Water Vapor: Observations of Galactic Sources

Meeks, M. L.; Carter, J. C.; Barrett, A. H.; Schwartz, P. R.; Waters, J. W.; Brown, William E

doi:10.1126/science.165.3889.180

Cited by 26 publications

(12 citation statements)

References 16 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The combination of these four objects (hereafter referred to as NGC 6334I, see Fig. 10) produce maser radiation from hydroxyl (OH), water (H 2 O) at 22.2 GHz (Meeks et al 1969), and methanol (CH 3 OH) at 12.2 GHz (Batrla et al 1987), 6.7 GHz (Menten 1991) and various other higher frequencies (see Val'tts et al 1999;Haschick et al 1990;Menten & Batrla 1989;. Many of these masers have been found to vary, as noted in several published works (see section 4).…”

Section: Introductionmentioning

confidence: 99%

A masing event in NGC 6334I: contemporaneous flaring of hydroxyl, methanol, and water masers

MacLeod

Smits

Goedhart

et al. 2018

Monthly Notices of the Royal Astronomical Society

View full text Add to dashboard Cite

As a product of the maser monitoring program with the 26 m telescope of the Hartebeesthoek Radio Astronomy Observatory (HartRAO), we present an unprecedented, contemporaneous flaring event of 10 maser transitions in hydroxyl, methanol, and water that began in 2015 January in the massive star-forming region NGC 6334I in the velocity range −10 to −2 km s −1 . The 6.7 GHz methanol and 22.2 GHz water masers began flaring within 22 days of each other, while the 12.2 GHz methanol and 1665 MHz hydroxyl masers flared 80 and 113 days later respectively. The 1665 MHz, 6.7 GHz, and 22.2 GHz masers have all remained in their flared state for nearly 3 years. The brightest flaring components increased by factors of 66, 21, 26, and 20 in the 12.2 and 6.7 GHz methanol, 1665 MHz hydroxyl and 22.2 GHz water maser transitions respectively; some weaker components increased by up to a factor of 145. We also report new maser emission in the 1720, 6031, and 6035 MHz OH lines and the 23.1 GHz methanol line, along with the detection of only the fifth 4660 MHz OH maser. We note the correlation of this event with the extraordinary (sub)millimeter continuum outburst from the massive protostellar system NGC 6334I-MM1 and discuss the implications of the observed time lags between different maser velocity components on the nature of the outburst. Finally, we identify two earlier epoch maser flaring events likely associated with this object, which suggest a recurring accretive phenomenon that generates powerful radiative outbursts.

show abstract

Section: Introductionmentioning

confidence: 99%

A masing event in NGC 6334I: contemporaneous flaring of hydroxyl, methanol, and water masers

MacLeod

Smits

Goedhart

et al. 2018

Monthly Notices of the Royal Astronomical Society

View full text Add to dashboard Cite

show abstract

“…Specific properties of VY CMa are summarized in Meeks et al (1969). This star was one of the four bright sources that were the subject of the first interferometric observations of 22-GHz water masers (Burke et al 1970), and it is also a source of several mm-wave and sub-mm water masers.…”

Section: Water Masers In Red Supergiantsmentioning

confidence: 99%

“…The original detection towards the Orion starforming region (Cheung et al 1969) was followed up by observations that included the red supergiant star VY CMa (Meeks et al 1969). Modern surveys of star-forming and evolved star sources have been carried out, or are in progress.…”

Section: Introductionmentioning

confidence: 99%

The physics of water masers observable with ALMA and SOFIA: model predictions for evolved stars

Gray

Baudry

Richards

et al. 2015

Mon. Not. R. Astron. Soc.

View full text Add to dashboard Cite

We present the results of models that were designed to study all possible water maser transitions in the frequency range 0-1.91 THz, with particular emphasis on maser transitions that may be generated in evolved-star envelopes and observed with the ALMA and SOFIA telescopes. We used tens of thousands of radiative transfer models of both spin species of H 2 O, spanning a considerable parameter space in number density, kinetic temperature and dust temperature. Results, in the form of maser optical depths, have been summarized in a master table, Table 6. Maser transitions identified in these models were grouped according to loci of inverted regions in the density/kinetic temperature plane, a property clearly related to the dominant mode of pumping. A more detailed study of the effect of dust temperature on maser optical depth enabled us to divide the maser transitions into three groups: those with both collisional and radiative pumping schemes (22,96,209,321,325,395,941 and 1486 GHz), a much larger set that are predominantly radiatively pumped, and another large group with a predominantly collisional pump. The effect of accelerative and decelerative velocity shifts of up to 5 km s −1 was found to be generally modest, with the primary effect of reducing computed maser optical depths. More subtle asymmetric effects, dependent on line overlap, include maximum gains offset from zero shift by >1 km s −1 , but these effects were predominantly found under conditions of weak amplification. These models will allow astronomers to use multi-transition water maser observations to constrain physical conditions down to the size of individual masing clouds (size of a few astronomical units).

show abstract

“…For a long time, the region between the stars was considered to be too hostile to contain quantities of molecules, but at the end of the 1960s, ammonia [2], water [3,4] and formaldehyde [5] were observed. So far, about 150 molecules (Table 1) and 100 isotopomers have been discovered in the ISM, and numerous reviews tried to explain the synthesis of these compounds in this medium [6][7][8][9][10].…”

Section: Introductionmentioning

confidence: 99%

“…Most of them are small by the number of atoms. Chemistry in the ISM can be performed in the gas phase or on the grains since solid mixtures containing H 2 O, CO 2 , CO, NH 3 , CH 3 OH or CH 4 were identified via IR spectroscopy toward the dense cloud TMC-1 [11]. Even with only 1% of the interstellar matter, the dust components play a key role in the chemistry of the ISM, and particularly shield molecules in the gas phase from the destructive external UV radiation field.…”

Section: Introductionmentioning

confidence: 99%

Organic synthesis applied to space sciences

Guillemin

2011

EPJ Web of Conferences

View full text Add to dashboard Cite

Abstract. About 160 molecules have been detected in the interstellar medium, the comae and the atmospheres of planets. The presence of these compounds leads to imagine a chemistry of these media to explain the formation of these species and to predict the possible presence of other ones. Many of them have never been synthesized or isolated in labs and their preparation can be challenging, up to necessitate news reactions or special equipments.

show abstract

Water Vapor: Observations of Galactic Sources

Cited by 26 publications

References 16 publications

A masing event in NGC 6334I: contemporaneous flaring of hydroxyl, methanol, and water masers

A masing event in NGC 6334I: contemporaneous flaring of hydroxyl, methanol, and water masers

The physics of water masers observable with ALMA and SOFIA: model predictions for evolved stars

Organic synthesis applied to space sciences

Contact Info

Product

Resources

About