Dust Grain-Size Distributions and Extinction in the Milky Way, Large Magellanic Cloud, and Small Magellanic Cloud

We construct size distributions for carbonaceous and silicate grain populations in different regions of the Milky Way, LMC, and SMC. The size distributions include sufficient very small carbonaceous grains (including polycyclic aromatic hydrocarbon molecules) to account for the observed infrared and microwave emission from the diffuse interstellar medium. Our distributions reproduce the observed extinction of starlight, which varies depending on the interstellar environment through which the light travels. As shown by Cardelli, Clayton, and Mathis in 1989, these variations can be roughly parameterized by the ratio of visual extinction to reddening, RV. We adopt a fairly simple functional form for the size distribution, characterized by several parameters. We tabulate these parameters for various combinations of values for RV and bC, the C abundance in very small grains. We also find size distributions for the line of sight to HD 210121 and for sight lines in the LMC and SMC. For several size distributions, we evaluate the albedo and scattering asymmetry parameter and present model extinction curves extending beyond the Lyman limit.

[1]  N. Wickramasinghe,et al.  Interstellar Extinction by Graphite Grains , 1965, Nature.

[2]  T. P. Stecher.  Interstellar Ectinction in the Ultraviolet. , 1965 .

[3]  Optical Measurements on Solids of Possible Interstellar Importance (presented by D. R. Huffman) , 1973 .

[4]  K. Nordsieck,et al.  The Size distribution of interstellar grains , 1977 .

[5]  B. Savage,et al.  A survey of interstellar H I from L-alpha absorption measurements. II , 1978 .

[6]  Z. Kam,et al.  Absorption and Scattering of Light by Small Particles , 1998 .

[7]  H. M. Lee,et al.  Optical properties of interstellar graphite and silicate grains , 1984 .

[8]  B. Draine,et al.  Temperature fluctuations and infrared emission from interstellar grains. , 1985 .

[9]  E. Fitzpatrick.  Interstellar extinction variations in the Large Magellanic Cloud , 1985 .

[10]  William H. Press,et al.  Numerical recipes in C. The art of scientific computing , 1987 .

[11]  J. Mathis,et al.  The relationship between infrared, optical, and ultraviolet extinction , 1989 .

[12]  T. Boroson,et al.  Spectroscopy of extended red emission in reflection nebulae , 1990 .

[13]  Peter G. Martin,et al.  Shape and clustering effects on the optical properties of amorphous carbon , 1991 .

[14]  D. Welty,et al.  Ultraviolet, optical, and infrared observations of the high-latitude molecular cloud toward HD 210121 , 1992 .

[15]  Y. Pei,et al.  Interstellar dust from the Milky Way to the Magellanic Clouds , 1992 .

[16]  On the diffuse interstellar bands , 1993 .

[17]  S. Malhotra,et al.  On graphite and the 2175 Å extinction profile , 1993 .

[18]  E. Fitzpatrick,et al.  Composition of Interstellar Clouds in the Disk and Halo. IV. HD 215733 , 1993 .

[19]  Ari Laor,et al.  Spectroscopic constraints on the properties of dust in active galactic nuclei , 1993 .

[20]  P. Martin,et al.  The Size Distribution of Interstellar Dust Particles as Determined from Extinction , 1993 .

[21]  B. Draine,et al.  Discrete-Dipole Approximation For Scattering Calculations , 1994 .

[22]  B. Savage,et al.  The abundant elements in interstellar dust , 1994 .

[23]  George H. Herbig,et al.  The Diffuse Interstellar Bands , 1995 .

[24]  Can We Improve upon Astronomical Silicate , 1995 .

[25]  D. Furton,et al.  Hac and the Ere , 1995 .

[26]  Takashi Onaka,et al.  Detection of the Mid-Infrared Unidentified Bands in the Diffuse Galactic Emission by IRTS , 1996 .

[27]  A. Witt,et al.  Interstellar Depletions Updated: Where All the Atoms Went , 1996 .

[28]  Kenneth R. Sembach,et al.  INTERSTELLAR ABUNDANCES FROM ABSORPTION-LINE OBSERVATIONS WITH THE HUBBLE SPACE TELESCOPE , 1996 .

[29]  B. Savage,et al.  The Abundance of Interstellar Carbon , 1996 .

[30]  P. Martin,et al.  On the Dust-to-Gas Ratio and Large Particles in the Interstellar Medium , 1996 .

[31]  D. Whittet,et al.  Interstellar Extinction, Polarization, and Grain Alignment in the High-Latitude Molecular Cloud toward HD 210121 , 1996 .

[32]  J. Mathis.  Dust Models with Tight Abundance Constraints , 1996 .

[33]  E. Dwek.  Can Composite Fluffy Dust Particles Solve the Interstellar Carbon Crisis? , 1997, astro-ph/9701109.

[34]  J. Cardelli,et al.  Carbon in the Diffuse Interstellar Medium , 1997 .

[35]  A. Lazarian,et al.  Diffuse Galactic Emission from Spinning Dust Grains , 1997, astro-ph/9710152.

[36]  N. Odegard,et al.  Detection and Characterization of Cold Interstellar Dust and Polycyclic Aromatic Hydrocarbon Emission, from COBE Observations , 1996, astro-ph/9610198.

[37]  T. Henning,et al.  Matrix-isolated Nano-sized Carbon Grains as an Analog for the 217.5 Nanometer Feature Carrier , 1998 .

[38]  K. Gordon,et al.  Starburst-like Dust Extinction in the Small Magellanic Cloud , 1998, astro-ph/9802003.

[39]  A. Lazarian,et al.  Electric Dipole Radiation from Spinning Dust Grains , 1998, astro-ph/9802239.

[40]  Larry D. Travis,et al.  Light Scattering by Nonspherical Particles , 1998 .

[41]  J. Mathis.  The Near-Infrared Interstellar Silicate Bands and Grain Theories , 1998 .

[42]  D. Furton,et al.  The Amount of Interstellar Carbon Locked in Solid Hydrogenated Amorphous Carbon , 1999, astro-ph/9908035.

[43]  Magnetic Dipole Microwave Emission from Dust Grains , 1998, astro-ph/9807009.

[44]  Interstellar Depletion onto Very Small Dust Grains , 1998, astro-ph/9812469.

[45]  K. Gordon,et al.  A Reanalysis of the Ultraviolet Extinction from Interstellar Dust in the Large Magellanic Cloud , 1998, astro-ph/9811036.

[46]  W. Kratschmer,et al.  Dust in the local interstellar wind , 1999 .

[47]  Abundances and Physical Conditions in the Warm Neutral Medium toward μ Columbae , 1999, astro-ph/9905187.

[48]  G. Wright,et al.  Spectropolarimetric Constraints on the Nature of the 3.4 Micron Absorber in the Interstellar Medium , 1999 .

[49]  Edward L. Fitzpatrick,et al.  Correcting for the Effects of Interstellar Extinction , 1998, astro-ph/9809387.

[50]  J. Mathis.  Properties of interstellar dust , 2000 .

[51]  T. Gombosi,et al.  Interstellar dust filtration at the heliospheric interface , 2000 .

[52]  T. Snow.  Composition of interstellar gas and dust , 2000 .

[53]  The Size Distribution of Dust toward HD 210121 as Determined from Extinction , 2000 .