Dusty Astronomical Systems Group
Ritter Astrophysical Research Center
The University of Toledo


We investigate the radiative transfer in astronomical systems in which dust provides the principal source of opacity. Specific problems under study are the effects of dust, its distribution and clumpy structure, on the photometric characteristics of galaxies, the analysis of high-b galactic background observations in the UV and visible, and the UV scattering properties of dust in individual clouds represented by reflection nebulae and globules illuminated by the galactic radiation field.

A particularly interesting application of radiative transfer through clumpy media is our study of attenuation in high-z star-forming galaxies (Lyman Break Galaxies), which are most sensitively detected at rest frame UV wavelengths, where attenuation can be severe.

Furthermore, we are involved in laboratory astrophysics, where we concentrate on the optical properties of hydrogenated amorphous carbon materials, carbon nanoparticles, silicon nanoparticles and sol gels. It is one of our principal goals to identify likely laboratory analogs to the source of extended red emission (ERE) in nebulae and the diffuse interstellar medium.

In addition, we have resumed an observational program directed at a more comprehensive assesment of photoluminescence phenomena associated with dust in a variety of interstellar environments.


Adolf Witt
Daniele Pierini
Tracy Smith (Louisiana State University)
Karl Gordon (Steward Observatory, University of Arizona)
Doug Furton (Rhode Island College)
Uma Vijh
Gregory Madsen (University of Wisconsin)
Lerothodi Leeuw


Reflection Nebulae (Witt, Gordon, Leeuw)
DGL (Witt, Gordon)
ERE (Witt, Gordon, Smith, Vijh)
Galaxies (Witt, Gordon, Pierini, Madsen, Leeuw)
Laboratory Astrophysics (Witt, Smith)
Lyman Break Galaxies (Vijh, Witt, Gordon, Pierini)

Selected Papers

Small PAHs in the Red Rectangle
U. P. Vijh, A. N. Witt, & K. D. Gordon, 2005, ApJ in press

Dust Attenuation in Late-Type Galaxies. I. Effects on Bulge and Disk Components
D. Pierini, K. D. Gordon, A. N. Witt, & G. J. Madsen, 2004, ApJ in press

Discovery of Blue Luminescence in the Red Rectangle: Possiblr Fluorescence from Neutral Polycyclic Aromatic Hydrocarbon Molecules ?
U. P. Vijh, A. N. Witt, & K. D. Gordon 2004, ApJ, 606, L65

Extremely Red Galaxies: Dust Attenuation and Classification
D. Pierini, C. Maraston, R. Bender, & A. N. Witt 2004, MNRAS, 347, 1

The Role of Polycyclic Aromatic Hydrocarbons in Ultraviolet Extinction. I. Probing Small Molecular Polycyclic Aromatic Hydrocarbons
G. C. Clayton, K. D. Gordon, F. Salama, L. J. Allamandola, P. G. Martin, T. P. Snow, D. C. B. Whittet, A. N. Witt, & M. J. Wolff, 2003, ApJ, 592, 947

Dust in Lyman Break Galaxies
U. Vijh, A. N. Witt, & K. Gordon, 2003, ApJ, 587, 583

Extendend Red Emission in the Evil Eye Galaxy NGC 4826
D. Pierini, A. Majeed, T. A. Bronson, & A. N. Witt, 2002, ApJ, 569, 184

The Photophysics of the Carrier of Extended Red Emission
T. L. Smith, & A. N. Witt, 2002, ApJ, 565, 304

The Chemical Composition of the Interstellar Medium
A. N. Witt, 2001, Philosophical Trans. Roy. Soc. Lon. A, 359:(1787),1958

The DIRTY Model. I. Monte Carlo Radiative Transfer Through Dust
K. D. Gordon, K. A. Misselt, & A. N. Witt, 2001, ApJ, 551, 269

X-Ray Halos and Large Grains in the Diffuse Interstellar Medium
A. N. Witt, R. K. Smith, & E. Dwek, 2001, ApJL, 550, 201

Dust Emission Features in NGC 7023 between 0.35 and 0.25 microns: Extended Red Emission (0.7 microns) and Two New Emission Line Features (1.15 and 1.5 microns)
K.D. Gordon, G. C. Clayton, & A. N. Witt, 2000, ApJ, 544, 859

The Flux Ratio Method for Determining the Dust Attenuation of Starburst Galaxies
K. D. Gordon, G. C. Clayton, & A. N. Witt, 2000, ApJ 533, 236

Small and Very Small Interstellar Grains
A. N. Witt, 2000, J. Geophy. Res. Space Phy., 105:(A5), 10299

Multiple Scattering in Clumpy Media. II. Galactic Environments
A. N. Witt, & K.D. Gordon, 2000, ApJ, 528, 799

The ammount of Interstellar Carbon Locked in Solid Hydrogenated Amorphous Carbon
D.G. Furton J. W. Laiho, & A. N. Witt, 1999, ApJ, 526, 752

Silicon Nanoparticles and Interstellar Extinction
V. G. Zubko, T. L. Smith, & A. N. Witt, 1999, ApJL, 511, L57

Silicon Nanoparticles: Source of Extended Red Emission
A. N. Witt, K. D. Gordon, & D. G. Furton, 1998, ApJL, 501, L111

Detection of Extended Red Emission in the Diffuse Interstellar Medium
K. D. gordon, A. N. Witt, & B. C. Friedmann, 1998, ApJ, 498, 522

Attenuation Effects in Spiral Galaxies: Multiwavelength Photometry and Disk Radiative Transfer Models
L. E. Kuchinski, D. M. Terndrup, K. D. Gordon, & A. N. Witt, 1998, AJ, 115, 1438

The 1997 Reference of Diffuse Night Sky Brightness
C. Leinert, S. Bowyer, & L. K. Haikala, 1998, A&A Supp., 127, 1

Dust in Starburst Galaxies
K. D. Gordon, D. Calzetti, & A. N. Witt, 1997, ApJ, 487, 625

Radiative Transfer Analysis of Far-UV Background Observations Obtained with the Far-Ultraviolet Space Telescope (FAUST)
A. N. Witt, B. C. Friedmann, & T. P. Sasseen 1997, ApJ, 481, 809

Multiple Scattering in Clumpy Media. I. Escape of Stellar Radiation from a Clumpy Scattering Environment
A. N. Witt & K. D. Gordon 1996, ApJ, 463, 681

Radiative Transfer in Cloudy Galaxies: Evolution of Far-IR Luminosity
A. N. Witt & K. D. Gordon 1996, in "Unveiling the Cosmic Infrared Background", (AIP Conference Proc. No. 348), ed. E. Dwek (NW: AIP Press)

Interstellar Depletion Updated: Where All The Atoms Went
T. P. Snow & A. N. Witt 1996, ApJ, 468, L65

The Interstellar Carbon Budget and the Role of Carbon in Dust and Large Molecules
T. P. Snow & A. N. Witt 1995, Science, 270, 1455

Scattering Properties of Dust in the Reflection Nebula IC 435
D. Calzetti, R. C. Bohlin, K. D. Gordon, A. N. Witt, & L. Bianchi 1995, ApJ, 446, L97

Imaging in the Optical and Near-Infrared Regimes II. Arcsecond Spatial Resolution of Widely Distributed Cold Dust in Spiral Galaxies
D. L. Block, A. N. Witt, P. Grosbol, A. Stockton, & A. Moneti 1994, A&A, 288, 383

K'-Band Observations of the Evil Eye Galaxy: Are the Optical and Near-Infrared Dust Albedos Identical?
A. N. Witt, R. S. Lindell, D. L. Block, & Rh. Evans 1994, ApJ, 427, 227

The Far-Ultraviolet Dust Albedo in the Upper Scorpius Subgroup in the Sco OB2 Association
K. D. Gordon, A. N. Witt, G. R. Carruthers, S. A. Christensen, & B. C. Dohne 1994, ApJ, 432, 641

Activation of ERE Photoluminescence in Carbon Solids by Exposure to Atomic Hydrogen and UV Radiation
D. G. Furton & A. N. Witt 1993, ApJ, 415,L51

Voyager 2 Observations of NGC 7023: Dust Scattering Shortward of 1600A
A. N. Witt, J. K. Petersohn, J. B. Holberg, J. Murthy, A. Dring, & R. C. Henry 1993, ApJ, 410, 714

Dust and the Transfer of Stellar Radiation within Galaxies
A. N. Witt, H. A. Thronson, & J. Capuano 1992, ApJ, 393, 611

UIT Images of the Reflection Nebula NGC 7023: Derivation of UV Scattering Properties of Dust Grains
A. N. Witt, J. K. Petersohn, R. C. Bohlin, R. W. O'Connell, M. S. Roberts, A. M. Smith, & T. P. Stecher 1992, ApJ, 395, L5

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