The Visibility of Stars Without Optical Aid

Weaver, Harold F.

doi:10.1086/125956

Cited by 24 publications

(24 citation statements)

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“…Thus, for the sun, M o = 4.83, 1 o L L = = , and for it to be invisible to the naked eye in the [nearly] total blackness of interstellar space, m = 6.5 [2] (discussed in Section 4).…”

Section: The Apparent Magnitude Of Blackbody Radiators In the Rest Framementioning

confidence: 99%

“…Both of these effects serve to in- 2 Whether the physical situations could exist for this effect to be realized is VERY uncertain. As an example, relativistic speeds might be obtainable in the expulsion of a low-mass star from the region of the Galactic Center as a consequence of a fly-by with the central massive black hole.…”

Section: The Apparent Magnitude Of Relativistic Blackbody Radiatorsmentioning

confidence: 99%

“…1 In honor of the 100 th anniversary of Einstein's general relativity, this note examines, as a gedanken experiment, the specific conditions under which this effect would occur. 2 Furthermore, relativistic blackbody radiators will emit spectral radiances which are increased (in the case of approaching) or decreased (in the case of receding), due to temperature inflation and relativistic beaming. By considering in the gedanken experi- 1 For this effect, CCD detectors could be considered in place of human eyes, but the nature of the phenomenon wouldn't change.…”

Section: Introductionmentioning

confidence: 99%

“…with the wavelengths of 700 nm and 390 nm published by Starr [12]. The limiting magnitude of the unassisted human eye is taken to be 6.5 [2]. This figure applies to all visible wavelengths and accounts for eye sensitivity.…”

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confidence: 99%

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Black Sun: Ocular Invisibility of Relativistic Luminous Astrophysical Bodies

Lee¹,

Cleaver²

2016

JHEPGC

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Considered as a gedanken experiment are the conditions under which the relativistic Doppler shifting of visible electromagnetic radiation to beyond the human ocular range could reduce the incident radiance of the source, and render a luminous astrophysical body (LAB) invisible to a naked eye. This paper determines the proper distance as a function of relativistic velocity at which a luminous object attains ocular invisibility.

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“…Thus, for the sun, M o = 4.83, 1 o L L = = , and for it to be invisible to the naked eye in the [nearly] total blackness of interstellar space, m = 6.5 [2] (discussed in Section 4).…”

Section: The Apparent Magnitude Of Blackbody Radiators In the Rest Framementioning

confidence: 99%

Section: The Apparent Magnitude Of Relativistic Blackbody Radiatorsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

mentioning

confidence: 99%

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Black Sun: Ocular Invisibility of Relativistic Luminous Astrophysical Bodies

Lee¹,

Cleaver²

2016

JHEPGC

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“…19 In spite of occasional references in the literature 20 to the effect that stars can be seen during the day when viewed from the bottom of a deep shaft, Hynek 10 and Smith**! showed experimentally (by viewing the sky through a long shaft) that the belief was without any foundation.…”

Section: Visualmentioning

confidence: 99%

Investigation of Electronic Fringe Detector for a Stellar Interferometer

Boardman¹,

Kellen²

1967

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A fringe detector was constructed to detect fringes from a Michelson stellar interferometer and to relate these measurements to the characteristics of the source of illumination. A rotating reflector, a single slit, and a phototube were combined to transform the spatially-varying intensity pattern of the fringe field into a time-varying voltage signal displayed on an oscilloscope face. The oscilloscope trace was photographed and analyzed to determine fringe contrast.The maximum sensitivity of the detector was determined to be equivalent to a source providing 10~^ V T /cm2 at a fringe contrast of 1 and a signal-tonoise ratio of 1. Modifications can provide a factor of 500 to 1000 improvement in detector sensitivity. The interferometer was determined to have potentially better resolution than a single-mirror telescope because it can electrically filter the effects of ambient background illumination and turbulence. The use of an interferometer to measure the angular size of a pieshapeJ source was studied and found to be not particularly suited to this purpose.The action of apodized and unapodized lens systems on the field due to an extended background and a small source was analyzed. The emphasis of the analysis was to consider such a system as linear in the mutual coherence function. The results indicate that no particular advantage in terms of contrast enhancement can be obtained by apodizing.iii

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