<i>Astrophysical Quantities</i>

Allen, C. W.; Graff, John De; Beiser, Arthur

doi:10.1063/1.3059970

Cited by 872 publications

(1,307 citation statements)

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“…Appendix: The Solar Spectrum and the Question of Planetary Atmospheres Figure 1 in this Appendix shows the received solar power outside the Earth according to Allen (1973). F(X) is the intensity of the mean solar disk; F (X) is the same as F(h) but refers to the continuum between the lines.…”

Section: Resultsmentioning

confidence: 99%

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The interstellar medium and the glacial eras during the Pleistocene

1988

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We study the hypothetical conditions for interstellar clouds dense enough to produce glaciations on the Earth. A simple differential formula (adequate to give lower limits to dust absorption) is used to relate mean temperatures and visual albedos today and during the glacial eras. For this, the geological and oceanographical records of the Pleistocene are used. The temperature decays are associated to an absorption of the solar light in visual magnitudes mu. As the effective albedo, integrated in all wavelengths are lower than the corresponding visual value, the adoption of a visual scale leads to an underestimation of the actual amount of dust. A minimum dust absorption Am0 = 0.02 mag, necessary to start a glacial era is then obtained. This should mean interstellar clouds with dust densities of 4100 mag. PC-' and sizes of 0.3 pc or more, taking into account the time span of the glacial eras and the mean velocity of the Sun with respect to the LSR. Such clouds were never observed and are uncompatible with what is known from the interstellar medium: the 'glaciation clouds' should be clouds with densities 50-100 times above the tolerable value for gravitational stability; on the other hand, the necessary number of clouds per cubic parsec should produce the collapse of the galactic disc as a whole. From a comparative analysis of the temperatures of the other planets it seems to be that the actual thermal temperatures in their surfaces depend less than one expects from the visual albedos. From this it is raised the suspicion that the cause of the ice ages was the Sun itself.

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Section: Resultsmentioning

confidence: 99%

“…T= 5850 K in the blue-visual (Allen, 1973). The 5970 K temperature was obtained testing numerically Planck functions with the observed F(X).…”

Section: Resultsmentioning

confidence: 99%

The interstellar medium and the glacial eras during the Pleistocene

1988

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“…For A =7 (used below) and R between 1.1 and 3, this expression for ne is within 10~ of Newkirk's (1967) equatorial solar minimum model and about 0.8 times Allen's (1973) …”

Section: Collisional Excitationmentioning

confidence: 95%

OSO-7 results on coronal emission near 304 ?

et al. 1975

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The spectral composition and spatial distribution of equatorial coronal emission near 304/~ is examined. Spectral scans indicate that the predominant line is from Si xI. Comparisons of observations with calculations of intensity changes with altitude indicate that collisional excitation is important near the Sun but that photoexcitation becomes dominant beyond about 1.3 R o from the solar center. Observed and calculated intensities are in approximate agreement for abundances and electron densities that are within the range of observed values.

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“…A supergiant having such a mass on the main sequence, has probably been a late B-early A star. The mean v sin i value for possible A0 main-sequence progenitor stars is ≈ 150 km s −1 (Allen 1973). Even if we suppose that the expansion of the evolving star involves no mass loss, then a supergiant that reaches a radius of about 20 R (an estimate for HD172365 using T eff and M bol values) will possess a rotational velocity:…”

Section: Lithium In Hd172365mentioning

confidence: 99%

“…Even if we assume that the progenitor of HD172365 rotates at break-up velocity during the main sequence phase with v max = 320 km s −1 (a value typical for A-stars; see, e.g., Allen 1973), then the equatorial velocity of HD172365 should be equal to 40 km s −1 . However, this value is less than the lower limit of the equatorial velocity of 50 km s −1 (i.e., the v sin i value) observed in the star.…”

Section: Lithium In Hd172365mentioning

confidence: 99%