Radio continuum measurements of compact H II regions and other sources

Matsakis, Demetrios; Evans, Neal J.; Sato, Taro; Zuckerman, B.

doi:10.1086/111871

Cited by 43 publications

(36 citation statements)

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“…NVSS, SHASSA and PMN, there is compact free–free emission coincident with the brightest star embedded in NGC 2068. It is the compact H ii region reported by Matsakis et al (1976). We see that the peak is coincident with HD38563N for both CBI and PMN images.…”

Section: Discussionsupporting

confidence: 71%

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Dust-correlated centimetre-wave radiation from the M78 reflection nebula

Castellanos

Casassus

Dickinson

et al. 2010

Monthly Notices of the Royal Astronomical Society

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Artículo de publicación ISIAn anomalous radio continuum component at cm-wavelengths has been observed in various sources, including dark clouds. This continuum component represents a new property of the ISM. In this work we focus on one particular dark cloud, the bright re ection nebula M 78. The main goal of this work is to investigate the cm-wave continuum emission in a prominent molecular cloud, nearby and with complementary observational data. We acquired Cosmic Background Imager (CBI) visibility data of M 78 at 31 GHz with an angular resolution of 5:80, and CBI2 data at an angular resolution of 4:20. A morphological analysis was undertaken to search for possible correlations with templates that trace di erent emission mechanisms. Using data from WMAP and the Rhodes/HartRAO 2326 MHz survey we constructed the spectral en- ergy distribution (SED) of M 78 in a 450 circular aperture. We used results from the literature to constrain the physical conditions and the stellar content. The 5 GHz { 31 GHz spectral index in ux density ( = 1:89 0:15) is signi cantly di erent from optically thin-free-free values. We also nd closer morphological agreement with IR dust tracers than with free-free sources. Dust-correlated cm-wave emission that is not due to free-free is signi cant at small scales (CBI resolutions). However, a free-free background dominates at cm-wavelengths on large scales ( 1 deg). We correct for this uniform background by di erencing against a set of reference elds. The di er- enced SED of M 78 shows excess emission at 10-70 GHz over free-free and a modi ed blackbody, at 3.4 . The excess is matched by the spinning dust model from Draine & Lazarian (1998).Marie Curie International Incoming Fellowship REA-236176 FONDECYT 1100221 Chilean Center for Astrophysics FONDAP 15010003 STFC ERC Strategic Alliance for the Implementation of New Technologies (SAINT) NASA/ADP 09-ADP09-0059 NASA Office of Space Science National Science Foundatio

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Section: Discussionsupporting

confidence: 71%

“…Besides the C ii regions, a compact H ii region (∼ 1 arcmin) was reported by Matsakis et al (1976) around the brightest star in NGC 2068, HD38563N. Matsakis et al (1976) measured 0.1 Jy at 2.4 GHz. By assuming a temperature of ∼7000 K, they found an electron density of 40 cm −3 .…”

Section: Environment and Physical Conditionsmentioning

confidence: 93%

Dust-correlated centimetre-wave radiation from the M78 reflection nebula

Castellanos

Casassus

Dickinson

et al. 2010

Monthly Notices of the Royal Astronomical Society

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“…Using the integrated radio continuum flux density from within the boundary of each HII region, we estimated the number of Lyman continuum photons from the following equation (Matsakis et al 1976), derived from the model developed by Mezger & Henderson (1967) and assumptions outlined by Rubin (1968):…”

Section: Lyman Continuum Fluxmentioning

confidence: 99%

Shape analysis of H ii regions – I. Statistical clustering

Campbell-White

Froebrich

Kume

2018

Monthly Notices of the Royal Astronomical Society

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We present here our shape analysis method for a sample of 76 Galactic HII regions from MAGPIS 1.4 GHz data. The main goal is to determine whether physical properties and initial conditions of massive star cluster formation is linked to the shape of the regions. We outline a systematic procedure for extracting region shapes and perform hierarchical clustering on the shape data. We identified six groups that categorise HII regions by common morphologies. We confirmed the validity of these groupings by bootstrap re-sampling and the ordinance technique multidimensional scaling. We then investigated associations between physical parameters and the assigned groups. Location is mostly independent of group, with a small preference for regions of similar longitudes to share common morphologies. The shapes are homogeneously distributed across Galactocentric distance and latitude. One group contains regions that are all younger than 0.5 Myr and ionised by low-to intermediate-mass sources. Those in another group are all driven by intermediate-to high-mass sources. One group was distinctly separated from the other five and contained regions at the surface brightness detection limit for the survey. We find that our hierarchical procedure is most sensitive to the spatial sampling resolution used, which is determined for each region from its distance. We discuss how these errors can be further quantified and reduced in future work by utilising synthetic observations from numerical simulations of HII regions. We also outline how this shape analysis has further applications to other diffuse astronomical objects.

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“…We have calculated the number of Lyman continuum photons (Nuv) using the radio continuum map and following the formulation of Matsakis et al (1976):…”

Section: Lyman Continuum Flux and Ionizing Feedbackmentioning

confidence: 99%

Star formation around the mid-infrared bubble CN 148

Dewangan

Ojha

Grave

et al. 2014

Monthly Notices of the Royal Astronomical Society

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We present a multi-wavelength study to analyse the star formation process associated with the mid-infrared bubble CN 148 (H ii region G10.3-0.1), which harbors an O5V-O6V star. The arc-shaped distribution of molecular CO(2-1) emission, the cold dust emission, and the polycyclic aromatic hydrocarbon features trace a photodissociation region (PDR) around the H ii region. We have identified 371 young stellar objects (YSOs) in the selected region and, interestingly, their spatial distribution correlates well with the PDR. 41% of these YSOs are present in 13 clusters, each having visual extinction larger than 16 mag. The clusters at the edges of the bubble (both northeast and southwest) are found to be relatively younger than the clusters located further away from the bubble. We also find that four 6.7 GHz methanol masers, two Extended Green Objects, an ultra-compact H ii region, and a massive protostar candidate (as previously reported) are spatially positioned at the edges of the bubble. The existence of an apparent age gradient in YSO clusters and different early evolutionary stages of massive star formation around the bubble suggest their origin to be influenced by an H ii region expanding into the surrounding interstellar medium. The data sets are suggestive of triggered star formation.

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Radio continuum measurements of compact H II regions and other sources

Cited by 43 publications

References 0 publications

Dust-correlated centimetre-wave radiation from the M78 reflection nebula

Dust-correlated centimetre-wave radiation from the M78 reflection nebula

Shape analysis of H ii regions – I. Statistical clustering

Star formation around the mid-infrared bubble CN 148

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