ALMA imaging study of methyl formate (HCOOCH$_{3}$) in the torsionally excited states towards Orion KL

摘要: We recently reported the first identification of rotational transitions methyl formate (HCOOCH$_{3}$) in second torsionally excited state toward Orion Kleinmann-Low (KL) observed with Nobeyama 45 m telescope. In combination identified ground and torsional state, it was found that there is a difference temperature vibrational temperature, where latter higher. this study, high spatial resolution analysis by using Atacama Large Millimeter/Submillimeter Array (ALMA) science verification data carried out to verify understand difference. Toward Compact Ridge, two different velocity components at 7.3 9.1 km s$^{-1}$ were confirmed, while single component towards Hot Core. The intensity maps ground, first, states have quite similar distributions. Using extensive ALMA data, we determined temperatures for Ridge Core conventional rotation diagram method. agree one Ridge. At be higher than temperature. This from what obtained results single-dish observation. might explained beam dilution effect and/or smaller number within limited range energy levels ($\leq$30 K) $E_u$ previous study.