New detections of H<sub>2</sub>O maser sources on the 13.7 m radio 
telescope of Purple Mountain Observatory

Han, Fuzhu; Mao, RQ; Lü, Jing; Wu, Yanlin; Sun, Jin; Wang, Jian‐Sheng; Pei, Chunchuan; Fan, Ying; Tang, G. S.; Ji, Huanhuan

doi:10.1051/aas:1998342

Cited by 33 publications

(5 citation statements)

References 7 publications

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“…Some previous studies have detected H 2 O masers (e.g. Han et al 1998;Valdettaro et al 2001), but not the 95 GHz Class I methanol maser here (e.g. Gan et al 2013).…”

Section: Outflow and Other Star-forming Activitiescontrasting

confidence: 54%

In search of infall motion in molecular clumps II: HCO⁺ (1–0) and HCN (1–0) observations toward a sub-sample of infall candidates

Yang

Jiang

Chen

et al. 2020

Res. Astron. Astrophys.

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The study of infall motion helps us to understand the initial stages of star formation. In this paper, we use the IRAM 30-m telescope to make mapping observations of 24 infall sources confirmed in previous work. The lines we use to track gas infall motions are HCO + (1-0) and H 13 CO + (1-0). All 24 sources show HCO + emissions, while 18 sources show H 13 CO + emissions. The HCO + integrated intensity maps of 17 sources show clear clumpy structures; for the H 13 CO + line, 15 sources show clumpy structures. We estimated the column density of HCO + and H 13 CO + using the RADEX radiation transfer code, and the obtained [HCO + ]/[H 2 ] and [H 13 CO + ]/[HCO +] of these sources are about 10 −11 -10 −7 and 10 −3 -1, respectively. Based on the asymmetry of the line profile of the HCO + , we distinguish these sources: 19 sources show blue asymmetric profiles, and the other sources show red profiles or symmetric peak profiles. For eight sources that have double-peaked blue line profiles and signal-to-noise ratios greater than 10, the RATRAN model is used to fit their HCO + (1-0) lines, and to estimate their infall parameters. The mean V in of these sources are 0.3 -1.3 km s −1 , and theṀ in are about 10 −3 -10 −4 M yr −1 , which are consistent with the results of intermediate or massive star formation in previous studies. The V in estimated from the Myers model are 0.1 -1.6 km s −1 , and theṀ in are within 10 −3 -10 −5 M yr −1 . In addition, some identified infall sources show other star-forming activities, such as outflows and maser emissions. Especially for those sources with a double-peaked blue asymmetric profile, most of them have both infall and outflow evidence.

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“…Some previous studies have detected H 2 O masers (e.g. Han et al 1998;Valdettaro et al 2001), but not the 95 GHz Class I methanol maser here (e.g. Gan et al 2013).…”

Section: Outflow and Other Star-forming Activitiescontrasting

confidence: 54%

In search of infall motion in molecular clumps II: HCO⁺ (1–0) and HCN (1–0) observations toward a sub-sample of infall candidates

Yang

Jiang

Chen

et al. 2020

Res. Astron. Astrophys.

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“…The optically thick 12 CO spectral line around the emission peak exhibits an obvious red asymmetric structure. We find that a 22 GHz H 2 O maser (Han et al 1998) and two H II regions (Blitz et al 1982) are associated with this cloud.…”

Section: Massive Mcs Presentationmentioning

confidence: 66%

“…The spectra shown in each plot, with the y-axis on the T MB scale, are averaged over a 90″ × 90″ (3 × 3 pixels) region selected around the brightest pixel of each MC. The magenta crosses denote the 22 GHz H 2 O masers detected toward the star formation regions(Han et al 1998;Valdettaro et al 2001;Sunada et al 2007;Urquhart et al 2011). The H II regions fromBlitz et al (1982) and the WISE catalog(Anderson et al 2014) are marked as green and yellow circles, respectively.…”

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confidence: 99%

Distributions and Physical Properties of Molecular Clouds in the Third Galactic Quadrant: l = [219.°75, 229.°75] and b = [−5.°25, 5.°25]

Dong,

Sun,

et al. 2023

ApJS

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We present the results of an unbiased 12CO/13CO/C18O (J = 1–0) survey in a portion of the third Galactic quadrant (TGQ): 219.°75 ≤ l ≤ 229.°75 and −5.°25 ≤ b ≤ 5.°25. The high-resolution and high-sensitivity data sets help to unravel the distributions and physical properties of the molecular clouds (MCs) in the mapped area. In the LSR velocity range from ∼−1 to ∼85 km s−1, the molecular material successfully traces the Local, Perseus, and Outer arms. In the TGQ, the Outer arm appears to be more prominent than that in the second Galactic quadrant (SGQ), but the Perseus arm is not as conspicuous as that in the SGQ. A total of 1,502 12CO, 570 13CO, and 53 C18O molecular structures are identified, spanning over ∼2 and ∼6 orders of magnitude in size and mass, respectively. Tight mass–radius correlations and virial parameter–mass anticorrelations are observable. Yet, it seems that no clear correlations between velocity dispersion and effective radius can be found over the full dynamic range. The vertical distribution of the MCs renders evident pictures of the Galactic warp and flare.

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“…However, its radial velocity is somewhat lower than that for the other HII regions, and as suggested by the authors, a possible explanation for the discrepancy between the velocities of the ionised and molecular material, would come from the effects of a "Champagne flow" (Tenorio-Tagle, 1979), which would be produced by the ionization front of the associated HII region located at the near edge of the molecular cloud. The presence of a far-IR source (IRAS07333-1838) that has colours characteristic of ultracompact HII regions (Wood & Churchwell, 1989), and the detection of a 22 GHz H2O maser by Han et al (1998), suggest that star formation is still occurring there. Moffat et al (1979) were the first group to obtain some photometric measurements of point sources in the region.…”

Section: Introductionmentioning

confidence: 99%

SOAR-OSIRIS observations of the Sh 2-307 H ii region: triggered star formation beyond the Solar Circle

Roman-Lopes

2009

Monthly Notices of the Royal Astronomical Society

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This work aims to the study of the Sh 2-307 HII region and related stellar population. Near-infrared imaging and spectroscopic observations in the direction of Sh 2-307 were performed using OSIRIS at SOAR Telescope. The photometric data were analysed from color-color, and colour-magnitude diagrams, while the spectroscopic results were interpreted from the comparison of the science spectra with that obtained from known OB stars. From J-, H-and K-band spectra of the brightest source in the cluster, we conclude that it has a near-infrared spectra compatible with that taken for O9v-O9.5v stars. Using the derived spectral type and the respective J, H and K-band photometry, we compute a heliocentric distance of 3.2±0.5 kpc, which for R 0 = 8 kpc, puts this cluster at more than 10 kpc from the Galactic centre. From the Brγ, H 2 , and continuum narrow-band images we were able to detect both the NIR counterpart of the associated HII region, as well as, the interface between the ionised and the cool molecular gas. Using the 5 Ghz continuum flux density taken from the PMN catalogue and the Brγ narrow band image we estimate that the HII region has a mean diameter of 0.94±0.15 pc, mean electron density of 550 cm −3 and an estimated dynamical age of 1.6×10 6 years. The large fraction of sources presenting excess emission at 2µm suggests that the stellar population is very young, with many sources still in the pre-main sequence accreting phase. By the use of theoretical pre-main sequence tracks we derived a cluster mean age of about 2.5 Myears, and from the analyses of the fraction of excess emission sources as a function of their spatial distribution we found evidence for an age spread for the embedded pre-main sequence stellar population. Finally, from the study of the spatial distribution of the low-mass sources relative to the main-cluster source and associated photo-dissociation zones, we conclude that the O-type star probably has been triggering the star formation process in the region.

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New detections of H₂O maser sources on the 13.7 m radio telescope of Purple Mountain Observatory

Cited by 33 publications

References 7 publications

In search of infall motion in molecular clumps II: HCO⁺ (1–0) and HCN (1–0) observations toward a sub-sample of infall candidates

In search of infall motion in molecular clumps II: HCO⁺ (1–0) and HCN (1–0) observations toward a sub-sample of infall candidates

Distributions and Physical Properties of Molecular Clouds in the Third Galactic Quadrant: l = [219.°75, 229.°75] and b = [−5.°25, 5.°25]

SOAR-OSIRIS observations of the Sh 2-307 H ii region: triggered star formation beyond the Solar Circle

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New detections of H2O maser sources on the 13.7 m radio telescope of Purple Mountain Observatory

Cited by 33 publications

References 7 publications

In search of infall motion in molecular clumps II: HCO+ (1–0) and HCN (1–0) observations toward a sub-sample of infall candidates

In search of infall motion in molecular clumps II: HCO+ (1–0) and HCN (1–0) observations toward a sub-sample of infall candidates

Distributions and Physical Properties of Molecular Clouds in the Third Galactic Quadrant: l = [219.°75, 229.°75] and b = [−5.°25, 5.°25]

SOAR-OSIRIS observations of the Sh 2-307 H ii region: triggered star formation beyond the Solar Circle

Contact Info

Product

Resources

About

New detections of H₂O maser sources on the 13.7 m radio telescope of Purple Mountain Observatory

In search of infall motion in molecular clumps II: HCO⁺ (1–0) and HCN (1–0) observations toward a sub-sample of infall candidates

In search of infall motion in molecular clumps II: HCO⁺ (1–0) and HCN (1–0) observations toward a sub-sample of infall candidates