过渡盘中盘变平或气体耗尽的赫歇尔证据
Herschel evidence for disk flattening or gas depletion in transitional disks
摘要:
过渡盘是原行星盘,其特征是相对于完整的盘,近红外和中红外辐射减少。这种特征性的光谱能量分布表明,在尘埃盘内存在一个光学薄的内腔,据信这标志着原始大质量盘的消失。我们提出了新的赫歇尔空间天文台PACS光谱的[OI] 63微米的21个过渡盘。我们的调查补充了更大的赫歇尔GASPS计划“原行星系统中的气体”(Dent et al. 2013),通过将PACS在该波长下观察到的过渡盘的数量增加了四倍。[OI]63微米的痕迹物质在盘的外部区域,超出大多数过渡盘的内腔。我们发现,过渡磁盘有[OI] 63微米线光度比他们的全磁盘同行的两倍微弱。我们自我一致地确定各种恒星属性(例如,热光度,FUV过剩等)。和磁盘属性(例如磁盘灰尘质量等)这可能会影响[OI] 63微米线的光度,我们发现没有相关性,可以解释较低的[OI] 63微米线的光度在过渡盘。使用网格的热化学原行星盘模型,我们的结论是,过渡盘比完整的磁盘或具有较低的气尘比由于气体质量的耗尽。这一结果表明,过渡盘比完整的盘更进化,甚至可能在大半径。
英文摘要:
Transitional disks are protoplanetary disks characterized by reduced near- and mid-infrared emission with respect to full disks. This characteristic spectral energy distribution indicates the presence of an optically thin inner cavity within the dust disk believed to mark the disappearance of the primordial massive disk. We present new Herschel Space Observatory PACS spectra of [OI] 63 micron for 21 transitional disks. Our survey complements the larger Herschel GASPS program "Gas in Protoplanetary Systems" (Dent et al. 2013) by quadrupling the number of transitional disks observed with PACS at this wavelength. [OI] 63 micron traces material in the outer regions of the disk, beyond the inner cavity of most transitional disks. We find that transitional disks have [OI] 63 micron line luminosities two times fainter than their full disk counterparts. We self consistently determine various stellar properties (e.g. bolometric luminosity, FUV excess, etc.) and disk properties (e.g. disk dust mass, etc.) that could influence the [OI] 63 micron line luminosity and we find no correlations that can explain the lower [OI] 63 micron line luminosities in transitional disks. Using a grid of thermo-chemical protoplanetary disk models, we conclude that either transitional disks are less flared than full disks or they possess lower gas-to-dust ratios due to a depletion of gas mass. This result suggests that transitional disks are more evolved than their full disk counterparts, possibly even at large radii.
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