New H2O Masers associated with Main-line OH Masers in the Galactic Longitude Range 3° to 60°

Caswell, J. L.; Batchelor, R.; Forster, J. R.; Wellington, K. J.

doi:10.1071/ph830443b

Cited by 12 publications

(8 citation statements)

References 1 publication

Supporting

Mentioning

Contrasting

Order By: Relevance

“…This source is an HC H ii region identified by Beltrán et al (2007), which is found to be associated with many CH 3 OH masers (Surcis et al 2015;Bartkiewicz et al 2016) and OH masers (Forster & Caswell 2000;Caswell et al 2013), H 2 O masers (Caswell et al 1983;Forster & Caswell 2000), and outflows traced by CO (Furuya et al 2002;Beltrán et al 2011) and SiO (Codella et al 2013). Its physical properties such as n e , diam, and EM (Table 8) are consistent with previous results (Beltrán et al 2007;Cesaroni et al 2019).…”

Section: G0247898+00833supporting

confidence: 87%

“…7). This source was found to host H 2 O masers (Caswell et al 1983), OH masers (Caswell et al 2013) and CH 3 OH masers (Bartkiewicz et al 2016), and is associated with CO outflows (Yang et al 2018), broad molecular lines such as SiO (2-1) (Csengeri et al 2016), N 2 H + , and HCO + (Shirley et al 2013) and millimeter RRLs (∆V = 40.34 km s −1 ; Kim et al 2017). The blue-shifted and red-shifted methanol masers spots mapped by Bartkiewicz et al (2016) have a similar orientation as the blue-shifted and red-shifted outflows mapped by Yang et al (2018).…”

Section: G0247898+00833mentioning

confidence: 98%

See 1 more Smart Citation

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

Yang

Urquhart

Menten

et al. 2021

A&A

View full text Add to dashboard Cite

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.

show abstract

Section: G0247898+00833supporting

confidence: 87%

Section: G0247898+00833mentioning

confidence: 98%

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

Yang

Urquhart

Menten

et al. 2021

A&A

View full text Add to dashboard Cite

show abstract

“…The OH 1665 MHz emission shows a similar morphology and velocity range (Argon et al 2000). Caswell (2001) reports the OH 6035 MHz emission and there may also be a water maser emission in the region (Caswell et al 1983). However, an uncertainty of the absolute position in declination is large and we are not able to verify the detailed association.…”

Section: Resultsmentioning

confidence: 74%

European VLBI Network imaging of 6.7 GHz methanol masers

Bartkiewicz

Szymczak

Langevelde

2016

A&A

View full text Add to dashboard Cite

Context. Methanol masers at 6.7 GHz are well known tracers of high-mass star-forming regions. However, their origin is still not clearly understood. Aims. We aimed to determine the morphology and velocity structure for a large sample of the maser emission with generally lower peak flux densities than those in previous surveys. Methods. Using the European VLBI Network (EVN) we imaged the remaining sources from a sample of sources that were selected from the unbiased survey using the Torun 32 m dish. In this paper we report the results for 17 targets. Together they form a database of a total of 63 source images with high sensitivity (3σ rms = 15−30 mJy beam −1 ), milliarcsecond angular resolution (6−10 mas) and very good spectral resolution (0.09 km s −1 or 0.18 km s −1 ) for detailed studies. Results. We studied in detail the properties of the maser clouds and calculated the mean and median values of the projected size (17.4 ± 1.2 au and 5.5 au, respectively) as well as the FWHM of the line (0.373 ± 0.011 km s −1 and 0.315 km s −1 for the mean and median values, respectively), testing whether it was consistent with Gaussian profile. We also found maser clouds with velocity gradients (71%) that ranged from 0.005 km s −1 au −1 to 0.210 km s −1 au −1 . We tested the kinematic models to explain the observed structures of the 6.7 GHz emission. There were targets where the morphology supported the scenario of a rotating and expanding disk or a bipolar outflow. Comparing the interferometric and single-dish spectra we found that, typically, 50-70% of the flux was missing. This phenomena is not strongly related to the distance of the source. Conclusions. The EVN imaging reveals that in the complete sample of 63 sources the ring-like morphology appeared in 17% of sources, arcs were seen in a further 8%, and the structures were complex in 46% cases. The ultra-compact (UC) H II regions coincide in position in the sky for 13% of the sources. They are related both to extremely high and low luminosity masers from the sample.

show abstract

“…Kesteven 78 (G32.8-0.1), with a partly brightened radio shell, was identified as a Galactic SNR by Caswell et al (1975) based on the 408 and 5000MHz observations. A distance of ∼ 8 pc was estimated using the radio surface brightness -diameter (Σ-D) relationship (Caswell et al 1983). A 21cm HI observation with a resolution 2 ′ × 130 ′ × 6.3 km s −1 was made by Gosachinskii & Khersonskii (1985), which suggested a corresponding local standard of rest (LSR) velocity of 90 km s −1 , a distance of 9 kpc, and an age of 12 kyr for the SNR.…”

Section: Introductionmentioning

confidence: 99%

Molecular Environment and an X-Ray Spectroscopy of Supernova Remnant Kesteven 78

Zhou

Chen

2011

ApJ

View full text Add to dashboard Cite

We investigate the molecular environment of the Galactic supernova remnant (SNR) Kesteven 78 and perform an XMM-Newton X-ray spectroscopic study for the northeastern edge of the remnant. SNR Kes 78 is found to interact with the molecular clouds (MCs) at a systemic local standard of rest velocity of 81 km s −1 . At around this velocity, the SNR appears to contact a long molecular strip in the northeast and a large cloud in the east as revealed in the 13 CO line, which may be responsible for the radio brightness peak and the OH maser, respectively. The 12 CO-line bright region morphologically matches the eastern bright radio shell in general, and the SNR is consistent in extent with a CO cavity. Broadened 12 CO line profiles discerned in the eastern maser region and the western clumpy molecular arc and the elevated 12 CO J=2-1/J=1-0 ratios along the SNR boundary may be signatures of shock perturbation in the molecular gas. The SNR-MC association places the SNR at a kinematic distance of 4.8 kpc. The X-rays arising from the northeastern radio shell are emitted by underionized hot (∼ 1.5 keV), low-density (∼ 0.1 cm −3 ) plasma with solar abundance, and the plasma may be of intercloud origin. The age of the remnant is inferred to be about 6 kyr. The size of the molecular cavity in Kes 78 implies an initial mass around 22M ⊙ for the progenitor.

show abstract

New H2O Masers associated with Main-line OH Masers in the Galactic Longitude Range 3° to 60°

Cited by 12 publications

References 1 publication

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

European VLBI Network imaging of 6.7 GHz methanol masers

Molecular Environment and an X-Ray Spectroscopy of Supernova Remnant Kesteven 78

Contact Info

Product

Resources

About

New H2O Masers associated with Main-line OH Masers in the Galactic Longitude Range 3° to 60°

Cited by 12 publications

References 1 publication

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

European VLBI Network imaging of 6.7 GHz methanol masers

Molecular Environment and an X-Ray Spectroscopy of Supernova Remnant Kesteven 78

Contact Info

Product

Resources

About

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