scholarly journals The discontinuous nature of chromospheric-activity evolution

2010 ◽  
pp. 305-309
Author(s):  
G. Pace
Keyword(s):  
Chromospheric Activity ◽  
Discontinuous Nature

Chromospheric activity as a function of age in main-sequence stars

1966 ◽  
Vol 24 ◽  
pp. 40-43
Author(s):  
O. C. Wilson ◽  
A. Skumanich
Keyword(s):  
Main Sequence ◽  
The Sun ◽  
Main Sequence Stars ◽  
Tentative Conclusion ◽  
Chromospheric Activity ◽  
General Field ◽  
Large Clusters

Evidence previously presented by one of the authors (1) suggests strongly that chromospheric activity decreases with age in main sequence stars. This tentative conclusion rests principally upon a comparison of the members of large clusters (Hyades, Praesepe, Pleiades) with non-cluster objects in the general field, including the Sun. It is at least conceivable, however, that cluster and non-cluster stars might differ in some fundamental fashion which could influence the degree of chromospheric activity, and that the observed differences in chromospheric activity would then be attributable to the circumstances of stellar origin rather than to age.

Chromospheric activity in several single late-type stars

2015 ◽  
Vol 15 (2) ◽  
pp. 252-274 ◽  
Author(s):  
Li-Yun Zhang ◽  
Qing-Feng Pi ◽  
Zhong-Zhong Zhu
Keyword(s):  
Late Type ◽  
Chromospheric Activity

Variations in Skin Resistance and Their Relationship to G.S.R. Conditioning

1960 ◽  
Vol 106 (442) ◽  
pp. 281-287 ◽  
Author(s):  
Irene Martin
Keyword(s):  
Action Potentials ◽  
Background Activity ◽  
Skin Resistance ◽  
Muscle Action ◽  
Muscle Tonus ◽  
Experimental Procedure ◽  
Discontinuous Nature ◽  
The Subject ◽  
Neural Excitation ◽  
Set Up

Any particular system which is being conditioned is likely to maintain a certain level of background activity throughout the experimental procedure; either of a discontinuous nature, as, for example, with eyeblink, heart rate and respiratory cycle, or continuously, as in the case of basal skin resistance and muscle tonus. This background activity or level of arousal does not remain constant but usually varies in time, presumably as a result of underlying neural excitation or inhibition. It may increase throughout an experiment if the subject becomes highly motivated, as with the gradients of muscle action potentials observed by Bartoshuk (1955), or decrease, if the subject becomes more relaxed and familiar with the set-up, as Duffy and Lacey (1946) found with level of skin conductance.

ON THE VALUATION OF DERIVATIVES WITH SNAPSHOT RESET FEATURES

2008 ◽  
Vol 11 (08) ◽  
pp. 905-941 ◽  
Author(s):  
ERIC C. K. YU ◽  
WILLIAM T. SHAW
Keyword(s):  
Convertible Bonds ◽  
Convertible Bond ◽  
Put Options ◽  
Risk Characteristics ◽  
Black Scholes ◽  
Barrier Type ◽  
Simple Change ◽  
Discontinuous Nature ◽  
Change Of Variable ◽  
Digital Options

We propose a general approach that requires only a simple change of variable that keeps the valuation of call and put options (convertible bonds) with strike (conversion) price resets two-dimensional in the classical Black–Scholes setting. A link between reset derivatives, compound options and "discrete barrier" type options, when there is one reset is then discussed, from which we analyze the risk characteristics of reset derivatives, which can be significantly different from their vanilla counterparts. We also generalize the prototype reset structure and show that the delta and gamma of a convertible bond with reset can both be negative. Finally, we show that the "waviness" property found in the delta and gamma of some reset derivatives is due to the discontinuous nature of the reset structure, which is closely linked to digital options.

scholarly journals The large scale magnetic field of the G0 dwarf HD 206860 (HN Peg)

2013 ◽  
Vol 9 (S302) ◽  
pp. 146-147
Author(s):  
Sudeshna Boro Saikia ◽  
Sandra V. Jeffers ◽  
Pascal Petit ◽  
Stephen Marsden ◽  
Julien Morin ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Spectral Type ◽  
Large Scale ◽  
Longitudinal Magnetic Field ◽  
Chromospheric Activity ◽  
Large Scale Magnetic Field ◽  
Debris Disk ◽  
Infrared Triplet

AbstractHD 206860 is a young planet (HN Peg b) hosting star of spectral type G0V and it has a potential debris disk around it. In this work we measure the longitudinal magnetic field of HD 206860 using spectropolarimetric data and we measure the chromospheric activity using Ca II H&K, H-alpha and Ca II infrared triplet lines.

scholarly journals An investigation of chromospheric activity spanning the Vaughan-Preston gap: impact on stellar ages

2009 ◽  
Vol 499 (1) ◽  
pp. L9-L12 ◽  
Author(s):  
G. Pace ◽  
J. Melendez ◽  
L. Pasquini ◽  
G. Carraro ◽  
J. Danziger ◽  
...  
Keyword(s):  
Chromospheric Activity ◽  
Stellar Ages

scholarly journals Fine structure of the age-chromospheric activity relation in solar-type stars

2016 ◽  
Vol 595 ◽  
pp. A11 ◽  
Author(s):  
D. Lorenzo-Oliveira ◽  
G. F. Porto de Mello ◽  
L. Dutra-Ferreira ◽  
I. Ribas
Keyword(s):  
Fine Structure ◽  
Chromospheric Activity ◽  
Solar Type

scholarly journals CHROMOSPHERIC ACTIVITY NATURE OF KIC 6044064

2021 ◽  
Vol 57 (2) ◽  
pp. 351-361
Author(s):  
E. Yoldaş
Keyword(s):  
Primary Component ◽  
Secondary Component ◽  
Migration Period ◽  
Chromospheric Activity ◽  
Spot Group ◽  
Kepler Mission ◽  
Phase Interval

This study presents results obtained from the data of KIC 6044064 (KOI 6652). KIC 6044064 was observed by the Kepler Mission for a total of 1384.254 days. 525 minima times were determined, 264 of which were primary minima and the rest were secondary minima. The OPEA model was derived and its parameters were obtained. On the secondary component, there are two different spot bands latitudinally outstretched, consisting of three spots located with a phase interval of 0.33. The average migration period was found to be 623.063±4.870 days (1.71±0.01 years) for the first spot group, while it was 1125.514±7.305 days (3.08±0.02 years) for the second group. The spectral types of the components seem to be G7V+K9V. Their masses and radii were determined to be 0.86Mʘ and 0.89Rʘ for the primary component and 0.54Mʘ and 0.62Rʘ for the secondary component.

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