scholarly journals Dust Condensation in the Ejecta of SN 1987A

1989 ◽  
Vol 120 ◽  
pp. 164-179 ◽  
Author(s):  
L.B. Lucy ◽  
I.J. Danziger ◽  
C. Gouiffes ◽  
P. Bouchet
Keyword(s):  
Quantitative Analysis ◽  
Light Curve ◽  
Amorphous Carbon ◽  
Interstellar Dust ◽  
Thermal Emission ◽  
Optical Emission ◽  
Emission Lines ◽  
Carbon Particles ◽  
Sn 1987A ◽  
Dust Condensation

AbstractAn asymmetry of optical emission lines that appeared in Sept. 1988 is interpreted as evidence of dust condensation within the metal-rich ejecta of SN 1987A. A quantitative analysis of this spectroscopic effect is given and shown to be compatible with the photometric record. Moreover, observational and theoretical estimates of the bolometric light curve come into agreement when the far-IR excess is interpreted as thermal emission by grains in the ejecta. A grain population comprising small silicate grains with an admixture of graphite or amorphous carbon particles is suggested by the data. The relevance of this discovery to suggestions that supernovae are major sources of interstellar dust is briefly discussed.

Analysis of the Optical Emission Lines of SN 1987A

1990 ◽  
Vol 99 ◽  
pp. 664 ◽  
Author(s):  
J. A. de Freitas Pacheco
Keyword(s):  
Optical Emission ◽  
Emission Lines ◽  
Sn 1987A

scholarly journals Thermal X-Rays due to Ejecta/CSM Interaction in SN 1987A

1988 ◽  
Vol 108 ◽  
pp. 450-451
Author(s):  
K. Masai ◽  
S. Hayakawa ◽  
H. Itoh ◽  
K. Nomoto ◽  
T. Shigeyama
Keyword(s):  
Light Curve ◽  
Photon Energy ◽  
Thermal Emission ◽  
Circumstellar Matter ◽  
Expansion Velocity ◽  
X Rays ◽  
X Ray ◽  
Sn 1987A ◽  
Inner Radius

The X-ray spectrum observed by Ginga is characterized by a component below 10keV which decreases with increasing photon energy, and a component above 10keV which is nearly flat. This unusual X-ray spectrum may be understood as follows; X-rays below 10keV is likely to be due to thermal emission coming from the shock-heated ejecta, and X-rays above 10keV to be due to γ-ray degradation inside the ejecta. If thermal emission due to the collision of the ejecta with circumstellar matter (CSM) is responsible for X-rays below 10keV, the epoch of the collision can be estimated to be ∼ 0.2yr after the explosion if ∼ 0.5yr is the time when the X-ray flux at ∼ 10keV reaches its maximum. The X-ray light curve then requires the inner radius of CSM to be ∼ 1×1016cm for an expansion velocity, Vex ≃2×109cm s−1.

scholarly journals Freeze out, IR-catastrophes and Non-thermal Emission in SNe

1996 ◽  
Vol 145 ◽  
pp. 211-222 ◽  
Author(s):  
Claes Fransson ◽  
John Houck ◽  
Cecilia Kozma
Keyword(s):  
Light Curve ◽  
Total Mass ◽  
Thermal Emission ◽  
Sharp Decrease ◽  
Light Curves ◽  
Thermal Excitation ◽  
Sn 1987A ◽  
Ubv Photometry ◽  
Optical Flux ◽  
Freeze Out

Freeze out effects and the IR-catastrophe are discussed for SN 1987A and for Type la SNe. We show that the light curves of the optical lines in SN 1987A provide strong evidence for the IR-catastrophe. We also argue that most optical lines are dominated by non-thermal excitation after ∼ 800 days. The level of this emission is set mainly by the total mass of the elements. Models of the [OI]λλ6300 — 64 light curve show that an oxygen mass of ∼ 1.5Mʘ is needed. Light curve models for Type la SNe display a sharp decrease in the optical flux as a result of the IR-catastrophe at ∼ 500 days, producing UBV-photometry inconsistent with observations of SN1972E by Kirshner & Oke (1975).

scholarly journals Effects of the soft X-ray burst from SN 1987A on its circumstellar medium

1989 ◽  
Vol 8 ◽  
pp. 223-228
Author(s):  
Peter Lundqvist ◽  
Claes Fransson
Keyword(s):  
Optical Emission ◽  
Emission Lines ◽  
X Ray ◽  
Physical Conditions ◽  
Sn 1987A ◽  
Circumstellar Medium

AbstractThe observations of the narrow UV and optical emission lines from SN 1987A are modelled as reprocessed radiation in a shell around the supernova, heated and ionized by the soft X-ray and EUV radiation at the shock breakout. Constraints on the early soft X-ray burst are discussed, as well as the physical conditions and abundances in the shell.

scholarly journals 17. Optical investigations of radio sources: Introductory Lecture

1957 ◽  
Vol 4 ◽  
pp. 107-122 ◽  
Author(s):  
R. Minkowski
Keyword(s):  
Thermal Emission ◽  
Optical Emission ◽  
Radio Spectrum ◽  
Visual Object ◽  
Supporting Evidence ◽  
Precise Position ◽  
Rosette Nebula ◽  
Important Argument ◽  
Astronomical Object ◽  
Order Of Magnitude

Loose agreement of a radio position of low accuracy with that of some object listed in the NGC is not sufficient to provide the identification of a radio source. Even satisfactory coincidence of a precise position with that of an astronomical object requires supporting evidence. Agreement of the size of the source with that of the visible object, at least in order of magnitude, is an important argument in favour of an identification; exact agreement of sizes can be expected only where radio and optical emission are physically connected. The radio spectrum, the optical spectrum, and the physical characteristics of the visual object also have to be taken into account. Observations of the radio spectrum should be particularly useful to support the identification of sources with H 11 regions which can be recognized from their thermal emission even if they are obscured and optically inaccessible. If all data are available, satisfactory agreement exists between optical and radio observations. The best example of this kind at the moment is perhaps NGC 2237, the Rosette nebula, reported as a source by Ko and Krauss (1955) [1] and also observed by Mills, Little and Sheridan (1956 [11]; see also paper 18).

scholarly journals Systematic errors in dust mass determinations: insights from laboratory opacity measurements

2020 ◽  
Vol 499 (4) ◽  
pp. 4666-4686
Author(s):  
Lapo Fanciullo ◽  
Francisca Kemper ◽  
Peter Scicluna ◽  
Thavisha E Dharmawardena ◽  
Sundar Srinivasan
Keyword(s):  
Interstellar Dust ◽  
Thermal Emission ◽  
High Redshift ◽  
Synthetic Data ◽  
Far Infrared ◽  
Systematic Errors ◽  
Experimental Measurements ◽  
Dust Mass ◽  
Dusty Galaxies ◽  
Different Temperatures

ABSTRACT The thermal emission of dust is one of the most important tracers of the interstellar medium: multiwavelength photometry in the far-infrared (FIR) and submillimetre (submm) can be fitted with a model, providing estimates of the dust mass. The fit results depend on the assumed value for FIR/submm opacity, which in most models – due to the scarcity, until recently, of experimental measurements – is extrapolated from shorter wavelengths. Lab measurements of dust analogues, however, show that FIR opacities are usually higher than the values used in models and depend on temperature, which suggests that dust mass estimates may be biased. To test the extent of this bias, we create multiwavelength synthetic photometry for dusty galaxies at different temperatures and redshifts, using experimental results for FIR/submm dust opacity and then we fit the synthetic data using standard dust models. We find that the dust masses recovered by typical models are overestimated by a factor of 2–20, depending on how the experimental opacities are treated. If the experimental dust samples are accurate analogues of interstellar dust, therefore, current dust masses are overestimated by up to a factor of 20. The implications for our understanding of dust, both Galactic and at high redshift, are discussed.

scholarly journals Infrared Observations of Radio Galaxies

1982 ◽  
Vol 97 ◽  
pp. 239-246
Author(s):  
George H. Rieke
Keyword(s):  
Thermal Emission ◽  
Optical Emission ◽  
Seyfert Galaxies ◽  
Radio Sources ◽  
Extragalactic Radio Source ◽  
Extragalactic Source ◽  
Infrared Observations ◽  
Infrared Studies ◽  
Complete Identification ◽  
Ultraviolet Photons

For technical reasons, infrared studies of active galaxies have lagged far behind optical and radio ones. This is unfortunate, since entirely new aspects of these sources are often revealed in the infrared. The extreme efficiency of dust at degrading ultraviolet photons into cool thermal emission frequently makes the luminosity of an extragalactic source inaccessible to optical and radio astronomers. At the same time, the effects of dust on optical emission line ratios and continuum shapes can be profound. The complete identification of samples of radio sources will require infrared observations to supplement the optical techniques now generally employed, and the extreme properties of the sources bright in the infrared can provide new insights to conditions in extragalactic nonthermal sources. To illustrate these points, I will discuss three cases: 1.) galaxies undergoing a powerful burst of star formation, 2.) intermediate type Seyfert galaxies, and 3.) an extreme infrared identification of an extragalactic radio source.

scholarly journals Molecular gas around the Wolf-Rayet star WR 18 (WN4)

2003 ◽  
Vol 212 ◽  
pp. 732-733
Author(s):  
Anthony P. Marston
Keyword(s):  
Mass Loss ◽  
Optical Emission ◽  
Emission Lines ◽  
Molecular Gas ◽  
Evolved Stars ◽  
Ring Nebula ◽  
History Of ◽  
Optical Ring ◽  
Ring Nebulae ◽  
Rayet Star

Optically observed ring nebulae and H i cavities around Wolf-Rayet stars have enabled us to obtain information on the history of mass-loss associated with these massive evolved stars. However, such studies have left a number of unanswered questions regarding the amount of mass-loss and the conditions of the stars during a sequence of mass-loss phases. Here we discuss the molecular gas environments of the WR star WR 18, which has an associated optical ring nebula NGC 3199. Our observations show that significant amounts of molecular gas appear close to and associated with the star. Mapping of molecular CO near the star shows that molecular materials appear to substantially avoid areas of optical emission and, instead, form a distorted clumpy shell interior to NGC 3199. Molecular emission lines are broader than lines seen in the interstellar medium and suggest the shell is composed of ejecta. This is further corroborated by the enhanced abundances of molecules containing C, N and O. Implications of the observations for the evolution of WR 18 are discussed.

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