Results 41 to 50 of about 1,130 (187)
Meteoritics &Planetary Science, EarlyView.Abstract This study provides the first petrographic, crystallographic, and chemical comparison between El Médano 300 (EM 300) and Northwest Africa 8155 (NWA 8155), two particular IAB‐ungrouped iron meteorites. Both contain exceptionally large graphite nodules and “flowers”, providing unique insights into carbon behavior in metallic melts and cooling ...
L. Perez +8 more
wiley +1 more source
Heavy X‐Ray Absorption in Soft X‐Ray–weak Active Galactic Nuclei [PDF]
The Astrophysical Journal, 2001 30 pages, 10 figures, LaTeX, uses aaspp4.sty; submitted to ...
Gallagher, S. C. +6 more
openaire +2 more sources
The 40K‐K dating system: 1. Improving data interpretation using new model calculations
Meteoritics &Planetary Science, EarlyView.Abstract The 40K‐K cosmic‐ray exposure (CRE) dating system offers a promising method for determining exposure ages of iron meteorites by combining the radioactive cosmogenic 40K with the stable cosmogenic isotopes 39K and 41K. However, earlier applications relied on semi‐empirical production models and inconsistent analytical data sets, limiting their ...
Farshid Nozarian +2 more
wiley +1 more source
The X-ray/UV ratio in active galactic nuclei: dispersion and variability [PDF]
Astronomy & Astrophysics, 2018 Context. The well established negative correlation between the αOX spectral slope and the optical/ultraviolet (UV) luminosity, a by-product of the relation between X-rays and optical/UV luminosity, is affected by relatively large dispersion. The main contributors to this dispersion can be variability in the X-ray/UV ratio and/or changes in fundamental ...
Chiaraluce, E +3 more
openaire +5 more sources
Investigation of the Quasi-periodic Oscillation Phase Lag of RE J1034+396
The Astrophysical JournalWe conduct an in-depth study of the quasi-periodic oscillation (QPO) properties of RE J1034+396 by constructing QPO phase-folded light curves from 10 XMM-Newton observations during 2020–2021.
Wen-Zhong Li +11 more
doaj +1 more source
The Astrophysical Journal Letters, 2023 Recent studies have proposed that the nuclear millimeter continuum emission observed in nearby active galactic nuclei (AGNs) could be created by the same population of electrons that gives rise to the X-ray emission that is ubiquitously observed in ...
Claudio Ricci +12 more
doaj +1 more source
Spaceborne and spaceborn: Physiological aspects of pregnancy and birth during interplanetary flight
Experimental Physiology, EarlyView.Abstract Crewed interplanetary return missions that are on the planning horizon will take years, more than enough time for initiation and completion of a pregnancy. Pregnancy is viewed as a sequence of processes – fertilization, blastocyst formation, implantation, gastrulation, placentation, organogenesis, gross morphogenesis, birth and neonatal ...
Arun V. Holden
wiley +1 more source
Extreme X-Ray Iron Lines in Active Galactic Nuclei
The Astrophysical Journal, 2002 We analyze X-ray spectra of heavily obscured (N_H > 10^{24} cm^{-2}) active galaxies obtained with Chandra, concentrating on the iron K alpha fluorescence line. We measure very large equivalent widths in most cases, up to 5 keV in the most extreme example.
Levenson, N. A. +6 more
openaire +2 more sources
The Astrophysical JournalWe present a high-resolution X-ray spectroscopic study of the narrow-line Seyfert 1 galaxy NGC 4051 using two XMM-Newton high-resolution Reflection Grating Spectrometer observations.
Roberto Serafinelli +8 more
doaj +1 more source
X-Ray Unveiling Events in a z ≈ 1.6 Active Galactic Nucleus in the 7 Ms Chandra Deep Field-South
The Astrophysical Journal, 2023 We investigate the extreme X-ray variability of a z = 1.608 active galactic nucleus in the 7 Ms Chandra Deep Field-South (XID 403), which showed two significant X-ray brightening events.
Li-Ming Yu +16 more
doaj +1 more source