travelers who had gone elsewherewere bringing a flood of exotic tales. … Anubelean studies languished until a global association of scientific and humanistic institutions had been founded and funded. … Not only the fascination of Ishtar and Tammuz spoke for establishing a permanent base on the former. A wish did, to help the living natives through the next of those crises which had dogged their entire history, indeed their evolution. …
Rhetoric. Dejerine wanted dullness. He skipped to a chapter self-proclaimed as dryly factual.
Per se, the system is nothing extraordinary. Companion stars often have widely differing masses, therefore developmental histories, and eccentric orbits are more a rule than an exception.
The three members of Anubelea seem to be approximately as old as Sol. Hence Bel, the G2 star, can expect four or five billion years of steady shining in the future. Ea, the red dwarf, will endure far longer than that. But Anu, the most massive, has inevitably aged faster.
It is not enormously bigger than Bel, 1.3 times, which is to say the mass is 1.22 Sol. In its heyday it did not shine too fiercely for at least one of its planets to spawn protein-in-water life and oxygen-releasing photosynthesis. But perhaps – we continue pathetically ignorant – the greater irradiation hastened evolution. Whatever the causes, we do know that about a billion years ago, Tammuz (Anu III) had brought forth intelligent beings who had in turn brought forth a technological civilization.
By then, their sun had burned sufficient hydrogen that it could no longer stay on the main sequence. It had begun to swell, to become a red giant. At present its total luminosity equals 280 Sols; and this is slowly, inexorably rising.
To understand the situation on Ishtar, let us imagine its sun, Bel, as stationary, Anu and Ea revolving around it. Needless to say, in actuality the three stars move around a common center of mass. But given their changing configurations, only mathematics can well describe this. (See Appendix A.) A Bel-centered diagram is valid geometrically, to a first approximation, though false dynamically.
In this picture, Anu moves around Bel in a huge ellipse. At its maximum distance, it is some 224 astronomical units off, scarcely more than the chief star in the skies of Ishtar. At closest approach, it comes within 40 astronomical units of Bel, i.e. between about 39 and 41 of Ishtar, depending on the planetary position. The orbital period is 1,041 Terrestrial years. That is, each millennium the red giant sweeps near. …
The path of Ea is still more majestic and eccentric. It is always too remote to have a measurable direct effect, although it looms large in every known Ishtarian mythology. And it is interesting in its own right for the single planet it possesses, a superjovian. …
In the present epoch – which for all practical purposes covers millions of past and future years – Anu at periastron to Bel adds approximately 20 per cent to the irradiation which Ishtar normally receives. This corresponds to a rise in black body temperature of 11° C.
Theoretical calculations must be used carefully. A planet, especially if it has atmosphere and hydrosphere, is
not
a black body. For example, heat will cause the formation of clouds from evaporated water, which will reflect back more radiation than formerly; but meanwhile greenhouse effect will operate the more strongly as more water vapor enters the air. And then there are the differing, though always large, thermal inertias of various regions. …
Since periastron passage is necessarily rapid, the time during which Anu is important to Ishtar is arbitrarily estimated at a century. As it approaches, at first there is small result except its increasing apparent size and brightness. Time is needed to heat an entire planet. Storms, droughts, and similar disasters do not become major until about the period when Anu is closest. Thereafter, while the red giant recedes, they
Rhetoric. Dejerine wanted dullness. He skipped to a chapter self-proclaimed as dryly factual.
Per se, the system is nothing extraordinary. Companion stars often have widely differing masses, therefore developmental histories, and eccentric orbits are more a rule than an exception.
The three members of Anubelea seem to be approximately as old as Sol. Hence Bel, the G2 star, can expect four or five billion years of steady shining in the future. Ea, the red dwarf, will endure far longer than that. But Anu, the most massive, has inevitably aged faster.
It is not enormously bigger than Bel, 1.3 times, which is to say the mass is 1.22 Sol. In its heyday it did not shine too fiercely for at least one of its planets to spawn protein-in-water life and oxygen-releasing photosynthesis. But perhaps – we continue pathetically ignorant – the greater irradiation hastened evolution. Whatever the causes, we do know that about a billion years ago, Tammuz (Anu III) had brought forth intelligent beings who had in turn brought forth a technological civilization.
By then, their sun had burned sufficient hydrogen that it could no longer stay on the main sequence. It had begun to swell, to become a red giant. At present its total luminosity equals 280 Sols; and this is slowly, inexorably rising.
To understand the situation on Ishtar, let us imagine its sun, Bel, as stationary, Anu and Ea revolving around it. Needless to say, in actuality the three stars move around a common center of mass. But given their changing configurations, only mathematics can well describe this. (See Appendix A.) A Bel-centered diagram is valid geometrically, to a first approximation, though false dynamically.
In this picture, Anu moves around Bel in a huge ellipse. At its maximum distance, it is some 224 astronomical units off, scarcely more than the chief star in the skies of Ishtar. At closest approach, it comes within 40 astronomical units of Bel, i.e. between about 39 and 41 of Ishtar, depending on the planetary position. The orbital period is 1,041 Terrestrial years. That is, each millennium the red giant sweeps near. …
The path of Ea is still more majestic and eccentric. It is always too remote to have a measurable direct effect, although it looms large in every known Ishtarian mythology. And it is interesting in its own right for the single planet it possesses, a superjovian. …
In the present epoch – which for all practical purposes covers millions of past and future years – Anu at periastron to Bel adds approximately 20 per cent to the irradiation which Ishtar normally receives. This corresponds to a rise in black body temperature of 11° C.
Theoretical calculations must be used carefully. A planet, especially if it has atmosphere and hydrosphere, is
not
a black body. For example, heat will cause the formation of clouds from evaporated water, which will reflect back more radiation than formerly; but meanwhile greenhouse effect will operate the more strongly as more water vapor enters the air. And then there are the differing, though always large, thermal inertias of various regions. …
Since periastron passage is necessarily rapid, the time during which Anu is important to Ishtar is arbitrarily estimated at a century. As it approaches, at first there is small result except its increasing apparent size and brightness. Time is needed to heat an entire planet. Storms, droughts, and similar disasters do not become major until about the period when Anu is closest. Thereafter, while the red giant recedes, they
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