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首页> 外文期刊>The Astrophysical journal >HIGH-RESOLUTION 4.7 MICRON KECK/NIRSPEC SPECTRA OF PROTOSTARS. I. ICES AND INFALLING GAS IN THE DISK OF L1489 IRS
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HIGH-RESOLUTION 4.7 MICRON KECK/NIRSPEC SPECTRA OF PROTOSTARS. I. ICES AND INFALLING GAS IN THE DISK OF L1489 IRS

机译：高分辨率4.7 MICROKECK / NIRSPEC的原恒星光谱。 I.L1489国税局磁盘中的冰和入侵气体

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摘要

We explore the infrared M-band (4.7 μm) spectrum of the Class Ⅰ protostar L1489 IRS in the Taurus molecular cloud. This is the highest-resolution wide-coverage spectrum at this wavelength of a low-mass protostar observed to date (R = 25,000; Δv = 12 km s~(-1)). A large number of narrow absorption lines of gas-phase ~(12)CO, ~(13)CO, and C~(18)O are detected, as well as a prominent band of solid ~(12)CO. The gas-phase ~(12)CO lines have redshifted absorption wings (up to 100 km s~(-1)), which likely originate from warm disk material falling toward the central object. Both the isotopes and the extent of the ~(12)CO line wings are successfully fitted with a contracting-disk model of this evolutionary transitional object. This shows that the inward motions seen in millimeter-wave emission lines continue to within ～0.1 AU of the star. The amount of high-velocity infalling gas is, however, overestimated by this model, suggesting that only part of the disk is Mailing, e.g., a hot surface layer or hot gas in magnetic field tubes. The colder parts of the disk are traced by the prominent CO-ice band. The band profile results from CO in " polar " ices (CO mixed with H_2O) and CO in " apolar " ices. At high spectral resolution, the " apolar " component is, for the first time, resolved into two distinct components, likely due to pure CO and CO mixed with CO_2, O_2, and/or N_2. The ices have probably undergone thermal processing in the upper disk layer traced by our pencil absorption beam: much of the volatile " apolar " ices has evaporated, the depletion factor of CO onto grains is remarkably low (～7%), and the CO_2 traced in the CO-band profile was possibly formed energetically. This study shows that high spectral resolution 4.7 μm observations provide important and unique information on the dynamics and structure of proto-stellar disks and on the origin and evolution of ice0s in these disks.
机译：我们探索了金牛座分子云中的Ⅰ类原恒星L1489 IRS的红外M波段（4.7μm）光谱。这是迄今为止观测到的低质量原恒星在该波长下的最高分辨率宽覆盖谱（R = 25,000;Δv= 12 km s〜（-1））。检测到大量的气相〜（12）CO，〜（13）CO和C〜（18）O窄吸收线，以及固体〜（12）CO的显着谱带。气相〜（12）CO线具有红移的吸收翼（最大100 km s〜（-1）），这可能是由于温暖的磁盘材料向中心物体坠落所致。同位素和〜（12）CO线翅的范围都成功地拟合了该演化过渡物体的收缩盘模型。这表明在毫米波发射线上看到的向内运动继续在恒星的〜0.1 AU之内。但是，该模型高估了高速落入气体的量，这表明仅磁盘的一部分是邮件，例如，热表面层或磁场管中的热气体。圆盘较冷的部分可通过突出的CO-ICE带找到。能带分布是由“极地”冰中的CO（CO与H_2O混合）和“非极地”冰中的CO产生的。在高光谱分辨率下，“非极性”成分首次被分解为两个不同的成分，这可能是由于纯CO和CO与CO_2，O_2和/或N_2混合所致。我们的铅笔吸收束追踪到的上部圆盘层中的冰可能已经过热处理：大部分挥发性的“非极性”冰已经蒸发，CO在谷物上的消耗因子非常低（〜7％），并且追踪到的CO_2 CO带轮廓中的α可能是能量形成的。这项研究表明，高光谱分辨率的4.7μm观测值提供了有关原恒星盘动力学和结构以及这些盘中冰的起源和演化的重要而独特的信息。

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