Linear filament and nested cluster evolution tomography (LANCET)

Astronomy and Astrophysics, vol. 708, pp. A251

Abstract

A dynamic view of mass assembly is essential for understanding the formation of massive stars and clusters. However, interpreting evolutionary diagnostics from Galactic-wide surveys requires careful consideration of distance and environmental variations. The G316.8 filament provides an excellent controlled case: a 14-parsec, nearly linear structure comprising three contiguous subregions with comparable molecular gas reservoirs (each ~10 000 M ⊙ ), yet spanning a clear evolutionary sequence from a northern infrared dark cloud (young) through a central massive young stellar object (intermediate), to a southern H II region (evolved). The Linear filament and nested cluster evolution tomography (LANCET) project mapped the entire G316.8 filament with the Atacama Compact Array (ACA) at 1.3 mm, achieving 6″ (0.08 pc) resolution over 26.7 arcmin 2 (17.1 pc 2 ). By combining ACA 7 m data with Herschel and APEX/ArTéMiS observations, we produced high-resolution temperature and column-density maps. We quantified subregional differences using (i) dense-fragment statistics, (ii) column-density probability distribution functions (N-PDFs), and (iii) the scale-dependent structural diagnostic, the Δ-variance. From young to intermediate to evolved, the maximum fragment mass increases from 8 to 160 to 490 M ⊙ , while the dense-gas mass fraction (>0.5 g cm −2 ) rises from 0.4 to 2.3 to 9.6%. Along this sequence, the N-PDF develops a slightly flatter primary power-law tail and an additional, steeper secondary tail; the Δ-variance slope becomes progressively shallower. Across G316.8, the subregional differences consistently indicate a coherent evolutionary trend of massive star formation, in which gas is continuously assembled into sub-parsec dense structures. The forthcoming 12 m array observations are about to extend this dynamic picture by resolving dense core formation and probing gas kinematics and magnetic fields.

Authors 15

1. Fengwei Xu

   Peking University · Max Planck Institute for Astronomy

   Affiliation as printed

   Kavli Institute for Astronomy and Astrophysics, Peking University

   Max Planck Institute for Astronomy

2. Ke Wang

   Peking University

   Affiliation as printed

   Kavli Institute for Astronomy and Astrophysics, Peking University

3. Nicola Schneider

   University of Cologne

   Affiliation as printed

   I. Physikalisches Institut, Universität zu Köln

4. Roberto Galván-Madrid

   Universidad Nacional Autónoma de México

   Affiliation as printed

   Instituto de Radioastronomía y Astrofísica, Universidad Nacional Autónoma de México, Morelia

5. Floris F. S. van der Tak Aachen SRON Netherlands Institute for Space Research & Kapteyn Astronomical Institute

   University of Groningen · Space Research Organisation Netherlands

   Affiliation as printed

   SRON Netherlands Institute for Space Research & Kapteyn Astronomical Institute, University of Groningen

6. Adam Ginsburg

   University of Florida

   Affiliation as printed

   Department of Astronomy, University of Florida

7. Jonathan C. Tan

   University of Virginia · Chalmers University of Technology

   Affiliation as printed

   Department of Astronomy, University of Virginia

   Department of Space, Earth & Environment, Chalmers University of Technology

8. Hauyu Baobab Liu

   National Taiwan Normal University · National Sun Yat-sen University

   Affiliation as printed

   Center of Astronomy and Gravitation, National Taiwan Normal University

   Department of Physics, National Sun Yat-Sen University

9. Qizhou Zhang

   Center for Astrophysics Harvard & Smithsonian

   Affiliation as printed

   Center for Astrophysics | Harvard & Smithsonian

10. Wenyu Jiao

    Chinese Academy of Sciences · Shanghai Astronomical Observatory

    Affiliation as printed

    Shanghai Astronomical Observatory, Chinese Academy of Sciences

11. Guido Garay

    Chinese Academy of Sciences · Chinese Academy of Science South America Center for Astronomy · National Astronomical Observatories · University of Chile

    Affiliation as printed

    Chinese Academy of Sciences South America Center for Astronomy, National Astronomical Observatories, Chinese Academy of Sciences

    Departamento de Astronomía, Universidad de Chile, Las Condes

12. Sihan Jiao

    Chinese Academy of Sciences · Max Planck Institute for Astronomy · National Astronomical Observatories

    Affiliation as printed

    Max Planck Institute for Astronomy

    National Astronomical Observatories, Chinese Academy of Sciences

13. Keyun Su

    Peking University

    Affiliation as printed

    Kavli Institute for Astronomy and Astrophysics, Peking University

14. B. Jones

    University of Cologne

    Affiliation as printed

    I. Physikalisches Institut, Universität zu Köln

15. Lei Zhu

    Chinese Academy of Sciences · Chinese Academy of Science South America Center for Astronomy · National Astronomical Observatories

    Affiliation as printed

    Chinese Academy of Sciences South America Center for Astronomy, National Astronomical Observatories, Chinese Academy of Sciences