An analysis of star formation with<i>Herschel</i>in the Hi-GAL survey

Veneziani, M.; Elia, D.; Noriega-Crespo, A.; Paladini, R.; Carey, Sean; Faimali, A.; Molinari, S.; Pestalozzi, M.; Piacentini, F.; Schisano, E.; Tibbs, C. T.

doi:10.1051/0004-6361/201219570

Cited by 45 publications

(82 citation statements)

References 46 publications

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“…The SFR obtained for the G29-SFR cloud ranges from 0.001 to 0.008 M yr −1 . These values are smaller than those of 0.01-0.02 M yr −1 estimated by Faimali et al (2012) for the G305 cloud, but consistent with the values of ∼0.0002-0.001 M yr −1 estimated by Veneziani et al (2013) for the whole l = 30 • SDP field, and with the SFRs of ∼0.0005 to ∼0.008 M yr −1 estimated for Galactic Hii regions by Chomiuk & Povich (2011). The fact that the SFR of the Milky Way is of about 2 M yr −1 (Chomiuk & Povich 2011), indicates that hundreds to a few thousands of molecular clouds similar to the G29-SFR cloud are needed to account for the Galactic star formation rate.…”

Section: The Star Formation Efficiency and Ratesupporting

confidence: 86%

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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Section: The Star Formation Efficiency and Ratesupporting

confidence: 86%

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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“…The scaled OH5 dust opacities are consistent with the values used in other high-mass star formation studies (e.g., Kauffmann et al 2008;Elia et al 2010Elia et al , 2013Veneziani et al 2013;Traficante et al 2015). The dust emissivity index has been fixed to be 2.0 b = , in agreement with the standard value for cold dust emission (Hildebrand 1983).…”

Section: 33supporting

confidence: 68%

High-mass Starless Clumps in the Inner Galactic Plane: The Sample and Dust Properties

Yuan

Ellingsen

et al. 2017

ApJS

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We report a sample of 463 high-mass starless clump (HMSC) candidates within l 60 60 - < <  and b 1 1 - < < . This sample has been singled out from 10,861 ATLASGAL clumps. None of these sources are associated with any known star-forming activities collected in SIMBAD and young stellar objects identified using color-based criteria. We also make sure that the HMSC candidates have neither point sources at 24 and 70 μmnor strong extended emission at 24 μm. Most of the identified HMSCs are infrared dark, and some are even dark at 70 μm. Their distribution shows crowding in Galactic spiral arms and toward the Galactic center and some wellknown star-forming complexes. Many HMSCs are associated with large-scale filaments. Some basic parameters were attained from column density and dust temperature maps constructed via fitting far-infrared and submillimeter continuum data to modified blackbodies. The HMSC candidates have sizes, masses, and densities similar to clumps associated with Class II methanol masers and HIIregions, suggesting that they will evolve into star-forming clumps. More than 90% of the HMSC candidates have densities above some proposed thresholds for forming highmass stars. With dust temperatures and luminosity-to-mass ratios significantly lower than that for star-forming sources, the HMSC candidates are externally heated and genuinely at very early stages of high-mass star formation. Twenty sources with equivalent radii r 0.15 eq < pc and mass surface densities 0.08 S > g cm −2 could be possible high-mass starless cores. Further investigations toward these HMSCs would undoubtedly shed light on comprehensively understanding the birth of high-mass stars.

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“…We note that the 70 µm images have the best angular resolution within the Hi-GAL data and therefore provide information about the point-like sources found within the clumps and likely associated with protostellar objects. Also it is an excellent probe of the population of intermediateand high-mass young stellar objects in star-forming regions (see, e.g., Ragan et al 2012;Veneziani et al 2013). Planck clumps without 70 µm sources are the best candidates to study the earliest phases of star formation, since the absence of 70 µm emission likely indicates that protostellar activity has affected its surrounding environment very little.…”

Section: Clump Categories Based On Hi-gal 70 µM Datamentioning

confidence: 99%

Physical properties of GalacticPlanckcold cores revealed by the Hi-GAL survey

Zahorecz

Jiménez-Serra

Wang

et al. 2016

A&A

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Context. Previous studies of the initial conditions of massive star and star cluster formation have mainly targeted infrared-dark clouds (or IRDCs) toward the inner Galaxy. This is because IRDCs were first detected in absorption against the bright mid-infrared (IR) background of the inner Galaxy, requiring a favorable location to be observed. By selection, IRDCs therefore represent only a fraction of the Galactic clouds capable of forming massive stars and star clusters. Owing their low dust temperatures, however, IRDCs are bright in the far-IR and millimeter and, thus, observations at these wavelengths have the potential to provide a complete sample of star-forming massive clouds across the Galaxy. Aims. Our aim is to identify the clouds at the initial conditions of massive star and star cluster formation across the Galaxy and compare their physical properties as a function of Galactic longitude and Galactocentric distance. Methods. We have examined the physical properties of a homogeneous Galactic cold core sample obtained with the Planck satellite across the Galactic plane. With the use of Herschel Hi-GAL observations, we characterized the internal structure of the most reliable Galactic cold clumps within the Early Cold Core (ECC) Planck catalog. By using background-subtracted Herschel images, we derived the H 2 column density and dust temperature maps for 48 Planck clumps covered by the Herschel Hi-GAL survey. We calculated and analyzed the basic physical parameters (size, mass, and average dust temperature) of these clumps as a function of location within the Galaxy. We also compared these properties with the empirical relation for massive star formation previously derived. Results. Most of the Planck clumps contain signs of star formation. About 25% of the clumps are massive enough to form highmass stars and star clusters since they exceed the empirical threshold for massive star formation. Planck clumps toward the Galactic center region show higher peak column densities and higher average dust temperatures than those of the clumps in the outer Galaxy. Although we only have seven clumps without associated YSOs, the Hi-GAL data show no apparent differences in the properties of Planck cold clumps with and without star formation.

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An analysis of star formation withHerschelin the Hi-GAL survey

Cited by 45 publications

References 46 publications

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

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

High-mass Starless Clumps in the Inner Galactic Plane: The Sample and Dust Properties

Physical properties of GalacticPlanckcold cores revealed by the Hi-GAL survey

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