[P-CG20] 宇宙における物質の形成と進化

[PCG20-P06] ALMA [CI](1-0) survey for protoplanetary disks

*塚越 崇¹、野村 英子¹、島尻 芳人¹、百瀬 宗武²、斎藤 正雄¹、川邊 良平¹ (1.国立天文台、2.茨城大学)

キーワード：原始惑星系円盤

Atomic carbon in protoplanetary disks is abundant near the disk surface PDR. Investigating the distribution and structure of the atomic carbon of protoplanetary disks is crucial for understanding the disk evolution because it is expected to be a tracer of photoevaporative disk dissipation and is one of the carbon reservoirs in the disk. However, only a few detections of [CI] line emission from the disk have been reported to date, and thus it is hard to reveal the properties and distribution of [CI] emission.

We thus conducted survey observations in [CI](1-0) toward nine protoplanetary disks with ALMA. The disk [CI] emission is detected for six sources. The extent of the [CI] emission is larger than the continuum emission and is comparable to the CO emission. We find that the carbon mass is 5x10^-5 M_J in typical and that there is a correlation between the stellar luminosity and the mass fraction of carbon to dust. The mass fraction of carbon to dust also weakly correlates with the color between mid-infrared and millimeter flux densities. Since the color indicates the degree of disk flaring, these results imply that the carbon mass increases probably due to the expansion of PDR when the disk surface is illuminated efficiently.