arXiv 1310.45162013-10-16astro-ph.SR

VLA对10颗硅酸盐碳星22 GHz H2O脉泽的巡天

VLA survey of the 22 GHz H2O masers toward 10 silicate carbon stars

K. Ohnaka, D. A. Boboltz, G. Mulitz-Schimel, H. Izumiura, M. Wittkowski

备注：: 6 pages, 2 figures, accepted for publication in Astronomy and Astrophysics

摘要：

尽管它们的光球富含碳，硅酸盐碳星显示出富含氧的星周物质的证据，这些物质被认为存在于盘中。硅酸盐碳星代表有趣的情况下，使我们能够研究双星的可能影响恒星演化和质量损失伴随着形成的磁盘。我们提出了一个小的调查22 GHz的H2O脉泽对10硅酸盐碳星，更好的灵敏度比以前的观测。我们用卡尔G. Jansky甚大天线阵使用最大基线为36公里的最大扩展配置（A配置）。对于我们的一些程序星与嘈杂的IRAS低分辨率光谱（LRS），我们提出了新的中红外光谱获得的甚大望远镜干涉仪和斯皮策太空望远镜。我们在10颗硅酸盐碳星中的5颗（EU And、V778 Cyg、IRAS 06017 +1011、V1415 Cyg和NC 83 =V1945 Cyg）上探测到了H2O脉泽，其中NC 83是新探测到的。在BM Gem、IRAS 07221 -0431、IRAS 08002 -3803、IRAS 18006 -3213和HD 189605方向未探测到H2O脉泽。大部分蓝移和红移脉泽特征之间的速度间隔为10- 14 km/s。如果我们假定脉泽起源于环绕伴星盘，则测得的速度分离转化为5- 7 km/s的旋转速度下限，而对于0.5- 1.7Msun的伴星，脉泽发射区半径的上限估计为10- 68 AU。NC 83、IRAS 06017 +1011和HD 189605的新中红外光谱证实了10微米硅酸盐发射。后两颗恒星在约11.5微米处显示出一个凸起，这可能是由于富含碳的主星持续的质量损失而产生的SiC，而不是由于结晶硅酸盐。我们还报告了对HD 189605在2271 A处的UV通量的检测。

英文摘要：

Despite their carbon-rich photospheres, silicate carbon stars show evidence of oxygen-rich circumstellar material, which is considered to exist in disks. Silicate carbon stars represent interesting cases that allow us to study the possible effects of binarity on stellar evolution and the mass loss accompanied by the formation of disks. We present a small survey of the 22 GHz H2O masers toward 10 silicate carbon stars with much better sensitivity than the previous observations. We observed our sample with the Karl G. Jansky Very Large Array (VLA) using the most expanded configuration (A-configuration) with a maximum baseline of 36 km. For some of our program stars with noisy IRAS Low Resolution Spectra (LRS), we present new mid-IR spectra obtained with the Very Large Telescope Interferometer and the Spitzer Space Telescope. We detected the H2O masers toward 5 out of 10 silicate carbon stars (EU And, V778 Cyg, IRAS06017+1011, V1415 Cyg, and NC83=V1945 Cyg), with NC83 being new detection. No H2O masers were detected toward BM Gem, IRAS07221-0431, IRAS08002-3803, IRAS18006-3213, and HD189605. The velocity separation between the most blue- and red-shifted maser features is 10--14 km/s. If we assume that the masers originate in circum-companion disks, the measured velocity separations translate into a lower limit of the rotational velocity of 5--7 km/s, and the upper limit of the radius of the maser emitting region is estimated to be 10--68 AU for a companion mass of 0.5--1.7 Msun. The new mid-IR spectra of NC83, IRAS06017+1011, and HD189605 confirm the 10 micron silicate emission. The latter two stars show a bump at ~11.5 micron, which is presumably due to SiC originating in the ongoing mass loss from the carbon-rich primary star, not due to crystalline silicate. We also report on the detection of the UV flux at 2271 A toward HD189605.

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英文摘要：

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