Gas kinematics in high-mass star-forming regions from the Perseus spiral arm

Abstract

We present results of a survey of 14 star-forming regions from the Perseus spiral arm in CS (2-1) and 13 CO (1-0) lines with the Onsala Space Observatory 20 m telescope. Maps of 10 sources in both lines were obtained. For the remaining sources a map in just one line or a single-point spectrum were obtained. On the basis of newly obtained and published observational data we consider the relation between velocities of the "quasi-thermal" CS (2-1) line and 6.7 GHz methanol maser line in 24 high-mass star-forming regions in the Perseus arm. We show that, surprisingly, velocity ranges of 6.7 GHz methanol maser emission are predominantly red-shifted with respect to corresponding CS (2-1) line velocity ranges in the Perseus arm. We suggest that the predominance of the "red-shifted masers" in the Perseus arm could be related to the alignment of gas flows caused by the large-scale motions in the Galaxy. Large-scale galactic shock related to the spiral structure is supposed to affect the local kinematics of the star-forming regions. Part of the Perseus arm, between galactic longitudes from 85 • to 124 • , does not contain blue-shifted masers at all. Radial velocities of the sources are the greatest in this particular part of the arm, so the velocity difference is clearly pronounced. 13 CO (1-0) and CS (2-1) velocity maps of G183.35-0.58 show gas velocity difference between the center and the periphery of the molecular clump up to 1.2 km s −1 . Similar situation is likely to occur in G85.40-0.00. This can correspond to the case when the large-scale shock wave entrains the outer parts of a molecular clump in motion while the dense central clump is less affected by the shock.

Molecular gas in high-mass filament WB673

“…The value of the difference in WB 673 is two times larger than in G183.35-0.58. Such velocity difference might be a result of the overflowing of molecular cloud by a large-scale wave, Kirsanova et al (2017), but we avoid straightforward interpretation of the velocity field in WB 673. V-shaped PV-diagram could be an indication of gravitational collapse of the ends to the center of the filament.…”

The survey of the regions with methanol masers in CS (J = 2–1) line emission. Statistical characteristics of the radiations

“…Ìà çåð íîå èç ëó ÷å íèå ìå òà íî ëà àñ ñî öè è ðó åò ñÿ ñ îá ëàñ òÿ ìè ìàñ ñèâíî ãî çâåç äî îá ðà çî âà íèÿ [42,59,60], èí ôðàê ðàñ íû ìè èñ òî÷ íè êà ìè [26,100] ìî ëî äû ìè çâåç äíû ìè îá ú åê òà ìè [42,67], îá ëàñ òÿ ìè UC H II [51], ïðî òÿ aeåí íû ìè çå ëå íû ìè îá ú åê òà ìè (EGOs) [27,31], îá ëàñ òÿ ìè, ãäå íà áëþ äà åò ñÿ ìà çåð íîå èç ëó ÷å íèå äðó ãèõ ìî ëå êóë [4], ñ îñòàò êà ìè ñâåðõ íî âûõ, êî òî ðûå ñòè ìó ëè ðó þò îá ðà çî âà íèå îá ëàñ òåé çâåç äî îá ðàçî âà íèÿ [4,128].  íà ñòî ÿ ùåå âðå ìÿ áîëü øè íñòâî èñ ñëå äî âàí íûõ îá úåê òîâ ñî áðà íû â îá øèð íûå êà òà ëî ãè [23,38,40,42,60,85,90,102,111].…”

“…Ýòó îñî áåí íîñòü ìîae íî òàê aeå óâè äåòü â ðà áî òàõ [22,57], íî â íèõ äëÿ îïðå äå ëå íèÿ ñèñòå ìà òè ÷åñ êèõ ñêî ðîñ òåé èñ ïîëü çî âà ëèñü äðó ãèå ìî ëå êó ëû.  ðà áî òå [59] áû ëî óêà çà íî íà íà ëè ÷èå êðàñ íîé àñèì ìåò ðèè â ðàñ ïðå äå ëå íèè ðàç íîñ òè ëó ÷å âûõ ñêî ðîñ òåé ìå òà íîëü íûõ ìà çå ðîâ íà ïå ðå õî äå [38,42,57,90], íî áîëü øàÿ ÷àñòü èñ òî÷ íè êîâ â íà øèõ ðå çóëü òà òàõ ðà íåå â óêà çàí íûõ ðà áî òàõ íå èñ ñëå äî âà ëàñü. Òàê aeå â ðà áî òàõ [38,42,57] ñèñòå ìà òè ÷åñ êèå ñêî ðîñ òè îïðå äå ëÿ ëèñü ïî íà áëþ äå íè ÿì ìî ëå êó ëû NH 3 .…”

“…Ñî îò íî øå íèå êî ëè ÷åñ òâà êðàñ íîñ ìå ùåí íûõ ìà çå ðîâ ê ñèíå-ñìå ùåí íûì ðàâ íÿ åò ñÿ 2.0, ÷òî ëèøü íå ìíî ãî âû øå, ÷åì ïî êà çà íî íà ðèñ. 1 â ðà áî òå[59]. Òà êèì îá ðà çîì, íà ñòî ÿ ùàÿ ðà áî òà ïîä òâåð aeäàåò íà ëè ÷èå á\ëüøå ãî êî ëè ÷åñ òâà ìà çå ðîâ íà ïå ðå õî äå 5 êàâå Ïåð ñåÿ, êî òî ðûå èìå þò ïî ëî aeè òåëü íîå îò êëî íå íèå ñêî ðîñ òåé ìàçå ðîâ îò ñèñ òåì íûõ ñêî ðîñ òåé ìî ëå êó ëÿð íî ãî ÿä ðà.Ðàñ ïðå äå ëå íèå ðàç íîñ òè öåí òðîâ ëè íèé ìå òà íîëü íûõ ìà çå ðîâ íà ïå ðå õî äå 7 (44 ÃÃö) è ëè íèé CS (J = 2-1), ïî êà çàí íîå â íà ñòî ÿùåé ðà áî òå íà ðèñ.…”

The first high-resolution observations of 37.7-, 38.3- and 38.5-GHz methanol masers

“…948−0.196 and G 9.621+0.196). Sobolev et al (2005) and Kirsanova et al (2017) have investigated the difference between the midvelocity of the 6.7-GHz masers and the systemic velocity of the thermal gas (as traced by CS (J = 2 − 1) emission), in two different longitude regions. They find that there is a preference for the methanol masers to be blueshifted with respect to the thermal gas in the Galactic Longitude range l = 320 • -350 • , but redshifted in the range l = 84 • -124 • .…”