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Mother of Dragons: A Massive, quiescent core in the dragon cloud (IRDC G028.37+00.07)

Barnes, AT, Liu, J, Zhang, Q, Tan, JC, Bigiel, F, Caselli, P, Cosentino, G, Fontani, F, Henshaw, JD, Jiménez-Serra, I, Kalb, D-S, Law, CY, Longmore, SN, Parker, RJ, Pineda, JE, Sánchez-Monge, A, Lim, W and Wang, K (2023) Mother of Dragons: A Massive, quiescent core in the dragon cloud (IRDC G028.37+00.07). Astronomy and Astrophysics, 675. ISSN 0004-6361

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Context. Core accretion models of massive star formation require the existence of massive, starless cores within molecular clouds. Yet, only a small number of candidates for such truly massive, monolithic cores are currently known.
Aims. Here we analyse a massive core in the well-studied infrared-dark cloud (IRDC) called the ‘dragon cloud’ (also known as G028.37+00.07 or ‘Cloud C’). This core (C2c1) sits at the end of a chain of a roughly equally spaced actively star-forming cores near the center of the IRDC.
Methods. We present new high-angular-resolution 1 mm ALMA dust continuum and molecular line observations of the massive core.
Results. The high-angular-resolution observations show that this region fragments into two cores, C2c1a and C2c1b, which retain significant background-subtracted masses of 23 M and 2 M (31 M and 6 M without background subtraction), respectively. The cores do not appear to fragment further on the scales of our highest-angular-resolution images (0.200, 0.005 pc ∼ 1000 AU). We find that these cores are very dense (nH2 > 106 cm−3 ) and have only trans-sonic non-thermal motions (Ms ∼ 1). Together the mass, density, and internal motions imply a virial parameter of < 1, which suggests the cores are gravitationally unstable, unless supported by strong magnetic fields with strengths of ∼1-10 mG. From CO line observations, we find that there is tentative evidence for a weak molecular outflow towards the lower-mass core, and yet the more massive core remains devoid of any star formation indicators.
Conclusions. We present evidence for the existence of a massive, pre-stellar core, which has implications for theories of massive star formation. This source warrants follow-up higher-angular-resolution observations to further assess its monolithic and pre-stellar nature.

Item Type: Article
Uncontrolled Keywords: astro-ph.GA; astro-ph.GA; astro-ph.SR
Subjects: Q Science > QB Astronomy
Q Science > QC Physics
Divisions: Astrophysics Research Institute
Publisher: EDP Sciences
Related URLs:
SWORD Depositor: A Symplectic
Date Deposited: 17 Apr 2023 09:38
Last Modified: 06 Jul 2023 13:30
DOI or ID number: 10.1051/0004-6361/202245668
URI: https://researchonline.ljmu.ac.uk/id/eprint/19243
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