Stare Results on a Single Field: Tens of New Pulsating Stars

2003 ◽  
pp. 13-16
Author(s):  
Roi Alonso ◽  
Juan Antonio Belmonte ◽  
Tim Brown
Keyword(s):  
Pulsating Stars ◽  
Single Field

B. The Non-Linear Calculations for Pulsating Stars

1967 ◽  
Vol 28 ◽  
pp. 105-176
Author(s):  
Robert F. Christy
Keyword(s):  
Major Part ◽  
Afternoon Session ◽  
Discussion Session ◽  
Pulsating Stars ◽  
Fourth Symposium ◽  
Non Linear ◽  
Considerable Discussion ◽  
Informal Approach ◽  
Preceding Session

(Ed. note: The custom in these Symposia has been to have a summary-introductory presentation which lasts about 1 to 1.5 hours, during which discussion from the floor is minor and usually directed at technical clarification. The remainder of the session is then devoted to discussion of the whole subject, oriented around the summary-introduction. The preceding session, I-A, at Nice, followed this pattern. Christy suggested that we might experiment in his presentation with a much more informal approach, allowing considerable discussion of the points raised in the summary-introduction during its presentation, with perhaps the entire morning spent in this way, reserving the afternoon session for discussion only. At Varenna, in the Fourth Symposium, several of the summaryintroductory papers presented from the astronomical viewpoint had been so full of concepts unfamiliar to a number of the aerodynamicists-physicists present, that a major part of the following discussion session had been devoted to simply clarifying concepts and then repeating a considerable amount of what had been summarized. So, always looking for alternatives which help to increase the understanding between the different disciplines by introducing clarification of concept as expeditiously as possible, we tried Christy's suggestion. Thus you will find the pattern of the following different from that in session I-A. I am much indebted to Christy for extensive collaboration in editing the resulting combined presentation and discussion. As always, however, I have taken upon myself the responsibility for the final editing, and so all shortcomings are on my head.)

Experiments in Bright-Field Imaging with Hollow-Cone Illumination

1981 ◽  
Vol 39 ◽  
pp. 226-227
Author(s):  
W. Kunath ◽  
K. Weiss ◽  
E. Zeitler
Keyword(s):  
Signal To Noise Ratio ◽  
Carbon Support ◽  
Electronic System ◽  
Optic Axis ◽  
Hollow Cone ◽  
Signal To Noise ◽  
Bright Field ◽  
Noise Ratio ◽  
Single Field ◽  
Field Imaging

Bright-field images taken with axial illumination show spurious high contrast patterns which obscure details smaller than 15 ° Hollow-cone illumination (HCI), however, reduces this disturbing granulation by statistical superposition and thus improves the signal-to-noise ratio. In this presentation we report on experiments aimed at selecting the proper amount of tilt and defocus for improvement of the signal-to-noise ratio by means of direct observation of the electron images on a TV monitor.Hollow-cone illumination is implemented in our microscope (single field condenser objective, Cs = .5 mm) by an electronic system which rotates the tilted beam about the optic axis. At low rates of revolution (one turn per second or so) a circular motion of the usual granulation in the image of a carbon support film can be observed on the TV monitor. The size of the granular structures and the radius of their orbits depend on both the conical tilt and defocus.

Connecting Gospels

2018 ◽  
Keyword(s):  
Second Century ◽  
Common Belief ◽  
Field Of Study ◽  
Early Christian ◽  
Single Field ◽  
Vantage Points ◽  
Canonical Texts ◽  
Normative Status ◽  
Two Bodies ◽  
Shed Light

By the late second century, early Christian gospels had been divided into two groups by a canonical boundary that assigned normative status to four of them while consigning their competitors to the margins. The project of this volume is to find ways to reconnect these divided texts. The primary aim is not to address the question whether the canonical/non-canonical distinction reflects substantive and objectively verifiable differences between the two bodies of texts—although that issue may arise at various points. Starting from the assumption that, in spite of their differences, all early gospels express a common belief in the absolute significance of Jesus and his earthly career, the intention is to make their interconnectedness fruitful for interpretation. The approach taken is thematic and comparative: a selected theme or topic is traced across two or more gospels on either side of the canonical boundary, and the resulting convergences and divergences shed light not least on the canonical texts themselves as they are read from new and unfamiliar vantage points. The outcome is to demonstrate that early gospel literature can be regarded as a single field of study, in contrast to the overwhelming predominance of the canonical four characteristic of traditional gospels scholarship.

Variation in Soybean Aphid (Hemiptera: Aphididae) Biotypes Within Fields

2021 ◽  
Author(s):  
S J Bhusal ◽  
R L Koch ◽  
A J Lorenz
Keyword(s):  
Resistance Genes ◽  
Environmental Sustainability ◽  
Soybean Aphid ◽  
Aphis Glycines ◽  
Aphid Resistance ◽  
Soybean Cultivars ◽  
Major Pest ◽  
Single Field ◽  
Aphis Glycines Matsumura ◽  
Multiple Resistance Genes

Abstract Soybean aphid (Aphis glycines Matsumura (Hemiptera: Aphididae)) has been a major pest of soybean in North America since its detection in this continent in 2000 and subsequent spread. Although several aphid resistance genes have been identified, at least four soybean aphid biotypes have been discovered, with three of them being virulent on soybean cultivars with certain soybean aphid resistance genes. These biotypes are known to vary across years and locations, but information on their variation within single fields is limited. An investigation was conducted to study the variation of soybean aphid biotypes within single townships and fields in Minnesota. Screening of 28 soybean aphid isolates collected from seven soybean fields (six soybean fields in Cairo and Wellington Townships of Renville County, MN and one field in Wilmar Township of Kandiyohi County, MN) revealed the existence of multiple known biotypes of soybean aphid within single fields of soybean. We found up to three biotypes of soybean aphid in a single field. Two biotypes were found in five fields while only one field had only a single biotype. Three isolates presented reactions on a panel of resistant and susceptible indicator lines that were different from known biotypes. These results highlight the importance of characterizing soybean aphid biotypes in small geographical areas and utilizing generated knowledge to develop soybean cultivars pyramided with multiple resistance genes. The outcome will be decreased use of insecticides, thereby improving economic and environmental sustainability of soybean production.

The study of short orbital period of delta scuti pulsating variable stars

2019 ◽  
Vol 15 (S356) ◽  
pp. 407-407
Author(s):  
Abduselam Mohammed
Keyword(s):  
Time Delay ◽  
Orbital Period ◽  
Binary Stars ◽  
Arrival Time ◽  
Periodic Variation ◽  
Variable Stars ◽  
Orbital Elements ◽  
Pulsating Stars ◽  
Delta Scuti ◽  
Arrival Time Delay

AbstractAs a pulsating star moves in its binary orbit, the path length of the light between us and the star varies, leading to the periodic variation in the arrival time of the signal from the star to us (earth). With the consideration of pulsators light arrival time delay effects several new methods which allows using Kepler photometric data (light curves) alone to find binary stars have been recently developed. Among these modern techniques we used binarogram method and we identified that several δSct pulsating stars have companions. The application of these method on detecting long periods(i.e. longer than about 50 d) δSct pulsating stars is not new, but the uniqueness of this study is we verified that it is also applicable to detect and determine the orbital elements of short periods (i.e short orbital period) δSct pulsating stars. With this investigation, we identified the possible way to overcome effects of fictious peaks, even, on the maximum peaks helpful to verify weather the star has companion or not depend up on the existence of the time-delay. Then, we applied the technique on known binary stars and their orbital elements are previously published. Finally, we identified some new short orbital period δSct pulsating stars and obtained their orbital frequency and period with the same procedures. Because of with our attempts we succeeded and verified the applicability of the method (the Binarogram method) on these stars (i.e short orbital period) for the first time, we expect that our present study will play a great role for similar study and to improve our binary statistics.

Realistic Line Models for Pulsating B Stars

1980 ◽  
Vol 4 (1) ◽  
pp. 80-83
Author(s):  
P. A. Stamford ◽  
R. D. Watson
Keyword(s):  
Detailed Examination ◽  
Stellar Disk ◽  
Stellar Winds ◽  
Line Profiles ◽  
Stellar Rotation ◽  
B Stars ◽  
Pulsating Stars ◽  
Velocity Gradients ◽  
Expanding Atmospheres ◽  
Realistic Line

Spectral line profiles in pulsating stars are affected by the interplay of a number of velocity fields. In addition to the basic velocities associated with the pulsation mode, the complications of stellar rotation, atmospheric velocity gradients, stellar winds and varying scales of turbulence may also be present. Initial modelling for line profiles in variables assumed a constant ‘intrinsic profile’ which was integrated over the limb-darkened stellar disk. This approach has been used even in recent work for nonradial pulsations (Stamford and Watson 1977; Kubiak 1978) because of computational ease. Employing an LTE analysis to predict centre-to-limb profile variations, which are then integrated over the disk, represents an improvement on this. This has been done, for example, by Parsons (1972) for radial pulsations in cepheids and by Smith (1978) for nonradial oscillations in B stars. Mihalas (1979) has recently made an even more detailed examination of profiles in expanding atmospheres which involved consideration of velocity gradients, departures from LTE and rotation.

scholarly journals Gravitational Waves and Pulsating Stars: What Can We Learn from Future Observations?

1996 ◽  
Vol 77 (20) ◽  
pp. 4134-4137 ◽  
Author(s):  
Nils Andersson ◽  
Kostas D. Kokkotas
Keyword(s):  
Gravitational Waves ◽  
Pulsating Stars

scholarly journals Inverse tides in pulsating binary stars

2020 ◽  
Vol 501 (1) ◽  
pp. 483-490
Author(s):  
Jim Fuller
Keyword(s):  
Binary Stars ◽  
Close Binary ◽  
Close Binaries ◽  
Spin Orbit ◽  
Misalignment Angle ◽  
Stellar Rotation ◽  
Transfer Energy ◽  
Pulsating Stars ◽  
Mode Amplitude ◽  
Rotation Periods

ABSTRACT In close binary stars, the tidal excitation of pulsations typically dissipates energy, causing the system to evolve towards a circular orbit with aligned and synchronized stellar spins. However, for stars with self-excited pulsations, we demonstrate that tidal interaction with unstable pulsation modes can transfer energy in the opposite direction, forcing the spins of the stars away from synchronicity, and potentially pumping the eccentricity and spin–orbit misalignment angle. This ‘inverse’ tidal process only occurs when the tidally forced mode amplitude is comparable to the mode’s saturation amplitude, and it is thus most likely to occur in main-sequence gravity mode pulsators with orbital periods of a few days. We examine the long-term evolution of inverse tidal action, finding the stellar rotation rate can potentially be driven to a very large or very small value, while maintaining a large spin–orbit misalignment angle. Several recent asteroseismic analyses of pulsating stars in close binaries have revealed extremely slow core rotation periods, which we attribute to the action of inverse tides.

scholarly journals Physics of Solar-Like Oscillations

2005 ◽  
Vol 13 ◽  
pp. 397-402 ◽  
Author(s):  
Jørgen Christensen-Dalsgaard
Keyword(s):  
Stochastic Processes ◽  
Pulsating Stars ◽  
Stellar Oscillations ◽  
Current State

AbstractThe physics of solar and stellar oscillations determine their observable characteristics. I provide a brief overview of the properties of solar-like oscillations, excited by stochastic processes, in other stars. In addition, I consider the current state of investigations of such oscillations, as well as the prospects for an improved understanding of their physics and the properties of the pulsating stars.

scholarly journals Finding binaries among Kepler pulsating stars from phase modulation of their pulsations

2014 ◽  
Vol 441 (3) ◽  
pp. 2515-2527 ◽  
Author(s):  
S. J. Murphy ◽  
T. R. Bedding ◽  
H. Shibahashi ◽  
D. W. Kurtz ◽  
H. Kjeldsen
Keyword(s):  
Phase Modulation ◽  
Pulsating Stars
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