The use of IRAS data to define H II regions

Hughes, V. A.; MacLeod, G. C.

doi:10.1086/115024

Cited by 47 publications

(40 citation statements)

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“…25 µm, 60 µm and 100 µm respectively, the use of these IRAS criteria only identify relatively compact sources. WC89 suggested that the IR colors of ultra-compact (UC) H II regions are distinct from other sources found in the IRAS PSC, which was supported by high resolution VLA observations (Wood & Churchwell 1989b Hughes & MacLeod (1989) found that similar colors select UC H II regions: log 10 (F 25 µm /F 12 µm ) ≥ 0.4 and log 10 (F 60 µm /F 25 µm ) ≥ 0.25 and estimated that there are ∼ 2300 UC H II regions in the Galaxy. It is often assumed that the WC89 criteria identify UC H II regions, but perhaps not more evolved nebulae (e.g.…”

Section: Do the Uc Hii Region Color Criteria Only Select Uc Hii Regions?mentioning

confidence: 83%

The Infrared and Radio Flux Densities of Galactic H ii regions

Makai¹,

Mascoop²,

Johnstone³

2017

ApJ

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We derive infrared and radio flux densities of all ∼ 1000 known Galactic H II regions in the Galactic longitude range 17• . 5 < < 65• . Our sample comes from the Wide-Field Infrared Survey Explorer (WISE) catalog of Galactic H II regions (Anderson et al. 2014). We compute flux densities at six wavelengths in the infrared (Spitzer GLIMPSE 8 µm, WISE 12 µm and 22 µm, Spitzer MIPSGAL 24 µm, and Herschel Hi-GAL 70 µm and 160 µm) and two in the radio (MAGPIS 20 cm and VGPS 21 cm). All H II region infrared flux densities are strongly correlated with their ∼ 20 cm flux densities. All H II regions used here, regardless of physical size or Galactocentric radius, have similar infrared to radio flux density ratios and similar infrared colors, although the smallest regions (r < 1 pc), have slightly elevated IR to radio ratios. The colors log 10 (F 24 µm /F 12 µm ) ≥ 0 and log 10 (F 70 µm /F 12 µm ) ≥ 1.2, and log 10 (F 24 µm /F 12 µm ) ≥ 0 and log 10 (F 160 µm /F 70 µm ) ≤ 0.67 reliably select H II regions, independent of size. The infrared colors of ∼ 22% of H II regions, spanning a large range of physical sizes, satisfy the IRAS color criteria of Wood & Churchwell (1989a) for H II regions, after adjusting the criteria to the wavelengths used here. Since these color criteria are commonly thought to select only ultra-compact H II regions, this result indicates that the true ultra-compact H II region population is uncertain. Comparing with a sample of IR color indices from star-forming galaxies, H II regions show higher log 10 (F 70 µm /F 12 µm ) ratios. We find a weak trend of decreasing infrared to ∼ 20 cm flux density ratios with increasing R gal , in agreement with previous extragalactic results, possibly indicating a decreased dust abundance in the outer Galaxy.

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Section: Do the Uc Hii Region Color Criteria Only Select Uc Hii Regions?mentioning

confidence: 83%

The Infrared and Radio Flux Densities of Galactic H ii regions

Makai¹,

Mascoop²,

Johnstone³

2017

ApJ

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“…Although van de Steene & Pottasch (1993) classify it as a possible PN, this source also fulfils the criteria used by Hughes & MacLeod (1989) to select HII regions from the IRAS Point Source Catalogue (log S 60 μm /log S 25 μm ≥ 0.25 and log S 25 μm /log S 12 μm ≥ 0.4). Therefore its classification as PN is doubtful.…”

Section: Iras 12405−6219mentioning

confidence: 99%

Water maser detections in southern candidate post-AGB stars and planetary nebulae

Suárez

Gómez

Miranda

et al. 2009

A&A

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Aims. We study the incidence and characteristics of water masers in the envelopes of stars in the post-AGB and PN evolutionary stages. Methods. We used the 64-m antenna in Parkes (Australia) to search for water maser emission at 22 GHz, towards a sample of 74 sources with IRAS colours characteristic of post-AGB stars and PNe, at declination < −32 o . In our sample, 39% of the sources are PNe or PNe candidates, and 50% are post-AGB stars or post-AGB candidates. Results. We detected four new water masers, all of them in optically obscured sources: three are in PNe candidates (IRAS 12405−6219, IRAS 15103−5754, and IRAS 16333−4807) and one is in a post-AGB candidate (IRAS 13500−6106). The PN candidate IRAS 15103−5754 has water fountain characteristics and could be the first PN of this class found. Conclusions. We confirm the trend suggested in Paper I that water maser emission during the post-AGB phase is more likely to be present in obscured sources with massive envelopes than in objects with optical counterpart. We propose an evolutionary scenario for water masers in the post-AGB and PNe stages, in which "water fountain" masers could develop during the post-AGB and early PN stages. Later PNe would exhibit lower velocity maser emission, both along jets and close to the central objects, with only the central masers remaining in more evolved PNe.

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“…These studies used the IRAS survey (Hughes & MacLeod 1989;Wood & Churchwell 1989;Bronfman et al 1996;Molinari et al 1996) to look for H ii regions and MYSOs (Sridharan et al 2002;Beuther et al 2002) based on their infrared colors. These samples were then extended using data from the more sensitive Midcourse Space Experiment (MSX; Price et al 2001) point source catalog (Egan et al 2003).…”

Section: Introductionmentioning

confidence: 99%

The ATLASGAL survey: a catalog of dust condensations in the Galactic plane

Csengeri¹,

Urquhart²,

Schüller³

et al. 2014

A&A

215

402

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Context. The formation processes and the evolutionary stages of high-mass stars are poorly understood compared to low-mass stars. Large-scale surveys are needed to provide an unbiased census of high column density sites that can potentially host precursors to high-mass stars. Aims. The ATLASGAL survey covers 420 sq. degree of the Galactic plane, between −80 • < < +60 • at 870 μm. Here we identify the population of embedded sources throughout the inner Galaxy. With this catalog we first investigate the general statistical properties of dust condensations in terms of their observed parameters, such as flux density and angular size. Then using mid-infrared surveys we aim to investigate their star formation activity and the Galactic distribution of star-forming and quiescent clumps. Our ultimate goal is to determine the statistical properties of quiescent and star-forming clumps within the Galaxy and to constrain the star formation processes. Methods. We optimized the source extraction method, referred to as MRE-GCL, for the ATLASGAL maps in order to generate a catalog of compact sources. This technique is based on multiscale filtering to remove extended emission from clouds to better determine the parameters corresponding to the embedded compact sources. In a second step we extracted the sources by fitting 2D Gaussians with the Gaussclumps algorithm. Results. We have identified in total 10861 compact submillimeter sources with fluxes above 5σ. Completeness tests show that this catalog is 97% complete above 5σ and >99% complete above 7σ. Correlating this sample of clumps with mid-infrared point source catalogs (MSX at 21.3 μm and WISE at 22 μm), we have determined a lower limit of 33% that is associated with embedded protostellar objects. We note that the proportion of clumps associated with mid-infrared sources increases with increasing flux density, achieving a rather constant fraction of ∼75% of all clumps with fluxes over 5 Jy/beam being associated with star formation. Examining the source counts as a function of Galactic longitude, we are able to identify the most prominent star-forming regions in the Galaxy. Conclusions. We present here the compact source catalog of the full ATLASGAL survey and investigate their characteristic properties. From the fraction of the likely massive quiescent clumps (∼25%), we estimate a formation time scale of ∼7.5 ± 2.5 × 10 4 yr for the deeply embedded phase before the emergence of luminous young stellar objects. Such a short duration for the formation of high-mass stars in massive clumps clearly proves that the earliest phases have to be dynamic with supersonic motions.

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The use of IRAS data to define H II regions

Cited by 47 publications

References 0 publications

The Infrared and Radio Flux Densities of Galactic H ii regions

The Infrared and Radio Flux Densities of Galactic H ii regions

Water maser detections in southern candidate post-AGB stars and planetary nebulae

The ATLASGAL survey: a catalog of dust condensations in the Galactic plane

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