G34.3 + 0.2 - A 'cometary' H II region

Reid, M. J.; Ho, Paul T. P.

doi:10.1086/184412

Cited by 69 publications

(62 citation statements)

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“…However, the SNR could play an indirect role in the exciting mechanism. The young stellar object responsible for the excitation of the maser might be born in a star forming region induced by the supernova shock wave like the scenario proposed for the Galactic cometary Hii region G34.3+0.2 (Reid & Ho 1985) which also host water masers (e.g. Fey et al 1994) and is believed to interact with a wind from the precursor of the supernova remnant W44.…”

Section: Association Of the Maser Emissionmentioning

confidence: 92%

Evidence of a pure starburst nature of the nuclear region of NGC 253

Brunthaler

Castangia

Tarchi

et al. 2009

A&A

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We present high-resolution spectral line and continuum VLBI and VLA observations of the nuclear region of NGC 253 at 22 GHz. While the water vapor masers in this region were detected on arcsecond and milliarcsecond scales, we could not detect any compact continuum emission with a 5σ upper limit of ∼1 mJy. The observations reveal that the water maser emission is not related to a possible low-luminosity active galactic nucleus but is almost certainly associated with star-formation activity. Not detecting any compact continuum source on milliarcsecond scales also questions the presence of a -previously assumed -active nucleus in NGC 253.

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Section: Association Of the Maser Emissionmentioning

confidence: 92%

Evidence of a pure starburst nature of the nuclear region of NGC 253

Brunthaler

Castangia

Tarchi

et al. 2009

A&A

Self Cite

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“…Reid & Ho (1985) were the first to pro- pose the relative motion between the ionizing source and the extended molecular environment. This led to the 'bowshock' model (van Buren et al 1990;Mac Low et al 1991;van Buren & Mac Low 1992), which requires highly supersonic motion of a wind-blowing, ionizing star through dense surrounding material.…”

Section: Emission From Ionized Gasmentioning

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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“…The cloud contains 1.1 × 10 4 M of dense gas (Hill et al 2005), and has a luminosity of 3.2 × 10 5 L (van der Tak et al 2013), with an age of a few × 10 4 yr (Paron et al 2009). From radio continuum observations, this source shows two very condensed UCH II regions (called A and B), a more evolved CH II region with a cometary shape (called C) and an extended ringlike H II region (called D) (Reid & Ho 1985;Mookerjea et al 2007). There are several outflows in G34, as evidenced by SiO emission extending to the north-west, south-east and north-east of the CH II region (Hatchell, Fuller & Millar 2001).…”

Section: Sourcesmentioning

confidence: 99%

Millimetre spectral line mapping observations towards four massive star-forming H ii regions

Wang

Zhang

et al. 2017

Mon. Not. R. Astron. Soc.

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We present spectral line mapping observations towards four massive star-forming regionsCepheus A, DR21S, S76E and G34.26+0.15 -with the IRAM 30-m telescope at the 2 and 3 mm bands. In total, 396 spectral lines from 51 molecules, one helium recombination line, 10 hydrogen recombination lines and 16 unidentified lines were detected in these four sources. An emission line of nitrosyl cyanide (ONCN, 14 0, 14 -13 0, 13 ) was detected in G34.26+0.15, as the first detection in massive star-forming regions. We found that c-C 3 H 2 and NH 2 D show enhancement in shocked regions, as suggested by the evidence of SiO and/or SO emission. The column density and rotational temperature of CH 3 CN were estimated with the rotational diagram method for all four sources. Isotope abundance ratios of 12 C/ 13 C were derived using HC 3 N and its 13 C isotopologue, which were around 40 in all four massive star-forming regions and slightly lower than the local interstellar value (∼65). The 14 N/ 15 N and 16 O/ 18 O abundance ratios in these sources were also derived using the double isotopic method, which were slightly lower than in the local interstellar medium. Except for Cep A, the 33 S/ 34 S ratios in the other three targets were derived, which were similar to that in the local interstellar medium. The column density ratios of N(DCN)/N(HCN) and N(DCO + )/N(HCO + ) in these sources were more than two orders of magnitude higher than the elemental [D]/[H] ratio, which is 1.5 × 10 −5 . Our results show that the later stage sources, G34.26+0.15 in particular, present more molecular species than earlier stage sources. Evidence of shock activity is seen in all stages studied.

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G34.3 + 0.2 - A 'cometary' H II region

Cited by 69 publications

References 0 publications

Evidence of a pure starburst nature of the nuclear region of NGC 253

Evidence of a pure starburst nature of the nuclear region of NGC 253

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

Millimetre spectral line mapping observations towards four massive star-forming H ii regions

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