The G305 star-forming complex: embedded massive star formation discovered by<i>Herschel</i>Hi-GAL

Faimali, A.; Thompson, M. A.; Hindson, L.; Urquhart, J. S.; Pestalozzi, M.; Carey, Sean; Shenoy, S.; Veneziani, M.; Molinari, S.; Clark, J. S.

doi:10.1111/j.1365-2966.2012.21765.x

Cited by 36 publications

(50 citation statements)

References 81 publications

(164 reference statements)

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“…The region toward l = 305 • is particularly interesting because it contains the G305 H ii complex (G305.4+0.1), one of the most massive starforming structures ever identified within the Galaxy (see Faimali et al 2012 These results are in accord with our findings for the field. In our sample, the spatially spread foreground population is represented by stars intrinsically fainter than −2 mag (see Fig.…”

Section: Comparison To Other Studiessupporting

confidence: 82%

Massive stellar content of the Galactic supershell GSH 305+01−24

Kaltcheva¹,

Golev²,

Moran³

2014

A&A

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Aims. The distribution of OB stars along with Hα, 12 CO, dust infrared emission, and neutral hydrogen is carried out to provide a more complete picture of interactions of the young massive stars and the observed supershell GSH 305+01−24. Methods. The studied field is located between 299The investigation is based on nearly 700 O-B9 stars with currently available uvbyβ photometry. The derived stellar physical parameters were used to establish a homogeneous scale for the distances and extinction of light for major apparent groups and layers of foreground and background stars in Centaurus and to study the interaction with the surrounding interstellar medium. Results. The distance to the entire Centaurus star-forming complex is revised, and a maximum of the OB-star distance distribution is found at 1.8 ± 0.4 (rms) kpc. The massive star component of GSH 305+01−24 is identified at about 85−90% completeness up to 11.5−12 mag. The projected coincidence of the OB stars with the shell and the similarities between the shell's morphology and the OB-star distribution indicate a strong interaction of the stellar winds with the superbubble material. We demonstrate that these stars contribute enough wind injection energy to explain the observed size and expansion velocity of the supershell. The derived stellar ages suggest an age gradient over the Coalsack Loop. Continuous star formation might be taking place within the shell with the youngest stars located toward its periphery, and the open cluster NGC 4755 is the oldest. A layer of very young stars at 1 kpc is detected, and its connection to both GSH 305+01−24 and the foreground GSH 304−00−12 H i shells is investigated.

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Section: Comparison To Other Studiessupporting

confidence: 82%

Massive stellar content of the Galactic supershell GSH 305+01−24

Kaltcheva¹,

Golev²,

Moran³

2014

A&A

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“…In contrast, IR emission is a reliable tracer of the photons produced by the forming source. Lawton et al (2010) finds that, among all the IR bands, the 70 μm band is the most reliable indicator of star formation because it is able to account for IR emission from HII regions (see for example Tibbs et al 2012;Faimali et al 2012). We then consider the 70 μm monochromatic estimator developed by Li et al (2010).…”

Section: Monochromatic Estimator At 70 μMmentioning

confidence: 99%

An analysis of star formation withHerschelin the Hi-GAL survey

Veneziani

Elia

Noriega-Crespo

et al. 2013

A&A

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Aims. The Herschel survey of the Galactic plane (Hi-GAL) provides a unique opportunity to study star formation over large areas of the sky and different environments in the Milky Way. We use the best-studied Hi-GAL fields to date, two 2 • · 2 • tiles centered on ( , b) = (30 • , 0 • ) and ( , b) = (59 • , 0 • ), to study the star formation activity in these regions of the sky using a large sample of well-selected young stellar objects (YSOs). Methods. We used the science demonstration phase Hi-GAL fields, where a tremendous effort has been made to identify the newly formed stars and to derive their properties as accurately as possible, e.g. distance, bolometric luminosity, envelope mass, and stage of evolution. We estimated the star formation rate (SFR) for these fields using the number of candidate YSOs and their average time scale to reach the zero age main sequence, and compared it with the rate estimated using their integrated luminosity at 70 μm, combined with an extragalactic star formation indicator. Results. We measure an SFR of (9.5 ± 4.3) × 10 −4 M /yr and (1.6 ± 0.7) × 10 −4 M /yr with the source counting method, in = 30 • and = 59 • , respectively. Results with the 70 μm estimator are (2.4 ± 0.4) × 10 −4 M /yr and (2.6 ± 1.1) × 10 −6 M /yr. Since the 70 μm indicator is derived from averaging extragalactic star forming complexes, we extrapolated of these values to the whole Milky Way and obtain SFR MW = (0.71 ± 0.13) M /yr from l = 30 • and SFR MW = (0.10 ± 0.04) M /yr from = 59 • . The estimates in = 30 • agree with the most recent results for Galactic star formation activity. Conclusions. The source-counting method gives results that are only valid for the particular region under consideration. In contrast, the construction of the IR indicator leads to results that can be extrapolated to the whole Galaxy. In particular, when it is applied to the = 30 • field, it provides an SFR that is consistent with previous estimates, indicating that the characteristics of this field are very likely close to those of the star formation-dominated galaxies used for its derivation. Since the sky coverage is limited, this analysis will improve when the full Hi-GAL survey is available. It will cover the whole Galactic plane, sampling almost the totality of Galactic star forming complexes. By means of the candidate YSO-counting method, it will then be possible to calibrate an SFR Galactic indicator and to test the validity of the extragalactic estimators.

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“…This seems to indicate that the population in the G29-SFR cloud, mostly massive sources, should be highly embedded. In a recent work, Faimali et al (2012) analyze Hi-GAL data on another massive star-forming region G305 and propose a far-IR color criterion to select massive embedded sources. According to these authors, the [70-500] and the colors should be most sensitive to the embedded population.…”

Section: Embedded Population In the G29-sfr Cloudmentioning

confidence: 99%

A Hi-GAL study of the high-mass star-forming region G29.96–0.02

Beltrán

Olmi

Cesaroni

et al. 2013

A&A

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Context. G29.96−0.02 is a high-mass star-forming cloud observed at 70, 160, 250, 350, and 500 μm as part of the Herschel survey of the Galactic plane (Hi-GAL) during the science demonstration phase. Aims. We wish to conduct a far-infrared study of the sources associated with this star-forming region by estimating their physical properties and evolutionary stage, and investigating the clump mass function, the star formation efficiency and rate in the cloud. Methods. We have identified the Hi-GAL sources associated with the cloud, searched for possible counterparts at centimeter and infrared wavelengths, fitted their spectral energy distribution and estimated their physical parameters. Results. A total of 198 sources have been detected in all 5 Hi-GAL bands, 117 of which are associated with 24 μm emission and 87 of which are not associated with 24 μm emission. We called the former sources 24 μm-bright and the latter ones 24 μm-dark. The color of the 24 μm-dark sources is smaller than that of the 24 μm-bright ones. The 24 μm-dark sources have lower L bol and L bol /M env than the 24 μm-bright ones for similar M env , which suggests that they are in an earlier evolutionary phase. The G29-SFR cloud is associated with 10 NVSS sources and with extended centimeter continuum emission well correlated with the 70 μm emission. Most of the NVSS sources appear to be early B or late O-type stars. The most massive and luminous Hi-GAL sources in the cloud are located close to the G29-UC region, which suggests that there is a privileged area for massive star formation toward the center of the G29-SFR cloud. Almost all the Hi-GAL sources have masses well above the Jeans mass but only 5% have masses above the virial mass, which indicates that most of the sources are stable against gravitational collapse. The sources with M env > M virial and that should be undergoing collapse and forming stars are preferentially located at < ∼ 4 of the G29-UC region, which is the most luminous source in the cloud. The overall SFE of the G29-SFR cloud ranges from 0.7 to 5%, and the SFR ranges from 0.001 to 0.008 M yr −1 , consistent with the values estimated for Galactic Hii regions. The mass spectrum of the sources with masses above 300 M , well above the completeness limit, can be well-fitted with a power law of slope α = 2.15 ± 0.30, consistent with the values obtained for the whole l = 30 • , associated with high-mass star formation, and l = 59 • , associated with low-to intermediate-mass star formation, Hi-GAL SDP fields.

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The G305 star-forming complex: embedded massive star formation discovered byHerschelHi-GAL

Cited by 36 publications

References 81 publications

Massive stellar content of the Galactic supershell GSH 305+01−24

Massive stellar content of the Galactic supershell GSH 305+01−24

An analysis of star formation withHerschelin the Hi-GAL survey

A Hi-GAL study of the high-mass star-forming region G29.96–0.02

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