منابع مشابه
Gaussian Spectral Line Profiles of Astrophysical Masers
Calculations are performed to demonstrate the deviations from Gaussian that occur in the spectral line profiles of a linear maser as a result of the amplification process. Near-Gaussian profiles are presented for bright, interstellar 22 GHz water masers obtained from high resolution Very Long Baseline Array (VLBA) observations of W3 IRS 5. For the profiles to be so close to Gaussian, the calcul...
متن کاملAstrophysical water masers : Line profiles analysis
The changes in the spectral line profile of the 22 GHz H 2 O maser are calculated as a function of emerging maser flux. We address not only the narrowing and re-broadening of the maser lines, but also the deviations of Gaussian symmetry as a result of the various hyperfine components of the 22 GHz maser line. Non-LTE models of the H 2 O maser transition, including hyperfine structure and cross-...
متن کاملIntrinsic Short Time Scale Variability in W3(oh) Hydroxyl Masers
We have studied the OH masers in the star forming region, W3(OH), with data obtained from the Very Long Baseline Array (VLBA). The data provide an angular resolution of ∼5 mas, and a velocity resolution of 106 m s−1. A novel analysis procedure allows us to differentiate between broadband temporal intensity fluctuations introduced by instrumental gain variations plus interstellar diffractive sci...
متن کامل3 Astrophysical constraints on hypothetical variability of fundamental constants
Many-multiplet (MM) method [1] applied to three inhomogeneous samples of Keck/HIRES quasar absorption spectra gives a shift in the value of the fine-structure constant of ∆α/α = (−5.4± 1.2)× 10−6 in the redshift range 0.2 < z < 3.7 [2]. The 1 σ error claimed in [2] is, however, much too small and cannot be maintained by current observations of quasars. We present a modified MM method to set an ...
متن کاملAstrophysical constraints on hypothetical variability of fundamental constants
Many-multiplet (MM) method [1] applied to Keck/HIRES quasar absorption spectra gives a shift in the value of the fine-structure constant of ∆α/α = (−5.4±1.2)×10−6 [2]. Theoretical models of the fundamental physical interactions predict in this case a shift in the protonto-electron mass ratio (μ = mp/me) of about ∆μ/μ ∼ −2× 10−4. We used VLT/UVES high-resolution observations of molecular hydroge...
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ژورنال
عنوان ژورنال: Monthly Notices of the Royal Astronomical Society
سال: 1978
ISSN: 0035-8711,1365-2966
DOI: 10.1093/mnras/183.3.491