Issue |
A&A
Volume 569, September 2014
|
|
---|---|---|
Article Number | A11 | |
Number of page(s) | 24 | |
Section | Interstellar and circumstellar matter | |
DOI | https://doi.org/10.1051/0004-6361/201424032 | |
Published online | 09 September 2014 |
A necklace of dense cores in the high-mass star forming region G35.20−0.74 N: ALMA observations⋆,⋆⋆
1
I. Physikalisches Institut, Universität zu Köln,
Zülpicher Str. 77, 50937
Köln, Germany
e-mail: sanchez@ph1.uni-koeln.de
2
Osservatorio Astrofisico di Arcetri, INAF,
Largo Enrico Fermi 5,
50125
Firenze,
Italy
3
Hamburger Sternwarte, Gojenbergsweg 112, 21029
Hamburg,
Germany
4
Jodrell Bank Centre for Astrophysics, School of Physics and
Astronomy, University of Manchester, Manchester
M13 9PL,
UK
5
Centro de Astrofísica da Universidade do Porto,
rua das Estrelas, 4150-762
Porto,
Portugal
6
ESO, Karl-Schwarzschilk-Strasse 2, 85748
Garching bei München,
Germany
7
SRON Netherlands Institute for Space Research,
PO Box 800, 9700 AV
Groningen, The
Netherlands
8
Kapteyn Astronomical Institute, University of
Groningen, 9700
AV
Groningen, The
Netherlands
9
Dpt. of Earth and Space Science, Indian Institute of Space Science
and Technology, Thiruvananthapuram, 695
547
Kerala,
India
10
Dublin Institute for Advanced Studies (DIAS),
31 Fitzwilliam Place, 2
Dublin,
Ireland
11
Leiden Observatory, Leiden University,
PO Box 9513, 2300 RA
Leiden, The
Netherlands
12
SOFIA Science Center, NASA Ames Research Center,
Mailstop 232-12, Moffett Field, CA
94035,
USA
13
Istituto di Astrofisica e Planetologia Spaziali
(IAPS-INAF), via Fosso del
Cavaliere 100, 00133
Roma,
Italy
14
Infrared Processing and Analysis Center, Institute of
Technology, Pasadena,
CA
91125,
USA
Received:
18
April
2014
Accepted:
9
June
2014
Context. The formation process of high-mass stars (with masses >8 M⊙) is still poorly understood, and represents a challenge from both the theoretical and observational points of view. The advent of the Atacama Large Millimeter Array (ALMA) is expected to provide observational evidence to better constrain the theoretical scenarios.
Aims. The present study aims at characterizing the high-mass star forming region G35.20−0.74 N, which is found associated with at least one massive outflow and contains multiple dense cores, one of them recently found associated with a Keplerian rotating disk.
Methods. We used the radio-interferometer ALMA to observe the G35.20−0.74 N region in the submillimeter continuum and line emission at 350 GHz. The observed frequency range covers tracers of dense gas (e.g., H13CO+, C17O), molecular outflows (e.g., SiO), and hot cores (e.g., CH3CN, CH3OH). These observations were complemented with infrared and centimeter data.
Results. The ALMA 870 μm continuum emission map reveals an elongated dust structure (~0.15 pc long and ~0.013 pc wide; full width at half maximum) perpendicular to the large-scale molecular outflow detected in the region, and fragmented into a number of cores with masses ~1–10 M⊙ and sizes ~1600 AU (spatial resolution ~960 AU). The cores appear regularly spaced with a separation of ~0.023 pc. The emission of dense gas tracers such as H13CO+ or C17O is extended and coincident with the dust elongated structure. The three strongest dust cores show emission of complex organic molecules characteristic of hot cores, with temperatures around 200 K, and relative abundances 0.2–2 × 10-8 for CH3CN and 0.6–5 × 10-6 for CH3OH. The two cores with highest mass (cores A and B) show coherent velocity fields, with gradients almost aligned with the dust elongated structure. Those velocity gradients are consistent with Keplerian disks rotating about central masses of 4–18 M⊙. Perpendicular to the velocity gradients we have identified a large-scale precessing jet/outflow associated with core B, and hints of an east-west jet/outflow associated with core A.
Conclusions. The elongated dust structure in G35.20−0.74 N is fragmented into a number of dense cores that may form high-mass stars. Based on the velocity field of the dense gas, the orientation of the magnetic field, and the regularly spaced fragmentation, we interpret this elongated structure as the densest part of a 1D filament fragmenting and forming high-mass stars.
Key words: stars: formation / stars: massive / ISM: individual objects: G35.20 / 0.74 N / ISM: molecules / ISM: jets and outflows
Appendix is available in electronic form at http://www.aanda.org
Reduced FITS files (cube and continum) are only available at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/569/A11
© ESO, 2014
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