Observations of the <sup>2</sup>π<sub>3/2</sub>, J = 7/2 State of OH

Balister, M.; Gardner, F. F.; Knowles, S. H.; Whiteoak, J. B.

doi:10.1017/s1323358000014661

Cited by 6 publications

(6 citation statements)

References 3 publications

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“…Guilloteau et al (1984) and Matthews et al (1986) detected absorption features only. On the other hand, the tentative emission features reported by Balister et al (1976) in M17 and W33 were not confirmed by Guilloteau et al and by us in this work. Balister et al reported a possible 3.7 Jy emission in G309.9+0.48 but give no detail apart from their spectrum; their detection looks rather convincing but was not repeated as far as we are aware.…”

Section: Individual Sources and Discussioncontrasting

confidence: 90%

Discovery of new highly excited OH sources in regions of high-mass star formation

Baudry

Desmurs

2002

A&A

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Abstract.We have carried out sensitive observations of the highly excited 2 Π 3 2 , J = 7 2 state of OH (290 K above the groundlevel) at 13 441 MHz (F = 4 − 4) and 13 435 MHz (F = 3 − 3) in both right and left circular polarizations with the Effelsberg 100-m telescope. Our sample included 27 compact or ultra-compact HII regions. Most of them have been selected from our previous J = , F = 4 − 4 and 3 − 3 absorption in 7 sources and discovered 3 new weak F = 4 − 4 maser sources at 13 441 MHz in addition to W3(OH). The new sources, 20081+3122 (ON1), 21413+5442 and G11.90−0.14, are 50 to 100 times or more weaker than the 13 441 MHz peak flux density observed in W3(OH). 21413+5442 and G11.90−0.14 exhibit extremely narrow velocity extents of the order of 0.4 km s −1 . However, in ON1 there are two groups of narrow velocity features separated by about 14 km s −1 ; these two groups are also observed in lower rotational levels and suggest complex kinematics in the envelope of the young ultra-compact HII region. Apart from a very weak, polarized, and narrow J = , F = 3 − 3 emission was discovered. We conclude that the 13 441 MHz OH maser emission from W3(OH) remains exceptionally strong but not unique. In contrast with the J = , 13 441 MHz emission is not widespread. This is expected from OH maser theory, and because the involved J = 7 2 levels are high in the OH energy ladder and not directly connected to the ground-state.

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Section: Individual Sources and Discussioncontrasting

confidence: 90%

Discovery of new highly excited OH sources in regions of high-mass star formation

Baudry

Desmurs

2002

A&A

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“…We now consider the discrepancy between our data and the data from 1975 November by Balister et al (1976). The solitary feature in the Balister et al spectrum was at −61 km s −1 , but should be adjusted to −59.97 km s −1 , to correct it to the now better‐known rest frequency used here.…”

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confidence: 80%

“…309.921+0.479. This was one of five sites that were reported as tentative detections, with intensities of several Jy, by Balister et al (1976). Most of these have not been verifiable in later observations of much greater sensitivity.…”

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confidence: 85%

New OH masers at 13 441 MHz

Caswell

2004

Monthly Notices of the Royal Astronomical Society

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The Parkes radio telescope has been used to study maser emission from the 13 441‐MHz transition of highly excited OH. The targets were 56 catalogued sites of 6035‐MHz maser emission. Eight 13 441‐MHz maser sites were detected, six of them new and two that had previously been reported. This more than doubles the number now known to 11. At every 13 441‐MHz maser site, spectral features occur as right‐ and left‐hand circularly polarized matched pairs, with small, but mostly significant, frequency separation. This is attributed to the Zeeman effect in magnetic fields of a few mG. Some of the 13 441‐MHz maser sites show features at several different velocities. All of the 13 441‐MHz maser features have 6035‐MHz counterparts that closely correspond in velocity. At three sites, features of 13 441‐MHz emission rival the intensities of their 6035‐MHz counterparts; at the other sites, features are weaker than at 6035 MHz by factors of between 3 and 50. Upper limits at some sites searched can be set more than 2 orders of magnitude weaker than 6035‐MHz emission. The detection statistics provide unique opportunities to test recent advances in maser modelling. A search for the 13 434‐MHz transition towards the same 56 targets yielded no detections.

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“…To date, only 11 sources are known to host 13441 MHz masers, most detected only recently (Turner et al 1970;Baudry & Desmurs 2002;Caswell 2004). In addition, several possible sources were detected by Balister et al (1976) but not subsequently redetected.…”

Section: Introductionmentioning

confidence: 98%

OH Masers in G11.904-0.141

Fish

2007

ApJ

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The massive star-forming region G11.904-0.141 is one of only 11 sources to show maser emission in the highly-excited 13441 MHz transition of OH. VLBA observations of the 1665, 1667, 4765, and 13441 MHz transitions of OH toward G11.904-0.141 are presented. Masers are detected at 1665, 1667, and 4765 MHz, but the 13441 MHz masers are not detected. Consistent magnetic field strengths of approximately +3.5 mG are detected in the ground-state masers, in contrast with a possible -3.0 mG magnetic field previously detected at 13441 MHz. The variable 13441 MHz masers may be associated with an outflow.Comment: 3 pages using emulateapj.cls including 1 table, accepted to ApJ

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Observations of the ²π_3/2, J = 7/2 State of OH

Cited by 6 publications

References 3 publications

Discovery of new highly excited OH sources in regions of high-mass star formation

Discovery of new highly excited OH sources in regions of high-mass star formation

New OH masers at 13 441 MHz

OH Masers in G11.904-0.141

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Observations of the 2π3/2, J = 7/2 State of OH

Cited by 6 publications

References 3 publications

Discovery of new highly excited OH sources in regions of high-mass star formation

Discovery of new highly excited OH sources in regions of high-mass star formation

New OH masers at 13 441 MHz

OH Masers in G11.904-0.141

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Observations of the ²π_3/2, J = 7/2 State of OH