Clustered and Triggered Star Formation in W5: Observations with<i>Spitzer</i>

Koenig, X.; Allen, Lori; Gutermuth, Robert; Hora, J. L.; Brunt, Christopher M.; Muzerolle, James

doi:10.1086/592322

Cited by 151 publications

(276 citation statements)

References 74 publications

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“…This data base provides excellent tools for identifying and classifying YSO candidates as Class I and II. We investigated the infrared excess by measuring the infrared spectral index α IR (=dlog (λF λ )/dlog λ) (see Lada 1987;Stahler & Palla 2005;Chavarria et al 2008;Koenig et al 2008).…”

Section: Star Formationmentioning

confidence: 99%

Unveiling the molecular environment of the ring nebula RCW 78

Cappa

Rubio

Martín

et al. 2009

A&A

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Aims. We present a study of the ionized, neutral atomic, and molecular gas associated with the ring nebula RCW 78 around the WR star HD 117688 (=WR 55) with the aim of analyzing the distribution of the associated gas and investigating its energetics. Methods. We base our study on 12 CO(1-0) and 12 CO(2-1) observations of the brightest section of the nebula carried out with the SEST telescope with angular resolutions of 45 and 22 , respectively; and on complementary 12 CO(1-0) data of a larger area obtained with the NANTEN telescope with an angular resolution of 2. 7, Hi 21-cm line data taken from the ATCA survey, IRAS HIRES data, and radio continuum data at 4.85 GHz from the Parkes survey. Results. We report the detection of molecular gas having velocities in the range -56 to -33 km s −1 associated with the western region of RCW 78. A few patches of molecular gas possibly linked to the eastern faint section are detected. The CO emission appears concentrated in a region of 23 × 18 in size, with a total molecular mass of (1.3 ± 0.5) × 10 5 M , mainly connected to the western section. The analysis of the neutral atomic gas distribution reveals the H i envelope of the molecular cloud, while the radio continuum emission shows a ring-like structure, which is the radio counterpart of the optical nebula. The gas distribution is compatible with the western section of RCW 78 having originated in the photodissociation and ionization of the molecular gas by the UV photons of the WN7 star HD 117688, and with the action of the stellar winds of the WR star on the surrounding gas. In this scenario, the interstellar bubble expanded more easily towards the east than towards the west due to the lack of dense molecular gas in the eastern section. The proposed scenario also explains the off center location of WR 55. A number of infrared point sources classified as YSO candidates showed that star formation activity is present in the molecular gas linked to the nebula. The possibility that the expansion of the bubble triggered star formation in this region cannot be discarded.

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Section: Star Formationmentioning

confidence: 99%

Unveiling the molecular environment of the ring nebula RCW 78

Cappa

Rubio

Martín

et al. 2009

A&A

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“…Elmegreen & Lada (1977) proposed the collect and collapse mechanism, whereby expanding HII regions would sweep up spherical shells of matter from the interstellar medium, which would then collapse to form stars. Recent work has identified such bubbles, together with accurate census data of their associated star forming regions (Koenig et al 2008;Deharveng et al 2009;Watson et al 2009). If the collect and collapse mechanism occurs in nature, one would expect the spatial distribution of the observed stars to bear the imprint of this process.…”

Section: Discussionmentioning

confidence: 99%

“…2 that there are several small clusters in the data, and the existence of these small clusters would tend to reduces cancelling out the signature of the radial anticlustering. Koenig et al (2008) have also published observations of protostars forming in association with expanding HII bubbles, and these form arcs and "elephants" trunks' which are very suggestive of triggered star formation.s would not be able to diagnose anticlustering in this situation, as the arcs do not form complete circles.s is only able to detect anticlustering when the stars are forming in a fairly homogeneous arrangement, and when there are no tight knots of stars.…”

Section: Discussionmentioning

confidence: 99%

Measuring anticlustering in regions of triggered star formation

Cartwright¹,

Whitworth²

2009

A&A

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Context. Statistical methods for quantifying clustering have not yet been tested against anti-clustered data. Aims. We investigate the performance of the normalised correlation length,s, and Q when applied to anti-clustered data. Methods. We tested the operation ofs on simulated data and recently published observations. Results.s successfully distinguishes anticlustered data in simulations and indicates anticlustering in an area where it is speculated that triggered star formation has occurred. The existence of radial anticlustering can cause the Q clustering analysis method to malfunction. Users of Q should therefore uses to rule out anticlustering before applying Q.

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“…As most open clusters are unbound stellar systems, i.e., expanding systems (Lada & Lada 2003), it is believed from theoretical approaches, that gas expulsion affects the dynamical evolution of the remaining clusters significantly (Tutukov 1978;Goodwin & Bastian 2006). In some SFRs, new generation stars are still forming in the natal clouds swept away by the stellar wind and the UV radiation from high-mass stars (e.g., SiciliaAguilar et al 2004;Koenig et al 2008;Lim et al 2014b). The observed structure is basically a projection onto the sky.…”

Section: Photometric Diagramsmentioning

confidence: 99%

The Sejong Open Cluster Survey (Sos). Iv. The Young Open Clusters NGC 1624 and NGC 1931

Lim

Sung

Bessell

et al. 2015

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Young open clusters located in the outer Galaxy provide us with an opportunity to study star formation activity in a different environment from the solar neighborhood. We present a UBVI and Hα photometric study of the young open clusters NGC 1624 and NGC 1931 that are situated toward the Galactic anticenter. Various photometric diagrams are used to select the members of the clusters and to determine the fundamental parameters. NGC 1624 and NGC 1931 are, on average, reddened by E B V ( ) á -ñ = 0.92 ± 0.05 and 0.74 ± 0.17 mag, respectively. The properties of the reddening toward NGC 1931 indicate an abnormal reddening law (R V,cl = 5.2 ± 0.3). Using the zero-age main sequence fitting method we confirm that NGC 1624 is 6.0 ± 0.6 kpc away from the Sun, whereas NGC 1931 is at a distance of 2.3 ± 0.2 kpc. The results from isochrone fitting in the Hertzsprung-Russell diagram indicate the ages of NGC 1624 and NGC 1931 to be less than 4 and 1.5-2.0 Myr, respectively. We derived the initial mass function (IMF) of the clusters. The slope of the IMF ( NGC 1624 G = −2.0 ± 0.2 and NGC 1931 G = −2.0 ± 0.1) appears to be steeper than that of the Salpeter/Kroupa IMF. We discuss the implication of the derived IMF based on simple Monte-Carlo simulations and conclude that the property of star formation in the clusters does not seem to be significantly different from that in the solar neighborhood.

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Clustered and Triggered Star Formation in W5: Observations withSpitzer

Cited by 151 publications

References 74 publications

Unveiling the molecular environment of the ring nebula RCW 78

Unveiling the molecular environment of the ring nebula RCW 78

Measuring anticlustering in regions of triggered star formation

The Sejong Open Cluster Survey (Sos). Iv. The Young Open Clusters NGC 1624 and NGC 1931

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