Triggered star formation on the borders of 
 the Galactic H ii region RCW 120

Zavagno, A.; Pomarès, M.; Deharveng, L.; Hosokawa, Takashi; Russeil, D.; Caplan, J.

doi:10.1051/0004-6361:20077474

Cited by 157 publications

(277 citation statements)

References 39 publications

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“…Several pieces of observational evidence have been found supporting this star formation mechanism (see e.g. Pomarès et al 2009;Zavagno et al 2007, and reference therein).…”

Section: Introductionmentioning

confidence: 90%

The environs of the ultracompact HII region G45.45+0.06

Paron¹,

Cichowolski²,

Ortega³

2009

A&A

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Aims. G45.45+0.06 is an ultra-compact HII (UCHII) region that has been extensively studied. It is known that G45.45+0.06 is embedded in a complex of UCHII regions, but to date, the surrounding ISM on a larger spatial scale has not been analyzed. Methods. Using data from large-scale surveys, the Two Micron All Sky Survey, GLIMPSE, MIPSGAL, MAGPIS and GRS, we performed a multiwavelength study of a region of about 7 × 7 in the vicinity of G45.45+0.06. Results. We found that the UCHII complex lies on the border of a larger (diameter of ∼3 ) and fainter HII region, which is located at the same distance as G45.45+0.06, ∼8 kpc. In this work, this larger HII region is called G45L. A good morphological correlation is observed between the PDRs and the molecular gas mapped in the 13 CO J = 1−0 and CS J = 2−1 lines, suggesting that G45L may be collecting molecular material. From a near-and mid-IR photometric study, we found three sources, likely O-type stars, that are possibly responsible for the creation of G45L. Additionally, we found several YSO candidates lying preferentially in the molecular shell that surrounds G45L. Our results confirm that the region southeast of the UCHII complex where G45.45+0.06 is embedded and east of G45L is undergoing active star formation. We suggest that G45L has been expanding for about 2 × 10 6 yr and could have triggered the formation of the zero-age main sequence stars that ionize the UCHII region G45.45+0.06. However we cannot discard that both HII regions are coeval.

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“…Several pieces of observational evidence have been found supporting this star formation mechanism (see e.g. Pomarès et al 2009;Zavagno et al 2007, and reference therein).…”

Section: Introductionmentioning

confidence: 90%

The environs of the ultracompact HII region G45.45+0.06

Paron¹,

Cichowolski²,

Ortega³

2009

A&A

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“…However, because they are found to be in pressure equilibrium with the parent molecular cloud once they have opened a cavity (see the example of M 17, Townsley et al 2003;or Orion, Güdel et al 2008), stellar winds cannot compress the surrounding medium and induce star formation. On the other hand, we now know many examples of HII "bubbles" apparently triggering star formation near their edges (e.g., Deharveng et al 2008;Zavagno et al 2007), but these bubbles have well-defined exciting stars.…”

Section: Introductionmentioning

confidence: 99%

Star formation history of Canis Major R1

Gregorio-Hetem¹,

Montmerle

Rodrigues

et al. 2009

A&A

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Aims. The CMa R1 star-forming region contains several compact clusters as well as many young early-B stars. It is associated with a well-known bright rimmed nebula, the nature of which is unclear (fossil HII region or supernova remnant). To help elucidate the nature of the nebula, our goal was to reconstruct the star-formation history of the CMa R1 region, including the previously unknown older, fainter low-mass stellar population, using X-rays. Methods. We analyzed images obtained with the ROSAT satellite, covering ∼5 sq. deg. Complementary VRI photometry was performed with the Gemini South telescope. Colour-magnitude and colour-colour diagrams were used in conjunction with pre-main sequence evolutionary tracks to derive the masses and ages of the X-ray sources.Results. The ROSAT images show two distinct clusters. One is associated with the known optical clusters near Z CMa, to which ∼40 members are added. The other, which we name the "GU CMa" cluster, is new, and contains ∼60 members. The ROSAT sources are young stars with masses down to M ∼ 0.5 M , and ages up to 10 Myr. The mass functions of the two clusters are similar, but the GU CMa cluster is older than the cluster around Z CMa by at least a few Myr. Also, the GU CMa cluster is away from any molecular cloud, implying that star formation must have ceased; on the contrary (as already known), star formation is very active in the Z CMa region.

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“…2.1). In RCW 120, nine condensations suspected of harboring ongoing star formation were observed in the mm continuum by Zavagno et al (2007). For the FTS observations, we selected six such condensations, labeled C1, C2, C6, C8, IRS1, and IRS2.…”

Section: Observations and Data Reductionmentioning

confidence: 99%

“…Observations in mm and sub-mm wavelengths (Zavagno et al 2007;Deharveng et al 2009) show a fragmented neutral layer along its PDR, which contains five of the nine mmcondensations found by Zavagno et al (2007). According to Deharveng et al (2009) the mass of the layer is ∼2000 M .…”

Section: Introductionmentioning

confidence: 95%

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HerschelSPIRE-FTS observations of RCW 120

Rodón

Zavagno

Baluteau

et al. 2015

A&A

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Context. The expansion of Galactic H ii regions can trigger the formation of a new generation of stars. However, little is know about the physical conditions that prevail in these regions.Aims. We study the physical conditions that prevail in specific zones towards expanding H ii regions that trace representative media such as the photodissociation region, the ionized region, and condensations with and without ongoing star formation.Methods. We use the SPIRE Fourier Transform Spectrometer (FTS) on board Herschel to observe the H ii region RCW 120.Continuum and lines are observed in the 190−670 μm range. Line intensities and line ratios are obtained and used as physical diagnostics of the gas. We used the Meudon PDR code and the RADEX code to derive the gas density and the radiation field at nine distinct positions including the PDR surface and regions with and without star-formation activity. Results. For the different regions we detect the atomic lines [NII] at 205 μm and [CI]at 370 and 609 μm, the 12 CO ladder between the J = 4 and J = 13 levels and the 13 CO ladder between the J = 5 and J = 14 levels, as well as CH + in absorption. We find gas temperatures in the range 45−250 K for densities of 10 4 −10 6 cm −3 , and a high column density on the order of N H ∼ 10 22 cm −2 that is in agreement with dust analysis. The ubiquitousness of the atomic and CH + emission suggests the presence of a low-density PDR throughout RCW 120. High-excitation lines of CO indicate the presence of irradiated dense structures or small dense clumps containing young stellar objects, while we also find a less dense medium (N H ∼ 10 20 cm −2 ) with high temperatures (80−200 K).

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Triggered star formation on the borders of the Galactic H ii region RCW 120

Cited by 157 publications

References 39 publications

The environs of the ultracompact HII region G45.45+0.06

The environs of the ultracompact HII region G45.45+0.06

Star formation history of Canis Major R1

HerschelSPIRE-FTS observations of RCW 120

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