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We have used the Australia Telescope Compact Array (ATCA) to make the first high resolution observations of a large sample of class~I methanol masers in the 95-GHz ($8_0$--$7_1$A$^+$) transition. The target sources consist of a…

星系天体物理 · 物理学 2018-03-28 Tiege P. McCarthy , Simon P. Ellingsen , Maxim A. Voronkov , Giuseppe Cimo

Methanol maser emission has proven to be an excellent signpost of regions undergoing massive star formation (MSF). To investigate their role as an evolutionary tracer, we have recently completed a large observing program with the ATCA to…

天体物理学 · 物理学 2009-11-13 S. N. Longmore , M. G. Burton , P. J. Barnes , T. Wong , C. R. Purcell , J. Ott

We have analyzed a uniform sample of 16 evolved HII regions located in a 2 deg X 2 deg Galactic field centered at (l,b) = (30 deg, 0 deg) and observed as part of the Herschel Hi-GAL survey. The evolutionary stage of these HII regions was…

We present an analysis of multi-wavelength observations of an area of 0.27 deg x 0.27 deg around the Galactic HII region G18.88-0.49, which is powered by an O-type star (age ~10^5 years). The Herschel column density map reveals a shell-like…

星系天体物理 · 物理学 2020-11-04 L. K. Dewangan , D. K. Ojha , Saurabh Sharma , S. del Palacio , N. K. Bhadari , A. Das

We report the results obtained from a multi-wavelength study of the HII region, G18.148$-$0.283, using the upgraded Giant Metre-wave Radio Telescope (uGMRT) at 1350 MHz along with other archival data. In addition to the radio continuum…

星系天体物理 · 物理学 2022-01-28 Jyotirmoy Dey , Jagadheep D. Pandian , Dharam Vir Lal

We investigate the star formation activity in the molecular complex associated with the Galactic HII region Sh2-90, using radio-continuum maps obtained at 1280 MHz and 610 MHz, Herschel Hi-GAL observations at 70 -- 500 microns, and deep…

太阳与恒星天体物理 · 物理学 2015-06-19 M. R. Samal , A. Zavagno , L. Deharveng , S. Molinari , D. K. Ojha , D. Paradis , J. Tigé , A. K. Pandey , D. Russeil

We present a survey of 56 massive star-forming regions in the 44 GHz methanol maser transition made with the Karl G. Jansky Very Large Array (VLA); 24 of the 56 fields showed maser emission. The data allow us to demonstrate associations, at…

We present an interferometric survey of the 44 GHz class I methanol maser transition toward a sample of 69 sources consisting of High Mass Protostellar Object candidates and Ultracompact (UC) H II regions. We found a 38% detection rate (16…

星系天体物理 · 物理学 2016-02-17 A. I. Gómez-Ruiz , S. E. Kurtz , E. D. Araya , P. Hofner , L. Loinard

We present deep echelle spectrophotometry of the brightest emission-line knots of the star-forming galaxies He 2-10, Mkn 1271, NGC 3125, NGC 5408, POX 4, SDSS J1253-0312, Tol 1457-262, Tol 1924-416 and the HII region Hubble V in the Local…

星系天体物理 · 物理学 2015-06-22 C. Esteban , J. García-Rojas , L. Carigi , M. Peimbert , F. Bresolin , A. R. López-Sánchez , A. Mesa-Delgado

Based on high quality observations of multiplet V1 of OII and the NLTE atomic computations of OII we study the density and temperature of a sample of HII regions. We find that the signature for oxygen rich clumps of high density and low…

星系天体物理 · 物理学 2015-06-17 Antonio Peimbert , Manuel Peimbert

High resolution 7 mm observations of the W49N massive star forming region have detected recombination line emission from the individual ultracompact (UC) HII regions on 50 milliarcsecond (600 AU) scales. These line observations, combined…

天体物理学 · 物理学 2009-11-10 C. G. De Pree , D. J. Wilner , A. J. Mercer , L. E. Davis , W. M. Goss , S. Kurtz

We present a new set of weak-line abundances of HII regions in M81, based on Gemini Multi-Object Spectrograph (GMOS) observations. The aim is to derive plasma and abundance analysis for a sizable set of emission-line targets to study the…

星系天体物理 · 物理学 2014-09-05 Letizia Stanghellini , Laura Magrini , Viviana Casasola , Eva Villaver

We have recently completed an observing program with the Australia Telescope Compact Array towards massive star formation regions traced by 6.7 GHz methanol maser emission. We found the molecular cores could be separated into groups based…

天体物理学 · 物理学 2007-11-29 S. N. Longmore , M. G. Burton , C. R. Purcell , P. Barnes , J. Ott

Ionised regions around OB-type stars are formed at an early stage of their evolution and are important to investigate the formation process of these objects. However, so far only few observations of their physical structure and interaction…

We present a new model to compute the luminosity of emission lines in star forming galaxies and apply this in the semi-analytical galaxy formation code GALFORM. The model combines a pre-computed grid of HII region models with an empirical…

星系天体物理 · 物理学 2022-01-11 C. M. Baugh , C. G. Lacey , V. Gonzalez-Perez , G. Manzoni

We have carried out a multi-epoch simultaneous survey of 22 GHz H$_2$O and 44 GHz Class I CH$_3$OH masers toward 103 ultracompact HII regions (UCHIIs) between 2010 and 2017. We detected H$_2$O and CH$_3$OH maser emission in 74 (72%) and 55…

太阳与恒星天体物理 · 物理学 2019-09-04 Won-Ju Kim , Kee-Tae Kim , Kwang-Tae Kim

The chemical changes of high-mass star-forming regions provide a potential method for classifying their evolutionary stages and, ultimately, ages. In this study, we search for correlations between molecular abundances and the evolutionary…

Recent JWST observations of HII regions in the Central Molecular Zone have shown a highly filamentary morphology distinct from HII regions in other parts of the galaxy. We present magnetohydrodynamic (MHD) simulations of strongly magnetized…

星系天体物理 · 物理学 2026-02-25 Samuel Crowe , Yisheng Tu , Zhi-Yun Li , Jeong-Gyu Kim , John Bally

We investigate which structures the 6.7 GHz methanol masers trace in the environment of high-mass protostar candidates by observing a homogenous sample of methanol masers selected from Torun surveys. We also probed their origins by looking…

星系天体物理 · 物理学 2015-05-13 A. Bartkiewicz , M. Szymczak , H. J. van Langevelde , A. M. S. Richards , Y. M. Pihlstrom

We analyze the distribution of the interstellar matter in the environs of the HII region Gum31, excited by the open cluster NGC3324, located in the complex Carina region, with the aim of investigating the action of the massive stars on the…

天体物理学 · 物理学 2009-11-13 C. Cappa , V. S. Niemela , R. Amorin , J. Vasquez