The comet-like composition of a protoplanetary disk as revealed by complex cyanides

The cometary composition of a protoplanetary disk as re- vealed by complex cyanides

Observations of comets and asteroids show that the Solar Nebula that spawned our planetary system was rich in water and organic molecules. Bombardment brought these organics to the young Earth’s surface, seeding its early chemistry. Unlike asteroids, comets preserve a nearly pristine record of the Solar Nebula composition. The presence of cyanides in comets, including 0.01% of methyl cyanide (C...

translating allusive devices:a survey of a portrait of the artist as a young man by james joyce

تلمیح یکی از عناصری است که تقریباً در همه ی متون ادبی یافت و باعث ایجاد شکاف های فرهنگی می شود. در این تحقیق به عنوان شکلی از بینامتنیت در ترجمه مورد توجه قرار می گیرد. تلاش شده است تا راهکارهای مترجمان برای ترجمه چهار نوع اسامی خاص و عبارات کلیدی تلمیحی (مذهبی، سیاسی، تاریخی و اسطوره ای) موجود در رمانِ چهره مرد هنرمند در جوانی به فارسی بررسی شود. این تحقیق مقایسه ای بر اساس راهکارهای ترجمه تلمیح...

Ringed Structures of the HD 163296 Protoplanetary Disk Revealed by ALMA.

We present Atacama Large Millimeter and Submillimeter Array observations of the protoplanetary disk around the Herbig Ae star HD 163296 that trace the spatial distribution of millimeter-sized particles and cold molecular gas on spatial scales as small as 25 astronomical units (A.U.). The image of the disk recorded in the 1.3 mm continuum emission reveals three dark concentric rings that indicat...

Comet Grains and Implications for Heating and Radial Mixing in the Protoplanetary Disk

Timescales of the Solar Protoplanetary Disk

We summarize geochemical, astronomical, and theoretical constraints on the lifetime of the protoplanetary disk. Absolute Pb-Pb-isotopic dating of CAIs in CV chondrites (4567.2 ± 0.7 m.y.) and chondrules in CV (4566.7 ± 1 m.y.), CR (4564.7 ± 0.6 m.y.), and CB (4562.7 ± 0.5 m.y.) chondrites, and relative Al-Mg chronology of CAIs and chondrules in primitive chondrites, suggest that high-temperatur...