Vlba Surveys of Oh Masers in Star-Forming Regions. I. Satellite Lines

Ruiz-Velasco, A. E.; Felli, Derek; Migenes, V.; Wiggins, Brandon

doi:10.3847/0004-637x/822/2/101

Cited by 8 publications

(5 citation statements)

References 37 publications

(44 reference statements)

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“…7. This complex also hosts H 2 O masers (Hofner & Churchwell 1996), OH masers (Forster & Caswell 1999;Ruiz-Velasco et al 2016), CH 3 OH masers (Breen et al 2015) and numerous molecules (Fu & Lin 2016;Kim et al 2000), as well as infall/outflows traced by CO or water masers (e.g. Wyrowski et al 2016;van der Tak et al 2019;Yang et al 2018;Imai et al 2011).…”

Section: G0247898+00833mentioning

confidence: 99%

A population of hypercompact H II regions identified from young H II regions

Yang

Urquhart

Menten

et al. 2021

A&A

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Context. The derived physical parameters for young H ii regions are normally determined assuming the emission region to be optically thin. However, this assumption is unlikely to hold for young H ii regions such as hyper-compact H ii (HC H ii) and ultra-compact H ii (UC H ii) regions and leads to underestimation of their properties. This can be overcome by fitting the SEDs over a wide range of radio frequencies. Aims. The two primary goals of this study are (1) to determine the physical properties of young H ii regions from radio SEDs in the search for potential HC H ii regions, and (2) to use these physical properties to investigate their evolution. Methods. We used the Karl G. Jansky Very Large Array (VLA) to observe the X-band and K-band with angular resolutions of ∼ 1.7 and ∼ 0.7 , respectively, toward 114 H ii regions with rising-spectra (α 5 GHz 1.4 GHz > 0). We complement our observations with VLA archival data and construct SEDs in the range of 1−26 GHz and model them assuming an ionization-bounded H ii region with uniform density. Results. Our sample has a mean electron density of n e = 1.6 × 10 4 cm −3 , diameter diam = 0.14 pc, and emission measure EM = 1.9 × 10 7 pc cm −6. We identify 16 HC H ii region candidates and 8 intermediate objects between the classes of HC H ii and UC H ii regions. The n e , diam, and EM change, as expected, but the Lyman continuum flux is relatively constant over time. We find that about 67% of Lyman-continuum photons are absorbed by dust within these H ii regions and the dust absorption fraction tends to be more significant for more compact and younger H ii regions. Conclusions. Young H ii regions are commonly located in dusty clumps; HC H ii regions and intermediate objects are often associated with various masers, outflows, broad radio recombination lines, and extended green objects, and the accretion at the two stages tends to be quickly reduced or halted.

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Section: G0247898+00833mentioning

confidence: 99%

A population of hypercompact H II regions identified from young H II regions

Yang

Urquhart

Menten

et al. 2021

A&A

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“…Previous surveys of the 1720 MHz OH maser line by Fish et al (2003) and Ruiz-Velasco et al (2016) suggested that this line is clearly observed from regions with relatively high magnetic field strengths which coincide with H II regions. The significant difference in the velocity between the 1720-MHz line detected by Edris et al (2007) and the main lines could be an indication that the 1720-MHz is tracing another protostellar object or that it is excited by different phenomena.…”

Section: Results and Data Analysismentioning

confidence: 89%

OH maser towards IRAS 06056+2131: polarization parameters and evolution status

Darwish

Richards

Etoka

et al. 2020

Monthly Notices of the Royal Astronomical Society

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We present high angular resolution observations of OH maser emission towards the high-mass star forming region IRAS 06056+2131. The observations were carried out using the UK radio interferometer array, Multi-Element Radio Linked Interferometer Network (MERLIN) in the OH main lines at 1665- and 1667-MHz, in addition to the OH satellite line at 1720-MHz. The results of this study reveal the small upper limit to the size of emission in the 1665-MHz line with an estimated total intensity of ∼4 Jy. We did not detect any emission from the 1667-MHz and 1720-MHz lines. The full polarization mode of MERLIN enables us to investigate the magnetic field in the OH maser region. In this transition, a Zeeman pair is identified from which a magnetic strength of ∼−1.5 mG is inferred. Our results show that IRAS 06056+2131 is highly polarized, with ∼ 96 % circular polarization and ∼ 6 % linear polarization. The linear polarization angle is ∼29○, implying a magnetic field which could be aligned with the outflow direction detected toward this region, but the actual magnetic field direction has an uncertainty of up to 110○ due to the possible effects of Faraday rotation. The star forming evolutionary status of the embedded proto-stellar object is discussed.

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“…IRAS 05168+3634 is a luminous YSO with estimated L=24 × 10 3 L (Varricatt et al 2010) and it is located in a high-mass star-forming region in the pre-UC HII phase (Wang et al 2009). This star-forming region associated with H 2 O, NH 3 , 44 GHz CH 3 OH, as well as 1665 MHz and 1667 MHz OH maser emission (Zhang et al 2005, Molinari et al 1996, Fontani et al 2010, Ruiz-Velasco et al 2016, the SiO (J = 2−1) line (Harju et al 1998), and four 13 CO cores (Guan et al 2008b). Molinari et al (1998) have detected 6-cm radio emission 102 arcsec away from the IRAS 05168+3634 source.…”

Section: Introductionmentioning

confidence: 97%

Study of stellar population in the new extended star formation region associated with five IRAS sources

Azatyan

Nikoghosyan

2018

ComBAO

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We present the investigation results of structure and stellar content of a molecular cloud surrounding the five IRAS sources: 05168+3634, 05184+3635, 05177+3636, 05162+3639, and IRAS 05156+3643. Using multi-color criteria, we identified a rich population of embedded YSO candidates with infrared excess (Class 0/I and Class II) and their characteristics in a quite large molecular cloud which is located in the region of 24 arcmin radius. The molecular cloud includes 240 candidates of YSOs within the radii of sub-regions around 5 IRAS sources. The color-magnitude diagrams of the sub-regions suggest a very young stellar population. We construct the K luminosity function (KLF) of the sub-regions and according to the values of the slopes of KLFs, the age of the sub-regions can be estimated between 0.1-3 Myr. The SEDs are constructed for 45 Class I and 75 Class II evolutionary stages YSOs and the received parameters of those YSOs are well correlated with the results obtained by other methods.

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Vlba Surveys of Oh Masers in Star-Forming Regions. I. Satellite Lines

Cited by 8 publications

References 37 publications

A population of hypercompact H II regions identified from young H II regions

A population of hypercompact H II regions identified from young H II regions

OH maser towards IRAS 06056+2131: polarization parameters and evolution status

Study of stellar population in the new extended star formation region associated with five IRAS sources

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Vlba Surveys of Oh Masers in Star-Forming Regions. I. Satellite Lines

Cited by 8 publications

References 37 publications

A population of hypercompact H II regions identified from young H II regions

A population of hypercompact H II regions identified from young H II regions

OH maser towards IRAS 06056+2131: polarization parameters and evolution status

Study of stellar population in the new extended star formation region associated with five IRAS sources

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A population of hypercompact H II regions identified from young H II regions

A population of hypercompact H II regions identified from young H II regions