我们目前的广域无线电（12毫米）Mopra望远镜观测的复杂和丰富的大质量恒星形成区G305。我们的目标是利用NH3追踪致密分子含量，从而确定G305内恒星形成的储层，从而确定可用于形成恒星的气体;估计检测到的NH3团块的物理参数（温度、柱密度、质量等）;通过H2O和甲醇脉泽的存在，以及与之相关的YSO和超致密HII区域的分布，定位当前活跃的恒星形成区域地区本文详细介绍了NH_3（J，K），（1，1），（2，2）和（3，3）反转跃迁和22 GHz H_2O脉泽的观测结果。我们观测到一个\sim 1.5 \circ x 1 \circ区域，其角分辨率为\sim 2“，灵敏度为\sim 60 mK/0.4 km s^-1通道。我们确定了15 NH3（1，1），12 NH3（2，2）和6 NH3（3，3）周围的中央HII区的团块。团簇的大小在< 2.6 ~ 10.1pc之间，气体的平均动力学温度为25 K。我们计算了大于10^4 M \odot的团块质量，发现复合物的总分子量为\sim 6 × 10^5 M \odot。我们注意到56个恒星形成示踪剂的位置，并发现与检测到的NH3团块高度相关。我们已经检测到16个H2O脉泽，发现它们与检测到的氨团块相关，并且通常比后期演化阶段的恒星形成示踪剂更接近NH3团块核心。
英文摘要：
We present wide area radio (12 mm) Mopra Telescope observations of the complex and rich massive star forming region G305. Our goals are to determine the reservoir for star formation within G305 using NH3 to trace the dense molecular content, and thus, the gas available to form stars; estimate physical parameters of detected NH3 clumps (temperature, column density, mass etc); locate current areas of active star formation via the presence of H2O and methanol masers and the distribution of YSOs and ultra compact HII regions associated with this region. This paper details the NH3 (J,K), (1,1), (2,2) and (3,3) inversion transition and 22 GHz H2O maser observations. We observed a \sim 1.5\circ x 1\circ region with \sim 2' angular resolution and a sensitivity of \sim 60 mK per 0.4 km s^-1 channel. We identify 15 NH3 (1,1), 12 NH3 (2,2) and 6 NH3 (3,3) clumps surrounding the central HII region. The sizes of the clumps vary between < 2.6 and 10.1 pc, the average kinetic temperature of the gas is 25 K. We calculate clump masses of > 10^4 M\odot and find the total molecular mass of the complex to be \sim 6x10^5 M\odot. We note the positions of 56 star formation tracers, and discover a high degree of correlation with detected NH3 clumps. We have detected 16 H2O masers, find they correlate with the detected ammonia clumps and in general are found closer to the NH3 clump cores than star formation tracers of later evolutionary stages.
High mass stars play an important role in the Interstellar Medium, but much remains to be known about their formation. Class I methanol masers may be unique tracers of an early stage of high mass star formation, and a better understanding of such masers will allow them to be used as more effective probes of the high mass star forming process. We present an investigation of the long-term variability of Class I methanol masers at 44 GHz toward the high mass star forming region DR21(OH). We compare observations taken in 2017 to 2012 and also to 2001 data from the literature. A total of 57 maser s…
We have used catalogues from several Galactic plane surveys and dedicated observations to investigate the relationship between various maser species and Galactic star forming clumps, as identified by the ATLASGAL survey. The maser transitions of interest are the 6.7 & 12.2 GHz methanol masers, 22.2 GHz water masers, and the masers emitting in the four ground-state hyperfine structure transitions of hydroxyl. We find clump association rates for the water, hydroxyl and methanol masers to be 56, 39 and 82 per cent respectively, within the Galactic longitude range of 60° > $l$ > -60°. We investiga…
Aims.Molecular masers, including methanol and hydroxyl masers, and in particular the ones in excited rotational states (ex-OHmasers), are one of the most informative tools for studying star-forming regions. So, the discovery, of new maser sources in theseregions is of great importance. Many studies and surveys of ex-OH maser sources have been carried out in the southern celestialhemisphere, but only a few have been done in the northern hemisphere. The specific aim of this work is to close this gap.Methods.The star-forming regions in the northern hemisphere with known active methanol masers wer…
Molecular maser lines are signposts of high-mass star formation, probing excitation and kinematics of very compact regions in the close environment of young stellar objects and providing useful targets for trigonometric parallax measurements. Only a few NH$_{3}$ (9,6) masers were known so far, and their origin is still poorly understood. Here we aim to find new NH$_{3}$ (9,6) masers to provide a better observational basis to study their role in high-mass star-forming regions. We carried out NH$_{3}$ (9,6) observations toward Cepheus A and G34.26$+$0.15 with the Effelsberg-100 m telescope and t…
A catalog of 44 GHz methanol masers in massive star-forming regions. IV. The high-mass protostellar object sample
本文报道了用卡尔G. Jansky甚大阵列（VLA）; 56个场中有24个显示出脉泽发射。这些数据使我们能够证明协会，在角秒精度，I类脉泽排放与流出，HII地区，和冲击跟踪4.5微米的排放。我们发现，共有83个脉泽组件的线宽范围从0.17至3.3公里秒$^{-1}$与近平坦的分布和一个中位数值为1.1公里秒$^{-1}$。脉泽相对于宿主云系统速度的相对速度范围从$-$ 2.5到3.1 km s $^{-1}$，分布峰值接近零。我们还研究了脉泽之间的相关性和所谓的扩展绿色物体（EGO）从GLIMPSE调查。在每个领域的多个来源，揭示了从红外图像以及从VLA档案数据厘米连续发射，在大多数情况下，44 GHz脉泽的位置相关的EGO似乎跟踪在外地的年轻来源。我们报告一个可能的情况下，44 GHz脉泽与低质量原恒星。如果得到证实，这个区域将是第五个已知的恒星形成区域，拥有与低质量原恒星相关的I类脉泽。我们讨论三种可能的情况下，微波激射器的可变性。
We present results of the investigations of the properties of the methanol $J_1 - J_0$ A$^{-+}$ line series motivated by the recent serendipitous detection of the maser emission in the $14_1 - 14_0$ A$^{-+}$ line at 349~GHz in S255IR-SMA1 soon after the accretion burst. The study includes further observations of several lines of this series in S255IR with the SMA, a mini-survey of methanol lines in the 0.8 mm range toward a sample of bright 6.7~GHz methanol maser sources with the IRAM-30m telescope, and theoretical modeling. We found that the maser component of the $14_1 - 14_0$ A$^{-+}$ line …
We observed H$_2$O (6$_{16}$ $\rightarrow$ 5$_{23}$) maser emission associated with the high-mass star-forming region IRAS 23139+5959 using the KaVA a combination of VLBI arrays between the KVN (Korea) and VERA (Japan). Through multi-epoch KaVA observations, we detected three groups of maser features, two of which coincide with those previously detected by the Karl G. Jansky Very Large Array (VLA). By determining the maser proper motions, we found that the first of maser groups exhibit an expanding motion that traces a wide-angle outflow almost along the line of sight, while the second one see…
OH Masers and the Dust Emissions Towards High Mass Protostellar Objects
背景：OH脉泽辐射与高质量恒星形成区有关。朝向这些区域中的一些区域，OH脉泽与HII区域相关联。对其他人来说，被认为是在一个较早的进化状态，OH脉泽是从HII区偏移。对于这些较晚的区域，人们认为OH脉泽与星周盘有关（例如Edris et al. 2005; Gray et al. 2003）。这些圆盘应该承载着密集的尘埃颗粒。热尘埃的存在可以通过毫米连续辐射以及红外辐射来追踪。目的：研究毫米波连续谱、OH脉泽辐射和红外天文台源之间的联系。方法：选取IRAS星表中的27个大质量恒星形成区（HMSFR）作为样本。2007年）已经在1.1毫米（mm）连续发射的Bolocam银河平面调查（BGPS）进行了研究。结果：在OH脉泽样品的23个源中，在~ 30'范围内发现了1.1mm的连续辐射。这些源被分为三组取决于最近的毫米峰从OH脉泽位置的偏移。OH，毫米和红外发射类型之间的关联已被证实为两个源。一般来说，红外天文台的位置与毫米峰的一致性要比与OH脉泽的一致性好，而且在10个源附近，红外天文台和OH脉泽的位置与同一毫米峰的一致性并不相同。结论：相对较大的位置不确定性不允许确定的结论，但它似乎是红外峰更接近毫米发射比OH脉泽。
We carried out a cyanopolyyne line survey towards a large sample of HMSFRs using the Shanghai Tian Ma 65m Radio Telescope (TMRT). Our sample consisted of 123 targets taken from the TMRT C band line survey. It included three kinds of sources, namely those with detection of the 6.7 GHz CH3OH maser alone, with detection of the radio recombination line (RRL) alone, and with detection of both (hereafter referred to as Maser-only, RRL-only, and Maser-RRL sources, respectively). We detected HC3N in 38 sources, HC5N in 11 sources, and HC7N in G24.790+0.084, with the highest detection rate being found …
We introduce a study of the massive star forming region IRAS 18144--1723 using observations of the 6.7 GHz methanol maser line. Such regions are opaque at short wavelengths but can be observed through radio emission lines. In this study we traced the kinematics of the source on milliarcsecond scales using the Multi-Element-Radio-Interferometer-Network (MERLIN). We found 52 maser spots in the LSR velocity range 45--52 km s$^{-1}$, near the centre of the previously-detected CO range of 21.3--71.3 km s$^{-1}$, lying within $\sim$ 0$''$.5 of IRAS 18144--1723 `B', thought to be a young Class I prot…
