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Related papers: Missing Fe: hydrogenated iron nanoparticles

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In this paper, we report on the gas-phase abundance of singly-ionized iron (Fe II) for 51 lines of sight, using data from the Far Ultraviolet Spectroscopic Explorer (FUSE). Fe II column densities are derived by measuring the equivalent…

Astrophysics · Physics 2010-11-05 Adam G. Jensen , Theodore P. Snow

Polyhedral nanocrystals of <alpha>-Fe2O3 are successfully synthesized by annealing FeCl3 on silicon substrate at 1000 oC in the presence of H2 gas diluted with argon (Ar). Uniformly shaped polyhedral nanoparticles (diameter ~50-100 nm) are…

Materials Science · Physics 2011-11-22 Rajesh Kumar , S. Gautam , In-Chul Hwang , K. H. Chae , Nagesh Thakur

The determination of effective temperatures of very hot central stars (Teff>70000K) by model atmosphere analyses of optical H and He line profiles is afflicted with considerable uncertainty, primarily due to the lack of neutral helium…

Astrophysics · Physics 2007-05-23 K. Werner , J. L. Deetjen , S. Dreizler , T. Rauch , J. W. Kruk

It is a fact that interstellar formation processes are thermodynamically affected. Based on this, the seven heterocycles; imidazole, pyridine, pyrimidine, pyrrole, quinoline, isoquinoline and furan that have been searched for from different…

Astrophysics of Galaxies · Physics 2021-09-08 Emmanuel E. Etim , ROA Adelagun , Chrysanthus Andrew , Oladimeji Enock Oluwole

Infrared OH lines at 1.5 - 1.7 um in the H band were obtained with the NIRSPEC high-resolution spectrograph at the 10m Keck Telescope for a sample of seven metal-poor stars. Detailed analyses have been carried out, based on optical…

Astrophysics · Physics 2009-11-07 Jorge Melendez , Beatriz Barbuy

When single-layer h-BN is subjected to a high-energy electron beam, triangular pores with nitrogen edges are formed. Because of the broken sp2 bonds, these pores are known to possess magnetic states. We report on the magnetism and…

Materials Science · Physics 2022-09-22 Mehmet Dogan , Marvin L. Cohen

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

Analysis of thermal dust emission spectra for dust mineralogy and physical grain properties depends on laboratory-measured or calculated comparison spectra. Often, the agreement between these two kinds of spectra is not satisfactory because…

Instrumentation and Methods for Astrophysics · Physics 2015-05-13 H. Mutschke , M. Min , A. Tamanai

Discontinuous magnetic multilayers [CoFe/Al2O3] are studied by use of magnetometry, susceptometry and numeric simulations. Soft ferromagnetic Co80Fe20 nanoparticles are embedded in a diamagnetic insulating a-Al2O3 matrix and can be…

Materials Science · Physics 2010-09-13 O. Petracic , X. Chen , S. Bedanta , W. Kleemann , S. Sahoo , S. Cardoso , P. P. Freitas

We report unusual magnetic behavior in iron oxide hollow nanospheres of 9.3 $nm$ in diameter. The large fraction of atoms existing at the inner and outer surfaces gives rise to a high magnetic disorder. The overall magnetic behavior can be…

Other Condensed Matter · Physics 2008-04-22 E. Lima , J. M. Vargas , R. D. Zysler , H. R. Rechenberg , J. Arbiol , G. F. Goya , A. Ibarra , M. R. Ibarra

Spectra of unevolved metal-poor halo stars uniquely reflect the elemental abundances incorporated during the earliest Galactic epoch. Their heavy-element content is well understood as the products of neutron capture on iron-peak elements.…

Solar and Stellar Astrophysics · Physics 2020-07-01 R. C. Peterson , B. Barbuy , M. Spite

The iron depletion factors found in Galactic planetary nebulae (PNe) span over two orders of magnitude, suggesting that there are differences in the grain formation and destruction processes from object to object. We explore here the…

Astrophysics of Galaxies · Physics 2015-05-30 G. Delgado-Inglada , M. Rodríguez

The iron depletion level and the gas-phase iron abundance in the hot ~10^6 K interstellar medium (ISM) is critical to the understanding of its energy balance as well as the thermal sputtering, cooling, and heating processes of dust grains.…

Astrophysics · Physics 2009-11-11 Yangsen Yao , Norbert Schulz , Q. Daniel Wang , Michael Nowak

Context. The study of old, metal-poor stars deepens our knowledge on the early stages of the universe. In particular, the study of these stars gives us a valuable insight into the masses of the first massive stars and their emission of…

Solar and Stellar Astrophysics · Physics 2021-10-04 A. Matas Pinto , M. Spite , E. Caffau , P. Bonifacio , L. Sbordone , T. Sivarani , M. Steffen , F. Spite , P. Francois , P. Di Matteo

Recent \herschel\ and \planck\ observations of submillimeter dust emission revealed the omnipresence of filamentary structures in the interstellar medium (ISM). The ubiquity of filaments in quiescent clouds as well as in star-forming…

Astrophysics of Galaxies · Physics 2017-12-05 Doris Arzoumanian

The interstellar medium (ISM) seems to have a significant surplus of oxygen which was dubbed as the "O crisis": independent of the adopted interstellar reference abundance, the total number of O atoms depleted from the gas phase far exceeds…

Astrophysics of Galaxies · Physics 2015-09-30 Shu Wang , Aigen Li , B. W. Jiang

The Li-centered "ferric wheel" molecules with six oxo-bridged iron atoms form molecular crystals. We probed their electronic structure by X-ray photoelectron (XPS) and soft X-ray emission spectroscopy (XES), having calculated in parallel…

Materials Science · Physics 2009-11-10 A. V. Postnikov , S. G. Chiuzbaian , M. Neumann , S. Bluegel

We present Infrared Space Observatory (ISO) spectra of fourteen isolated Herbig Ae/Be (HAEBE) stars, to study the characteristics of their circumstellar dust. These spectra show large star-to-star differences, in the emission features of…

Astrophysics · Physics 2014-10-13 G. Meeus , L. B. F. M. Waters , J. Bouwman , M. E. van den Ancker , C. Waelkens , K. Malfait

We explore the effect of varying the spectral energy distribution of the incident continuum, by simultaneously and self-consistently computing the structure of an H II region and a photodissociation region that are in pressure equilibrium.…

Astrophysics of Galaxies · Physics 2013-12-25 Jiali. Zhu , M. Huang

We reexamine the spectroscopic underpinnings of recent suggestions that [O I] and [Fe II] lines from the Orion H II region are produced in gas where the iron-carrying grains have been destroyed and the electron density is surprisingly high.…