The VSOP Prelaunch H<sub>2</sub>O Maser Survey. I. VLBA Observations

Migenes, V.; Horiuchi, S.; Slysh, V. I.; Вальтц, И. Е.; Golubev, Vladimir V.; Edwards, Philip; Fomalont, Edward B.; Okayasu, R.; Diamond, P. J.; Umemoto, T.; Shibata, Katsunori M.; Inoue, Makoto

doi:10.1086/313238

Cited by 56 publications

(63 citation statements)

References 29 publications

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“…Previous H 2 O maser observations by Migenes et al (1999) using the VLBA, and by Forster & Caswell (1999) using the VLA, similarly show the maser groups toward MM1, MM3, and CM2. However, we note that the Forster & Caswell (1999) positions must be shifted by approximately −0.…”

Section: H 2 O Maser Emissionsupporting

confidence: 59%

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THE MASSIVE PROTOSTELLAR CLUSTER NGC 6334I AT 220 au RESOLUTION: DISCOVERY OF FURTHER MULTIPLICITY, DIVERSITY, AND A HOT MULTI-CORE

Brogan

Hunter

Cyganowski

et al. 2016

ApJ

122

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We present VLA and ALMA imaging of the deeply-embedded protostellar cluster NGC6334I from 5 cm to 1.3 mm at angular resolutions as fine as 0.′′ 17 (220 AU). The dominant hot core MM1 is resolved into seven components at 1.3 mm, clustered within a radius of 1000 AU. Four of the components have brightness temperatures > 200 K, radii ∼ 300 AU, minimum luminosities ∼ 10 4 L ⊙ , and must be centrally heated. We term this new phenomenon a "hot multi-core". Two of these objects also exhibit compact free-free emission at longer wavelengths, consistent with a hypercompact HII region (MM1B) and a jet (MM1D). The spatial kinematics of the water maser emission centered on MM1D are consistent with it being the origin of the highvelocity bipolar molecular outflow seen in CO. The close proximity of MM1B and MM1D (440 AU) suggests a proto-binary or a transient bound system. Several components of MM1 exhibit steep millimeter SEDs indicative of either unusual dust spectral properties or time variability. In addition to resolving MM1 and the other hot core (MM2) into multiple components, we detect five new millimeter and two new centimeter sources. Water masers are detected for the first time toward MM4A, confirming its membership in the protocluster. With a 1.3 mm brightness temperature of 97 K coupled with a lack of thermal molecular line emission, MM4A appears to be a highly optically-thick 240 L ⊙ dust core, possibly tracing a transient stage of massive protostellar evolution. The nature of the strongest water maser source CM2 remains unclear due to its combination of non-thermal radio continuum and lack of dust emission.

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Section: H 2 O Maser Emissionsupporting

confidence: 59%

“…Likewise, the position uncertainty of the Migenes et al (1999) is unclear as they apparently did not employ phase referencing. However, they do note that their position for another object in their survey differs from the VLA position by 0.…”

Section: H 2 O Maser Emissionmentioning

confidence: 99%

THE MASSIVE PROTOSTELLAR CLUSTER NGC 6334I AT 220 au RESOLUTION: DISCOVERY OF FURTHER MULTIPLICITY, DIVERSITY, AND A HOT MULTI-CORE

Brogan

Hunter

Cyganowski

et al. 2016

ApJ

122

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“…O: sources with strong obscuration, based on their infrared colours (Table 9 in Ramos-Larios et al 2012). ( f ) Migenes et al (1999) reported a water maser of 56 Jy, which was incorrectly labelled as IRAS 18434−0042. The maser is 2 • away from this infrared source and it is associated with the star-forming region W43S instead.…”

Section: Discussionmentioning

confidence: 99%

A search for water maser emission toward obscured post-AGB star and planetary nebula candidates

Gómez

Rizzo

Suárez

et al. 2015

A&A

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Context. Water maser emission at 22 GHz is a useful probe for studying the transition between the nearly spherical mass loss in the asymptotic giant branch (AGB) to a collimated one in the post-AGB phase. In their turn, collimated jets in the post-AGB phase could determine the shape of planetary nebulae once photoionization starts. Aims. We intend to find new cases of post-AGB stars and planetary nebulae (PNe) with water maser emission, including some especially interesting and rare types: water fountains (evolved objects with high velocity collimated jets traced by water masers) or water-maser-emitting PNe. Since previous studies have shown a higher detection rate of water maser emission in evolved objects that are optically obscured, we selected a sample that contains a significant fraction of post-AGB and young PN candidate sources showing signs of strong obscuration. Methods. We searched for water maser emission in 133 evolved objects using the radio telescopes in Robledo de Chavela, Parkes, and Green Bank. Results. We detected water maser emission in 15 sources of our sample, of which seven are reported here for the first time (IRAS 13483−5905, IRAS 14249−5310, IRAS 15408−5413, IRAS 17021−3109, IRAS 17348−2906, IRAS 17393−2727, and IRAS 18361−1203. We identified three water fountain candidates: IRAS 17291−2147, with a total velocity spread of 96 km s −1 in its water maser components and two sources (IRAS 17021−3109 and IRAS 17348−2906) that show water maser emission whose velocity lies outside the velocity range covered by OH masers. We have also identified IRAS 17393−2727 as a possible new watermaser-emitting PN. Conclusions. The detection rate is higher in obscured objects (14%) than in those with optical counterparts (7%), which is consistent with previous results. Water maser emission seems to be common in objects that are bipolar in the near-IR (43% detection rate in such sources). The water maser spectra of water fountain candidates like IRAS 17291−2147 show significantly fewer maser components than others (e.g., IRAS 18113−2503). We speculate that most post-AGBs may show water maser emission with wide enough velocity spread (≥100 km s −1 ) when observed with enough sensitivity and/or for long enough periods of time. Therefore, it may be necessary to single out a special group of "water fountains", probably defined by their high maser luminosities. We also suggest that the presence of both water and OH masers in a PN is a better tracer of its youth, than is the presence of just one of these species.

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“…Besides, several maser lines have been observed from NH 3 (Beuther et al 2007), CH 3 OH (Walsh et al 1998) and H 2 O (Migenes et al 1999) as well as bipolar outflows in CO (Leurini et al 2006;Qiu et al 2011) and SiO (Gibb et al 2007). This source is part of the CHESS program (Chemical HErschel Surveys of Star forming regions), a key program of the Herschel Space Observatory (Ceccarelli et al 2010).…”

Section: Introductionmentioning

confidence: 97%

Molecular line survey of the high-mass star-forming region NGC 6334I withHerschel/HIFI and the Submillimeter Array

Zernickel

Schilke

Schmiedeke

et al. 2012

A&A

107

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Aims. We aim at deriving the molecular abundances and temperatures of the hot molecular cores in the high-mass star-forming region NGC 6334I and consequently deriving their physical and astrochemical conditions. Methods. In the framework of the Herschel guaranteed time key program CHESS (Chemical HErschel Surveys of Star forming regions), NGC 6334I is investigated by using the Heterodyne Instrument for the Far-Infrared (HIFI) aboard the Herschel Space Observatory. A spectral line survey is carried out in the frequency range 480-1907 GHz, and further auxiliary interferometric data from the Submillimeter Array (SMA) in the 230 GHz band provide spatial information for disentangling the different physical components contributing to the HIFI spectrum. The spectral lines in the processed Herschel data are identified with the aid of former surveys and spectral line catalogs. The observed spectrum is then compared to a simulated synthetic spectrum, assuming local thermal equilibrium, and best fit parameters are derived using a model optimization package. Results. A total of 46 molecules are identified, with 31 isotopologues, resulting in about 4300 emission and absorption lines. Highenergy levels (E u > 1000 K) of the dominant emitter methanol and vibrationally excited HCN (ν 2 = 1) are detected. The number of unidentified lines remains low with 75, or <2% of the lines detected. The modeling suggests that several spectral features need two or more components to be fitted properly. Other components could be assigned to cold foreground clouds or to outflows, most visible in the SiO and H 2 O emission. A chemical variation between the two embedded hot cores is found, with more N-bearing molecules identified in SMA1 and O-bearing molecules in SMA2. Conclusions. Spectral line surveys give powerful insights into the study of the interstellar medium. Different molecules trace different physical conditions like the inner hot core, the envelope, the outflows or the cold foreground clouds. The derived molecular abundances provide further constraints for astrochemical models.

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The VSOP Prelaunch H₂O Maser Survey. I. VLBA Observations

Cited by 56 publications

References 29 publications

THE MASSIVE PROTOSTELLAR CLUSTER NGC 6334I AT 220 au RESOLUTION: DISCOVERY OF FURTHER MULTIPLICITY, DIVERSITY, AND A HOT MULTI-CORE

THE MASSIVE PROTOSTELLAR CLUSTER NGC 6334I AT 220 au RESOLUTION: DISCOVERY OF FURTHER MULTIPLICITY, DIVERSITY, AND A HOT MULTI-CORE

A search for water maser emission toward obscured post-AGB star and planetary nebula candidates

Molecular line survey of the high-mass star-forming region NGC 6334I withHerschel/HIFI and the Submillimeter Array

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The VSOP Prelaunch H2O Maser Survey. I. VLBA Observations

Cited by 56 publications

References 29 publications

THE MASSIVE PROTOSTELLAR CLUSTER NGC 6334I AT 220 au RESOLUTION: DISCOVERY OF FURTHER MULTIPLICITY, DIVERSITY, AND A HOT MULTI-CORE

THE MASSIVE PROTOSTELLAR CLUSTER NGC 6334I AT 220 au RESOLUTION: DISCOVERY OF FURTHER MULTIPLICITY, DIVERSITY, AND A HOT MULTI-CORE

A search for water maser emission toward obscured post-AGB star and planetary nebula candidates

Molecular line survey of the high-mass star-forming region NGC 6334I withHerschel/HIFI and the Submillimeter Array

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Product

Resources

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The VSOP Prelaunch H₂O Maser Survey. I. VLBA Observations