Molecular emission in dense massive clumps from the star-forming regions S231–S235

Abstract

The article deals with observations of star-forming regions S231-S235 in 'quasi-thermal' lines of ammonia (NH3), cyanoacetylene (HC3N) and maser lines of methanol (CH3OH) and water vapor (H2O). S231-S235 regions is situated in the giant molecular cloud G174+2.5. We selected all massive molecular clumps in G174+2.5 using archive CO data. For the each clump we determined mass, size and CO column density. After that we performed observations of these clumps. We report about first detections of NH3 and HC3N lines toward the molecular clumps WB89 673 and WB89 668. This means that high-density gas is present there. Physical parameters of molecular gas in the clumps were estimated using the data on ammonia emission. We found that the gas temperature and the hydrogen number density are in the ranges 16-30 K and 2.8-7.2×10 3 cm −3 , respectively. The shock-tracing line of CH3OH molecule at 36.2 GHz is newly detected toward WB89 673.

Molecular gas in high-mass filament WB673

“…Ladeyschikov et al (2016) Figure 2, are not appropriate for the velocity gradient in the WB 673 filament. We postpone the analysis of the gas kinematics in details for the next study.…”

“…They find evidence for the compression of the molecular gas by H regions and mention interconnected molecular filaments in the vicinity of optical H regions. A list of the H regions as well as the their mutual location and location of young stellar clusters can be found in recent studies by Bieging et al (2016) and Ladeyschikov et al (2016). Kirsanova et al (2008Kirsanova et al ( , 2014 and Dewangan et al (2016) present evidence of triggered star formation process in the G174+2.5 cloud around the brightest H region Sh2-235 (S235 below), Sharpless catalogue Sharpless (1959).…”

“…The center of the filamentary structure is given by WB 673. Analysis of 12 CO and 13 CO (1-0) emission shows that the clumps are gravitationally unstable, Ladeyschikov et al (2016). Their masses range from about 1000 to 2000 M ⊙ .…”

“…Ladeyschikov et al (2015) also propose triggered star formation near H region Sh2-233 (S233 below). Ladeyschikov et al (2016) find a large filamentary molecular structure with dense clumps and embedded young stellar clusters on the border of G174+2.5 to the west from the extended H region Sh2-231 (S231 below): G173.57+2.43 associated with IRAS 05361+3539, S233 IR asociated with IRAS 05358+3543, WB89-673 (WB 673 below) and WB89-668 (WB 668 below) associated with IRAS 05345+3556 and IRAS 05335+3609, respectively, see Wouterloot, Brand (1989). The center of the filamentary structure is given by WB 673.…”

“…Inspection of infrared images by the Wide-field Infrared Survey Explorer (WISE) and Herschel reveals a large unidentified bubble-shaped nebula in between S231-S235 star-forming region and H regions Sh2-234 and Sh2-237. Image of the nebula at 22µm by WISE is shown in Ladeyschikov et al (2016) is observed toward the place of possible intersection of the nebula and H regions S231 and Sh2-232. Kang et al (2012) discuss an old supernova remnant FVW 172.8+1.5 whose center and south-west arc coincide with the white dashed circle in our Figure 1.…”