Dense clumps survive in the vicinity of R136 in 30 Doradus

¹ Departamento de Astronomía, Universidad de Chile, Santiago, Chile
² Max-Planck-Institut für extraterrestrische Physik, Giessenbachstrasse 1, 85748 Garching, Germany
³ European Southern Observatory, Karl-Schwarzschild-Strasse 2, 85748 Garching bei Munchen, Munchen, Germany
⁴ Gemini Observatory/NSF’s NOIRLab, Casilla 603, La Serena, Chile
⁵ Instituto de Investigaciones en Energía no Convencional, Universidad Nacional de Salta, C.P. 4400, Salta, Argentina
⁶ Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Godoy Cruz 2290, CABA, CPC 1425FQB, Argentina
⁷ Department of Astronomy, University of Maryland, College Park, Maryland 20742, USA
⁸ University of Virginia Astronomy Department, PO Box 400325, Charlottesville, VA 22904, USA
⁹ National Radio Astronomy Observatory, 520 Edgemont Rd., Charlottesville, VA 22903, USA
¹⁰ Nucleo de Astroquímica y Astrofísica, Universidad Autónoma de Chile, Pedro de Valdivia 425, Providencia, Santiago de Chile, Chile
¹¹ Institut Laue-Langevin, 71 Avenue des Martyrs, 38042 Grenoble, France
¹² Institut de Radioastronomie Millimétrique (IRAM), 300 Rue de la Piscine, 38406 Saint-Martin-d’Hères, France

^★ Corresponding author: mariateresa.valdiviamena@eso.org

Received: 28 February 2025
Accepted: 27 May 2025

Abstract

Context. The young massive cluster R136 at the center of 30 Doradus (30 Dor) in the Large Magellanic Cloud (LMC) generates a cavity in the surrounding molecular cloud. However, there is molecular gas between 2 and 10 pc in projection from R136’s center. The region, known as the Stapler nebula, hosts the closest known molecular gas clouds to R136.

Aims. We investigated the properties of molecular gas in the Stapler nebula to better understand why these clouds survive so close in projection to R136.

Methods. We used Atacama Large Millimeter/Sub-millimeter Array 7m observations in Band 7 (345 GHz) of continuum emission, ¹²CO and ¹³CO, together with dense gas tracers CS, HCO⁺, and HCN. Our observations resolve the molecular clouds in the nebula into individual parsec-sized clumps. We determined the physical properties of the clumps using both dust and molecular emission, and compared the emission properties observed close to R136 to other clouds in the LMC.

Results. The densest clumps in our sample, where we observe CS, HCO⁺, and HCN, are concentrated in a northwest-southeast diagonal seen as a dark dust lane in HST images. Resolved clumps have masses between ~200-2500 M_⊙, and the values obtained using the virial theorem are higher than the masses obtained through ¹²CO and ¹³CO luminosity. The velocity dispersion of the clumps is due both to self-gravity and to the external pressure of the gas. Clumps at the center of our map, which have detections of dense gas tracers (n_crit ~ 10⁶ cm^-3 and above), are spatially coincident with young stellar objects.

Conclusions. The clumps’ physical and chemical properties are consistent with other clumps in 30 Dor. We suggest that these clumps are the densest regions of a molecular cloud carved by the radiation of R136.