Results 51 to 60 of about 136,681 (287)
A view of PKS 2155-304 with XMM-Newton Reflection Grating Spectrometers
, 2003 We present the high resolution X-ray spectrum of the BL Lac object PKS 2155-304 taken with the RGS units onboard XMM-Newton in November 2000. We detect a OVII Kalpha resonant absorption line from warm/hot local gas at 21.59A (~4.5 sigma detection).
A. Treves +5 more
core +1 more source
UV-Vis Spectra of Carbonic Acid: Rationalizing Experimental Redshifts between Monomer and Bulk based on (H<sub>2</sub>CO<sub>3</sub>)<sub>n</sub> Calculations. [PDF]
ChemphyschemIn bulk carbonic acid (e.g., in interstellar icy dust grains) cluster formation produces two distinct UV‐Vis spectral features redshifted by ≈2 eV (25 nm) and by ≈5 eV (80 nm) compared to gas phase single molecule carbonic acid 's adiabatic ionization energy. Theory and experiment were used to investigate the origin of these shifts.
Dinu DF +7 more
europepmc +2 more sources
Predicted profiles of ultraviolet interstellar absorption lines
The Astrophysical Journal Supplement Series, 1991 In this paper, values of the column density, line width parameter, and velocity are determined for as many components derived from optical interstellar absorption-line profiles of Na I and K I as needed to reproduce the observed high-resolution optical profiles of the D lines of Na I toward eight lightly reddened stars and of the 7698 A line of K I ...
D. E. Welty, L. M. Hobbs, D. G. York
openaire +1 more source
New 3-D gas density maps of NaI and CaII interstellar absorption within 300pc
, 2009 We present new high resolution (R>50,000) absorption measurements of the NaI doublet (5889 - 5895A) along 482 nearby sight-lines, in addition to 807 new measurements of the CaII K (3933A) absorption line.
Lallement, Rosine +3 more
core +3 more sources
Abundances of interstellar atoms from ultaviolet absorption lines
The Astrophysical Journal, 1986 The equivalent widths of interstellar absorption lines of Mg II, P II, Cl I and II, Mn II, Fe II, Cu II, and Ni II, obtained in a Copernicus survey of Bohlin et al (1983) have been analyzed to yield column densities along the lines of sight. The measured depletions are clearly correlated with n sub H, the mean hydrogen column density along the line of ...
E. B. Jenkins +2 more
openaire +1 more source
A photospheric metal line profile analysis of hot DA white dwarfs with circumstellar material
, 2012 Some hot DA white dwarfs have circumstellar high ion absorption features in their spectra, in addition to those originating in the photosphere. In many cases, the line profiles of these absorbing components are unresolved.
Barstow, Martin A. +2 more
core +1 more source
How to Imagine Educational AI: The Filling of a Pail or the Lighting of a Fire?
Educational Theory, EarlyView.Abstract Recent advances in artificial intelligence (e.g., machine learning, generative AI) have led to increased interest in its application in educational settings. AI companies hope to revolutionize teaching and learning by tailoring material to the individual needs of students, automating parts of teachers' jobs, or analyzing educational data to ...
Michał Wieczorek, Alberto Romele
wiley +1 more source
Regarding the Detection of Interstellar C4 and C5 Molecules
The Astrophysical JournalAnalysis of very high signal-to-noise ratio (S/N) spectra of reddened stars allowed us to determine an upper limit (UL) of the column density N (C _4 ).
G. A. Galazutdinov +2 more
doaj +1 more source
High-Resolution Optical Observations of Interstellar Absorption Lines [PDF]
Highlights of Astronomy, 2005 AbstractWe briefly note several current topics concerning the properties of interstellar clouds for which high-resolution optical spectra play a significant role: (1) the recognition and characterization of small-scale (sub-pc) structure in both atomic and molecular gas; (2) the discovery of variations in the 7Li/6Li isotopic ratio in the nearby ...
openaire +1 more source