J/A+A/601/A69 MWC 922 XSHOOTER spectra (Wehres+, 2017)
Medium resolution echelle spectroscopy of the Red Square Nebula, MWC 922.
Wehres N., Ochsendorf B.B., Tielens A.G.G.M., Cox N.L.J., Kaper L.,
Bally J., Snow T.P.
<Astron. Astrophys. 601, A69 (2017)>
=2017A&A...601A..69W 2017A&A...601A..69W (SIMBAD/NED BibCode)
ADC_Keywords: Nebulae ; Stars, emission ; Spectroscopy
Keywords: astrochemistry - methods: observational - techniques: spectroscopic -
stars: emission-line, Be - circumstellar matter - ISM: abundances
Abstract:
Medium-resolution echelle spectra of the Red Square Nebula
surrounding the star MWC 922 are presented. The spectra have been
obtained in 2010 and 2012 using the XSHOOTER spectrograph mounted on
the Very Large Telescope (VLT) in Paranal, Chile. The spectrum covers
a wavelength range between 300nm-2.5um and shows that the
nebula is rich in emission lines.
We aim to identify the emission lines and use them as a tool to
determine the physical and chemical characteristics of the nebula. The
emission lines are also used to put constraints on the structure of
the nebula and on the nature of the central stars.
We analyzed and identified emission lines that indicated that the Red
Square Nebula consists of a low density bipolar outflow, eminent in
the broad emission component seen in [FeII], as well as in P Cygni
line profiles indicative of fast outflowing material. The narrow
component in the [FeII] lines is most likely formed in the
photosphere of a surrounding disk. Some of the emission lines show a
pronounced double peaked profile, such as CaII, indicating an
accretion disk in Keplerian rotation around the central star. [OI]
emission lines are formed in the neutral atomic zone separating the
ionized disk photosphere from the molecular gas in the interior of the
disk, which is prominent in molecular CO emission in the near-IR.
[NII] and [SII] emission clearly originates in a low density but
fairly hot (7000-10000K) nebular environment. HI recombination
lines trace the extended nebula as well as the photosphere of the
disk.
Description:
XSHOOTER fully data reduced spectra, including the UV, VIS and NIR
spectra.
Objects:
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RA (2000) DE Designation(s)
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18 21 16.06 -13 01 25.7 MWC 922 = NAME Red Square Nebula
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
uvb_flux.dat 23 19407 MWC 922 UVB spectrum
vis_flux.dat 23 32423 MWC 922 VIS spectrum
nir_flux.dat 23 49499 MWC 922 NIR spectrum
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Byte-by-byte Description of file: uvb_flux.dat vis_flux.dat nir_flux.dat
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Bytes Format Units Label Explanations
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1- 10 F10.5 nm lambda Wavelength
12- 23 E12.6 10mW/m2/nm/arcsec2 Flux Flux (in erg/s/cm2/Å/arcsec2
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Acknowledgements:
Nadine Wehres, wehres(at)ph1.uni-koeln.de
(End) Patricia Vannier [CDS] 05-Apr-2017