Facial reconstruction

Search LJMU Research Online

Browse Repository | Browse E-Theses

Probing the Dragonfish star-forming complex: the ionizing population of the young massive cluster Mercer 30

de la Fuente, D and Najarro, F and Borissova, J and Ramirez Alegria, S and Hanson, MM and Trombley, C and Figer, DF and Davies, B and Garcia, M and Kurtev, R and Urbaneja, MA and Smith, LC and Lucas, PW and Herrero, A (2016) Probing the Dragonfish star-forming complex: the ionizing population of the young massive cluster Mercer 30. ASTRONOMY & ASTROPHYSICS, 589 (A69). ISSN 1432-0746

Full text not available from this repository. Please see publisher or open access link below:
Open Access URL: https://arxiv.org/pdf/1602.02503 (Accepted version)


It has recently been claimed that the nebula, Dragonfish, is powered by a superluminous but elusive OB association. However, systematic searches in near-infrared photometric surveys have found many other cluster candidates in this region of the sky. Among these, the first confirmed young massive cluster was Mercer 30, where Wolf-Rayet stars were found.We perform a new characterization of Mercer 30 with unprecedented accuracy, combining NICMOS/HST and VVV photometric data with multi-epoch ISAAC/VLT H- and K-band spectra. Stellar parameters for most of spectroscopically observed cluster members are found through precise non-LTE atmosphere modeling with the CMFGEN code. Our spectrophotometric study for this cluster yields a new, revised distance of d = (12.4 ± 1.7) kpc and a total of QHMc30 ≈ 6.70 × 1050 s-1 Lyman ionizing photons. A cluster age of (4.0 ± 0.8) Myr is found through isochrone fitting, and a total mass of (1.6 ± 0.6) × 104M⊙ is estimated, thanks to our extensive knowledge of the post-main-sequence population. As a consequence, membership of Mercer 30 to the Dragonfish star-forming complex is confirmed, allowing us to use this cluster as a probe for the whole complex, which turns out to be extremely large (~400 pc across) and located at the outer edge of the Sagittarius-Carina spiral arm (~11 kpc from the Galactic center). The Dragonfish complex hosts 19 young clusters or cluster candidates (including Mercer 30 and a new candidate presented in this work) and an estimated minimum of nine field Wolf-Rayet stars. All these contributions account for, at least 73% of the ionization of the Dragonfish nebula and leaves little or no room for the alleged superluminous OB association; alternative explanations are discussed.

Item Type: Article
Uncontrolled Keywords: 0201 Astronomical And Space Sciences
Subjects: Q Science > QB Astronomy
Divisions: Astrophysics Research Institute
Related URLs:
Date Deposited: 10 Apr 2017 09:40
Last Modified: 10 Apr 2017 09:40
DOI or Identification number: 10.1051/0004-6361/201528004
URI: http://researchonline.ljmu.ac.uk/id/eprint/6230

Actions (login required)

View Item View Item