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200 papers

Magnetic fields have only recently been included in theoretical simulations of high-mass star formation. The simulations show that magnetic fields play an important role in the formation and dynamics of molecular outflows. Masers, in…

Solar and Stellar Astrophysics · Physics 2015-06-16 G. Surcis , W. H. T. Vlemmings , H. J. van Langevelde , B. Hutawarakorn Kramer , L. H. Quiroga-Nunez

Aims: Accurate distances to evolved stars with high mass loss rates are needed for studies of many of their fundamental properties. However, as these stars are heavily obscured and variable, optical and infrared astrometry is unable to…

Astrophysics · Physics 2009-11-13 W. H. T. Vlemmings , H. J. van Langevelde

We present results of 13CO(1-0), C18O(1-0), and HCO+(1-0) map observations and N2H+2 (1-0) single point observations directed towards a sample of nine low-luminosity 6.7-GHz masers. N2H+ line emission has been detected from six out of nine…

Astrophysics of Galaxies · Physics 2015-05-19 Y. W. Wu , Y. Xu , J. Yang

OH(1720 MHz) masers are excellent signposts of interaction between supernova remnants(SNRs) and molecular clouds. Using the GBT and VLA we have surveyed 75 SNRs and six candidates for maser emission. Four new interacting SNRs are detected…

Astrophysics of Galaxies · Physics 2009-11-13 John W. Hewitt , Farhad Yusef-Zadeh

We wish to understand the reasons for the strong variability of H2O masers in circumstellar shells of late-type stars. We monitored RX Boo and SV Peg in the 22-GHz maser line of water vapour with single-dish telescopes. The monitoring…

Astrophysics · Physics 2009-11-13 A. Winnberg , D. Engels , J. Brand , L. Baldacci , C. M. Walmsley

Far-infrared line and continuum fluxes are presented for a sample of 227 galaxies observed with the Long Wavelength Spectrometer on the Infrared Space Observatory. The galaxy sample includes normal star-forming systems, starbursts, and…

Astrophysics · Physics 2009-11-13 James R. Brauher , Daniel A. Dale , George Helou

We characterize the molecular environment of candidate massive young stellar objects (MYSOs) signposted by methanol masers. Single pixel observations of 10 transitions of HCO^+, CO and CS isotopomers were carried out, using the IRAM 30m…

Astrophysics · Physics 2009-11-13 M. Szymczak , A. Bartkiewicz , A. M. S. Richards

The revised version of the class I methanol maser catalog is presented. It contains 198 sources - new class I methanol masers detected in the direction of EGOs were added to the previous number (~160 sources have been published in the first…

Astrophysics of Galaxies · Physics 2010-06-18 I. E. Val'tts , G. M. Larionov , O. S. Bayandina

We present single-dish monitoring of the spectra of 13 extragalactic water megamasers taken over a period of 9 years and a single epoch of sensitive spectra for 7 others. Our data include the first K-band science observations taken with the…

Astrophysics · Physics 2009-11-07 J. A. Braatz , A. S. Wilson , C. Henkel , R. Gough , M. Sinclair

Observations of dust-enshrouded evolved stars selected from infrared catalogs requiring high positional accuracy, like infrared spectroscopy or long baseline radio interferometric observations, often require preparational observational…

Globular clusters produce many exotic stars due to a much higher frequency of dynamical interactions in their dense stellar environments. Some of these objects were observed together with several hundred thousands other stars in our MUSE…

We report high spatial and spectral resolution measurements of masers towards R Aqr and H1-36, both of which are examples of the sub-class of symbiotic stars that contain a long-period Mira-type variable. Our observations have resulted in…

Astrophysics · Physics 2009-10-30 Rob Ivison , J. A. Yates , P. J. Hall

We report the first detection of an extragalactic millimeter wavelength H2O maser at 183 GHz towards NGC 3079 using the Submillimeter Array (SMA), and a tentative submillimeter wave detection of the 439 GHz maser towards the same source…

We present high spatial resolution observations of ground-state OH masers, achieved using the Australia Telescope Compact Array (ATCA). These observations were conducted towards 171 pointing centres, where OH maser candidates were…

We present the results of observations of cold IRAS sources in the Galactic disk area, -10 < l < 100 and |b|<5, in the SiO J=1-0, v=1 and 2 maser lines. SiO masers were detected in 51 out of 143 observed sources; 45 were new detections in…

Astrophysics · Physics 2015-06-24 Jun-ichi Nakashima , Shuji Deguchi

Oxygen-rich Asymptotic Giant Branch (AGB) stars can be intense emitters of SiO ($v$=1 and 2, J=1$\rightarrow$0) and H$_2$O maser lines at 43 and 22 GHz, respectively. VLBI observations of the maser emission provide a unique tool to probe…

We describe the monitoring program we have been carrying out during the past 10 years on a sample of late-type stars, with the Medicina 32-m and Effelsberg 100-m antennas. We discuss the observations on the Mira-variable R Cas in some…

Astrophysics · Physics 2007-05-23 J. Brand , L. Baldacci , D. Engels

Galactic nuclei are well known sources of OH and H2O maser emission. It appears that intense star formation in ultra-luminous infrared galaxies drives most OH sources. In contrast, nuclear activity appears to drive most H2O sources. When…

Astrophysics · Physics 2009-11-13 L. J. Greenhill

Class II CH3OH masers are used as a convenient tracer of disc-like structures in high-mass star formation. However, more than half of them show a complex distribution in Very Long Baseline Interferometry (VLBI) maps. The origin of such a…

Solar and Stellar Astrophysics · Physics 2023-10-05 M. Nakamura , K. Motogi , H. Nakamura , Y. Yonekura , K. Fujisawa

We present searches for 22 GHz H$_2$O masers toward 36 narrow-line Seyfert 1 galaxies (NLS1s), selected from known NLS1s with $v_{sys}$ $\lesssim$ 41000 km/s. Out of the 36 NLS1s in our sample, 11 NLS1s have been first surveyed in our…

Astrophysics of Galaxies · Physics 2018-05-03 Yoshiaki Hagiwara , Akihiro Doi , Kazuya Hachisuka , Shinji Horiuchi