Discovery of a Candidate for the Central Star of the Ultracompact H
                    <scp>ii</scp>
                    Region G5.89-0.39

Feldt, M.; Puga, E.; Lenzen, R.; Henning, Th.; Brandner, W.; Stecklum, B.; Lagrange, Anne-Marie; Gendron, É.; Rousset, G.

doi:10.1086/381174

Cited by 45 publications

(98 citation statements)

References 16 publications

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“…1], the extinction is higher toward the southwest of G5.89, coincident with all three absorption features observed here. With follow-up observations, they confirmed their findings with broadband H-, K 0 -, and L-band imaging (Feldt et al 2003).…”

Section: The Overlying Cloudsupporting

confidence: 68%

“…G5.89 is a useful object to study because it is reasonably isolated and it has a simple morphology compared to many other young massive star formation regions. Specifically, G5.89 is a shell-type UC H ii region (Wood & Churchwell 1989) located $1.9 kpc from the Sun (Feldt et al 2003;Acord et al1998). Acord et al (1998) measured the angular expansion of G5.89 to be 4 mas yr À1 using high-resolution radio continuum observations over a 6 yr baseline.…”

Section: Observational History Of G589à039mentioning

confidence: 99%

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The Bipolar Outflow toward G5.89−0.39

Watson

Churchwell

Zweibel

et al. 2007

ApJ

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We present high-resolution observations of G5.89À0.39 in CO(1 ! 0), 13 CO(1 ! 0), C 18 O(1 ! 0), and HCO + (1 ! 0). We characterize the G5.89À0.39 outflow using the 13 CO emission. The outflow is found to be young, massive, and powerful. We conclude that (1) the outflow is nearly along the line of sight, (2) there is dynamical evidence for entrainment of ambient interstellar material into the outflow, (3) the mass entrainment rate is $4 ; 10 À3 M yr À1 , (4) in the blue lobe, only $27% of the outflow mass is due to entrainment, and (5) expansion of the outflow lobes perpendicular to the flow axis is occurring at $1Y10 v sound . A neutral and ionized outflow tracer are compared. Watson and coworkers predicted that if entrainment through the Kelvin-Helmholtz shear instability adds significantly to the outflow mass, a difference in the turbulent velocity widths of neutral and ionized outflow tracers could be measurable. We cannot conclude that the Kelvin-Helmholtz shear instability is the physical process causing this entrainment, but it may operate at a level below our detection limit.

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Section: The Overlying Cloudsupporting

confidence: 68%

Section: Observational History Of G589à039mentioning

confidence: 99%

The Bipolar Outflow toward G5.89−0.39

Watson

Churchwell

Zweibel

et al. 2007

ApJ

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“…For instance, adaptive optics observations with the 8.2 m Very Large Telescope (VLT) of the UCHII region G5.89-0.39 (Feldt et al 2003) in the K s and L bands reveal structure at such small scales. However, those observations were obtained much before recent theoretical developments to allow direct comparison.…”

Section: Introductionmentioning

confidence: 99%

Radiatively driven Rayleigh-Taylor instability candidates around a forming massive star system

Kumar¹

2013

A&A

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The formation of the highest mass stars are thought to be dominated by instabilities resulting from gravitation and radiation. Instabilities due to gravitation are commonly demonstrated by observations of fragmentation, but those due to effects of radiation have thus far not been found. Here I report on the NACO adaptive optics and mid-infrared diffraction-limited VISIR imaging data of an extemely luminous ultra-compact HII region G333.6-0.2. Two infrared sources, one bright in the near-infrared (appearing pointlike) and another in the mid-infrared (resolved with an elliptical shape) are uncovered through this data, which are located at the heart of this region. These infrared sources appear to be embedded in the waist of a bipolar-shaped nebula and UCHII region, the lobes of which are separated by a dark patch. Dense filamentary features with finger/hook morphology are found; they appear to be connected to the two bright infrared sources and the sizes of these hook features are sharply limited to <5000 AU. The observed properties of this target and a large amount of previous data obtained from the literature are compared together with the results of various numerical simulations of high-mass star formation. This comparison favours the interpretation that the finger/hook-like structures likely represent radiatively driven Rayleigh-Taylor instabilities arising in the outflow cavity of a forming high-mass binary star system.

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“…The emission of warm dust, the dominant source of emission at midinfrared wavelengths, is much fainter in the near-infrared and the actual photospheres of the high-mass stars can be probed. The success of this approach is demonstrated by several near-infrared imaging studies (e.g., Hanson et al 1997;Blum et al 2000;Feldt et al 2003;Alvarez et al 2004;Bik 2004, L. Kaper et al 2010. These imaging studies reveal the stellar content hidden in those star-forming regions, but also show the limitations, as these studies are limited to regions with A V less than ∼30 mag.…”

Section: Introductionmentioning

confidence: 99%

Sequential Star Formation in RCW 34: A Spectroscopic Census of the Stellar Content of High-Mass Star-Forming Regions

Bik

Puga

Waters

et al. 2010

ApJ

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In this paper, we present VLT/SINFONI integral field spectroscopy of RCW 34 along with Spitzer/IRAC photometry of the surroundings. RCW 34 consists of three different regions. A large bubble has been detected in the IRAC images in which a cluster of intermediate-and low-mass class II objects is found. At the northern edge of this bubble, an H ii region is located, ionized by 3 OB stars, of which the most massive star has spectral type O8.5V. Intermediate-mass stars (2-3 M ) are detected of G-and K-spectral type. These stars are still in the premain-sequence (PMS) phase. North of the H ii region, a photon-dominated region is present, marking the edge of a dense molecular cloud traced by H 2 emission. Several class 0/I objects are associated with this cloud, indicating that star formation is still taking place. The distance to RCW 34 is revised to 2.5 ± 0.2 kpc and an age estimate of 2 ± 1 Myr is derived from the properties of the PMS stars inside the H ii region. Between the class II sources in the bubble and the PMS stars in the H ii region, no age difference could be detected with the present data. The presence of the class 0/I sources in the molecular cloud, however, suggests that the objects inside the molecular cloud are significantly younger. The most likely scenario for the formation of the three regions is that star formation propagated from south to north. First the bubble is formed, produced by intermediate-and low-mass stars only, after that, the H ii region is formed from a dense core at the edge of the molecular cloud, resulting in the expansion similar to a champagne flow. More recently, star formation occurred in the rest of the molecular cloud. Two different formation scenarios are possible. (1) The bubble with the cluster of low-and intermediate-mass stars triggered the formation of the O star at the edge of the molecular cloud, which in its turn induces the current star formation in the molecular cloud. (2) An external triggering is responsible for the star formation propagating from south to north.

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Discovery of a Candidate for the Central Star of the Ultracompact H ii Region G5.89-0.39

Cited by 45 publications

References 16 publications

The Bipolar Outflow toward G5.89−0.39

The Bipolar Outflow toward G5.89−0.39

Radiatively driven Rayleigh-Taylor instability candidates around a forming massive star system

Sequential Star Formation in RCW 34: A Spectroscopic Census of the Stellar Content of High-Mass Star-Forming Regions

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