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New mid-infrared (10 and 20 micron) spectro-photometry of the ultraluminous infrared galaxy IRAS 08572+3915 is presented. The 10 micron spectrum reveals a deep silicate absorption feature, while the 20 micron spectrum shows no clear…

Astrophysics · Physics 2009-10-30 C. C. Dudley , C. G. Wynn-Williams

Highly reddened type Ia Supernovae (SNe Ia) with low total-to-selective visual extinction ratio values, $R_V$, also show peculiar linear polarization wavelength dependencies with peak polarizations at short wavelengths ($\lambda_{max}…

We investigate the composition and shape distribution of silicate dust grains in the interstellar medium. The effect of the amount of magnesium in the silicate lattice is studied. We fit the spectral shape of the interstellar 10 mu…

The abundance of both amorphous and crystalline silicates in very small grains is limited by the fact that the 10 micron silicate emission feature is not detected in the diffuse ISM. On the basis of the observed IR emission spectrum for the…

Astrophysics · Physics 2009-10-31 Aigen Li , B. T. Draine

We aim to compare variations in the full-UV dust extinction curve (912-3000 Angstrom), with the HI/H$_2$/total H content along diffuse Milky Way sightlines, to investigate possible connections between ISM conditions and dust properties. We…

Astrophysics of Galaxies · Physics 2023-02-15 Dries Van De Putte , Stefan I. B. Cartledge , Karl D. Gordon , Geoffrey C. Clayton , Julia Roman-Duval

A sample of SiO-masing late-type stars located in the inner Galaxy is analyzed with the goal of better constraining their obscuration. This reference sample allows us to define mathematical relations between their dereddened infrared…

Astrophysics of Galaxies · Physics 2024-06-19 Maria Messineo

We present the Spitzer IRS spectra for 33 young stars in Tr 37 and NGC 7160. The sample includes the high- and intermediate-mass stars with MIPS 24 microns excess, the only known active accretor in the 12 Myr-old cluster NGC 7160, and 19…

Understanding the effects of dust extinction is important to properly interpret observations. The optical total-to-selective extinction ratio, Rv = Av/E(B-V), is widely used to describe extinction variations in ultraviolet and optical…

Astrophysics of Galaxies · Physics 2017-11-01 Shu Wang , Biwei Jiang , He Zhao , Xiaodian Chen , Richard de Grijs

A search for the near-infrared water-ice absorption band was made in a number of very red OH/IR stars which are known to exhibit the 10um silicate absorption. As a by-product, accurate positions of these highly reddened objects are…

Astrophysics · Physics 2009-11-11 K. Justtanont , G. Olofsson , C. Dijkstra , A. W. Meyer

Recent results indicate that the grain size and crystallinity inferred from observations of silicate features may be correlated with spectral type of the central star and/or disk geometry. In this paper, we show that grain size, as probed…

The dynamical structure and infrared emission of winds around late-type stars are studied in a self-consistent model that couples the equations of motion and radiative transfer. Both the dynamics and IR spectrum of the solution are fully…

Astrophysics · Physics 2016-08-30 Zeljko Ivezic , Moshe Elitzur

The dust extinction curve is typically parameterized by a single variable, R(V), in optical and near-infrared wavelengths. R(V) controls the slope of the extinction-vs.-wavelength curve, and is thought to reflect the grain-size distribution…

Astrophysics of Galaxies · Physics 2025-06-26 Gregory M. Green , Xiangyu Zhang , Ruoyi Zhang

Dust extinction law is crucial to recover the intrinsic energy distribution of celestial objects and infer the characteristics of interstellar dust. Based on the traditional pair method, an improved pair method is proposed to model the dust…

Instrumentation and Methods for Astrophysics · Physics 2023-04-26 Yuxi Wang , Jian Gao , Yi Ren , Jun Li

Distance estimates derived from spectroscopy or parallax have been unified by considering extinction by large grains. The addition of such a population of what is called Dark Dust to models of the diffuse interstellar medium is tested…

Astrophysics of Galaxies · Physics 2023-02-22 Ralf Siebenmorgen

In this paper we study the effects of inclusions and porosities on the emission properties of silicate grains and compare the model curves with the observed infrared emission from circumstellar dust. We calculate the absorption efficiency…

Solar and Stellar Astrophysics · Physics 2015-03-17 D. B. Vaidya , Ranjan Gupta

We present a sample of 75 extinction curves derived from FUSE far-ultraviolet spectra supplemented by existing IUE spectra. The extinction curves were created using the standard pair method based on a new set of dereddened FUSE+IUE…

Astrophysics of Galaxies · Physics 2014-11-20 Karl D. Gordon , Stefan Cartledge , Geoffrey C. Clayton

We present 8-13 micron imaging and spectroscopy of 9 type 1 and 10 type 2 AGN obtained with the VLT/VISIR instrument at spatial resolution <100 pc. The emission from the host galaxy sources is resolved out in most cases. The silicate…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-18 S. F. Hoenig , M. Kishimoto , P. Gandhi , A. Smette , D. Asmus , W. Duschl , M. Polletta , G. Weigelt

The dust extinction curves toward individual sight lines in M33 are derived for the first time with a sample of reddened O-type and B-type supergiants obtained from the LGGS. The observed photometric data are obtained from the LGGS, PS1…

Astrophysics of Galaxies · Physics 2022-06-29 Yuxi Wang , Jian Gao , Yi Ren , Bingqiu Chen

The spatial variations in PAH band intensities are normally attributed to the physical conditions of the emitting PAHs, however in recent years it has been suggested that such variations are caused mainly by extinction. To resolve this…

Astrophysics of Galaxies · Physics 2015-06-16 D. J. Stock , E. Peeters , A. G. G. M. Tielens , J. N. Otaguro , A. Bik