Nonequilibrium Excitation of Methanol in Galactic Molecular Clouds: Multitransitional Observations at 2 Millimeters

Slysh, V. I.; Kalenskii, S. V.; Вальтц, И. Е.; Golubev, Vladimir V.; Mead, Kathryn N.

doi:10.1086/313240

Cited by 28 publications

(29 citation statements)

References 13 publications

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“…Thermal, broad line (FWHM > 20 km s −1 ) SiO emission in the ground vibrational state (J = 2−1 and 3−2) was detected by Harju et al (1998). Caswell et al (2000) detected thermal CH 3 OH emission from the 156.6 GHz (see also Slysh et al 1999) and 107.0 GHz transitions, this latter superimposed on a maser component. Methanol maser emission was also reported at 6.7 GHz (e.g., Menten 1991;Goedhart et al 2004), 12.2 GHz (e.g., Caswell et al 1993;Błaszkiewicz & Kus 2004), 44.1 GHz (Slysh et al 1994), and 95.2 GHz (Val'tts et al 2000).…”

Section: The Hmsfr G2301-041mentioning

confidence: 95%

VLBI study of maser kinematics in high-mass star-forming regions

Sanna

Moscadelli

Cesaroni

et al. 2010

A&A

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Aims. We performed a detailed study of maser and radio continuum emission toward the high-mass star-forming region G23.01−0.41. This study aims at improving our knowledge of the high-mass star-forming process by comparing the gas kinematics near a newly born young stellar object (YSO), analyzed through high spatial resolution maser data, with the large-scale environment of its native hot molecular core (HMC), identified in previous interferometric observations of thermal continuum and molecular lines. Methods. Using the VLBA and the EVN arrays, we conducted phase-referenced observations of the three most powerful maser species in G23.01−0.41: H 2 O at 22.2 GHz (4 epochs), CH 3 OH at 6.7 GHz (3 epochs), and OH at 1.665 GHz (1 epoch). In addition, we performed high-resolution (≥0. 1), high-sensitivity (<0.1 mJy) VLA observations of the radio continuum emission from the HMC at 1.3 and 3.6 cm. Results. We have detected H 2 O, CH 3 OH, and OH maser emission clustered within 2000 AU from the center of a flattened HMC, oriented SE-NW, from which emerges a massive 12 CO outflow, elongated NE-SW, extended up to the pc-scale. Although the three maser species show a clearly different spatial and velocity distribution and sample distinct environments around the massive YSO, the spatial symmetry and velocity field of each maser specie can be explained in terms of expansion from a common center, which possibly denotes the position of the YSO driving the maser motion. Water masers trace both a fast shock (up to 50 km s −1 ) closer to the YSO, powered by a wide-angle wind, and a slower (20 km s −1 ) bipolar jet, at the base of the large-scale outflow. Because the compact free-free emission is found offset from the putative location of the YSO along a direction consistent with that of the maser jet axis, we interpret the radio continuum in terms of a thermal jet. The velocity field of methanol masers can be explained in terms of a composition of slow (4 km s −1 in amplitude) motions of radial expansion and rotation about an axis approximately parallel to the maser jet. Finally, the distribution of line-of-sight velocities of the hydroxyl masers suggests that they can trace gas less dense (n H 2 ≤ 10 6 cm −3 ) and more distant from the YSO than that traced by the water and methanol masers, which is expanding toward the observer. A few pairs of OH masers, with different circular polarization, are well aligned in position on the sky and we interpret them as Zeeman pairs. From Zeeman splitting, the derived typical values of the magnetic field are of a few mG.

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Section: The Hmsfr G2301-041mentioning

confidence: 95%

VLBI study of maser kinematics in high-mass star-forming regions

Sanna

Moscadelli

Cesaroni

et al. 2010

A&A

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“…Other observations across the millimeter bands have detected multiple COMs, including CH 3 OH, CH 3 CN, CH 3 CCH, HCOOCH 3 (g.s. and v t = 1), HCOO 13 CH 3 , C 2 H 5 OH, CH 3 CHO, c-C 2 H 4 O, trans-HCOOH, CH 3 COOH, C 2 H 5 CN (g.s., v t = 1, and v b = 1), C 2 H 3 CN, and, tentatively, (CH 2 OH) 2 (Dickens et al 1997;Slysh et al 1999;Kalenskii et al 2000aKalenskii et al , 2000bKalenskii et al , 2002Ikeda et al 2001;Alakoz et al 2002;Minier & Booth 2002;Remijan et al 2002Remijan et al , 2008Demyk et al 2008;Jordan et al 2008;Wirström et al 2011;Favre et al 2014;Hernández-Hernández et al 2014;Lykke et al 2015;Suzuki et al 2016). The rotational temperatures of CH 3 OH, CH 3 CN, C 2 H 5 OH, and C 2 H 3 CN were derived to be above 150K, whereas those of CH 3 CHO and HCOOCH 3 were below 100K (Ikeda et al 2001;Remijan et al 2002Remijan et al , 2004b.…”

Section: W51mentioning

confidence: 93%

“…Small molecules such as CS, OCS, H 2 CO, HDCO, H 2 CS, and c-C 3 H 2 (cyclopropenylidene) have been observed in the centimeter band toward this cloud (Angerhofer et al 1978;Goldsmith & Linke 1981;Madden et al 1989;Chandler et al 1993;Richardson et al 1994;Mehringer et al 1995;Wootten & Mangum 2009 (Kalenskii et al 1997(Kalenskii et al , 2000a(Kalenskii et al , 2000bSlysh et al 1999Slysh et al , 2002van der Tak et al 2000;Ikeda et al 2001;Alakoz et al 2002;Charnley 2004;Kalenskii & Johansson 2010a;Wirström et al 2011;Zapata et al 2012;Girart et al 2013;Suzuki et al 2016). Kalenskii & Johansson (2010a) found low to moderate rotational temperatures, 9-56K, for most molecules detected.…”

Section: Dr21(oh)mentioning

confidence: 96%

“…H 2 CO, CH 3 OH, and CH 3 CN were detected in the millimeter bands (Slysh et al 1999;Kalenskii et al 2000aKalenskii et al , 2000bvan der Tak et al 2000;Wirström et al 2011), and one C 2 H 5 OH line was reported in the centimeter (Menten et al 1986 3 . Among these molecules, the hottest ones are CH 3 OH at 156K, C 2 H 5 OH and NH 2 CHO, both at 164K, and HCOOCH 3 at 134K.…”

Section: Ngc7538mentioning

confidence: 99%

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Deep, Broadband Spectral Line Surveys of Molecule-rich Interstellar Clouds

Weaver

Laas

Zou

et al. 2017

ApJS

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Spectral line surveys are an indispensable tool for exploring the physical and chemical evolution of astrophysical environments due to the vast amount of data that can be obtained in a relatively short amount of time. We present deep, broadband spectral line surveys of 30 interstellar clouds using two broadband λ=1.3 mm receivers at the Caltech Submillimeter Observatory. This information can be used to probe the influence of physical environment on molecular complexity. We observed a wide variety of sources to examine the relative abundances of organic molecules as they relate to the physical properties of the source (i.e., temperature, density, dynamics, etc.). The spectra are highly sensitive, with noise levels 25 mK at a velocity resolution of ∼0.35kms −1 . In the initial analysis presented here, column densities and rotational temperatures have been determined for the molecular species that contribute significantly to the spectral line density in this wavelength regime. We present these results and discuss their implications for complex molecule formation in the interstellar medium.

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“…At the same time there are indications that the masing regions have extensions much greater than these spot sizes. Indeed, analysis of multi-transitional observations of a masing molecule such as methanol (CH 3 OH) shows that the sizes of the masing regions can be comparable to those of the associated molecular cores (see, e.g., Sobolev, 1993, Slysh et al, 1999. There are indications that strong masers also form in rather extended regions.…”

Section: Possibility Of Combined Analysis Of Data On Maser and 'Quasimentioning

confidence: 99%

Model of the W3(OH) Environment Based on Data for Both Maser and ?Quasi-Thermal? Methanol Lines

Соболев

Sutton

Cragg

et al. 2005

Astrophys Space Sci

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Abstract. In studies of the environment of massive young stellar objects, recent progress in both observations and theory allows a unified treatment of data for maser and 'quasi-thermal' lines. Interferometric maser images provide information on the distribution and kinematics of masing gas on small spatial scales. Observations of multiple masing transitions provide constraints on the physical parameters.Interferometric data on 'quasi-thermal' molecular lines permits an investigation of the overall distribution and kinematics of the molecular gas in the vicinity of young stellar objects, including those which are deeply embedded. Using multiple transitions of different molecules, one can obtain good constraints on the physical and chemical parameters. Combining these data enables the construction of unified models, which take into account spatial scales differing by orders of magnitude.Here we present such a combined analysis of the environment around the ultracompact HII region in W3(OH). This includes the structure of the methanol masing region, physical structure of the near vicinity of W3(OH), detection of new masers in the large-scale shock front and embedded sources in the vicinity of the TW young stellar object.Keywords: radiolines -ISM: molecules Possibility of combined analysis of data on maser and 'quasi-thermal' linesModern studies of the kinematical, physical and chemical status of star forming regions are largely based on the information delivered by emission in molecular lines. Different molecular transitions have different excitation temperatures, as a result of the radiative and collisional population exchange between quantum levels. In the stationary case these take the form of pumping cycles (see, e.g., Sobolev and Deguchi, 1994). Excitation states of molecular transitions are mostly characterized by positive excitation temperatures and, hence, the optical depths

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Nonequilibrium Excitation of Methanol in Galactic Molecular Clouds: Multitransitional Observations at 2 Millimeters

Cited by 28 publications

References 13 publications

VLBI study of maser kinematics in high-mass star-forming regions

VLBI study of maser kinematics in high-mass star-forming regions

Deep, Broadband Spectral Line Surveys of Molecule-rich Interstellar Clouds

Model of the W3(OH) Environment Based on Data for Both Maser and ?Quasi-Thermal? Methanol Lines

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