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arXiv 1007.5149astro-ph.GA
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富氧与富碳的星周壳的比较光谱:VY大犬座和IRC +10216在215-285 GHz

Comparative Spectra of Oxygen-Rich vs. Carbon-Rich Circumstellar Shells: VY Canis Majoris and IRC+10216 at 215-285 GHz

E. D. Tenenbaum, J. L. Dodd, S. N. Milam, N. J. Woolf, L. M. Ziurys

摘要:

对大犬座VY(VY CMa)和IRC+10216进行了1 mm谱线(214.5- 285.5GHz)的高灵敏度(1σ rms,1 MHz分辨率~3 mK)测量,比较了富氧和富碳的星周包层的化学性质。这项研究是使用亚利桑那射电天文台(ARO)的亚毫米波望远镜(SMT)与一个新的ALMA型接收机进行的。这项调查是第一次在毫米波长下对富氧的拱星壳进行化学表征。在VY CMa中,检测到来自18种不同分子的128个发射特征,在IRC+10216中,观察到720条谱线,分配给32种不同的物质。VY CMa的1 mm光谱主要由SO2和SiS组成; IRC +10216中,C4 H和SiC 2是最常见的物种。两种来源共有10种分子:CO、SiS、SiO、CS、CN、HCN、HNC、NaCl、PN和HCO+。硫在VY CMa中起重要作用,但饱和/不饱和碳主导IRC+10216的分子含量,例如产生CH 2NH。虽然IRC+10216的分子复杂性更大,但VY CMa支持独特的“无机”化学,导致氧化物PO,AlO和AlOH。在VY CMa中只观察到双原子和三原子化合物,而IRC+10216中常见的是4个或更多原子的物质,反映了碳形成强多重键的能力,不像氧。在VY CMa中,发现了一个新的水脉泽(v_2=2)和振动激发的NaCl。对于IRC+10216,首次检测到振动激发的CCH。

英文摘要:

A sensitive (1σ rms at 1 MHz resolution ~3 mK) 1 mm spectral line survey (214.5-285.5 GHz) of VY Canis Majoris (VY CMa) and IRC+10216 has been conducted to compare the chemistries of oxygen and carbon-rich circumstellar envelopes. This study was carried out using the Submillimeter Telescope (SMT) of the Arizona Radio Observatory (ARO) with a new ALMA-type receiver. This survey is the first to chemically characterize an O-rich circumstellar shell at millimeter wavelengths. In VY CMa, 128 emission features were detected arising from 18 different molecules, and in IRC+10216, 720 lines were observed, assigned to 32 different species. The 1 mm spectrum of VY CMa is dominated by SO2 and SiS; in IRC +10216, C4H and SiC2 are the most recurrent species. Ten molecules were common to both sources: CO, SiS, SiO, CS, CN, HCN, HNC, NaCl, PN, and HCO+. Sulfur plays an important role in VY CMa, but saturated/unsaturated carbon dominates the molecular content of IRC+10216, producing CH2NH, for example. Although the molecular complexity of IRC+10216 is greater, VY CMa supports a unique "inorganic" chemistry leading to the oxides PO, AlO, and AlOH. Only diatomic and triatomic compounds were observed in VY CMa, while species with 4 or more atoms are common in IRC+10216, reflecting carbon's ability to form strong multiple bonds, unlike oxygen. In VY CMa, a new water maser (v_2=2) has been found, as well as vibrationally-excited NaCl. Toward IRC+10216, vibrationally-excited CCH was detected for the first time.

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