Abstract

Development of analytic binary star models is discussed in historical and on-going perspective, beginning with an overview of paradigm shifts, the merits of direct (rectification-free) models, and fundamental four-type binary system morphology. Attention is called to the likelihood that many or even most cataclysmic variables may be of the double contact morphological type. Eclipsing binary distance estimates differ from those of standard candles in being individually measurable—without reliance on (usually nearby) objects that are assumed similar. Recent progress on circumstellar accretion disk models is briefly summarized, with emphasis on the separate roles of fluid dynamic, structural, and analytic models. Time-related parameters (ephemeris, apsidal motion, and light travel time) now can be found with a unified algorithm that processes light curves, velocity curves, and pre-existing eclipse timings together, without need to compute any new timings. Changes in data publication practices are recommended and logical errors and inconsistencies in terminology are noted. Parameter estimation strategies are discussed.

Highlights

  • Development of analytic binary star models is discussed in historical and on-going perspective, beginning with an overview of paradigm shifts, the merits of direct models, and fundamental four-type binary system morphology

  • Strides taken with the new models included optional built-in precise morphology; generation of objectively computed error estimates; proper treatment of physical phenomena such as tides, gravity brightening, reflection, and radiation physics; simultaneous solution of multiband light curves, RV curves, and eclipse timings; easy insertion of further modeling improvements; reduced workload and increased productivity for investigators; and—not appreciated until at least a decade later—increased numbers of observers, theorists, and analyzers brought into the binary star field, perhaps due to a renewed sense of doing real science

  • With ’contact’ meaning accurate contact of a star with its limiting lobe, the resulting four-type morphology form a consistent system that leads to astrophysical insights connected in various ways to lobe filling and overfilling

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Summary

A Sense of Direction

A common thread running through this essay is change—accumulated changes that helped in reaching our present understanding of close binaries, and changes needed to fix a few mis-steps and stimulate further advances. A comfortable starting point for perspective can be changes in style. Style is not easy to quantify, astrophysical styles are surely changing over the decades. Primary enablers for assessing progression of style are journals and other written records, readily searchable via computer. A library visit of long ago stands out in memory, where it was break time and there on the shelf—recreation ready—were the earliest Astrophysical Journals. It is not necessary to say that the colors are real, though, no doubt, the impression of difference of color which the eye receives is heightened by the effect of contrast, through the nearness of the stars.”. Anything so relaxed in an astrophysics journal would be hard to find or even within the last century. Our stroll down memory lane will need no math, even on its many side excursions

Rectification Era
Developing Model Capabilities
Binary System Morphology—The Four Types
Distances
Disk Models
Ephemeris Analysis Reconsidered
Data Publication Practices
Overview
Meaning of Stellar Evolution
Meaning of Contact
Meaning of β Lyrae Type
Term Used with Multiple Meanings
Inappropriate Application or Naming of Terms
Are Detached EBs Preferable to Other Morphologies for Parameter Accuracy?
Temperature Ratio as an EB Parameter?
Parameter No-Nos
Last Comment
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