R. Stapelfeldt , Mark S. Marley

We derive a simple analytical model for the propagation of HSSs from the Sun to Earth and thereby show how the area of coronal holes and the size of their boundary regions affect the HSS velocity, temperature, and density near Earth. We…

Current solar wind prediction is based on the Wang & Sheeley empirical relationship between the solar wind speed observed at 1 AU and the rate of magnetic flux tube expansion (FTE) between the photosphere and the inner corona, where FTE is…

Solar and Stellar Astrophysics · Physics 2020-10-21 Bala Poduval , Gordon Petrie , Luca Bertello

Understanding the evolution of radial sizes and instantaneous expansion speeds of coronal mass ejections (CMEs) is crucial for assessing their impact duration on Earth's environment. We introduce a non-conventional approach to derive the…

Solar and Stellar Astrophysics · Physics 2024-09-30 Anjali Agarwal , Wageesh Mishra

How and where are coronal loops rooted in the solar lower atmosphere? The details of the magnetic environment and its evolution at the footpoints of coronal loops are crucial to understanding the processes of mass and energy supply to the…

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