J/A+A/429/837 IJKs photometry of late-type stars in NGC 6822 (Cioni+, 2005)
Near-IR observations of NGC 6822: AGB stars, distance, metallicity and
structure.
Cioni M.-R.L., Habing H.J.
<Astron. Astrophys. 429, 837 (2005)>
=2005A&A...429..837C 2005A&A...429..837C
ADC_Keywords: Galaxies, photometry ; Photometry, infrared ; Stars, late-type
Keywords: stars: late-type - stars: distances - galaxies: local group -
galaxies: abundances - galaxies: photometry - infrared: stars
Abstract:
Observations in the IJKs wave bands covering the central 20'x20' of
the Local Group galaxy NGC 6822 have been made with the William
Herschel Telescope in La Palma. They have allowed us to characterize,
for the first time in the near-infrared across the whole galaxy, its
late-type stellar population (i.e. red giant and asymptotic giant
branch stars) and to derive from the ratio between carbon-rich and
oxygen-rich asymptotic giant branch stars an indication about spatial
variations in metallicity. These amount to about 1.56dex, twice of
what has been previously found within each Magellanic Cloud using the
same technique. We have calibrated our photometry on the DENIS
(I-band) and 2MASS (J and Ks bands) data and obtained a distance
modulus of (m-M)0=23.34(0.12) from the position of the tip of the
RGB. The large scale distribution of late-type stars suggests that
either the galaxy is viewed under a high inclination angle or it has a
non-negligible thickness.
Description:
Observations were performed with the William Herschel Telescope in La
Palma during two runs in July 2002. The Isaac Newton Group Red Imaging
Device was used to observe in the J and Ks band from 20th to 22nd July
while observations in the I band were obtained using the Prime Focus
imaging camera on July 14th.
Objects:
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RA (2000) DE Designation(s)
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19 44 57.8 -14 48 11 NGC 6822 = IC 4895
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 64 9375 NGC 6822 catalogue of sources detected in the
three wave bands, I, J and Ks
table2.dat 63 16354 NGC 6822 catalogue of sources detected in both
J and Ks bands, but not in I band.
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See also:
B/denis : The DENIS database (DENIS Consortium, 2003)
II/246 : 2MASS All-Sky Catalog of Point Sources (Cutri+ 2003)
II/228 : DENIS Catalogue toward Magellanic Clouds (DCMC) (Cioni+ 2000)
J/AJ/123/832 : C star population in NGC 6822 (Letarte+, 2002)
J/AJ/121/2020 : CTIO and WFPC2 photometry in NGC 6822 (Bianchi+, 2001)
J/AJ/109/173 : BVR photometry of NGC 6822 (Marconi+ 1995)
J/AJ/110/2715 : UBV photometry in NGC 6822, M31 and M33 (Massey+ 1995)
Byte-by-byte Description of file: table1.dat table2.dat
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Bytes Format Units Label Explanations
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1- 10 F10.6 deg RAdeg Right ascension (J2000)
12- 21 F10.6 deg DEdeg Declination (J2000)
23- 27 F5.2 mag Imag ? I magnitude
29- 32 F4.2 mag e_Imag ? Error in I magnitude
34- 35 I2 --- f_Imag ? SExtractor flag in I magnitude (1)
37- 41 F5.2 mag Jmag J magnitude
43- 46 F4.2 mag e_Jmag Error in J magnitude
48- 49 I2 --- f_Jmag [0/2] SExtractor flag in J magnitude (1)
51- 55 F5.2 mag Ksmag Ks magnitude
57- 60 F4.2 mag e_Ksmag Error in Ks magnitude
62- 63 I2 --- f_Ksmag SExtractor flag in Ks magnitude (1)
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Note (1): SExtractor flag is 2 when the object was originally blended
with another one.
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Acknowledgements: Maria-Rosa Cioni, mcioni(at)eso.org
(End) Patricia Vannier [CDS] 26-Oct-2004