21. Light of the Night Sky (Lumiere Du Ciel Nocturne)

1988 ◽  
Vol 20 (1) ◽  
pp. 211-218
Author(s):  
K. Mattila ◽  
A. C. Levasseur-Regourd ◽  
R. Dumont ◽  
Yu. I. Galperin ◽  
R. H. Giese ◽  
...  
Keyword(s):  
Background Radiation ◽  
Scattered Light ◽  
Point Of View ◽  
Zodiacal Light ◽  
Extragalactic Background Light ◽  
Infrared Wavelength ◽  
Background Radiations ◽  
Infrared Background ◽  
Night Sky ◽  
Photometric Measurements

The different components of the light of the night sky have their origin in different formations of matter in the universe - encompassing a huge scale of distances ranging from a few kilometers in the earth’s atmosphere to the most distant known galaxies and beyond. Correspondingly, the borderlines to other Commissions are not very well defined and thus material relevant to Commission 21 can also be found in the reports of other Commissions on the following topics: zodiacal light and zodiacal IR emission (Comm. 22, 44), integrated starlight (33, 25), diffuse galactic light (34), extragalactic background light (47), airglow and atmospheric scattered light (50), and space-borne observations of the LONS (44). From the Commission 21 point of view the connecting link between these various fields is the special techniques utilized in the surface photometric measurements and reductions of background radiations which extend over the entire sky. One crucial problem is the separation of the LONS into its several components. The approach for solving this task is to utilize the different spatial distributions and different broad and narrow band spectral properties of each of the LONS component. Thus the successful measurement and separation of one of the LONS components requires a knowledge of the properties of all the other components. This situation has become apparent in recent years as the infrared background radiation database, provided by the Infrared Astronomical Satellite (IRAS), has been analyzed: both the zodiacal and galactic dust emissions have to be analyzed hand in hand, and both these components must be very accurately mastered before any conclusions are possible on the extragalactic component. It is also obvious that very similar problems are encountered in the ultraviolet and infrared wavelength regions as in the more traditional optical domain. Thus the techniques developed in one of these wavelength domains are directly applicable in the others.

scholarly journals 21. Light of the Night Sky / Lumière du Ciel Nocturne

1997 ◽  
Vol 23 (1) ◽  
pp. 231-236
Author(s):  
Christoph Leinert
Keyword(s):  
Interstellar Dust ◽  
Thermal Emission ◽  
Scattered Light ◽  
Diffuse Radiation ◽  
Interplanetary Dust ◽  
Dust Particles ◽  
Zodiacal Light ◽  
Interplanetary Dust Particles ◽  
Extragalactic Background Light ◽  
Night Sky

The light of the night sky is a difficult to disentangle mixture of tropospherically scattered light, airglow, zodiacal light (including the thermal emission by interplanetary dust particles), unresolved stellar light, diffuse scattering and emission by interstellar dust and gas, and finally an extragalactic component. It has the reputation of being a very traditional field of astronomy, which certainly is true if we look at the long history of the subject. The recent renewed interest in this topic, which continued during this triennium, appears mainly to come from three sources: - first from the impressive results of the IRAS and COBE infrared satellites. They brought to general consciousness the fact that the infrared sky is characterised by strong emission from interplanetary and interstellar dust, and made clear that this emission may interfere with the study of faint interesting sources. - then from the development of sensitive detectors and arrays for essentially all of the wavelength range to be covered in this report, from the Lyman limit to ≈ 300 μm. Now the difficult measurements of the ultraviolet diffuse radiation and of the extragalactic background light in the infrared cosmological windows around 3 μm and 200 μm have become feasible and state of the art projects. - finally, the threat to astronomical observations arising from man-made development and lighting has become important enough to further studies of uncontaminated and contaminated night sky brightnesses. This report will refer mainly to those areas and is meant to highlight noteworthy developments. It was prepared with the help of Drs. Bowyer and Mattila.

scholarly journals 21. Light of the Night Sky (Lumiere du Ciel Nocturne)

1991 ◽  
Vol 21 (1) ◽  
pp. 205-210
Keyword(s):  
Interstellar Medium ◽  
Background Radiation ◽  
Interplanetary Medium ◽  
Line Of Sight ◽  
Zodiacal Light ◽  
Earth’S Atmosphere ◽  
Earth's Atmosphere ◽  
Night Sky

The different components of the light of the night sky are integrated along the line of sight of the observer located on planet Earth or on the near Earth’s environment. They encompass a huge scale of distances, ranging from hundreds of kilometers in the Earth’s atmosphere (airglow lines, bands and continuum), to astronomical units in the interplanetary medium (zodiacal light continuum), thousand of light years in the interstellar medium (diffuse galactic light and integrated starlight) and even much more in the extragalactic universe (extragalactic background radiation).

scholarly journals Spectrophotometric measurement of the Extragalacic Background Light

2011 ◽  
Vol 7 (S284) ◽  
pp. 429-436 ◽  
Author(s):  
Kalevi Mattila ◽  
Kimmo Lehtinen ◽  
Petri Väisänen ◽  
Gerhard von Appen-Schnur ◽  
Christoph Leinert
Keyword(s):  
Scattered Light ◽  
Spectral Lines ◽  
Spectral Signature ◽  
Zodiacal Light ◽  
Differential Measurement ◽  
Extragalactic Background Light ◽  
Background Light ◽  
The Difference ◽  
Lower Limits ◽  
Night Sky Brightness

AbstractThe Extragalactic Background Light (EBL) at UV, optical and NIR wavelengths consists of the integrated light of all unresolved galaxies along the line of sight plus any contributions by intergalactic matter including hypothetical decaying relic particles. The measurement of the EBL has turned out to be a tedious problem. This is because of the foreground components of the night sky brightness, much larger than the EBL itself: the Zodiacal Light (ZL), Integrated Starlight (ISL), Diffuse Galactic Light (DGL) and, for ground-based observations, the Airglow (AGL) and the tropospheric scattered light. We have been developing a method for the EBL measurement which utilises the screening effect of a dark nebula on the EBL. A differential measurement in the direction of a high-latitude dark nebula and its surrounding area provides a signal that is due to two components only, i.e. the EBL and the diffusely scattered ISL from the cloud. We present a progress report of this method where we are now utilising intermediate resolution spectroscopy with ESO's VLT telescope. We detect and remove the scattered ISL component by using its characteristic Fraunhofer line spectral signature. In contrast to the ISL, in the EBL spectrum all spectral lines are washed out. We present a high quality spectrum representing the difference between an opaque position within our target cloud and several clear OFF positions around the cloud. We derive a preliminary EBL value at 400 nm and an upper limit to the EBL at 520 nm. These values are in the same range as the EBL lower limits derived from galaxy counts.Unit: We will use in this paper the abbreviation 1 cgs = 10−9erg s−1cm−2sr−1Å−1

scholarly journals Commission 21: Light of the Night Sky

2005 ◽  
Vol 1 (T26A) ◽  
pp. 161-166
Author(s):  
Bo Å. S. Gustafson ◽  
Adolf N. Witt ◽  
E. Dwek ◽  
P. Lamy ◽  
R. Henry ◽  
...  
Keyword(s):  
Emission Line ◽  
Thermal Emission ◽  
Background Radiation ◽  
Scattered Light ◽  
Full Range ◽  
Line Emission ◽  
Diffuse Light ◽  
Diffuse Emission ◽  
Night Sky ◽  
Physical Phenomena

Commission 21, one of IAU's smallest commissions, consists of some hundred members and consultants working to understand and describe the light of the night sky with emphasis on the diffuse components. Many more work on these topics without being members of the commission. Light is here defined in its broader sense of electromagnetic radiation of any frequency. The diffuse components of the light of the night sky encompass a variety of physical phenomena over the full range of cosmic distance scales and include scattered light, thermal emission, line emission, and any other emission phenomena producing a diffuse light source. These attract interest not only as scientific topics of study in their own right but also as an unwanted foreground or background against which all other sky phenomena are observed. Commission 21 has for mandate to promote research and availability of results on issues related to the diffuse light of the night sky. This document is a report on activities in this field and is not confined to the activities of its members, no distinction is made between work carried out by commission members and non commission members. The report is organized starting with a summary of the state of broad surveys that provide most of the observations. The report on developments in the various disciplines start with the sources closest to the observer known as airglow and progresses by way of the interplanetary and interstellar mediums to the increasingly distant integrated starlight, diffuse galactic light and diffuse emission in other galaxies ending with the extragalactic background radiation.

Measurement of the Far-Infrared Background Radiation in the Night Sky

1971 ◽  
Vol 27 (17) ◽  
pp. 1154-1157 ◽  
Author(s):  
A. G. Blair ◽  
J. G. Beery ◽  
F. Edeskuty ◽  
R. D. Hiebert ◽  
J. P. Shipley ◽  
...  
Keyword(s):  
Background Radiation ◽  
Far Infrared ◽  
Infrared Background ◽  
Night Sky

scholarly journals 21. Light of the Night Sky

1982 ◽  
Vol 18 (1) ◽  
pp. 211-218
Author(s):  
H. Tanabe ◽  
R.H. Giese ◽  
R. Dumont ◽  
M. Harwit ◽  
C. Leinert ◽  
...  
Keyword(s):  
Light Source ◽  
Large Distance ◽  
Zodiacal Light ◽  
Extragalactic Background Light ◽  
Background Light ◽  
Night Sky ◽  
Light Components ◽  
Celestial Sphere

The light of the night sky includes several components which spread all over the celestial sphere. These light components are terrestrial (airglow), interplanetary (zodiacal light), galactic (integrated starlight, diffuse galactic light) and extragalactic (extragalactic background light). Thus the study of nature of each light source, covering large distance, is pursued in different fields of astronomy. However, the techniques of measurement for respective components are similar and the knowledge of other lights is indispensable even in the study of a particular component.

scholarly journals 21. Light of the Night Sky

1985 ◽  
Vol 19 (1) ◽  
pp. 227-234
Author(s):  
R. H. Giese ◽  
k Mattila ◽  
R. Dumont ◽  
Yu. I. Galperin ◽  
M. S. Hanner ◽  
...  
Keyword(s):  
Scattered Light ◽  
Statistical Significance ◽  
Dust Cloud ◽  
Interplanetary Dust ◽  
Sources Of Information ◽  
Zodiacal Light ◽  
Manned Spacecraft ◽  
Lunar Samples ◽  
Night Sky

The light of the night sky consists of atmospheric components (airglow, light scattered in the atmosphere) and – even in the case of spaceborne observations – of zodiacal, galactic and extragalactic light. Although all components are of similar importance, investigations on zodiacal light have profitted most by the space age since their object of research, the interplanetary dust cloud, became accessible to direct in-situ measurements. Lunar samples and measurements by micrometeoroid detectors provide individual and eventually detailed information on impact events, which however are limited in number and therefore restricted in statistical significance. Zodiacal light investigations involve scattered light of many particles in large volume elements and therefore provide global information about physical properties and spatial distribution of interplanetary dust grains, however just in terms of average values. Therefore both sources of information are complementary and a synthesis can only be achieved by synoptic interpretation of zodiacal light, micrometeoroid, and meteoroid investigations also including dynamical aspects. Measurements of zodiacal light (and emission) from rockets, manned or non manned spacecraft, and deep space probes gained drastically in importance compared to ground based observations. On the other hand investigations on airglow have become more and more a topic of geophysics Caeronomy). They remain relevant however to astronomy as far as photometric features are concerned. These general trends continued in the last triennium and have influenced the activities of our commission.

scholarly journals Introductory Remarks

2001 ◽  
Vol 204 ◽  
pp. 5-15
Author(s):  
P. J. E. Peebles
Keyword(s):  
Star Formation ◽  
Background Radiation ◽  
Cosmic Background Radiation ◽  
Morphological Type ◽  
Star Formation History ◽  
Cosmic Background ◽  
Formation History ◽  
Infrared Background

I review the assumptions and observations that motivate the concept of the extragalactic cosmic background radiation, and the issues of energy accounts and star formation history as a function of galaxy morphological type that figure in the interpretation of the measurements of the extragalactic infrared background.

scholarly journals Background Light from Population III Stars

1987 ◽  
Vol 117 ◽  
pp. 414-414
Author(s):  
Jonathan C. McDowell
Keyword(s):  
Dark Matter ◽  
Background Radiation ◽  
Large Fraction ◽  
Rest Mass ◽  
Critical Density ◽  
Density Parameter ◽  
Extragalactic Background Light ◽  
Background Light ◽  
Far Ultraviolet ◽  
The Universe

It has been proposed (e.g. Carr, Bond and Arnett 1984) that the first generation of stars may have been Very Massive Objects (VMOs, of mass above 200 M⊙) which existed at large redshifts and left a large fraction of the mass of the universe in black hole remnants which now provide the dynamical ‘dark matter’. The radiation from these stars would be present today as extragalactic background light. For stars with density parameter Ω* which convert a fraction ϵ of their rest-mass to radiation at a redshift of z, the energy density of background radiation in units of the critical density is ΩR = εΩ* / (1+z). The VMOs would be far-ultraviolet sources with effective temperatures of 105 K. If the radiation is not absorbed, the constraints provided by measurements of background radiation imply (for H =50 km/s/Mpc) that the stars cannot close the universe unless they formed at a redshift of 40 or more. To provide the dark matter (of one-tenth closure density) the optical limits imply that they must have existed at redshifts above 25.

scholarly journals Measurement and Implications of the Cosmic Microwave Background Spectrum

1996 ◽  
Vol 168 ◽  
pp. 17-29
Author(s):  
John C. Mather
Keyword(s):  
Background Radiation ◽  
Far Infrared ◽  
Big Bang ◽  
Scale Invariant ◽  
Background Spectrum ◽  
Nasa Goddard Space ◽  
Wide Range ◽  
Infrared Background ◽  
Microwave Radiometers ◽  
The Big Bang

The Cosmic Background Explorer (COBE) was developed by NASA Goddard Space Flight Center to measure the diffuse infrared and microwave radiation from the early universe. It also measured emission from nearby sources such as the stars, dust, molecules, atoms, ions, and electrons in the Milky Way, and dust and comets in the Solar System. It was launched 18 November 1989 on a Delta rocket, carrying one microwave instrument and two cryogenically cooled infrared instruments. The Far Infrared Absolute Spectrophotometer (FIRAS) mapped the sky at wavelengths from 0.01 to 1 cm, and compared the CMBR to a precise blackbody. The spectrum of the CMBR differs from a blackbody by less than 0.03%. The Differential Microwave Radiometers (DMR) measured the fluctuations in the CMBR originating in the Big Bang, with a total amplitude of 11 parts per million on a 10° scale. These fluctuations are consistent with scale-invariant primordial fluctuations. The Diffuse Infrared Background Experiment (DIRBE) spanned the wavelength range from 1.2 to 240 μm and mapped the sky at a wide range of solar elongation angles to distinguish foreground sources from a possible extragalactic Cosmic Infrared Background Radiation (CIBR). In this paper we summarize the COBE mission and describe the results from the FIRAS instrument. The results from the DMR and DIRBE were described by Smoot and Hauser at this Symposium.

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