The Initial Mass Function of a Massive Star‐forming Region W51

Okumura, Shin-ichiro; Mori, Atsushi; Nishihara, Eiji; Watanabe, E.; Yamashita, Takuya

doi:10.1086/317116

Cited by 52 publications

(123 citation statements)

References 40 publications

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“…W51A sports the very massive young stellar object W51 IRS2E showing infall ) that might be an example of a "quenched" H ii region (Keto 2003). Just the main MYSC complex, G49.5−0.4, has >30 O stars (Okumura et al 2000).…”

Section: W51amentioning

confidence: 99%

The Massive Star-Forming Regions Omnibus X-Ray Catalog

Townsley

Broos

Garmire

et al. 2014

ApJS

150

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We present the Massive Star-forming Regions (MSFRs) Omnibus X-ray Catalog (MOXC), a compendium of X-ray point sources from Chandra/ACIS observations of a selection of MSFRs across the Galaxy, plus 30 Doradus in the Large Magellanic Cloud. MOXC consists of 20,623 X-ray point sources from 12 MSFRs with distances ranging from 1.7 kpc to 50 kpc. Additionally, we show the morphology of the unresolved X-ray emission that remains after the cataloged X-ray point sources are excised from the ACIS data, in the context of Spitzer and WISE observations that trace the bubbles, ionization fronts, and photon-dominated regions that characterize MSFRs. In previous work, we have found that this unresolved X-ray emission is dominated by hot plasma from massive star wind shocks. This diffuse X-ray emission is found in every MOXC MSFR, clearly demonstrating that massive star feedback (and the several-million-degree plasmas that it generates) is an integral component of MSFR physics.

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Section: W51amentioning

confidence: 99%

The Massive Star-Forming Regions Omnibus X-Ray Catalog

Townsley

Broos

Garmire

et al. 2014

ApJS

150

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“…The age distribution shows that young stars tend to be located close to the Orion molecular cloud (e.g., Warren & Hesser 1978). Okumura et al (2000) observed the W51 H ii region in the near-infrared to search for young stellar Present address: Nishi-Harima Astronomical Observatory, Sayocho, Hyogo, 679-5313, Japan. objects (YSOs) and confirmed the age alignment of the YSOs with an age distribution of 1-2 Myr.…”

Section: Triggered Star Formationmentioning

confidence: 99%

Millimeter-wave survey of molecular clouds around the W5-East triggered star-forming region

Niwa¹,

Tachihara

Itoh³

et al. 2009

A&A

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Aims. We examined the physical properties of molecular clouds (morphology, column density, number density, mass) to investigate the mechanism of triggered star formation by UV radiation from a massive star.Methods. We made extensive, high-resolution maps of molecular clouds associated and interacting with the W5-East H ii region using the 45-m telescope at the Nobeyama Radio Observatory (HPBW = 15. 6) in 13 CO (J = 1−0) and C 18 O (J = 1−0) to reveal details in the high-density regions of the molecular clouds. In addition, to investigate the spatial distributions of young stellar objects (YSOs) in the W5-East H ii region, we mapped the spatial distributions of Class I and II candidates.Results. We identified eight 13 CO molecular clouds (three of them are known bright-rimmed clouds) and nine C 18 O clumps. The masses of the clouds and clumps range from 460 to 36 000 M and from 55 to 740 M , respectively. The peak 13 CO column densities of the clouds facing the H ii region are twice as large as the others. They have steep density gradients toward the H ii region, indicating interactions with the H ii region. We selected 55 Class I candidates and 778 Class II candidates associated with the W5-East H ii region from the previous Spitzer IRAC/MIPS survey. Most Class I candidates are located around integrated intensity peaks of 13 CO, whereas most Class II candidates are distributed along the front sides of the BRC arcs close to the exciting star. Conclusions. The alignments of the YSO candidates and the molecular clouds in order of age indicate that triggered star formation occurs in the W5-East H ii region as a result of gas compression by strong UV radiation. Based on the column densities of 13 CO and the spatial distribution of YSO candidates, we identified a new bright-rimmed cloud candidate on the west side of the W5-East H ii region.

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“…The radio continuum sources comprising W51 are within a massive giant molecular cloud (GMC) (Mufson & Liszt 1979). Observations showing the star forming activity have been carried out in various wavelengths of radio continuum, HI line, molecular lines, water masers, near-IR, X-ray (Bieging 1975;Carpenter & Sanders 1998;Imai et al 2002;Koo 1997;Koo & Moon 1997;Koo 1999;Mehringer 1994;Okumura et al 2000). W51 is a region of ongoing massive star formation (Lacy et al 2007;Zapata et al 2008) and therefore a good place to study the feedback between stars and the ISM.…”

Section: Introductionmentioning

confidence: 99%

Embedded Young Stellar Object Candidates in the Active Star-Forming Complex W51: Mass Function and Spatial Distribution

Kang

Bieging

Povich

et al. 2009

ApJ

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We present 737 candidate Young Stellar Objects (YSOs) near the W51 Giant Molecular Cloud (GMC) over an area of 1.25 • × 1.00 • selected from Spitzer Space Telescope data. We use spectral energy distribution (SED) fits to identify YSOs and distinguish them from main-sequence or red giant stars, asymptotic giant branch stars, and background galaxies. Based on extinction of each YSO, we separate a total of 437 YSOs associated with the W51 region from the possible foreground sources. We identify 69 highly embedded Stage 0/I candidate YSOs in our field with masses > 5 M ⊙ (corresponding to mid-to early-B main-sequence spectral types) 46 of which are located in the central active star forming regions of W51A and W51B. From the YSOs associated with W51, we find evidence for mass segregation showing that the most massive YSOs are concentrated on the W51 H II region complex. We find a variation in the spatial distribution of the mass function (MF) of YSOs in the mass range between 5 M ⊙ and 18 M ⊙ . The derived slopes of the MF are −1.26 and −2.36 in the active starforming region and the outer region, respectively. The variation of the MF for YSOs embedded in the molecular cloud implies that the distribution of stellar masses in clusters depends on the local conditions in the parent molecular cloud.

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The Initial Mass Function of a Massive Star‐forming Region W51

Cited by 52 publications

References 40 publications

The Massive Star-Forming Regions Omnibus X-Ray Catalog

The Massive Star-Forming Regions Omnibus X-Ray Catalog

Millimeter-wave survey of molecular clouds around the W5-East triggered star-forming region

Embedded Young Stellar Object Candidates in the Active Star-Forming Complex W51: Mass Function and Spatial Distribution

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