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A Sensitive Survey for Water Maser Emission Toward Bok Globules Using the Robledo 70 m Antenna
We report on the most sensitive water maser survey toward Bok globulesto date, performed using NASA's 70 m antenna at Robledo de Chavela(Spain). We observed 207 positions within the Clemens and Barvainiscatalog with a higher probability of harboring a young star, using asselection criteria the presence of radio continuum emission (fromsubmillimeter to centimeter wavelengths), geometric centers of molecularoutflows, peaks in maps of high-density gas tracers (NH3 orCS), and IRAS point sources. We have obtained seven maser detections,six of which (in CB 34, CB 54, CB 65, CB 101, CB 199, and CB 232) arereported for the first time here. Most of the water masers we detectedare likely to be associated with young stellar objects (YSOs), exceptfor CB 101 (probably an evolved object) and CB 65 (uncertain nature).The water maser in CB 199 shows a relatively high shift (~=30 kms-1) of its velocity centroid with respect to the cloudvelocity, which is unusual for low-mass YSOs. We speculate thathigh-velocity masers in this kind of object could be related to episodesof energetic mass loss in close binaries. Alternatively, the maser in CB199 could be pumped by a protoplanetary or a young planetary nebula. CB232 is the smallest Bok globule (~=0.6 pc) known to be associated withwater maser emission, although it would be superseded by the cases of CB65 (~=0.3 pc) and CB 199 (~=0.5 pc) if their association with YSOs isconfirmed. All our selection criteria have statistically compatibledetection rates, except for IRAS sources, which tend to be somewhatworse predictors for the presence of maser emission.
| Stellar Spectra in Milky way Regions. I. a. Region in Aquila.
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1949ApJ...109..426M&db_key=AST
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