نتایج جستجو برای: cyclotron maser
تعداد نتایج: 8010 فیلتر نتایج به سال:
Monitoring of theH2Omaser inOH39.7+1.5 aswell as spatial interferometry show clear evidence that the maser switches occasionally its beaming direction between radial and tangential paths in step with the stellar pulsation cycle. Outside the minimum, several radially beamed maser features are present, which are absent (≤ 20 mJy) during the minimum. Competition between gain paths causes tangentia...
The application of masers is limited by its demanding working conditions (high vacuum or low temperature). A room-temperature solid-state maser is highly desirable, but the lifetimes of emitters (electron spins) in solids at room temperature are usually too short (∼ns) for population inversion. Masing from pentacene spins in p-terphenyl crystals, which have a long spin lifetime (∼0.1 ms), has b...
We report on the first space-VLBI observations of the OH34.26+0.15 maser in two main line OH transitions at 1665 and 1667 MHz. The observations involved the space radiotelescope on board the Japanese satellite HALCA and an array of ground radio telescopes. The map of the maser region and images of individual maser spots were produced with an angular resolution of 1 milliarcsec which is several ...
An overview is given of the analysis of more than a decade of H2O maser data from our monitoring program. We find the maser emission to generally depend on the luminosity of the YSO as well as on the geometry of the SFR. There appears to be a threshold luminosity of a few times 10 4 L⊙ above and below which we find different maser characteristics.
We have investigated the influence of several line overlaps between 28SiO, 29SiO and 30SiO on maser emission from the envelopes of late-type stars using the Large Velocity Gradient radiative transfer formalism modified to account for overlaps. Our model includes: (i) 40 rotational levels for each of the v = 0 to 4 vibrational states and each isotopic species; (ii) collisions with molecular and ...
We report observations with the VLA of 22 GHz H2O maser emission in the circumstellar envelopes of 11 late-type stars. We model the maser emission towards six of them (IRC +60169, R Crt, U Her, RX Boo, R LMi, and R Cas) with a computer program we have developed, that fits threedimensional Gaussian sources (in position and velocity) to the measured intensity distribution. This approach to the pr...
The southern maser site OH 300.969+1.147 has been studied using the Long Baseline Array of the Australia Telescope National Facility. The 1665and 1667-MHz hydroxyl ground-state transitions were observed simultaneously. A series of maps with tenth-arcsec spatial resolution, at velocity spacing 0.09 km s, and in both senses of circular polarization, reveal 59 small diameter maser spots. The spots...
The results of the first complete survey for 6668-MHz CH3OH and 6035-MHz excitedstate OH masers in the Small and Large Magellanic Clouds are presented. A new 6668-MHz CH3OH maser in the Large Magellanic Cloud has been detected towards the star-forming region N 160a, together with a new 6035-MHz excited-state OH maser detected towards N 157a. We also re-observed the previously known 6668-MHz CH3...
We present OH maser observations at 1612, 1665, 1667, and 1720 MHz for 86 post-asymptotic giant branch (post-AGB) stars selected from a survey of 1612 MHz maser sources in the Galactic Plane. The observations were taken with the Parkes Telescope and the Australia Telescope Compact Array between 2002 September and 2003 August. Post-AGB stars are the precursors to planetary nebulae, the diverse m...
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