Results 11 to 20 of about 2,579,062 (253)
Extreme Quasars as Distance Indicators in Cosmology
Frontiers in Astronomy and Space Sciences, 2020 Quasars accreting matter at very high rates (known as extreme Population A [xA] quasars, possibly associated with super-Eddington accreting massive black holes) may provide a new class of distance indicators covering cosmic epochs from present day up to ...
Deborah Dultzin +10 more
doaj +1 more source
Studying Nearby Galactic Planetary Nebulae with MUSE: On the Physical Properties of IC 418
Galaxies, 2022 Spectroscopic mapping of planetary nebulae (PNe) is particularly useful to capture the richness in terms of physical and chemical properties that exist in these objects.
Ana Monreal-Ibero , Jeremy R. Walsh
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The excitation mechanisms of X-ray oxygen emission-lines [PDF]
, 2021 We present the Catalogue of High REsolution Spectra of Obscured Sources (CHRESOS) from the XMM-Newton Science Archive. It comprises soft X-ray emission-lines from C to Si and the Fe 3C and Fe 3G L-shell transitions.
Storchi-Bergmann, T. +10 more
core +2 more sources
CORONAL EMISSION LINES AS THERMOMETERS [PDF]
The Astrophysical Journal, 2009 Accepted by ApJ, November ...
openaire +2 more sources
Corona ions from high-voltage power lines : nature of emission and dispersion [PDF]
, 2011 Positive and negative small ions, aerosol ion and number concentration and dc electric fields were monitored at an overhead high-voltage power line site. We show that the emission of corona ions was not spatially uniform along the lines and occurred from
Ling, Xuan +2 more
core +1 more source
Off-Axis Variability of AGNs: A New Paradigm for Broad Lines and Continuum Emitting Regions
Open Astronomy, 2011 The general picture of how thermal AGNs work has become clearer in recent years but major observational puzzles threaten to undermine this picture. These puzzles include AGNs with extremely asymmetric emission line profiles, inconsistent multi-wavelength
Gaskell C. Martin
doaj +1 more source
Searching for Emission-Line Galaxies [PDF]
International Astronomical Union Colloquium, 1984 Survey methods for finding emission-line galaxies are reviewed. Observational selection effects are investigated by comparing different surveys and the limitations of the different techniques are discussed. The advantages of Ha surveys for finding low luminosity galaxies and those with low excitation emission spectra are emphasized.
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Quasars in the 4D Eigenvector 1 Context: a stroll down memory lane
Frontiers in Astronomy and Space Sciences, 2015 Recently some pessimism has been expressed about our lack of progress in understanding quasars over more than fifty year since their discovery. It is worthwhile to look back at some of the progress that has been made – but still lies under the radar ...
Jack W. Sulentic, Paola eMarziani
doaj +1 more source
The assembly bias of emission-line galaxies [PDF]
Monthly Notices of the Royal Astronomical Society, 2021 ABSTRACT The next generation of spectroscopic surveys will target emission-line galaxies (ELGs) to produce constraints on cosmological parameters. We study the large-scale structure traced by ELGs using a combination of a semi-analytical model of galaxy formation, a code that computes the nebular emission from H ii regions using the ...
Esteban Jiménez +5 more
openaire +3 more sources
Spectral properties of AGN with very weak [O III] lines [PDF]
Serbian Astronomical Journal, 2011 The spectral properties of a sample of 58 Active Galactic Nuclei (AGN) spectra, in which emission [O III] λλ4959, 5007 Å lines are weak or totally absent, are analyzed.
Kovačević J.
doaj +3 more sources