J/A+A/537/A2 8.6um imaging of 47 Tuc (Momany+, 2012)
The VLT/VISIR mid-IR view of 47 Tucanae. A further step in solving the puzzle of
RGB mass loss.
Momany Y., Saviane I., Smette A., Bayo A., Girardi L., Marconi G.,
Milone A.P., Bressan A.
<Astron. Astrophys., 537, A2 (2012)>
=2012A&A...537A...2M 2012A&A...537A...2M
ADC_Keywords: Clusters, globular ; Photometry, infrared ; Photometry, HST
Keywords: stars: mass-loss - stars: winds, outflows - stars: Population II -
globular clusters: individual: 47 Tucanae (NGC 104)
Abstract:
There is an ongoing debate regarding the onset luminosity of dusty
mass loss in population-II red giant stars. We present VLT/VISIR
mid-infrared (MIR) 8.6um imaging of 47 Tuc, the centre of attention
of a number of space-based Spitzer observations and studies. The VISIR
high-resolution (diffraction limited) observations allow excellent
matching to existing optical Hubble Space Telescope catalogues. The
optical-MIR coverage of the inner core of the cluster provide the
cleanest possible blending-free sampling of the upper 3mag of the
giant branch. Our diagrams show no evidence of faint giants with
MIR-excess. A combined near/mid-infrared diagram additionally confirms
the near absence of dusty red giants. Dusty red giants and asymptotic
giant stars are confined to the 47 Tuc long-period variable
population. In particular, dusty red giants are limited to the upper
one N8.6um magnitude below the giant branch tip. This particular
luminosity level corresponds to ∼1000L☉, which was suggested in
previous determinations to mark the onset of dusty mass loss.
Interestingly, starting from this luminosity level we detected a
gradual deviation between the colours of red giants and the
theoretical isochrones.
Description:
Our observations were obtained using the VLT spectrometer and imager
for the MIR (VISIR) currently located at the Cassegrain focus of UT3.
These observations were carried out in service mode in the period
between October 3, 2009 and January 30, 2010.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table3.dat 88 102 The VISIR N8.6um catalogue of the 47 Tuc
central region
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See also:
J/ApJS/85/293 : HST Observations of core of 47 Tuc (de Marchi+ 1993)
J/A+AS/106/161 : (V,I) photometry in NGC 6356 and 47 Tuc (Bica+ 1994)
J/A+A/372/85 : Detected sources at 12µm in 47 Tuc (Ramdani+, 2001)
Byte-by-byte Description of file: table3.dat
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Bytes Format Units Label Explanations
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1- 3 I3 --- Seq Sequential number
5- 14 F10.8 deg RAdeg Right ascension in decimal degrees (J2000)
16- 27 F12.8 deg DEdeg Declination in decimal degrees (J2000)
29- 34 F6.3 mag F606W HST/ACS F606W magnitude (1)
36- 41 F6.3 mag F814W ?=- HST/ACS F814W magnitude (1)
43- 48 F6.3 mag F336W ?=- HST/ACS F336W magnitude (2)
50- 55 F6.3 mag F435W ?=- HST/ACS F435W magnitude (2)
57- 62 F6.3 mag [8.6] ?=- Magnitude in VISIR N8.6um magnitude
64- 69 F6.3 mag Jmag ?=- ESO SOFI J magnitude (3)
71- 76 F6.3 mag Kmag ?=- ESO SOFI Ks magnitude (3)
78- 82 F5.3 Jy Flux Flux value at 8.6um
84- 87 A4 --- LPV Known LPV identification (4)
88 A1 --- u_LPV [?] Uncertainty flag on LPV identification
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Note (1): F606W and F814W magnitudes from Anderson et al., 2009ApJ...697L..58A 2009ApJ...697L..58A
Note (2): F336W and F435W magnitudes reduced in this paper
Note (3): J- and K-magnitudes from Salaris et al., 2007A&A...476..243S 2007A&A...476..243S
Note (4): VN = <Cl* NGC 104 SAW VN> in Simbad and
LWNN = <Cl* NGC 104 LW NN> in Simbad
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History:
From electronic version of the journal
(End) Patricia Vannier [CDS] 15-Mar-2012