Parameters of warm molecular clouds from methyl acetylene observations

Alakoz, A. V.; Kalenskii, S. V.; Promislov, V. G.; Johansson, Lars; Winnberg, A.

doi:10.1134/1.1495032

Cited by 11 publications

(16 citation statements)

References 21 publications

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“…However, the search for Class II methanol and hydroxyl masers yielded negative results (van der Walt, Gaylard & MacLeod 1995; Edris, Fuller & Cohen 2007). Several molecules like CS, HCO + , NH3, N2H + , CH3CCH have also been observed towards this region (Bronfman, Nyman & May 1996;Alakoz et al 2002;Shirley et al 2013;Lu et al 2014).…”

Section: Introductionmentioning

confidence: 99%

Radio and infrared study of the star-forming region IRAS 20286+4105

Ramachandran

Das

Tej

et al. 2016

Mon. Not. R. Astron. Soc.

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A multi-wavelength investigation of the star forming complex IRAS 20286+4105, located in the Cygnus-X region, is presented here. Near-infrared K-band data is used to revisit the cluster / stellar group identified in previous studies. The radio continuum observations, at 610 and 1280 MHz show the presence of a HII region possibly powered by a star of spectral type B0 -B0.5. The cometary morphology of the ionized region is explained by invoking the bow-shock model where the likely association with a nearby supernova remnant is also explored. A compact radio knot with non-thermal spectral index is detected towards the centre of the cloud. Mid-infrared data from the Spitzer Legacy Survey of the Cygnus-X region show the presence of six Class I YSOs inside the cloud. Thermal dust emission in this complex is modelled using Herschel far-infrared data to generate dust temperature and column density maps. Herschel images also show the presence of two clumps in this region, the masses of which are estimated to be ∼ 175 M and 30 M . The mass-radius relation and the surface density of the clumps do not qualify them as massive star forming sites. An overall picture of a runaway star ionizing the cloud and a triggered population of intermediate-mass, Class I sources located toward the cloud centre emerges from this multiwavelength study. Variation in the dust emissivity spectral index is shown to exist in this region and is seen to have an inverse relation with the dust temperature.

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Section: Introductionmentioning

confidence: 99%

Radio and infrared study of the star-forming region IRAS 20286+4105

Ramachandran

Das

Tej

et al. 2016

Mon. Not. R. Astron. Soc.

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“…(Helmich & van Dishoeck 1997;Fontani et al 2007;Qin et al 2015), and CH 3 OH has two temperature components (Qin et al 2015). Cold CH 3 OH, CH 3 CCH, C 2 H 5 OH, and CH 3 CHO lines were also observed at low frequency (3 mm and centimeter; Menten et al 1986;Alakoz et al 2002;Charnley 2004;Kim et al 2006).…”

Section: W3(h 2 O)mentioning

confidence: 99%

“…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: 99%

“…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: 99%

“…Both cores have a rich inventory of COMs, revealed by extensive line surveys across the millimeter bands (Helmich et al 1994;Helmich & van Dishoeck 1997;Kalenskii et al 1997Kalenskii et al , 2000aWyrowski et al 1999a;van der Tak et al 2000;Ikeda et al 2001;Alakoz et al 2002;Charnley 2004;Sutton et al 2004;Kim et al 2006;Bisschop et al 2007;Fontani et al 2007;Ratajczak et al 2011;Reiter et al 2011;Li et al 2012;Gerner et al 2014;Hernández-Hernández et al 2014;Ligterink et al 2015;Qin et al 2015). (Helmich & van Dishoeck 1997;Fontani et al 2007;Qin et al 2015), and CH 3 OH has two temperature components (Qin et al 2015).…”

Section: W3(h 2 O)mentioning

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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Photodissociation dynamics of propyne at 193 nm: a trajectory surface hopping study

Ghosh

Rauta

Maiti

2016

Phys. Chem. Chem. Phys.

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Photodissociation dynamics of propyne at 193 nm are studied using the fewest switches nonadiabatic trajectory surface hopping method on its first excited singlet electronic state (1(1)A''). The trajectories are propagated based on potential energies, gradients and nonadiabatic couplings calculated at the MRCIS(6,7) level with the 6-31++G(d,p) basis set. Our trajectory calculations have revealed that H + H3CCC is the major dissociation channel, which has also been predicted experimentally. For the primary photodissociation channel H + H3CCC we demonstrate that nonadiabatic dynamics do not play a significant role. This observation is however contradictory to most of the previously reported experimental predictions. The calculated product translation energy distribution for the acetylenic H atom elimination peaked at ∼ 18 kcal mol(-1), indicating that the dissociation occurs adiabatically on a moderately repulsive excited surface that correlates with the ground state products (CH3C ≡ C + H). The H atom elimination process from the methyl fragment involving a transition state, which has to compete with the acetylenic H atom dissociation channel with no barrier in the excited singlet surface, was found to be too less probable to make a contribution to product branching. We observed that a fewer but significant number of trajectories led to CH3 + CCH product formation which has not been observed experimentally when propyne is excited at 193 nm.

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Parameters of warm molecular clouds from methyl acetylene observations

Cited by 11 publications

References 21 publications

Radio and infrared study of the star-forming region IRAS 20286+4105

Radio and infrared study of the star-forming region IRAS 20286+4105

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

Photodissociation dynamics of propyne at 193 nm: a trajectory surface hopping study

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