J/A+A/540/A135 AGB population of NGC 6822 (Sibbons+, 2012)
The AGB population of NGC 6822: distribution and C/M ratio from JHK photometry.
Sibbons L.F., Cioni S.G., Ryan M.-R., Irwin M., Napiwotzki R.
<Astron. Astrophys. 540, A135 (2012)>
=2012A&A...540A.135S 2012A&A...540A.135S
ADC_Keywords: Galaxies, nearby ; Stars, giant ; Stars, carbon ;
Photometry, infrared
Keywords: techniques: photometric - stars: AGB and post-AGB - stars: carbon -
galaxies: dwarf - galaxies: irregular
Abstract:
NGC 6822 is an irregular dwarf galaxy and part of the Local Group. Its
close proximity and apparent isolation provide a unique opportunity to
study galactic evolution without any obvious strong external
influences.
This paper aims to study the spatial distribution of the asymptotic
giant branch (AGB) population and metallicity in NGC 6822.
Using deep, high quality JHK photometry, taken with WFCAM on UKIRT,
carbon- and oxygen-rich AGB stars have been isolated. The ratio
between their number, the C/M ratio, has then been used to derive the
[Fe/H] abundance across the galaxy.
Description:
Observations were performed with WFCAM on UKIRT in Hawai'i during two
runs in April 2005 and November 2006. Observations in the J-band have
a total exposure time of 150's, while in the H and K bands the
exposure time was 270s. The magnitudes were calibrated against 2MASS
but the magnitudes and colours quoted are on the WFCAM instrumental
system.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table2.dat 71 2368 Candidate carbon and oxygen rich AGB sources
within 4kpc of the galactic centre of NGC 6822
(Catalogue 1)
table3.dat 78 149390 All sources from the original observations that
were identified as stellar or probably-stellar
in all three photometric bands (Catalogue 2)
table4.dat 78 210979 All sources from the original observations that
were identified as stellar or probably-stellar
in only two photometric bands (Catalogue 3)
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See also:
J/AJ/109/173 : BVR photometry of NGC 6822 (Marconi+ 1995)
J/AJ/121/2020 : CTIO and WFPC2 photometry in NGC 6822 (Bianchi+, 2001)
J/AJ/123/832 : C star population in NGC 6822 (Letarte+, 2002)
J/A+A/429/837 : IJKs photometry of late-type stars in NGC 6822 (Cioni+, 2005)
J/A+A/431/1189 : BV photometry of NGC 6822 variables (Baldacci+, 2005)
J/A+A/454/717 : Near-IR photometry of C & AGB stars in NGC 6822 (Kang+, 2006)
J/A+A/456/905 : JKs, i'g'r' photometry of C stars in NGC 6822 (Demers+, 2006)
J/AJ/132/378 : HST and UV photometry of NGC 6822 (Bianchi+, 2006)
J/AJ/132/1372 : Chandra observation of NGC 6822 (Tennant+, 2006)
J/A+A/537/A108 : NGC 6822 AGB spectroscopic catalogue (Kacharov+, 2012)
Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 10 F10.6 deg RAdeg Right ascension in decimal degrees (J2000)
12- 21 F10.6 deg DEdeg Declination in decimal degrees (J2000)
23- 31 F9.6 mag Jmag UKIRT J-band magnitude
33- 37 F5.3 mag e_Jmag Error in J-band magnitude
39- 47 F9.6 mag Hmag UKIRT H-band magnitude
49- 53 F5.3 mag e_Hmag Error in H-band magnitude
55- 63 F9.6 mag Kmag UKIRT K-band magnitude
65- 69 F5.3 mag e_Kmag Error in K-band magnitude
71 A1 --- Type [CMT] (C) Carbon- or (M) Oxygen-rich candidate
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Byte-by-byte Description of file: table[34].dat
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Bytes Format Units Label Explanations
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1- 10 F10.6 deg RAdeg Right ascension in decimal degrees (J2000)
12- 21 F10.6 deg DEdeg Declination in decimal degrees (J2000)
23- 31 F9.6 mag Jmag ?=- UKIRT J-band magnitude
33- 37 F5.3 mag e_Jmag ?=- Error in J-band magnitude
39- 40 I2 --- f_Jmag [-9,1]?=- Flag numerical value as assigned
during reduction (1)
42- 50 F9.6 mag Hmag ?=- UKIRT H-band magnitude
52- 56 F5.3 mag e_Hmag ?=- Error in H-band magnitude
58- 59 I2 --- f_Hmag [-9,1]?=- Flag numerical value as assigned
during reduction (1)
61- 69 F9.6 mag Kmag ?=- UKIRT K-band magnitude
71- 75 F5.3 mag e_Kmag ?=- Error in K-band magnitude
77- 78 I2 --- f_Kmag [-9,1]?=- Flag numerical value as assigned
during reduction (1)
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Note (1): The meaning of the numerical flags assigned to each source in each
wavelength band are as follows;
-1 = stellar
-2 = probably-stellar
-3 = compact non-stellar
-8 = poor astrometry match
-9 = saturated
0 = noise-like
1 = non-stellar
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Acknowledgements:
Lisette Sibbons, l.sibbons1(at)herts.ac.uk
(End) Patricia Vannier [CDS] 07-May-2012