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The OH Megamaser emission in the merging galaxy Arp220 has been re-observed with the Multi-Element Radio Linked Interferometer Network (MERLIN) and the European VLBI Network (EVN). Imaging results of the OH line emission at the two nuclei…

Astrophysics of Galaxies · Physics 2023-06-28 W. A. Baan , J. N. H. S. Aditya , T. An , H-R. Klöckner

Observations of H$_2$O masers towards the post-AGB star and water fountain source OH 009.1--0.4 were made as part of HOPS (The H$_2$O southern galactic Plane Survey), with the Mopra radiotelescope. Together with followup observations using…

Astrophysics · Physics 2008-12-11 A. J. Walsh , S. L. Breen , I. Bains , W. H. T. Vlemmings

We present high-resolution Karl G. Jansky Very Large Array observations of the 22 GHz $\mathrm{H_2O}$ maser line in the extended Sagittarius B2 cloud. We detect 499 $\mathrm{H_2O}$ masers across the observed velocities between -39 and 172…

Outside the Milky Way, the most luminous H2O masers at 22 GHz, called 'megamasers' because of their extreme luminosity with respect to the Galactic and extragalactic H2O masers associated with star formation, are mainly detected in active…

Astrophysics of Galaxies · Physics 2020-05-20 G. Surcis , A. Tarchi , P. Castangia

Astrophysical masers are one of the most readily detected signposts of high-mass star formation. Their presence indicates special conditions, probably indicative of a specific evolutionary phase. Masers also represent the ultimate…

Astrophysics · Physics 2007-05-23 Simon Ellingsen

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 database of maser sources in H2O, OH and SiO lines that can be used to identify and study variable stars at evolved stages. Detecting the maser emission in H2O, OH and SiO molecules toward infrared-excess objects is one of…

Solar and Stellar Astrophysics · Physics 2019-04-03 A. M. Sobolev , D. A. Ladeyschikov , J. -I. Nakashima

We present the first variability study of the 1720 MHz OH masers located in the Galactic Center. Most of these masers are associated with the interaction between the supernova remnant SgrAEast and the interstellar medium, but a few masers…

Astrophysics of Galaxies · Physics 2015-05-28 Y. M. Pihlström , L. O. Sjouwerman , R. A. Mesler

We present high resolution (sub-mas) VLBI maps of nuclear H2O megamasers for seven galaxies. In UGC6093, the well-aligned systemic masers and high-velocity masers originate in an edge-on, flat disk and we determine the mass of the central…

Astrophysics of Galaxies · Physics 2018-02-28 W. Zhao , J. A. Braatz , J. J. Condon , K. Y. Lo , M. J. Reid , C. Henkel , D. W. Pesce , J. E. Greene , F. Gao , C. Y. Kuo , C. M. V. Impellizzeri

We conducted radio observations searching for OH 18-cm maser emission from a sample of 169 unclassified MIPSGAL compact Galactic bubbles. These sources are thought to be the circumstellar envelopes of different kinds of evolved stars. Our…

Solar and Stellar Astrophysics · Physics 2015-10-02 A. Ingallinera , C. Trigilio , P. Leto , G. Umana , C. Buemi , L. Cerrigone , C. Agliozzo

OH megamasers (OHMs) are extragalactic masers found primarily in gas-rich galaxy major mergers. To date, only $\sim$120 OHMs have been cataloged since their discovery in 1982, and efforts to identify distinct characteristics of OHM host…

Astrophysics of Galaxies · Physics 2025-06-09 Hayley Roberts , Jeremy Darling , Kelley M. Hess , Andrew J. Baker , Elizabeth A. K. Adams , Helga Dénes

The OH main line masers in circumstellar shells were observed with astrometric VLBI in order to accurately determine the position of the star, as well as its motion, including the parallax. Results are presented on 4 Mira stars monitored…

Astrophysics · Physics 2007-05-23 Wouter Vlemmings , Huib Jan van Langevelde , Phil Diamond

I present here the summary of results from a survey by De Buizer (2003) searching for outflows using near-infrared imaging. Targets were massive young stellar objects associated with methanol masers in linear distributions. Presently, it is…

Astrophysics · Physics 2007-05-23 James M. De Buizer

Studying stars that are located off the Galactic plane is important for understanding the formation history of the Milky Way. We searched for SiO masers toward off-plane O-rich asymptotic giant branch (AGB) stars from the catalog presented…

Astrophysics of Galaxies · Physics 2023-10-23 Wenjin Yang , Yuanwei Wu , Yan Gong , Nicolas Mauron , Bo Zhang , Karl M. Menten , Xiaofeng Mai , Dejian Liu , Juan Li , Jingjing Li

Maser lines from different molecular species, including water, hydroxyl, and methanol, are common observational phenomena associated with massive star forming regions. In particular, the methanol maser appears as an ideal tool to study the…

Astrophysics of Galaxies · Physics 2014-06-04 L. Olmi , E. D. Araya , P. Hofner , S. Molinari , J. Morales Ortiz , L. Moscadelli , M. Pestalozzi

Aims.Molecular masers, including methanol and hydroxyl masers, and in particular the ones in excited rotational states (ex-OHmasers), are one of the most informative tools for studying star-forming regions. So, the discovery, of new maser…

Astrophysics of Galaxies · Physics 2021-08-04 O. Patoka , O. Antyufeyev , I. Shmeld , V. Bezrukovs , M. Bleiders , A. Orbidans , A. Aberfelds , V. Shulga

A new class of OH (1720 MHz) masers unaccompanied by main-line transitions have recently been discovered (Frail, Goss and Slysh 1994). These masers lie at the interface between supernova remnants (SNRs) interacting with molecular clouds. We…

Astrophysics · Physics 2007-05-23 F. Yusef-Zadeh , D. A. Roberts , G. Bower , M. Wardle

Water vapor maser emission in the 6_{16}-5_{23} transition towards the narrow-line Seyfert 1 (NLS1) galaxy NGC 4051 has been discovered during an ongoing single-dish extragalactic water maser survey. The Doppler-shifted maser components…

We studied class I methanol masers in the transition 7_0-6_1 A+ at the frequency 44 GHz with the VLA. The observations on the VLA were made with the angular resolution 0''.1, which was the highest at the moment. It was shown that the masers…

Astrophysics · Physics 2007-05-23 V. I. Slysh , I. E. Val'tts , S. V. Kalenskii

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…

Astrophysics · Physics 2009-11-10 R. M. Deacon , J. M. Chapman , A. J. Green