Title: Matryoshka Holes: Nested Emission Rings in the Transitional Disk Oph IRS 48 Show Chinese title

Title: 套娃孔洞：过渡盘Oph IRS 48中的嵌套发射环

Abstract: The processes that form transition disks - disks with depleted inner regions - are not well understood; possible scenarios include planet formation, grain growth and photoevaporation. Disks with spatially resolved dust holes are rare, but, in general, even less is known about the gas structure. The disk surrounding A0 star Oph IRS 48 in the nearby Rho Ophiuchus region has a 30 AU radius hole previously detected in the 18.7 micron dust continuum and in warm CO in the 5 micron fundamental ro-vibrational band. We present here Submillimeter Array 880 micron continuum imaging resolving an inner hole. However, the radius of the hole in the millimeter dust is only 13 AU, significantly smaller than measured at other wavelengths. The nesting structure of the disk is counter-intuitive, with increasingly large radii rings of emission seen in the millimeter dust (12.9 +1.7/-3.4 AU), 5 micron CO (30 AU) and 18.7 micron dust (peaking at 55 AU). We discuss possible explanations for this structure, including self-shadowing that cools the disk surface layers, photodissociation of CO, and photoevaporation. However, understanding this unusual disk within the stringent multi-wavelength spatial constraints will require further observations to search for cold atomic and molecular gas. Show Chinese abstract

Abstract: 形成过渡盘——内区物质耗尽的盘——的过程尚不明确；可能的场景包括行星形成、颗粒增长和光致蒸发。空间分辨的尘埃空洞盘较为罕见，但总体而言，对气体结构的了解更少。邻近的蛇夫座Rho区域中，A0型恒星Oph IRS 48周围的盘在18.7微米尘埃连续谱和5微米基本振转带的温暖CO中之前已检测到30 AU半径的空洞。我们在此展示了Submillimeter Array 880微米连续谱成像，解析了内部空洞。然而，毫米波段尘埃空洞的半径仅为13 AU，明显小于其他波长测量的值。盘的嵌套结构出乎意料，随着波长增加，观测到的发射环半径逐渐增大，在毫米波段尘埃（12.9 +1.7/-3.4 AU）、5微米CO（30 AU）和18.7微米尘埃（峰值在55 AU）中均可见。我们讨论了这种结构的可能解释，包括自遮挡冷却盘表面层、CO的光离解和光致蒸发。然而，在严格的多波长空间约束下理解这一异常盘仍需进一步观测以寻找冷原子和分子气体。