Results 41 to 50 of about 5,095,486 (206)

The location and kinematics of the emission line regions in Active Galactic Nuclei [PDF]

, 2008
This thesis contains the results from a study of the optical emission lines of various samples of active galactic nuclei (AGN). We have used three separate techniques to determine the precise kinematics and the relative location of the emission line ...
Mullaney, J R, Mullaney, J.R.
core  

Detection of Helium Recombination Lines in the Cygnus X Diffuse Ionized Gas: Implications for Galactic Interstellar Medium Studies

The Astronomical Journal
We present the first detection of helium radio recombination lines (HeRRLs) at 800 MHz from the diffuse ionized gas (DIG) in the Cygnus X region, with an ionized helium-to-hydrogen ratio ( ${{n}}_{{\rm{H}}{\rm{e}}}^{+}/{{n}}_{{\rm{H}}}^{+}$ ) of 0.06 ± 0.
D. Anish Roshi, J. Poojapriyatharsheni, Mayumi Sato, Kimberly L. Emig, Pedro Salas, L. D. Anderson, R. Nimma Elizabeth   +6 more
doaj   +1 more source

Simulations of High-redshift [O iii] Emitters: Chemical Evolution and Multiline Diagnostics

The Astrophysical Journal, 2023
Recent observations by the James Webb Space Telescope discovered a number of high-redshift galaxies with strong emission lines from doubly ionized oxygen.
Yurina Nakazato, Naoki Yoshida, Daniel Ceverino   +2 more
doaj   +1 more source

The Great Cosmic Silence: What Does the Fermi Paradox Tell About the Future of Humanity?

Global Policy, Volume 17, Issue 4, Page 553-565, September 2026.
ABSTRACT This article examines how institutional time horizons shape the long‐term survival prospects of human technological civilisation. While research on global catastrophic and existential risks has expanded, the temporal structures of political‐economic institutions remain underexamined.
Heikki Patomäki
wiley   +1 more source

The formation of molecular hydrogen in the interstellar medium [PDF]

, 2010
H2 is the most abundant molecule in the interstellar medium and forms on the surface of interstellar dust grains. Laboratory studies have been conducted of HD formation on a dust grain analogue, which is a highly-oriented pyrolytic graphite surface ...
Islam, F.
core  

Detection of Deuterated Hydrocarbon Nanoparticles in the Whirlpool Galaxy, M51

The Astrophysical Journal Letters
Deuteration of hydrocarbon material, including polycyclic aromatic hydrocarbons (PAHs), has been proposed to account for the low gas-phase abundances of D in the interstellar medium (ISM). JWST spectra of four star-forming regions in M51 show an emission
B. T. Draine, Karin Sandstrom, Daniel A. Dale, J.-D. T. Smith, Ryan Chown, Grant P. Donnelly, Sara E. Duval, Cory M. Whitcomb, Angela Adamo, L. Armus, Danielle A. Berg, Torsten Böker, Alberto D. Bolatto, Martha L. Boyer, Daniela Calzetti, B. G. Elmegreen, Brandt A. L. Gaches, Karl D. Gordon, L. K. Hunt, R. C. Kennicutt, Ralf S. Klessen, Thomas S.-Y. Lai, Adam K. Leroy, Sean T. Linden, Alex Pedrini, Noah S. J. Rogers, Julia C. Roman-Duval, Eva Schinnerer, Evan B. Skillman, Fabian Walter, Tony D. Weinbeck, Benjamin F. Williams   +31 more
doaj   +1 more source

When Communication Enables Catastrophe: Nuclear Risk and the Short Lifetimes of Technological Civilizations

Risk Analysis, Volume 46, Issue 9, September 2026.
ABSTRACT The Fermi paradox may partly reflect technological self‐destruction acting as a Great Filter during post‐industrial development. Because the empirical record consists of a single civilization observed over an eighty‐year nuclear age, the exercise reported here is best understood as a structured, historically anchored scenario analysis rather ...
Vincenzo Alfano
wiley   +1 more source

Optical polarimetry studies of Seyfert galaxies [PDF]

, 1999
Optical imaging polarimetry has been performed on seven nearby Seyfert galaxies, three with face-on and four with edge-on host galaxies of various morphological classifications.
Felton, Michelle Ann
core  

Broad line emission from iron K- and L-shell transitions in the active galaxy 1H 0707-495

, 2009
Since the 1995 discovery of the broad iron K-line emission from the Seyfert galaxy MCG-6-30-15 (ref. 1), broad iron K lines have been found in emission from several other Seyfert galaxies, from accreting stellar-mass black holes and even from accreting ...
T. Boller, Reynolds, C., Tanaka, Y, Larsson, J., Reynolds, C.S., Boller, T., Zoghbi, A., Y. Tanaka, G. Miniutti, Brandt, W.N., Zoghbi, A, Blustin, A., Reis, R.C., W. N. Brandt, Ponti, G, Ross, R., Uttley, P., Cadallero-Garcia, M., C. S. Reynolds, Blustin, A. J., Caballero-Garcia, M.D., Young, A.J., P. Uttley, Reynolds, C.S, Miller, J.M., Ross, R.R., A. C. Fabian, Uttley, P, Tanaka, Y., Young, A.J, L. C. Gallo, J. M. Miller, Miniutti, G, Brandt, W. N., G. Ponti, Fabian, A.C., Brandt, W, Blustin, A.J, Reis, R., Reis, R. C., Blustin, A.J., A. J. Blustin, J. Larsson, Ross, R. R., Miller, J.M, A. Zoghbi, R. C. Reis, M. D. Caballero-Garcia, A. J. Young, Ross, R.R, Miller, Jon M., Brandt, W., Gallo, L. C., Fabian, A., Caballero-Garcia, M. D., Ponti, G., Miniutti, G., Larsson, J, R. R. Ross, Gallo, L., Young, A., Fabian, A.C, Fabian, Andy C., Caballero-Garcia, M.D, Boller, T, Reynolds, Christopher S., Miniutti, Giovanni, Gallo, L.C., Miller, J., Reis, R.C, Young, A. J.   +70 more
core   +1 more source

Spaceborne and spaceborn: Physiological aspects of pregnancy and birth during interplanetary flight

Experimental Physiology, Volume 111, Issue 9, Page 4015-4040, 1 September 2026.
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