scholarly journals Interferometric imaging of stellar surfaces

1996 ◽  
Vol 176 ◽  
pp. 131-138
Author(s):  
D. Mozurkewich
Keyword(s):  
Surface Structure ◽  
Turbulent Atmosphere ◽  
Stellar Surface ◽  
The Sun ◽  
Interferometric Imaging ◽  
Direct Imaging ◽  
Indirect Methods ◽  
State Of Affairs ◽  
Optical Astronomy ◽  
Near Future

Until recently, all study of stellar surface structure, except for the sun, has been limited to indirect methods. This state of affairs is rapidly changing. With the introduction of interferometric techniques to optical astronomy, direct imaging of stellar surfaces is finally possible. Within a few years we will have images with sub-milliarcsecond resolution and 10 or more resolution elements across the stellar surface.In this talk, I will describe the technique of optical interferometry and explain how it can be made to work through the earth's turbulent atmosphere. I will show some actual data and describe what can be expected in the near future.

scholarly journals A review of the SCOSTEP’s 5-year scientific program VarSITI—Variability of the Sun and Its Terrestrial Impact

2021 ◽  
Vol 8 (1) ◽  
Author(s):  
Kazuo Shiokawa ◽  
Katya Georgieva
Keyword(s):  
Solar Wind ◽  
Interplanetary Space ◽  
Solar Wind Plasma ◽  
The Sun ◽  
Scientific Program ◽  
Solar Cycles ◽  
Grand Minimum ◽  
The Earth ◽  
Earth Connection ◽  
Near Future

AbstractThe Sun is a variable active-dynamo star, emitting radiation in all wavelengths and solar-wind plasma to the interplanetary space. The Earth is immersed in this radiation and solar wind, showing various responses in geospace and atmosphere. This Sun–Earth connection variates in time scales from milli-seconds to millennia and beyond. The solar activity, which has a ~11-year periodicity, is gradually declining in recent three solar cycles, suggesting a possibility of a grand minimum in near future. VarSITI—variability of the Sun and its terrestrial impact—was the 5-year program of the scientific committee on solar-terrestrial physics (SCOSTEP) in 2014–2018, focusing on this variability of the Sun and its consequences on the Earth. This paper reviews some background of SCOSTEP and its past programs, achievements of the 5-year VarSITI program, and remaining outstanding questions after VarSITI.

scholarly journals Doppler imaging of stellar surface structure

2003 ◽  
Vol 411 (3) ◽  
pp. 595-604 ◽  
Author(s):  
K. G. Strassmeier ◽  
T. Pichler ◽  
M. Weber ◽  
T. Granzer
Keyword(s):  
Surface Structure ◽  
Stellar Surface ◽  
Doppler Imaging

scholarly journals Stellar Surface Convection, Line Asymmetries, and Wavelength Shifts

1999 ◽  
Vol 170 ◽  
pp. 268-277 ◽  
Author(s):  
Dainis Dravins
Keyword(s):  
Adaptive Optics ◽  
Temporal Variability ◽  
Stellar Surface ◽  
Time Variability ◽  
The Sun ◽  
Atmospheric Physics ◽  
Spatially Resolved ◽  
Activity Cycles ◽  
To Come ◽  
Surface Convection

AbstractWavelength positions of photospheric absorption lines may be affected by surface convection (stellar granulation). Asymmetries and wavelength shifts originate from correlated velocity and brightness patterns: rising (blueshifted) elements are hot (bright), and convective blueshifts result from a larger contribution of such blueshifted photons than of redshifted ones from the sinking and cooler (darker) gas. For the Sun, the effect is around 300 m s−1, expected to increase in F-type stars, and in giants. Magnetic fields affect convection and induce lineshift variations over stellar activity cycles. A sufficient measuring precision reveals also the temporal variability of line wavelengths (due to the evolution of granules on the stellar surface). A major future development to come from adaptive optics and optical interferometry will be the study of wavelength variations across spatially resolved stars, together with their spatially resolved time variability. Thus, precise radial velocities should soon open up new vistas in stellar atmospheric physics.

scholarly journals Doppler imaging of stellar surface structure

2006 ◽  
Vol 463 (3) ◽  
pp. 1071-1080 ◽  
Author(s):  
Zs. Kővári ◽  
J. Bartus ◽  
K. G. Strassmeier ◽  
K. Oláh ◽  
M. Weber ◽  
...  
Keyword(s):  
Surface Structure ◽  
Stellar Surface ◽  
Doppler Imaging

scholarly journals Observational Needs for Progress in Solar/Stellar Magnetic Activity: Overview

1983 ◽  
Vol 102 ◽  
pp. 499-502
Author(s):  
Robert W. Noyes
Keyword(s):  
Magnetic Activity ◽  
The Sun ◽  
Guiding Principle ◽  
Physical Mechanisms ◽  
Near Future ◽  
Major Progress ◽  
Important Progress ◽  
Stellar Magnetic Activity ◽  
The Way

Recent observational and theoretical findings have clarified the physical mechanisms which underlie magnetic activity production in stars, and point the way naturally to a number of new or more crisply defined questions, whose answers can lead to major progress in the near future. Concerning observational programs, a guiding principle has been evident throughout this symposium: We should rely heavily on the Sun for understanding the detailed physics of magnetic activity and its generation, while at the same time we study analogous stellar phenomena for comparison with the Sun, and for new insights and extension to different regions. I list below some broad observational areas in which conditions seem ripe for important progress in understanding solar and stellar magnetic activity, leaving to other summarizers the discussion of particular observational programs.

scholarly journals Optical and Near-IR Observations of SN 1998bw

2005 ◽  
Vol 192 ◽  
pp. 381-390
Author(s):  
Ferdinando Patat
Keyword(s):  
Gamma Ray ◽  
Line Emission ◽  
Nuclear Astrophysics ◽  
The Sun ◽  
Near Ir ◽  
Low Threshold ◽  
Near Future

Thus, the observation of gamma-ray line emission from a young supernova seems very promising in the near future. The observation, or even a null observation at a low threshold, will give significance in the fields of nuclear astrophysics and supernova theory. The scientific importance of a positive measurement would be analogous with and comparable to the importance of successful detection of neutrinos from the Sun.Clayton, Colgate, and Fishman [2].

scholarly journals German Teachers’ Digital Habitus and Their Pandemic Pedagogy

2020 ◽  
Vol 2 (3) ◽  
pp. 879-905
Author(s):  
Carolyn Blume
Keyword(s):  
Public Schools ◽  
Technology Acceptance ◽  
Teaching And Learning ◽  
Decision Makers ◽  
Positive Development ◽  
Teacher Professionalization ◽  
Current State ◽  
Explanatory Account ◽  
State Of Affairs ◽  
Near Future

Abstract After closing public schools in early 2020 to slow the spread of Covid-19, attempts to provide continuity of education in Germany by means of digital tools faltered in variety of ways, with insufficient competence and inadequate technology leading to inequitable access and uneven implementation. Understanding how German teachers were caught unprepared in this time of crisis, especially in comparison with their European neighbors, requires an examination of their habitus as discussed by Bourdieu and Wacquant (1992) that accounts for their behaviors beyond existing models regarding technology acceptance. Drawing on existing sociological and media-related studies, this contribution will describe the attitudes of German teachers and educational decision-makers in light of their digital, cultural, and educational habitus to provide a partial explanatory account for the current state of affairs. It will show how traditional skepticism for innovation among teachers in general, and German teachers in particular, is reinforced by demographic and sociological characteristics of the German teacher population and the nature of German schooling. After describing extant conditions regarding digitally mediated educational experiences during the initial Covid-19 phase in Germany based on emerging data, this article will subsequently identify prospective issues in this area in the near future. While the transition to digital teaching and learning has the potential to bring about a number of challenges, early data suggests that a possibility of significant positive development may occur as well. Based on these indications, the article will conclude with implications for teacher professionalization going forward.

scholarly journals Measurements of spontaneous rates of mutations in the recent past and the near future

2010 ◽  
Vol 365 (1544) ◽  
pp. 1169-1176 ◽  
Author(s):  
Fyodor A. Kondrashov ◽  
Alexey S. Kondrashov
Keyword(s):  
Spontaneous Mutation ◽  
Natural Populations ◽  
Fundamental Parameter ◽  
Indirect Methods ◽  
The Past ◽  
Genome Wide ◽  
Related Individuals ◽  
Methodological Approaches ◽  
Near Future ◽  
Generation Sequencing

The rate of spontaneous mutation in natural populations is a fundamental parameter for many evolutionary phenomena. Because the rate of mutation is generally low, most of what is currently known about mutation has been obtained through indirect, complex and imprecise methodological approaches. However, in the past few years genome-wide sequencing of closely related individuals has made it possible to estimate the rates of mutation directly at the level of the DNA, avoiding most of the problems associated with using indirect methods. Here, we review the methods used in the past with an emphasis on next generation sequencing, which may soon make the accurate measurement of spontaneous mutation rates a matter of routine.

scholarly journals Using SONG to probe rapid variability and evolution of starspots

2010 ◽  
Vol 6 (S273) ◽  
pp. 451-454
Author(s):  
James E. Neff ◽  
Jon Hakkila ◽  
Frank Hill ◽  
Jason Jackiewicz ◽  
Travis S. Metcalfe ◽  
...  
Keyword(s):  
High Resolution ◽  
Surface Structure ◽  
Real Time ◽  
Stellar Surface ◽  
Secondary Science ◽  
Doppler Imaging ◽  
Rapid Variability ◽  
Current Technology ◽  
Spectroscopic Observations ◽  
Short Timescale

AbstractThe Stellar Observations Network Group (SONG) is being developed as a network of 1-meter spectroscopic telescopes designed for and primarily dedicated to asteroseismology. It is patterned after the highly successful GONG project. The Danish prototype telescope will be installed in Tenerife in early 2011. Ultimately we hope to have as many as 8 identical nodes providing continuous high-resolution spectroscopic observations for targets anywhere in the sky. The primary scientific goals of SONG are asteroseismology and the search for Earth-mass exoplanets. The spectroscopic requirements for these programs push the limits of current technology, but the resulting spectrograph design will enable many secondary science programs with less stringent requirements. Doppler imaging of starspots can be accomplished using continuous observations over several stellar rotations using identical instrumentation at each node. It should be possible to observe the evolution of starspot morphology in real-time, for example. We discuss the design and status of the SONG project in general, and we describe how SONG could be used to probe short timescale changes in stellar surface structure.

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