RCW36: characterizing the outcome of massive star formation

Ellerbroek, L. E.; Bik, Arjan; Kaper, L.; Maaskant, K. M.; Paalvast, Mieke; Tramper, F.; Sana, H.; Waters, L.B.F.M.; Balog, Z.

doi:10.1051/0004-6361/201321752

Cited by 41 publications

(64 citation statements)

References 70 publications

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“…This supports the previous study in Minier et al (2013) showing that, based on the morphology of the regions, the gravitational collapse of these condensations (Fig. 10) was likely to be triggered This is also confirmed by the recent age determination of the different stellar populations done by Ellerbroek et al (2013). Furthermore, the exponent α decreases to a value of 1.54 ± 0.02 in region 1+2+3+4.…”

Section: Vela C/rcw 36supporting

confidence: 91%

Ionization compression impact on dense gas distribution and star formation

Tremblin

Schneider

Minier

et al. 2014

A&A

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Aims. Ionization feedback should impact the probability distribution function (PDF) of the column density of cold dust around the ionized gas. We aim to quantify this effect and discuss its potential link to the core and initial mass function (CMF/IMF). Methods. We used Herschel column density maps of several regions observed within the HOBYS key program in a systematic way: M 16, the Rosette and Vela C molecular clouds, and the RCW 120 H ii region. We computed the PDFs in concentric disks around the main ionizing sources, determined their properties, and discuss the effect of ionization pressure on the distribution of the column density. Results. We fitted the column density PDFs of all clouds with two lognormal distributions, since they present a "double-peak" or an enlarged shape in the PDF. Our interpretation is that the lowest part of the column density distribution describes the turbulent molecular gas, while the second peak corresponds to a compression zone induced by the expansion of the ionized gas into the turbulent molecular cloud. Such a double peak is not visible for all clouds associated with ionization fronts, but it depends on the relative importance of ionization pressure and turbulent ram pressure. A power-law tail is present for higher column densities, which are generally ascribed to the effect of gravity. The condensations at the edge of the ionized gas have a steep compressed radial profile, sometimes recognizable in the flattening of the power-law tail. This could lead to an unambiguous criterion that is able to disentangle triggered star formation from pre-existing star formation. Conclusions. In the context of the gravo-turbulent scenario for the origin of the CMF/IMF, the double-peaked or enlarged shape of the PDF may affect the formation of objects at both the low-mass and the high-mass ends of the CMF/IMF. In particular, a broader PDF is required by the gravo-turbulent scenario to fit the IMF properly with a reasonable initial Mach number for the molecular cloud. Since other physical processes (e.g., the equation of state and the variations among the core properties) have already been said to broaden the PDF, the relative importance of the different effects remains an open question.

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Section: Vela C/rcw 36supporting

confidence: 91%

Ionization compression impact on dense gas distribution and star formation

Tremblin

Schneider

Minier

et al. 2014

A&A

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“…Note that Gagné et al (2011) adopted an extinction law with reddening parameter R V = 4.0 for Carina, while Kiminki et al (2015) adopted R V = 3.6 for W3; in reality the reddening parameter can vary even among different stars in the same star-forming region. Ellerbroek et al (2012), (4) e If checked, star was among the 67 selected independently by our procedure for identifying OB candidates among IR SEDs that were counterparts to MYStIX X-ray sources.…”

Section: Sed Fitting Results For Previously-publishedmentioning

confidence: 99%

Candidate X-Ray-emitting OB Stars in MYStIX Massive Star-forming Regions

Povich

Busk

Feigelson³

et al. 2017

ApJ

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Massive, O and early B-type (OB) stars remain incompletely catalogued in the nearby Galaxy due to high extinction, bright visible and infrared nebular emission in H II regions, and high field star contamination. These difficulties are alleviated by restricting the search to stars with X-ray emission. Using the X-ray point sources from the Massive Young star-forming complex Study in Infrared and X-rays (MYStIX) survey of OB-dominated regions, we identify 98 MYStIX candidate OB (MOBc) stars by fitting their 1-8 µm spectral energy distributions (SEDs) with reddened stellar atmosphere models. We identify 27 additional MOBc stars based on JHK S photometry of X-ray stars lacking SED fitting. These candidate OB stars indicate that the current census of stars earlier than B1, taken across the 18 MYStIX regions studied, is less than 50% complete. We also fit the SEDs of 239 previously-published OB stars to measure interstellar extinction and bolometric luminosities, revealing six candidate massive binary systems and five candidate O-type (super)giants. As expected, candidate OB stars have systematically higher extinction than previously-published OB stars. Notable results for individual regions include: identification of the OB population of a recently discovered massive cluster in NGC 6357; an older OB association in the M17 complex; and new massive luminous O stars near the Trifid Nebula. In several relatively poorly-studied regions (RCW 38, NGC 6334, NGC 6357, Trifid, and NGC 3576), the OB populations may increase by factors of 2.

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“…H97 reported that their strength did not vary with A V (or E(B − V)) as seen in other Galactic sightlines. Massive star forming regions are known to exhibit anomalous extinction properties (Dahlstrom et al 2013;Oka et al 2013;Ellerbroek et al 2013a). We will report the DIB behaviour towards sightlines in M17 in a separate paper.…”

Section: From the Total Hydrogen Column Density N(h)mentioning

confidence: 99%

“…The overall conclusion is that the extinction is quite patchy, with substantial variation on a spatial scale of 50 arcsec (corresponding to a geometrical scale of 0.5 pc at the distance of M17), similar as to the findings of H97. A dust disk local to the star, for example, may dominate the line-of-sight extinction towards the sources (see Ellerbroek et al 2013a). Studies of individual sources therefore should not rely on average properties of the region, but should be based on a detailed investigation of the extinction in the line of sight.…”

Section: Age Distribution Of the Massive Pms Population In M17mentioning

confidence: 99%

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Massive pre-main sequence stars in M17

et al. 2015

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The formation process of massive stars is still poorly understood. Massive young stellar objects (mYSOs) are deeply embedded in their parental clouds, they are rare and thus typically distant, and their reddened spectra usually preclude the determination of their photospheric parameters. M17 is one of the best studied H ii regions in the sky, is relatively nearby, and hosts a young stellar population. With X-shooter on the ESO Very Large Telescope we have obtained optical to near-infrared spectra of candidate mYSOs, identified by Hanson et al. (1997), and a few OB stars in this region. The large wavelength coverage enables a detailed spectroscopic analysis of their photospheres and circumstellar disks. We confirm the pre-main sequence (PMS) nature of six of the stars and characterise the O stars. The PMS stars have radii consistent with being contracting towards the main sequence and are surrounded by a remnant accretion disk. The observed infrared excess and the (double-peaked) emission lines provide the opportunity to measure structured velocity profiles in the disks. We compare the observed properties of this unique sample of young massive stars with evolutionary tracks of massive protostars by Hosokawa & Omukai (2009), and propose that these mYSOs near the western edge of the H ii region are on their way to become main-sequence stars (∼ 6 − 20 M ) after having undergone high mass-accretion rates (Ṁ acc ∼ 10 −4 − 10 −3 M yr −1 ). Their spin distribution upon arrival at the zero age main sequence (ZAMS) is consistent with that observed for young B stars, assuming conservation of angular momentum and homologous contraction.

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RCW36: characterizing the outcome of massive star formation

Cited by 41 publications

References 70 publications

Ionization compression impact on dense gas distribution and star formation

Ionization compression impact on dense gas distribution and star formation

Candidate X-Ray-emitting OB Stars in MYStIX Massive Star-forming Regions

Massive pre-main sequence stars in M17

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