Results 21 to 30 of about 154 (145)
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
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Variability of Interstellar Water Vapor Masers [PDF]
Highlights of Astronomy, 1998 We present some results of observations of H2O masers (1.35 cm line) in Star-Forming Regions. The observations have been made from the beginning of the eighties at the 22 m radiotelescope at Pushchino, Russia (Lekht et al. 1995). The time interval between two consecutive observations is about one month.
J.E. Mendoza-Torres, E.E. Lekht
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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
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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
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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 ...
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Surveys of the Milky Way and Magellanic System in the λ21-cm line of atomic hydrogen
EPJ Web of Conferences, 2012 In the next three years, surveys of the Northern and Southern skies using focal plane arrays on aperture synthesis radio telescopes will lead to a breakthrough in our knowledge of the warm and cool atomic phases of the interstellar medium and their ...
Dickey J.M.
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ALMA Detection of Masers and Dasars in the Hydrogen Recombination Lines of the Planetary Nebula Mz3
The Astrophysical JournalThe hydrogen recombination lines H30 α , H40 α , H42 α , H50 β , and H57 γ and the underlying bremsstrahlung continuum emission were detected with ALMA in the bipolar nebula Mz3.
Zulema Abraham +7 more
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Radio Science, Volume 61, Issue 6, June 2026.Abstract Since its observation in 2019, the first image of a super‐massive black hole using Very Long Baseline Interferometry (VLBI) with an Earth‐scale baseline has generated much scientific and public interest. Work is now underway to extend the baseline into space to obtain higher image resolution.
E. A. Burt +5 more
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Deep Space Network Radio Science and Ground‐Based Planetary Radar in the Next Decade
Radio Science, Volume 60, Issue 7, July 2025.Abstract The Deep Space Network (DSN) has been a core operational element of NASA's crewed and robotic exploration of the Solar System since the early 1960s. The primary role of the DSN has been to acquire telemetry and navigation data, but over the years, its radiometric and radar capabilities have expanded to form a system for obtaining unique ...
R. S. Park +13 more
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5 cm OH Masers in Northern Star Formation Regions
The Astronomical JournalWe present a 6.0 GHz excited-state OH maser survey toward 155 northern star formation regions utilizing the Shanghai Tianma Radio Telescope. In total, we detect 44 6.0 GHz OH masers, 8 of which are new detections (one at 6016 MHz, two at 6030 MHz, and ...
Hai-Hua Qiao +6 more
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