성간분자운(interstellar molecular clouds; cold dard clouds)의 중력수축에 의한 계층적 분화를 통해 별의 씨앗인 고밀도 분자운핵(dense cores)들이 형성되고, 이후 계속된 질량 유입(mass accretion)과 중력 수축에 의해서 최종적으로 별이 형성된다고 알려져 있다. 최근 허셜우주망원경(Herschel Space Observatory)의 관측결과에 의해 이들 성간분자운이 모두 필라멘트 구조(filamentary structures; filaments)를 갖고 있으며, 필라멘트 구조가 고밀도 분자운핵과 별의 생성에 중요한 역할을 담당하고 있음이 밝혀졌다. 이번 저널클럽에서는 지난 2013년에 열린 Protostars and Planets VI 학회 발표논문집에 실린 André et al. (2014) "From Filamentary Networks to Dense Cores in Molecular Clouds: Toward a New Paradigm for Star Formation" 논문의 내용 중 Secsion 2. UNIVERSALITY OF THE FILAMENTARY STRUCTURE OF THE COLD ISM 부분을 바탕으로 필라멘트 구조에 대한 관측 결과에 대해 이야기를 나누고자 한다.

Abstract (reference): Recent studies of the nearest star-forming clouds of the Galaxy at submillimeter wavelengths with the Herschel Space Observatory have provided us with unprecedented images of the initial and boundary conditions of the star-formation process. The Herschel results emphasize the role of interstellar filaments in the star-formation process and connect remarkably well with nearly a decade’s worth of numerical simulations and theory that have consistently shown that the interstellar medium (ISM) should be highly filamentary on all scales, and star formation is intimately related to self-gravitating filaments. In this review, we trace how the apparent complexity of cloud structure and star formation is governed by relatively simple universal processes — from filamentary clumps to galactic scales. We emphasize two crucial and complementary aspects: (1) the key observational results obtained with Herschel over the past three years, along with relevant new results obtained from the ground on the kinematics of interstellar structures; and (2) the key existing theoretical models and the many numerical simulations of interstellar cloud structure and star formation. We then synthesize a comprehensive physical picture that arises from the confrontation of these observations and simulations.