Star formation in the S233 region

Ladeyschikov, D. A.; Соболев, А. М.; Parfenov, S. Yu.; Alexeeva, Sofya; Bieging, John H.

doi:10.1093/mnras/stv1422

Cited by 12 publications

(12 citation statements)

References 62 publications

(74 reference statements)

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“…Such analyses will allow us to test whether star formation is being initiated by compression of the molecular gas, a process often referred to as "triggering." For example, Ladeyschikov et al (2015) have argued, based in part on data from the present study, that a "collect and collapse" process at the compact H II region Sh2-233 has led to recent star formation on the boundary of the ionized gas.…”

Section: The Sh2-235 Molecular Cloudmentioning

confidence: 78%

“…The CO velocity dispersion map (Figure 14) shows that the molecular line widths are significantly broadened in the vicinity of Sh2-235, indicating a dynamical interaction. The more compact and embedded Sh2-233 also appears to have begun to compress the molecular gas in its vicinity and possibly to have initiated star formation on the periphery of the ionized gas, as argued by Ladeyschikov et al (2015). Triggered Star Formation.…”

Section: Discussionmentioning

confidence: 90%

“…On a smaller scale, Ladeyschikov et al (2015) compared the CO and 13 COdistributions presented here with the locations and morphologies of IR features in the vicinity of the small H II region Sh2-233. They concluded that a very red IR source, IRAS05351+3549, is likely a class 0 YSO, or possibly a prestellar core in the process of collapsing under the external pressure of the expanding H II region, leading to formation of a star.…”

Section: Discussionmentioning

confidence: 99%

“…They present optical images showing the relationship among the nebulae and massive stars that recently formed there-see their Figures 1 and 5. The most probable distance to the molecular cloud and associated H II regions is 2.0±0.3 kpc (Montillaud et al 2015), based on various published distances to the ionizing stars (Evans & Blair 1981;Porras et al 2000;Ladeyschikov et al 2015). This distance places the cloud in the middle of the Perseus spiral arm (Reid et al 2014).…”

Section: The Sh2-235 Molecular Cloudmentioning

confidence: 99%

“…f Beuther et al (2002Beuther et al ( , 2007. g Ladeyschikov et al (2015). (velocity channel maps of CO/ 13 CO J=2−1 intensity ratio).…”

Section: Comparison With Associated Ysosmentioning

confidence: 99%

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THE ARIZONA RADIO OBSERVATORY CO MAPPING SURVEY OF GALACTIC MOLECULAR CLOUDS. V. THE SH2-235 CLOUD IN CO J = 2 − 1, ¹³CO J = 2 − 1, AND CO J = 3 − 2

Bieging

Patel

Peters

et al. 2016

ApJS

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We present the results of a program to map the Sh2-235 molecular cloud complex in the CO and 13 COJ=2−1 transitions using the Heinrich Hertz Submillimeter Telescope. The map resolution is 38″ (FWHM), with an rms noise of 0.12 K brightness temperature, for a velocity resolution of 0.34 km s −1. With the same telescope, we also mapped the CO J=3−2 line at a frequency of 345 GHz, using a 64 beam focal plane array of heterodyne mixers, achieving a typical rms noise of 0.5 K brightness temperature with a velocity resolution of 0.23 km s −1. The three spectral line data cubes are available for download. Much of the cloud appears to be slightly sub-thermally excited in the J=3 level, except for in the vicinity of the warmest and highest column density areas, which are currently forming stars. Using the CO and 13 COJ=2−1 lines, we employ an LTE model to derive the gas column density over the entire mapped region. Examining a 125 pc 2 region centered on the most active star formation in the vicinity of Sh2-235, we find that the young stellar object surface density scales as approximately the 1.6-power of the gas column density. The area distribution function of the gas is a steeply declining exponential function of gas column density.Comparison of the morphology of ionized and molecular gas suggests that the cloud is being substantially disrupted by expansion of the H II regions, which may be triggering current star formation.

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Section: The Sh2-235 Molecular Cloudmentioning

confidence: 78%

Section: Discussionmentioning

confidence: 90%

Section: Discussionmentioning

confidence: 99%

Section: The Sh2-235 Molecular Cloudmentioning

confidence: 99%

“…f Beuther et al (2002Beuther et al ( , 2007. g Ladeyschikov et al (2015). (velocity channel maps of CO/ 13 CO J=2−1 intensity ratio).…”

Section: Comparison With Associated Ysosmentioning

confidence: 99%

See 3 more Smart Citations

THE ARIZONA RADIO OBSERVATORY CO MAPPING SURVEY OF GALACTIC MOLECULAR CLOUDS. V. THE SH2-235 CLOUD IN CO J = 2 − 1, ¹³CO J = 2 − 1, AND CO J = 3 − 2

Bieging

Patel

Peters

et al. 2016

ApJS

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Star formation towards the Galactic H II region RCW 120

Figueira

Zavagno

Deharveng

et al. 2017

A&A

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Context. The expansion of H ii regions can trigger the formation of stars. An overdensity of young stellar objects (YSOs) is observed at the edges of H ii regions but the mechanisms that give rise to this phenomenon are not clearly identified. Moreover, it is difficult to establish a causal link between H ii -region expansion and the star formation observed at the edges of these regions. A clear age gradient observed in the spatial distribution of young sources in the surrounding might be a strong argument in favor of triggering. Aims. We aim to characterize the star formation observed at the edges of H ii regions by studying the properties of young stars that form there. We aim to detect young sources, derive their properties and their evolution stage in order to discuss the possible causal link between the first-generation massive stars that form the H ii region and the young sources observed at their edges. Methods. We have observed the Galactic H ii region RCW 120 with Herschel PACS and SPIRE photometers at 70, 100, 160, 250, 350 and 500 µm. We produced temperature and H 2 column density maps and use the getsources algorithm to detect compact sources and measure their fluxes at Herschel wavelengths. We have complemented these fluxes with existing infrared data. Fitting their spectral energy distributions (SEDs) with a modified blackbody model, we derived their envelope dust temperature and envelope mass. We computed their bolometric luminosities and discuss their evolutionary stages. Results. The overall temperatures of the region (without background subtraction) range from 15 K to 24 K. The warmest regions are observed towards the ionized gas. The coldest regions are observed outside the ionized gas and follow the emission of the cold material previously detected at 870 µm and 1.3 mm. The H 2 column density map reveals the distribution of the cold medium to be organized in filaments and highly structured. Column densities range from 7 × 10 21 cm −2 up to 9 × 10 23 cm −2 without background subtraction. The cold regions observed outside the ionized gas are the densest and host star formation when the column density exceeds 2 × 10 22 cm −2 . The most reliable 35 compact sources are discussed. Using exisiting CO data and morphological arguments we show that these sources are likely to be associated with the RCW 120 region. These sources' volume densities range from 2 × 10 5 cm −3 to 10 8 cm −3 . Five sources have envelope masses larger than 50 M and are all observed in high column density regions (>7 × 10 22 cm −2 ). We find that the evolutionary stage of the sources primarily depends on the density of their hosting condensation and is not correlated with the distance to the ionizing star. Conclusions. The Herschel data, with their unique sampling of the far infrared domain, have allowed us to characterize the properties of compact sources observed towards RCW 120 for the first time. We have also been able to determine the envelope temperature, envelope mass and evolutionary stage of these sources. Usin...

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APEX CO observations towards the photodissociation region of RCW 120

Figueira

Zavagno

Bronfman

et al. 2020

A&A

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Context. The edges of ionized (H II) regions are important sites for the formation of (high-mass) stars. Indeed, at least 30% of the Galactic high-mass-star formation is observed there. The radiative and compressive impact of the H II region could induce star formation at the border following different mechanisms such as the collect and collapse or the radiation-driven implosion (RDI) models and change their properties. Aims. We aim to study the properties of two zones located in the photo dissociation region (PDR) of the Galactic H II region RCW 120 and discuss them as a function of the physical conditions and young star contents found in both clumps. Methods. Using the APEX telescope, we mapped two regions of size 1.5′ × 1.5′ toward the most massive clump of RCW 120 hosting young massive sources and toward a clump showing a protrusion inside the H II region and hosting more evolved low-mass sources. The 12CO (J = 3−2), 13CO (J = 3−2) and C18O (J = 3−2) lines observed, together with Herschel data, are used to derive the properties and dynamics of these clumps. We discuss their relation with the hosted star formation. Results. Assuming local thermodynamic equilibrium, the increase of velocity dispersion and Tex are found toward the center of the maps, where star-formation is observed with Herschel. Furthermore, both regions show supersonic Mach numbers (7 and 17 in average). No substantial information has been gathered about the impact of far ultraviolet radiation on C18O photodissociation at the edges of RCW 120. The fragmentation time needed for CC to be at work is equivalent to the dynamical age of RCW 120 and the properties of region B are in agreement with bright-rimmed clouds. Conclusions. Although conclusions from this fragmentation model should be taken with caution, it strengthens the fact that, together with evidence of compression, CC might be at work at the edges of RCW 120. Additionally, the clump located at the eastern part of the PDR is a good candidate pre-existing clump where star-formation may be induced by the RDI mechanism.

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Star formation in the S233 region

Cited by 12 publications

References 62 publications

THE ARIZONA RADIO OBSERVATORY CO MAPPING SURVEY OF GALACTIC MOLECULAR CLOUDS. V. THE SH2-235 CLOUD IN CO J = 2 − 1, ¹³CO J = 2 − 1, AND CO J = 3 − 2

THE ARIZONA RADIO OBSERVATORY CO MAPPING SURVEY OF GALACTIC MOLECULAR CLOUDS. V. THE SH2-235 CLOUD IN CO J = 2 − 1, ¹³CO J = 2 − 1, AND CO J = 3 − 2

Star formation towards the Galactic H II region RCW 120

APEX CO observations towards the photodissociation region of RCW 120

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Star formation in the S233 region

Cited by 12 publications

References 62 publications

THE ARIZONA RADIO OBSERVATORY CO MAPPING SURVEY OF GALACTIC MOLECULAR CLOUDS. V. THE SH2-235 CLOUD IN CO J = 2 − 1, 13CO J = 2 − 1, AND CO J = 3 − 2

THE ARIZONA RADIO OBSERVATORY CO MAPPING SURVEY OF GALACTIC MOLECULAR CLOUDS. V. THE SH2-235 CLOUD IN CO J = 2 − 1, 13CO J = 2 − 1, AND CO J = 3 − 2

Star formation towards the Galactic H II region RCW 120

APEX CO observations towards the photodissociation region of RCW 120

Contact Info

Product

Resources

About

THE ARIZONA RADIO OBSERVATORY CO MAPPING SURVEY OF GALACTIC MOLECULAR CLOUDS. V. THE SH2-235 CLOUD IN CO J = 2 − 1, ¹³CO J = 2 − 1, AND CO J = 3 − 2

THE ARIZONA RADIO OBSERVATORY CO MAPPING SURVEY OF GALACTIC MOLECULAR CLOUDS. V. THE SH2-235 CLOUD IN CO J = 2 − 1, ¹³CO J = 2 − 1, AND CO J = 3 − 2