Results 21 to 30 of about 4,855 (170)
AGN Obscuration and the Unified Model
Advances in Astronomy, Volume 2012, Issue 1, 2012., 2012 Unification Models of Active Galactic Nuclei postulate that all the observed differences between type 1 and type 2 objects are due to orientation effects with respect to the line of sight to the observer. The key ingredient of these models is the obscuring medium, historically envisaged as a toroidal structure on a parsec scale.
Stefano Bianchi +3 more
wiley +1 more source
Review of Zeeman Effect Observations of Regions of Star Formation
Frontiers in Astronomy and Space Sciences, 2019 The Zeeman effect is the only observational technique available to measure directly the strength of magnetic fields in regions of star formation. This chapter reviews the physics of the Zeeman effect and its practical use in both extended gas and in ...
Richard M. Crutcher, Athol J. Kemball
doaj +1 more source
The Role of Gravitational Instabilities in the Feeding of Supermassive Black Holes
Advances in Astronomy, Volume 2012, Issue 1, 2012., 2012 I review the recent progresses that have been obtained, especially through the use of high‐resolution numerical simulations, on the dynamics of self‐gravitating accretion discs. A coherent picture is emerging, where the disc dynamics is controlled by a small number of parameters that determine whether the disc is stable or unstable, whether the ...
Giuseppe Lodato, Francesco Shankar
wiley +1 more source
Kinematical Conformal Cosmology: Fundamental Parameters from Astrophysical Observations
International Scholarly Research Notices, Volume 2011, Issue 1, 2011., 2011 We continue the presentation of an alternative cosmology based on conformal gravity, following our kinematical approach to the subject introduced in a recent paper. In line with the assumptions of our model, which proposes a closed‐form expression for the cosmic scale factor R(t), we revise the Hubble and deceleration parameters and introduce modified ...
Gabriele U. Varieschi +2 more
wiley +1 more source
Rotationally Inelastic Scattering of Formaldehyde
Laser Chemistry, Volume 5, Issue 6, Page 375-384, 1986., 1986 State to state rotationally inelastic and elastic differential cross‐sections for the system D2CO‐H2 have been measured at a center of mass energy of 17 meV. A single rotational state of D2CO (110) of high state purity is focused into the scattering region by combining rotational cooling and electric state selection.
N. F. Van Hulst +2 more
wiley +1 more source
An Essay On Interactive Investigations Of The Zeeman Effect In The Interstellar Medium [PDF]
, 2015 The paper presents an interactive module created through the Wolfram Demonstrations Project that visualizes the Zeeman effect for the small magnetic field strengths present in the interstellar medium.
Woolsey, Lauren N.
core +3 more sources
Methanol in W3(H2O) and Surrounding Regions [PDF]
, 2004 We present the results of an interferometric study of 38 millimeter-wave lines of CH3OH in the region around the water maser source W3(H2O) and a region extending about 30" to the south and west of the hydroxyl maser source W3(OH).
A. B. Ostrovskii +23 more
core +2 more sources
Variability of interstellar hydroxyl masers
The Astrophysical Journal, 1991 The spectra of 10 interstellar OH maser complexes were monitored in the 1665 MHz transition for variability on short (minutes-hours) and long (days-years) time scales. Eight of the sources exhibit short time scale variability in the relative amplitudes of the spectral features above that expected due to radiometer noise, and all sources for which ...
Andrew W. Clegg, James M. Cordes
openaire +1 more source
An ASCA Study of the High Luminosity SNR G349.7+0.2 [PDF]
, 2002 We present ASCA observations of supernova remnant (SNR) G349.7+0.2. The remnant has an irregular shell morphology and is interacting with a molecular cloud, evident from the presence of OH(1720 MHz) masers and shocked molecular gas.
Caswell J. L. +5 more
core +2 more sources
Magnetic Fields in Interstellar Masers [PDF]
Symposium - International Astronomical Union, 1990 Zeeman splitting in the spectra of molecular masers that arise in the envelopes of newly formed stars (called interstellar masers) offers a method of estimating the magnetic field in these dense regions (106–1011 cm−3). The magnetic field strengths in regions of OH and H2O masers scale as the square root of the density when compared to the density and ...
openaire +1 more source