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Recent calculations have shown that the UV bump at about 217.5 nm in the extinction curve can be explained by a complex mixture of PAHs in several charge states. Other studies proposed that the carriers are a restricted population made of…

Astrophysics · Physics 2009-11-13 G. Malloci , G. Mulas , C. Cecchi-Pestellini , C. Joblin

We derive the extinction curve towards the Galactic Center from 1 to 19 micron. We use hydrogen emission lines of the minispiral observed by ISO-SWS and SINFONI. The extinction free flux reference is the 2 cm continuum emission observed by…

The 9.7$\mu$m interstellar spectral feature, arising from the Si--O stretch of amorphous silicate dust, is the strongest extinction feature in the infrared (IR). In principle, the spectral profile of this feature could allow one to diagnose…

Solar and Stellar Astrophysics · Physics 2018-07-04 Z. Z. Shao , B. W. Jiang , Aigen Li , Jian Gao , Z. P. Lv , J. W. Yao

This paper summarizes the evidence of the ultraviolet properties of dust grains found in starburst galaxies. Observations of starburst galaxies clearly show that the 2175 A feature is weak or absent. This can be the result of radiative…

Astrophysics · Physics 2009-11-10 Karl D. Gordon

The extreme brightness of gamma-ray burst (GRB) afterglows and their simple spectral shape make them ideal beacons to study the interstellar medium of their host galaxies through absorption line spectroscopy. Using 69 low-resolution GRB…

In this research, a mid-infrared wide-angle ultra-broadband perfect absorber which composed of pyramid grating structure has been comprehensively studied. The structure was operated in the reststrahlem band of SiC and with the presence of…

Optics · Physics 2023-08-28 Kaidi Xu , Gaige Zheng

We discuss dust properties in the interstellar medium (ISM) of nearby normal galaxies, by comparing observations in the ultraviolet (UV) with simulations by a radiative transfer model. The observed UV colours of nearby galaxies show a…

We use a combined generalized spectroscopic ellipsometry and density functional theory approach to determine and analyze the anisotropic dielectric functions of an $\alpha$-Ga$_2$O$_3$ thin film. The sample is grown epitaxially by…

The pi bands of epitaxially grown graphene are studied by using high resolution angle resolved photoemission spectroscopy. Clear deviations from the conical dispersion expected for massless Dirac fermions and an anomalous increase of the…

Materials Science · Physics 2008-07-30 S. Y. Zhou , D. A. Siegel , A. V. Fedorov , A. Lanzara

We present an all sky map of the diffuse Galactic far ultraviolet (1344-1786 Angstroms) background using GALEX data, covering 65% of the sky with 11.79 arcmin square pixels. We investigate the dependence of the background on Galactic…

Astrophysics of Galaxies · Physics 2015-06-17 Erika Hamden , David Schiminovich , Mark Seibert

A multiwavelength study of laboratory carbons with varying degrees of hydrogenation and sp$^2$ hybridization is required to characterize the structure of the carbonaceous carriers of interstellar and circumstellar extinction. Analogs to…

Instrumentation and Methods for Astrophysics · Physics 2017-11-21 Lisseth Gavilan , Kim Cuong Le , Thomas Pino , Ivan Alata , Alexandre Giuliani , Emmanuel Dartois

The mid-infrared spectra (2.5 to 5 and 5.7 to 11.6 mu) obtained by ISO-PHOT reveal the interstellar medium emission from galaxies powered by star formation to be strongly dominated by the aromatic features at 6.2, 7.7, 8.6 and 11.3 mu.…

Astrophysics · Physics 2009-10-31 G. Helou , N. Y. Lu , M. W. Werner , S. Malhotra , N. Silbermann

We consider the Maxwell's system for a periodic array of dielectric `fibers' embedded into a `matrix', with respective electric permittivities $\epsilon_0$ and $\epsilon_1$, which serves as a model for cladding in photonic crystal fibers…

Mathematical Physics · Physics 2014-11-04 Shane Cooper , Ilia Kamotski , Valery Smyshlyaev

We present K-band interferometric measurements of the limb-darkened intensity profile of the M4 giant star psi Phoenicis obtained with VLTI/VINCI. High-precision squared visibility amplitudes in the second lobe of the visibility function…

Astrophysics · Physics 2007-05-23 M. Wittkowski , J. P. Aufdenberg , P. Kervella

We model the infrared (IR) emission from the double-ring disk of HD 141569A, using a porous dust model that was previously shown successful in reproducing the spectral energy distributions (SEDs) of the disks around $\beta$ Pictoris and HR…

Astrophysics · Physics 2009-11-10 Aigen Li , J. I. Lunine

The 9.7$\mu m$ and 18$\mu m$ interstellar spectral features, arising from the Si--O stretching and O--Si--O bending mode of amorphous silicate dust, are the strongest extinction feature in the infrared. Here we use the "pair method" to…

Solar and Stellar Astrophysics · Physics 2024-01-17 Zhenzhen Shao , Biwei Jiang

The refraction of space-time (ST) wave packets offers many fascinating surprises with respect to conventional pulsed beams. In paper (I) of this sequence, we described theoretically the refraction of all families of ST wave packets at…

We have studied a sample of 809 Mg II absorption systems with 1.0 < z_abs < 1.86 in the spectra of SDSS QSOs, with the aim of understanding the nature and abundance of the dust and the chemical abundances in the intervening absorbers.…

NGC 2992 is an intermediate Seyfert 1 galaxy showing outflows on kilo parsec scales which might be due either to AGN or starburst activity. We therefore aim at investigating its central region for a putative starburst in the past and its…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-19 S. Friedrich , R. I. Davies , E. K. S. Hicks , H. Engel , F. Müller-Sánchez , R. Genzel , L. J. Tacconi

The sky-averaged (global) 21-cm signal is a powerful probe of the intergalactic medium (IGM) prior to the completion of reionization. However, it has so far been unclear that even in the best case scenario, in which the signal is accurately…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-17 Jordan Mirocha , Geraint J. A. Harker , Jack O. Burns
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