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The 6.7 GHz maser transition of methanol has been found exclusively towards massive star forming regions. A majority of the masers have been found to lack the presence of any associated radio continuum. This could be due to the maser…

星系天体物理 · 物理学 2015-05-19 J. D. Pandian , E. Momjian , Y. Xu , K. M. Menten , P. F. Goldsmith

We report the first detection of a methanol maser in the 10(1)-9(2)A- transition at 23.4 GHz, discovered during the H2O southern Galactic Plane Survey (HOPS) with the 22-m Mopra radio telescope. In the region covered by HOPS, the 23.4 GHz…

The Australia Telescope Compact Array (ATCA) has been used to image class I methanol masers at 9.9, 25 (a series from J=2 to J=9), 84, 95 and 104 GHz located in the vicinity of IRAS 16547-4247 (G343.12-0.06), a luminous young stellar object…

天体物理学 · 物理学 2008-11-26 M. A. Voronkov , K. J. Brooks , A. M. Sobolev , S. P. Ellingsen , A. B. Ostrovskii , J. L. Caswell

We have conducted the first parallax and proper motion measurements of 6.7 GHz methanol maser emission using the Australian Long Baseline Array (LBA). The parallax of G339.884$-$1.259 measured from five epochs of observations is 0.48$\pm…

We report the detection of new 12.178, 12.229, 20.347, and 23.121 GHz methanol masers in the massive star-forming region G358.93-0.03, which are flaring on similarly short timescales (days) as the 6.668 GHz methanol masers also associated…

We report on the interferometric detection of 36.2 GHz Class I methanol emission with the new 27-40 GHz Ka band receivers available on the Expanded Very Large Array (EVLA). The brightness temperatures of the interferometric 36 GHz…

星系天体物理 · 物理学 2015-05-18 Lorant O. Sjouwerman , Ylva M. Pihlstrom , Vincent L. Fish

We report the discovery of a widespread population of collisionally excited methanol J = 4_{-1} to 3$_0 E sources at 36.2 GHz from the inner 66'x18' (160x43 pc) of the Galactic center. This spectral feature was imaged with a spectral…

星系天体物理 · 物理学 2015-06-12 F. Yusef-Zadeh , W. Cotton , S. Viti , M. Wardle , M. Royster

General characteristics of methanol (CH3OH) maser emission are summarized. It is shown that methanol maser sources are concentrated in the spiral arms. Most of the methanol maser sources from the Perseus arm are associated with embedded…

As the recent publication by Breen et al (2013) found Class II methanol masers are exclusively associated with high mass star forming regions. Based on the positions of the Class I and II methanol and H$_{2}$O masers, UC H II regions and…

星系天体物理 · 物理学 2014-11-19 Hontas Farmer

Context. The importance of the magnetic field in high-mass-star formation is not yet fully clear and there are still many open questions concerning its role in the accretion processes and generation of jets and outflows. In the past few…

太阳与恒星天体物理 · 物理学 2017-11-29 D. Dall'Olio , W. H. T. Vlemmings , G. Surcis , H. Beuther , B. Lankhaar , M. V. Persson , A. M. S. Richards , E. Varenius

In this study, we present an unbiased sample of the earliest stages of massive star formation across 20 square-degree of the sky. Within the region 10deg < l < 20deg and |b| < 1deg, we search the ATLASGAL survey at 870 micron for dense gas…

The role of magnetic fields during the protostellar phase of high-mass star-formation is a debated topic. In particular, it is still unclear how magnetic fields influence the formation and dynamic of disks and outflows. Most current…

太阳与恒星天体物理 · 物理学 2015-05-14 G. Surcis , W. H. T. Vlemmings , R. Dodson , H. J. van Langevelde

We present the second portion of a catalogue of 12.2-GHz methanol masers detected towards 6.7-GHz methanol masers observed in the unbiased Methanol Multibeam (MMB) Survey. Using the Parkes radio telescope we have targeted all 207 6.7-GHz…

星系天体物理 · 物理学 2015-06-05 Shari Breen , Simon Ellingsen , James Caswell , James Green , Maxim Voronkov , Gary Fuller , Lyshia Quinn , Adam Avison

Context: Methanol masers of Class I (collisionally-pumped) and Class II (radiatively-pumped) have been studied in great detail in our Galaxy in a variety of astrophysical environments such as shocks and star-forming regions and are helpful…

Periodic flares of maser emission are thought to be induced either by variations of the seed photon flux in young binary systems or the pump rate regulated by stellar and accretion luminosities. We seek to study the variability of four…

太阳与恒星天体物理 · 物理学 2020-02-05 Mateusz Olech , Marian Szymczak , Paweł Wolak , Eric Gérard , Anna Bartkiewicz

We report the results of 10 years of monitoring of six regularly varying 6.7 GHz methanol masers using the Hartebeesthoek 26m telescope. Observations were done at intervals of 1--2 weeks, with faster sampling during flaring episodes. Four…

太阳与恒星天体物理 · 物理学 2013-11-08 S. Goedhart , J. P. Maswanganye , M. J. Gaylard , D. J. van der Walt

Results of the long-term monitoring observations of the 6.7 GHz Class II methanol masers associated with the four high-mass star-forming regions by Hitachi 32-m radio telescope are presented. We detected periodic flux variability in…

星系天体物理 · 物理学 2024-02-28 Yoshihiro Tanabe , Yoshinori Yonekura

Methanol (CH$_{3}$OH) ice is abundant in space and is a key feedstock for seeding chemical complexity in interstellar and circumstellar environments. Despite its ubiquity, gas-phase methanol has only been detected in one disk around a…

星系天体物理 · 物理学 2025-10-07 John D. Ilee , Catherine Walsh , Jenny C. Calahan

(Abridged) Understanding the details of the formation process of massive (i.e. M<8-10M$_\odot$) stars is a long-standing problem in astrophysics. [...] We present a method to derive accurate timescales of the different evolutionary phases…

星系天体物理 · 物理学 2021-10-14 G. Sabatini , S. Bovino , A. Giannetti , T. Grassi , J. Brand , E. Schisano , F. Wyrowski , S. Leurini , K. M. Menten

We have measured the internal proper motions of the 6.7 GHz methanol masers associated with Cepheus A (Cep A) HW2 using Very Long Baseline Interferometery (VLBI) observations. We conducted three epochs of VLBI monitoring observations of the…

太阳与恒星天体物理 · 物理学 2015-06-18 K. Sugiyama , K. Fujisawa , A. Doi , M. Honma , H. Kobayashi , Y. Murata , K. Motogi , K. Niinuma , H. Ogawa , K. Wajima , S. Sawada-Satoh , S. P. Ellingsen