J/MNRAS/399/195 Blue and red spectra of ω Cen HB stars (Van Loon+, 2009)
Detailed maps of interstellar clouds in front of ω Centauri:
small-scale structures in the galactic disc-halo interface.
van Loon J.T., Smith K.T., McDonald I., Sarre P.J., Fossey S.J.,
Sharp R.G.
<Mon. Not. R. Astron. Soc., 399, 195-208 (2009)>
=2009MNRAS.399..195V 2009MNRAS.399..195V
ADC_Keywords: Clusters, globular ; Stars, horizontal branch ;
Equivalent widths ; Spectra, red
Keywords: stars: horizontal branch - ISM: molecules - ISM: structure -
Galaxy: disc - globular clusters: individual- omega Cen (NGC 5139) -
Galaxy: halo
Abstract:
The multiphase interstellar medium (ISM) is highly structured, on
scales from the size of the Solar System to that of a galaxy. In
particular, small-scale structures are difficult to study and hence
are poorly understood. We used the multiplex capabilities of the
AAOmega spectrograph at the Anglo-Australian Telescope to create a
half-square-degree map of the neutral and low-ionized ISM in front of
the nearby (∼5kpc), most massive Galactic globular cluster, ω
Centauri. Its redshifted, metal-poor and hot horizontal branch stars
probe the medium-strong CaII K and NaI D2 line absorption, and weak
absorption in the λ5780 and λ5797 diffuse interstellar
bands (DIBs), on scales around a parsec. The kinematical and
thermodynamical picture emerging from these data is that we
predominantly probe the warm neutral medium and weakly ionized
medium of the Galactic Disc-Halo interface, ∼0.3-1kpc above the
mid-plane. A comparison with Spitzer Space Telescope 24um and
DIRBE/IRAS maps of the warm and cold dust emission confirms that both
NaI and CaII trace the overall column density of the warm neutral and
weakly ionized medium. Clear signatures are seen of the depletion of
calcium atoms from the gas phase into dust grains.
Description:
The observations were undertaken, in service mode, at the
Anglo-Australian Telescope (AAT) on the night of 2008 March 28.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 120 460 Catalogue of observed stars in ω Cen,
plus the 8 stars not used in the analysis
sp/* . 920 Individual blue and red spectra for the 460 stars
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See also:
J/A+A/360/472 : Proper motions in omega Centauri (van Leeuwen+, 2000)
J/MNRAS/382/1353 : Spectral atlas of omega Cen post-MS stars (Van Loon+, 2007)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 5 I5 --- LEID LEID number (Van Leeuwen et al., 2000,
Cat. J/A+A/360/472,
<Cl* NGC 5139 LEID NNNNN> in Simbad)
6 A1 --- n_LEID [*] * for the six stars having spectra but not
used in the analysis (just name and position)
7- 15 F9.5 deg RAdeg Right ascension (J2000)
17- 25 F9.5 deg DEdeg Declination (J2000)
27- 33 F7.3 deg GLON ? Galactic longitude
35- 41 F7.4 deg GLAT ? Galactic latitude
43- 50 F8.6 mag E(B-V) ? Redenning E(B-V) from the DIRBE/IRAS maps of
Schlegel et al., 1998ApJ...500..525S 1998ApJ...500..525S
52- 56 F5.1 km/s VCa ?=- CaII K central velocity with respect to
the Local Standard of Rest
58- 61 F4.1 0.1pm DCa ?=- CaII K line width
63- 67 F5.1 0.1pm WCa ?=- CaII K equivalent width
69- 73 F5.1 0.1pm e_WCa ?=- Error on WCa
75- 79 F5.1 km/s VNa ? NaI D2 central velocity with respect to the
Local Standard of Rest
81- 84 F4.1 0.1pm DNa ? NaI D2 line width
86- 90 F5.1 0.1pm WNa ? NaI D2 equivalent width
92- 96 F5.1 0.1pm e_WNa ? Error on WNa
98-102 F5.1 0.1pm W5780 ?=- Equivalent width of the lambda5780 DIB
104-108 F5.1 0.1pm e_W5780 ?=- Error on W5780
110-114 F5.1 0.1pm W5797 ?=- Equivalent width of the lambda5797 DIB
116-120 F5.1 0.1pm e_W5797 ?=- Error on W5797
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Byte-by-byte Description of file: sp/*
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Bytes Format Units Label Explanations
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1- 7 F7.2 0.1nm lambda Wavelength
9- 15 F7.1 --- Int ?=* Intensity, in arbitrary units
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Acknowledgements:
Jacco van Loon, jacco(at)astro.keele.ac.uk
(End) Patricia Vannier [CDS] 08-Mar-2010