<i>Herschel</i>far-infrared observations of the Carina Nebula complex

Roccatagliata, V.; Preibisch, Thomas; Ratzka, Thorsten; Gaczkowski, B.

doi:10.1051/0004-6361/201321081

Cited by 64 publications

(89 citation statements)

References 58 publications

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“…For our study, we obtained the raw data from the Herschel archive for the following sources (see Table 1 Roccatagliata et al (2013). These clouds were selected to cover different masses, sizes, and levels of SF.…”

Section: Herschel Column Density Mapsmentioning

confidence: 99%

Understanding star formation in molecular clouds

Schneider

Ossenkopf

Csengeri

et al. 2015

A&A

134

203

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Column-density maps of molecular clouds are one of the most important observables in the context of molecular cloud-and starformation (SF) studies. With the Herschel satellite it is now possible to precisely determine the column density from dust emission, which is the best tracer of the bulk of material in molecular clouds. However, line-of-sight (LOS) contamination from fore-or background clouds can lead to overestimating the dust emission of molecular clouds, in particular for distant clouds. This implies values that are too high for column density and mass, which can potentially lead to an incorrect physical interpretation of the column density probability distribution function (PDF). In this paper, we use observations and simulations to demonstrate how LOS contamination affects the PDF. We apply a first-order approximation (removing a constant level) to the molecular clouds of Auriga and Maddalena (low-mass star-forming), and Carina and NGC 3603 (both high-mass SF regions). In perfect agreement with the simulations, we find that the PDFs become broader, the peak shifts to lower column densities, and the power-law tail of the PDF for higher column densities flattens after correction. All corrected PDFs have a lognormal part for low column densities with a peak at A v ∼ 2 mag, a deviation point (DP) from the lognormal at A v (DP) ∼ 4−5 mag, and a power-law tail for higher column densities. Assuming an equivalent spherical density distribution ρ ∝ r −α , the slopes of the power-law tails correspond to α PDF = 1.8, 1.75, and 2.5 for Auriga, Carina, and NGC 3603. These numbers agree within the uncertainties with the values of α ≈ 1.5, 1.8, and 2.5 determined from the slope γ (with α = 1 − γ) obtained from the radial column density profiles (N ∝ r γ ). While α ∼ 1.5−2 is consistent with a structure dominated by collapse (local free-fall collapse of individual cores and clumps and global collapse), the higher value of α > 2 for NGC 3603 requires a physical process that leads to additional compression (e.g., expanding ionization fronts). From the small sample of our study, we find that clouds forming only low-mass stars and those also forming high-mass stars have slightly different values for their average column density (1.8 × 10 21 cm −2 vs. 3.0 × 10 21 cm −2 ), and they display differences in the overall column density structure. Massive clouds assemble more gas in smaller cloud volumes than low-mass SF ones. However, for both cloud types, the transition of the PDF from lognormal shape into power-law tail is found at the same column density (at A v ∼ 4−5 mag). Low-mass and high-mass SF clouds then have the same low column density distribution, most likely dominated by supersonic turbulence. At higher column densities, collapse and external pressure can form the power-law tail. The relative importance of the two processes can vary between clouds and thus lead to the observed differences in PDF and column density structure.

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Section: Herschel Column Density Mapsmentioning

confidence: 99%

Understanding star formation in molecular clouds

Schneider

Ossenkopf

Csengeri

et al. 2015

A&A

134

203

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“…In both cases we used the Herschel maps after applying the Planck offsets. While the first approach conserves the angular resolution of the 160 μm image (as was done in Preibisch et al 2012 andSicilia-Aguilar et al 2014), the second uses the PACS and SPIRE images all convolved to the 500 μm resolution (as was done in Roccatagliata et al 2013). The fit of the fluxes is obtained by using a blackbody leaving as free parameters the temperature T and the surface density Σ [g/cm 2 ], with the same procedure presented in Roccatagliata et al (2013).…”

Section: Temperature and Column Density Of The Cloudsmentioning

confidence: 99%

A network of filaments detected byHerschelin the Serpens core

Roccatagliata¹,

Dale²,

Ratzka³

et al. 2015

A&A

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Context. Filaments represent a key structure during the early stages of the star formation process. Simulations show that filamentary structures commonly formed before and during the formation of cores. Aims. The Serpens core is an ideal laboratory for testing the state of the art of simulations of turbulent giant molecular clouds. Methods. We used Herschel observations of the Serpens core to compute temperature and column density maps of the region. We selected the early stages of a recent simulation of star-formation, before stellar feedback was initiated, with similar total mass and physical size as the Serpens core. We also derived temperature and column density maps from the simulations. The observed distribution of column densities of the filaments was analyzed, first including and then masking the cores. The same analysis was performed on the simulations as well. Results. A radial network of filaments was detected in the Serpens core. The analyzed simulation shows a striking morphological resemblance to the observed structures. The column density distribution of simulated filaments without cores shows only a log-normal distribution, while the observed filaments show a power-law tail. The power-law tail becomes evident in the simulation if the focus is only the column density distribution of the cores. In contrast, the observed cores show a flat distribution. Conclusions. Even though the simulated and observed filaments are subjectively similar-looking, we find that they behave in very different ways. The simulated filaments are turbulence-dominated regions; the observed filaments are instead self-gravitating structures that will probably fragment into cores.

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“…This is also the hottest region of the nebula with temperatures ranging between 30 and 50 K, whereas the molecular cloud at the western side of Tr 14 has a temperature of about 30 K and a decrease in density from the inner to the edge part (Roccatagliata et al 2013). Our studied region CrW contains this cloud, which can be seen in our infrared extinction map (see Fig.…”

Section: Discussion: Star Formation Scenariomentioning

confidence: 56%

“…If we plot the spatial distribution of the red dots and black crosses, we clearly see that all the red dots are uniformly distributed, whereas all the black crosses are distributed away from the obscured region of the molecular cloud. It means that the black crosses are most probably background stars, and their light is seen through the molecular cloud (see Preibisch et al 2011a;Roccatagliata et al 2013, and references therein). Therefore, the ratios [E(V − λ)]/[E(B − V)] (λ ≥ λ I ) for the stars in the background yield a high value for R V (∼3.7 ± 0.1), indicating an abnormal grain size in the observed region.…”

Section: Reddening Lawmentioning

confidence: 99%

Investigation of the stellar content in the western part of the Carina nebula

Kumar¹,

Sharma²,

Manfroid³

et al. 2014

A&A

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Context. The low obscuration and proximity of the Carina nebula make it an ideal place to study the ongoing star formation process and impact of massive stars on low-mass stars in their surroundings. Aims. To investigate this process, we generated a new catalog of the pre-main-sequence stars in the Carina west (CrW) region and studied their nature and spatial distribution. We also determined various parameters (reddening, reddening law, age, mass), which are used further to estimate the initial mass function and K-band luminosity function for the region under study. Methods. We obtained deep UBVRI Hα photometric data of the field situated to the west of the main Carina nebula and centered on WR 22. Medium-resolution optical spectroscopy of a subsample of X-ray selected objects along with archival data sets from Chandra, XMM-Newton and 2MASS surveys were used for the present study. Different sets of color-color and color-magnitude diagrams are used to determine reddening for the region and to identify young stellar objects (YSOs) and estimate their age and mass. Results. Our spectroscopic results indicate that the majority of the X-ray sources are late spectral type stars. The region shows a large amount of differential reddening with minimum and maximum values of E(B − V) as 0.25 and 1.1 mag, respectively. Our analysis reveals that the total-to-selective absorption ratio R V is ∼3.7 ± 0.1, suggesting an abnormal grain size in the observed region. We identified 467 YSOs and studied their characteristics. The ages and masses of the 241 optically identified YSOs range from ∼0.1 to 10 Myr and ∼0.3 to 4.8 M , respectively. However, the majority of them are younger than 1 Myr and have masses below 2 M . The high mass star WR 22 does not seem to have contributed to the formation of YSOs in the CrW region. The initial mass function slope, Γ, in this region is found to be −1.13 ± 0.20 in the mass range of 0.5 < M/M < 4.8. The K-band luminosity function slope (α) is also estimated as 0.31 ± 0.01. We also performed minimum spanning tree analysis of the YSOs in this region, which reveals that there are at least ten YSO cores associated with the molecular cloud, and that leads to an average core radius of 0.43 pc and a median branch length of 0.28 pc.

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Herschelfar-infrared observations of the Carina Nebula complex

Cited by 64 publications

References 58 publications

Understanding star formation in molecular clouds

Understanding star formation in molecular clouds

A network of filaments detected byHerschelin the Serpens core

Investigation of the stellar content in the western part of the Carina nebula

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