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J/A+A/606/A8        Bubble HII region Sh2-39 (N5)               (Duronea+, 2017)

Triggered massive star formation associated with the HII region bubble Sh2-39 (N5). Duronea N.U., Cappa C.E., Bronfman L., Borissova J., Gromadzki M., Kuhn M.A. <Astron. Astrophys. 606, A8 (2017)> =2017A&A...606A...8D (SIMBAD/NED BibCode)
ADC_Keywords: H II regions ; Infrared sources ; Radio lines Keywords: molecules: data - infrared: ISM - stars: formation - H II regions - stars: massive Abstract: Aiming at studying the physical properties of Galactic IR bubbles and to explore their impact in triggering massive star formation, we perform a multiwavelength analysis of the bubble HII region Sh2-39 (N5) and its environs. To analyze the molecular gas we use CO(3-2) and HCO+(4-3) line data obtained with the on-the-fly technique from the ASTE telescope. To study the distribution and physical characteristics of the dust, we make use of archival data from ATLASGAL, Herschel, and MSX, while the ionized gas was studied making use of an NVSS image. We use public WISE, Spitzer, and MSX point source catalogs to search for infrared candidate YSOs in the region. To investigate the stellar cluster [BDS2003] 6 we use IR spectroscopic data obtained with the ARCoIRIS spectrograph, mounted on Blanco 4-m Telescope at CTIO, and new available IR Ks band observations from the VVVeXtended ESO Public Survey (VVVX). The new ASTE observations allowed the molecular gas component in the velocity range from 30km/s to 46km/s, associated with Sh2-39, to be studied in detail. The morphology of the molecular gas suggests that the ionized gas is expanding against its parental cloud. We have identified four molecular clumps, that were likely formed by the expansion of the ionization front, and determined some of their physical and dynamical properties. Clumps having HCO+ and 870um counterparts show evidence of gravitational collapse. We identified several candidate YSOs across the molecular component. Their spatial distribution, as well as the fragmentation time derived for the collected layers of the molecular gas, suggest that massive star formation might have been triggered by the expansion of the nebula via the collect and collapse mechanism. The spectroscopical distance obtained for the stellar cluster [BDS2003] 6, placed over one of the collapsing clumps in the border of the HII region, reveals that this cluster is physically associated with the nebula and gives more support to the triggered massive star formation scenario. A radio continuum data analysis indicates that the nebula is older and expands at lower velocity than typical IR Galactic bubbles. Description: The molecular observations were carried out in August 2015 with the 10m Atacama Submillimeter Telescope Experiment (ASTE). We used DASH345, a two sideband single-polarization heterodyne receiver, tunable in LO frequency range from 327GHz to 370GHz at observable frequency range from 321GHz to 376GHz. The XF digital spectrometer was set to a bandwidth and spectral resolution of 128MHz and 125KHz, respectively. The spectral velocity resolution was 0.11km/s, the half power beamwidth (HPBW) is ∼22", and the main beam efficiency (mb) is 0.65. Observations were made using the on-the-fly (OTF) mode with two orthogonal scan directions along RA and Dec. (J2000) centered on RA, Dec.(J2000)= (18:17:02.1, -18:40:19). We observed simultaneously the lines CO(3-2) (345.796GHz) and HCO+(4-3) (356.734) in a region of ∼17'x17' (see Fig. 1). The spectra were reduced with NOSTAR2 using the standard procedure. The brightest star projected at the center of [BDS2003] 6 (2MASS J18165113-1841488) was observed on August 2016 with Astronomy Research using the Cornell Infra Red Imaging Spectrograph (ARCoIRIS), a cross-dispersed, single-object, longslit, infrared imaging spectrograph,mounted on Blanco 4-m Telescope, CTIO. The spectra cover a simultaneous wavelength range of 0.80 to 2.47um, at a spectral resolution of about 3500 λ{δλ, encompassing the entire zYJHK photometric range. The spectrum was taken with 480 sec integration time, at 1.03 average airmass. The HD163336 telluric A0 V standard is observed immediately after target. The basic steps of the reduction procedure are described in Chene et al. (2012A&A...545A..54C, Cat. J/A+A/545/A54, 2013A&A...549A..98C). We used the corresponding pipeline. Objects: -------------------------------------------------------- RA (2000) DE Designation(s) -------------------------------------------------------- 18 16 59 -18 40.2 [CPA2006] N5 = [CPA2006] N5 18 16 51 -18 41.9 [BDS2003] 6 = [BDS2003] 6 18 16 51.13 -18 41 48.8 2MASS J18165113-1841488 -------------------------------------------------------- File Summary:
FileName Lrecl Records Explanations
ReadMe 80 . This file list.dat 98 2 List of datacubes centered on bubble HII region Sh2-39 ([CPA2006] N5) fits/* 0 2 Individual datacubes 2m1816ma.dat 70 8447 2MASS J18165113-1841488 ARCoIRIS spectrum
Byte-by-byte Description of file: list.dat
Bytes Format Units Label Explanations
1- 9 F9.5 deg RAdeg Right Ascension of center (J2000) 10- 18 F9.5 deg DEdeg Declination of center (J2000) 20- 22 I3 --- Nx Number of pixels along X-axis 24- 26 I3 --- Ny Number of pixels along Y-axis 28- 31 I4 --- Nz Number of slices 33- 42 A10 "date" Obs.dat Observation date 44- 51 F8.1 m/s bVlsr Lower value of LSR velocity interval 53- 59 F7.1 m/s BVlsr Upper value of LSR velocity interval 61- 65 F5.1 m/s dVlsr LSR velocity resolution 67- 71 I5 Kibyte size Size of FITS file 73- 81 A9 --- FileName Name of FITS file, in subdirectory fits 83- 98 A16 --- Title Title of the FITS file
Byte-by-byte Description of file (# headlines): 2m1816ma.dat
Bytes Format Units Label Explanations
7- 16 F10.8 um lambda Wavelength 21- 34 E14.8 mW/m2 Flux ?=- Flux 40- 52 E13.8 mW/m2 e_Flux ?=- rms uncertainty on Flux 62- 70 F9.7 --- --- [0]
Acknowledgements: Nicolas Urbano Duronea, duronea(at)
(End) Patricia Vannier [CDS] 19-Jun-2017
The document above follows the rules of the Standard Description for Astronomical Catalogues.From this documentation it is possible to generate f77 program to load files into arrays or line by line

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