A search for water masers associated with class II methanol masers - I. Longitude range 6°-20°
A search for water masers associated with class II methanol masers - I. Longitude range 6°-20°
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DOI：
10.1093/mnras/stu1346
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发表时间：
2014-07
影响因子：
4.8
通讯作者：
A. Titmarsh;A. Titmarsh;S. Ellingsen;S. Breen;J. Caswell;M. Voronkov
中科院分区：
文献类型：
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作者：
A. Titmarsh;A. Titmarsh;S. Ellingsen;S. Breen;J. Caswell;M. Voronkov
澳大利亚望远镜紧凑阵列已被用来寻找22-GHz水脉泽，对119个6.7-GHz甲醇脉泽在甲醇多波束调查发现银河系倾角6°和20°之间;我们发现水脉泽与55（~ 46%）。甲醇脉泽与相关的水脉泽有一个更高的平均积分光度比那些没有和有一个更明亮的6.7-GHz的甲醇脉泽与更明亮的水脉泽发射源的一般趋势。我们已经检查了银河遗产红外线中面巡天（GLIMPSE）的三幅脉泽周围区域的彩色图像，并将脉泽位置与现有的扩展绿色天体和红外暗云目录进行了交叉匹配。我们发现更多的扩展绿色物体在甲醇和水脉泽都存在的网站比只有甲醇脉泽的网站，但没有显着差异的分数嵌入红外暗云。分析的1.1毫米尘埃排放表明，尘埃团块与脉泽，有更大的通量密度和更高的柱密度比那些没有。与水和6.7 GHz甲醇脉泽相关的尘埃团块通常是最紧凑的团块，其次是仅与甲醇相关的团块，然后是没有相关脉泽发射的团块。我们的结论是，原恒星与甲醇和水脉泽往往比那些只有甲醇，但是，我们认为，水脉泽跟踪的演化阶段是不一样的定义为6.7 GHz的甲醇脉泽。
The Australia Telescope Compact Array has been used to search for 22-GHz water masers towards the 119 6.7-GHz methanol masers detected in the Methanol MultiBeam survey between Galactic longitudes 6° and 20°; we find water masers associated with 55 (~46 per cent). Methanol masers with associated water masers have a higher mean integrated luminosity than those without and there is a general trend for sources with more luminous 6.7-GHz methanol masers to be associated with more luminous water maser emission. We have inspected the GLIMPSE (Galactic Legacy Infrared Mid-plane Survey Extraordinaire) three colour images of the regions surrounding the masers and cross-matched the maser positions with existing catalogues of Extended Green Objects and infrared dark clouds. We find more Extended Green Objects at sites where both methanol and water masers are present than at sites with only methanol masers, but no significant difference in the fraction embedded within infrared dark clouds. Analysis of the 1.1-mm dust emission shows dust clumps associated with masers that have greater flux densities and higher column densities than those without. Dust clumps associated with both water and 6.7-GHz methanol masers are generally the most compact clumps followed by those associated with only methanol then the clumps without associated maser emission. We conclude that protostars with both methanol and water masers are often older than those with only methanol; however, we suggest that the evolutionary phase traced by water masers is not as well defined as for 6.7-GHz methanol masers.