J/AJ/123/832 C star population in NGC 6822 (Letarte+, 2002)
The extent of NGC 6822 revealed by its C star population.
Letarte B., Demers S., Battinelli P., Kunkel W.E.
<Astron. J. 123, 832 (2002)>
=2002AJ....123..832L 2002AJ....123..832L
ADC_Keywords: Stars, carbon - Photometry
Keywords: galaxies: individual (NGC 6822) - galaxies: stellar content -
galaxies: structure - stars: carbon
Description:
Using the CFH12K camera, we apply the four-band photometric technique
to identify 904 carbon stars in an area 28'x42' centered on NGC 6822.
A few C stars outside of this area were also discovered with the Las
Campanas Swope Telescope.
The NGC 6822 survey employs two sets of observations obtained by
rather different telescopes and with different procedures: the Swope
Telescope on Las Campanas was used in 1999 October to secure images of
NGC 6822 in Kron-Cousins RKC, CN (810nm), and TiO (770nm) filters.
The 2048x2048 SITe No. 1 CCD yields a field of view of 23.7'x23.7';
NGC 6822 was also observed with the CFH12K at the beginning of one
night in 2000 September. The camera consists of a 12Kx8K pixel mosaic
covering a field of 42'x28', with each pixel corresponding to 0.206".
Images were obtained through Mould I and R filters and through the CN
and TiO filters.
The NGC 6822 C star population has =19.26 leading to an
<MI≥-4.70, value essentially identical to the mean magnitude
obtained for the C stars in IC 1613. Contrary to stars highlighting
the optical image of NGC 6822, C stars are seen at large radial
distances and trace a huge, slightly elliptical halo, which does not
coincide with the huge H I cloud surrounding NGC 6822. The previously
unknown stellar component of NGC 6822 has a exponential scale length
of 3.0±0.1' and can be traced to 5 scale lengths. The C/M ratio of
NGC 6822 is evaluated to be 1.0±0.2.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table2.dat 79 904 C stars in NGC 6822 (includes also table3)
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See also:
J/AJ/110/2715 : UBV photometry in NGC 6822, M31 and M33 (Massey+ 1995)
J/AJ/119/2780 : C stars in IC 1613 (Albert+, 2000)
J/AJ/120/1801 : C stars in Pegasus, DDO 210 and Tucana (Battinelli+, 2000)
J/AJ/121/2020 : CTIO and WFPC2 photometry in NGC 6822 (Bianchi+, 2001)
J/AJ/125/1298 : C star population in outer disk of M31 (Battinelli+, 2003)
J/A+A/410/795 : Photometry of NGC 3109 carbon stars (Demers+, 2003)
J/AJ/125/3037 : RI photometry of NGC 205 carbon stars (Demers+, 2003)
J/A+A/416/111 : C stars in Wolf-Lundmark-Melotte galaxy (Battinelli+, 2004)
J/A+A/417/479 : RI photometry of NGC 185 carbon stars (Battinelli+, 2004)
J/A+A/418/33 : RI photometry of C stars in NGC 147 (Battinelli+, 2004)
Table 1: Journal of observations
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Dates Filter Time (s) FWHM (") AirMass
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NGC 6822 west:
1999 Oct 2 R 3 x 480 2.5 1.06
1999 Oct 2 TiO 4 x 900 2.0 1.17
1999 Oct 2 CN 3 x 900 2.0 1.50
1999 Oct 3 R 480 1.6 1.32
1999 Oct 3 CN 900 1.7 1.49
1999 Oct 3 TiO 2 x 900 1.7 1.54
NGC 6822 east:
1999 Oct 3 R 3 x 480 1.7 1.04
1999 Oct 3 TiO 3 x 900 2.2 1.09
1999 Oct 3 CN 3 x 900 1.7 1.21
CFH12K:
2000 Sep 24 I 300 1.0 1.22
2000 Sep 24 R 400 0.7 1.22
2000 Sep 24 CN 1500 0.7 1.23
2000 Sep 24 TiO 1500 0.8 1.26
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Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 4 I4 --- [LDB2002] The C star identification number
6- 7 I2 h RAh Hour of Right Ascension (J2000)
9- 10 I2 min RAm Minute of Right Ascension (J2000)
12- 16 F5.2 s RAs Second of Right Ascension (J2000)
19 A1 --- DE- Sign of the Declination (J2000)
20- 21 I2 deg DEd Degree of Declination (J2000)
23- 24 I2 arcmin DEm Arcminute of Declination (J2000)
26- 29 F4.1 arcsec DEs Arcsecond of Declination (J2000)
33- 38 F6.3 mag Imag The Kron-Cousins I band magnitude
42- 46 F5.3 mag e_Imag The error in Imag
50- 54 F5.3 mag R-I The Kron-Cousins (R-I) band color
58- 62 F5.3 mag e_R-I The error in R-I
66- 70 F5.3 mag CN-TiO The (CN-TiO) band color
74- 78 F5.3 mag e_CN-TiO The error in CN-TiO
80 I1 --- T3 [3]? identifies the 3 stars outside
of the CFH12K field
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History:
From electronic version of the journal
References:
Albert et al., Paper I 2000AJ....119.2780A 2000AJ....119.2780A Cat. J/AJ/119/2780
Battinelli & Demers, Paper II 2000AJ....120.1801B 2000AJ....120.1801B Cat. J/AJ/120/1801
Battinelli et al., Paper V 2003AJ....125.1298B 2003AJ....125.1298B Cat. J/AJ/125/1298
Demers et al., Paper VI 2003AJ....125.3037D 2003AJ....125.3037D Cat. J/AJ/125/3037
Demers et al., Paper VII 2003A&A...410..795D 2003A&A...410..795D Cat. J/A+A/410/795
Battinelli & Demers, Paper VIII 2004A&A...418...33B 2004A&A...418...33B Cat. J/A+A/418/33
Battinelli & Demers, Paper IX 2004A&A...417..479B 2004A&A...417..479B Cat. J/A+A/417/479
Battinelli & Demers, Paper X 2004A&A...416..111B 2004A&A...416..111B Cat. J/A+A/416/111
(End) Greg Schwarz [AAS], Patricia Bauer [CDS] 30-May-2002