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arXiv 1302.3018astro-ph.GA
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解读大质量恒星形成复合体G75 .78+0.34中的电离气体含量

Deciphering the ionized gas content in the massive star forming complex G75.78+0.34

Alvaro Sanchez-Monge, Stan Kurtz, Aina Palau, Robert Estalella, Debra Shepherd, Susana Lizano, Jose Franco, Guido Garay

摘要:

我们目前的大质量恒星形成区G75.78+0.34的亚弧秒观测。我们用甚大射电列阵研究了厘米级连续谱和H_2O、CH_3OH脉泽发射,用欧文斯谷射电天文台和亚毫米射电列阵研究了毫米级连续谱和复合谱线(H_40 α和H_30 α)。我们发现了所有波长的无线电连续辐射,来自三个组成部分:(1)彗星超致密(UC)HII区,电子密度为3.7 × 10^4 cm^{-3},由B 0型恒星激发,没有相关的尘埃辐射;(2)一个几乎无法分辨的UCHII区(EAST),位于彗星UCHII区以东6角秒,电子密度为1.3 × 10^5 cm^{-3},与一个在毫米和中红外波段探测到的致密尘埃团有关;(3)一个致密源(CORE),位于彗星弧西南2角秒处,通量密度随频率增加而增加,并嵌入30 Msun的尘埃凝结中。CORE源被分解成两个紧凑的和未解决的源,可以很好地拟合由两个均匀的超紧凑HII区域,每个区域由B0.5 ZAMS星光电离,或由自由自由辐射的冲击电离气体产生的喷流/流出系统与周围环境的相互作用。水脉泽的空间分布和运动学接近的核心-N和S源,在4.5妈妈的过量排放和检测到的尘埃排放,一起表明,核心源是一个巨大的原恒星驱动的喷流/流出。

英文摘要:

We present sub-arcsecond observations toward the massive star forming region G75.78+0.34. We used the Very Large Array to study the centimeter continuum and H2O and CH3OH maser emission, and the Owens Valley Radio Observatory and Submillimeter Array to study the millimeter continuum and recombination lines (H40alpha and H30alpha). We found radio continuum emission at all wavelengths, coming from three components: (1) a cometary ultracompact (UC) HII region with an electron density 3.7x10^4 cm^{-3}, excited by a B0 type star, and with no associated dust emission; (2) an almost unresolved UCHII region (EAST), located 6 arcsec to the east of the cometary UCHII region, with an electron density 1.3x10^5 cm^{-3}, and associated with a compact dust clump detected at millimeter and mid-infrared wavelengths; and (3) a compact source (CORE), located 2 arcsec to the southwest of the cometary arc, with a flux density increasing with frequency, and embedded in a dust condensation of 30 Msun. The CORE source is resolved into two compact and unresolved sources which can be well-fit by two homogeneous hypercompact HII regions each one photo-ionized by a B0.5 ZAMS star, or by free-free radiation from shock-ionized gas resulting from the interaction of a jet/outflow system with the surrounding environment. The spatial distribution and kinematics of water masers close to the CORE-N and S sources, together with excess emission at 4.5 mum and the detected dust emission, suggest that the CORE source is a massive protostar driving a jet/outflow.

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