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

Povich, Matthew S.; Busk, Heather A.; Feigelson, E. D.; Townsley, Leisa K.; Kuhn, Michael A.

doi:10.3847/1538-4357/aa5b99

Cited by 19 publications

(37 citation statements)

References 113 publications

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“…In addition, we confirm spectroscopically the B-type status for four OB stars candidates which we have in common (stars 140, 120, 225, and 527 listed in their Table 7). We also confirm spectroscopically eight of the OB candidates listed by Povich et al (2017): their stars 5 and 8 of NGC 6334 and 2,3,17,18,19, and 22 of NGC 6357. Just as reported by Antokhin et al (2008) we also find an X-ray power demarcation between B and O stars corresponding to L bol ∼ 1.4 × 10 38 erg/s.…”

Section: X-ray Counterpartsupporting

confidence: 68%

NGC 6334 and NGC 6357

Russeil

Adami

Bouret

et al. 2017

A&A

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Aims. The formation of high-mass stars is still debated. For this reason, several projects such as Herschel-HOBYS are focussed on the study of the earliest phases of massive star formation. As a result, massive star-forming complexes such as NGC 6334 and NGC 6357 have been observed in the far-infrared to study their massive dense cores where massive stars are expected to form. However, to better characterise the environments of these cores we need to understand the previous massive star formation history. To better characterise the environment of these massive dense cores we study the previous high-mass star formation and how these stars act on their environments. Methods. This study is based on the spectral classification of the OB stars identified towards NGC 6334 and NGC 6357 with spectra taken with the AAOmega spectrograph on the Anglo-Australian Telescope (AAT). From the subsequent spectral classification of 109 stars across these regions we were able to evaluate the following: distance, age, mass, global star-forming efficiency (SFE), and star formation rate (SFR) of the regions. The physical conditions of the ionised gas for both complexes was also derived. Results. We confirm that NGC 6334 and NGC 6357 belong to the Saggitarius-Carina arm which, in this direction, extends from 1 kpc to 2.2 kpc. From the location of the stars in Hertzprung-Russell diagram we show that stars older than ∼10 Myr are broadly spread across these complexes, while younger stars are mainly located in the H ii regions and stellar clusters. Our data also suggests that some of the young stars can be considered runaway stars. We evaluate a SFE of 0.019 +0.008 −0.007 and 0.021 +0.004 −0.003 and a SFR of 1.1 × 10 3 ± 300 M Myr −1 and 1.7 × 10 3 ± 400 M Myr −1 for NGC 6334 and NGC 6357, respectively. We note that 29 OB stars have X-ray counterparts, most of them belonging to NGC 6357. This suggests that molecular clouds in NGC 6357 are more impacted by X-ray flux and stellar winds than in NGC 6334. Finally, from the analysis of nebular lines (Hα, [NII], and [SII]) from spectra from several regions of ionised gas, we confirm that the filaments in NGC 6357 are shock heated.

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Section: X-ray Counterpartsupporting

confidence: 68%

NGC 6334 and NGC 6357

Russeil

Adami

Bouret

et al. 2017

A&A

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“…It stands out as one of the brightest regions in the southern sky at radio wavelengths (Wilson et al 1970), and is one of the few regions within 2 kpc, along with the Orion Nebula Cluster (ONC), to contain over 2000 young stars identified at infrared wavelengths and in X-rays, although it is more embedded and younger (∼1 Myr) than the ONC (Wolk et al 2006(Wolk et al , 2008Winston et al 2011). These studies have identified around 30 OB star candidates, some of which have been confirmed (DeRose et al 2009;Povich et al 2017). At infrared wavelengths the region is dominated by two sources, the mid-infrared bright RCW 38 IRS1 and the near-infrared bright RCW 38 IRS2 (Figure 4; Furniss et al 1975;Frogel & Persson 1974;Smith et al 1999).…”

Section: Introductionmentioning

confidence: 91%

A Low Frequency Pilot Survey of Southern HII Regions in the Vela Constellation

Tremblay,

Bourke,

Green

et al. 2021

Preprint

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Atomic ionised regions with strong continuum emission are often associated with regions of high-mass star formation and low-frequency (<2 GHz) observations of these regions are needed to help build star formation models. The region toward the Vela Supernova Remnant is particularly interesting as it is a complex structure of recent supernova explosions and molecular clouds containing a number of H regions that are not well characterised. We searched publicly available catalogues for H regions, both candidate and identified, which also have low-frequency emission. In the area of ∼400 square degrees toward the Vela Supernova remnant, we found 10 such H regions, some of which have multiple components in catalogues. In this work we use data from the Australian Square Kilometre Array Pathfinder and previously unpublished data from the Murchison Widefield Array and the Australian Telescope Compact Array to analyse these sources. The high-mass star forming region RCW 38, with observations specifically targeted on the source, is used as a pilot study to demonstrate how low-frequency, wide-field continuum observations can identify and study H regions in our Galaxy. For the 9 other H regions, we discuss their properties; including information about which clouds are interacting, their ages, whether they are dominated by infrared or optical H𝛼 lines, distances, ionising photon flux, and upper limits on the infrared luminosity. In future work, these 9 regions will be analysed in more detail, similar to the result for RCW 38 presented here.

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“…We also use class 0/I YSOs (from Povich et al 2017) to probe the star formation activity of filaments where the starless MDCs are. Indeed, Rivilla et al ( , 2014 show that YSOs and low mass pre-main sequence stars tend to be clustered at the massive star-forming sites.…”

Section: Relation Between Mdcs and Filamentsmentioning

confidence: 99%

“…Such statistical lifetime is estimated from the relative number of a given MDC phase to the OB stars. For NGC 6357 we estimate a total number of 60 O-B3 stars from Russeil et al (2012Russeil et al ( , 2017 and Povich et al (2017). We assume a median age of the O-B3 stars to be 1 × 10 6 yr according to Fang et al (2012) and Getman et al (2014).…”

Section: Ngc 6357 and Ngc 6334 Historymentioning

confidence: 99%

“…The black dashed circles are the WISE detected compact H II regions from Anderson et al (2014). Magenta symbols are class 0/I YSOs from Povich et al (2017 In addition to extracting filaments with the Vialactea Filamentary Structures Extraction Package (hereafter VFSEP, Schisano et al 2014 and in prep.) we also performed the extraction using getfilaments a multi-scale, multi-wavelength filament extraction method (Men'shchikov 2013).…”

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confidence: 99%

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Herschel-HOBYS study of the earliest phases of high-mass star formation in NGC 6357

Russeil

Figueira

Zavagno

et al. 2019

A&A

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Aims. To constrain models of high-mass star formation it is important to identify the massive dense cores (MDCs) that are able to form high-mass star(s). This is one of the purposes of the Herschel/HOBYS key programme. Here, we carry out the census and characterise of the properties of the MDCs population of the NGC 6357 H II region. Methods. Our study is based on the Herschel/PACS and SPIRE 70−500 μm images of NGC 6357 complemented with (sub-)millimetre and mid-infrared data. We followed the procedure established by the Herschel/HOBYS consortium to extract ~0.1 pc massive dense cores using the getsources software. We estimated their physical parameters (temperatures, masses, luminosities) from spectral energy distribution (SED) fitting. Results. We obtain a complete census of 23 massive dense cores, amongst which one is found to be IR-quiet and twelve are starless, representing very early stages of the star-formation process. Focussing on the starless MDCs, we have considered their evolutionary status, and suggest that only five of them are likely to form a high-mass star. Conclusions. We find that, contrarily to the case in NGC 6334, the NGC 6357 region does not exhibit any ridge or hub features that are believed to be crucial to the massive star formation process. This study adds support for an empirical model in which massive dense cores and protostars simultaneously accrete mass from the surrounding filaments. In addition, the massive star formation in NGC 6357 seems to have stopped and the hottest stars in Pismis 24 have disrupted the filaments.

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

Cited by 19 publications

References 113 publications

NGC 6334 and NGC 6357

NGC 6334 and NGC 6357

A Low Frequency Pilot Survey of Southern HII Regions in the Vela Constellation

Herschel-HOBYS study of the earliest phases of high-mass star formation in NGC 6357

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