J/MNRAS/421/2998 NGC 6822 Cepheids JHKs light curves (Feast+, 2012)
The Cepheid distance to the Local Group galaxy NGC 6822.
Feast M.W., Whitelock P.A., Menzies J.W., Matsunaga N.
<Mon. Not. R. Astron. Soc., 421, 2998-3003 (2012)>
=2012MNRAS.421.2998F 2012MNRAS.421.2998F
ADC_Keywords: Galaxies, nearby ; Stars, variable ; Photometry, infrared
Keywords: stars: variables: Cepheids - galaxies: distances and redshifts -
galaxies: individual: NGC 6822 - Local Group
Abstract:
Recent estimates of the Cepheid distance modulus of NGC 6822 differ by
0.18mag. To investigate this we present new multi-epoch JHKs
photometry of classical Cepheids in the central region of NGC 6822 and
show that there is a zero-point difference from earlier work. These
data together with optical and mid-infrared observations from the
literature are used to derive estimates of the distance modulus of NGC
6822. A best value of 23.40mag is adopted, based on a Large
Magellanic Cloud (LMC) distance modulus of 18.50mag. The standard
error of this quantity is ∼0.05mag. We show that to derive
consistent moduli from Cepheid observations at different wavelengths,
it is necessary that the fiducial LMC period-luminosity relations at
these wavelengths should refer to the same subsample of stars. Such a
set is provided. A distance modulus based on RR Lyrae variables agrees
with the Cepheid result.
Description:
Our survey of NGC 6822 is confined to the optical bar which is aligned
nearly north-south. We used the Japanese-South African IRSF (InfraRed
Survey Facility) telescope equipped with the SIRIUS camera, which
permits simultaneous imaging in the J, H and Ks bands.
We defined three overlapping fields, with field 1 centred at
RA=19:44:56 and DE=-14:48:06 (2000.0). Fields 2 and 3 are centred 6.7
arcmin north and south, respectively, from field 1. The three fields,
approximately 7.8 arcmin2, were observed in JHKs at 19, 18 and 16
epochs, respectively, over a period of 3.5yr.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table3.dat 78 19 Flux-weighted mean JHKs for Cepheids in NGC 6822
table2.dat 57 382 Cepheid variables observed in NGC 6822
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See also:
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)
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/450/873 : Araucaria: NGC 6822 bright variables VI mag (Mennickent+ 2006)
J/A+A/454/717 : NGC 6822 near-IR photometry of C and AGB stars (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/495/447 : PN and HII regions in NGC6822 (Hernandez-Martinez+, 2009)
J/A+A/537/A108 : NGC 6822 AGB spectroscopic catalogue (Kacharov+, 2012)
J/A+A/540/A135 : AGB population of NGC 6822 (Sibbons+, 2012)
J/A+A/548/A129 : HST photometry in NGC 6822 (Fusco+, 2012)
J/AJ/128/2815 : Araucaria: NGC 6822 Cepheid variables (Pietrzynski+, 2004)
J/ApJ/647/1056 : Araucaria: NGC 6822 Cepheid variables (Gieren+, 2006)
Byte-by-byte Description of file: table3.dat
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Bytes Format Units Label Explanations
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1- 3 A3 --- --- [cep]
4- 6 I03 --- cep [1/101] Cepheid number,
<[PGU2004] cepNNN> in Simbad (1)
8- 12 I5 --- IRSF IRSF number
14- 19 F6.3 mag Jmag Flux-weighted mean J magnitude
21- 25 F5.3 mag e_Jmag rms uncertainty on Jmag
27- 32 F6.3 mag Hmag Flux-weighted mean H magnitude
34- 38 F5.3 mag e_Hmag rms uncertainty on Hmag
40- 45 F6.3 mag Ksmag Flux-weighted mean Ks magnitude
47- 51 F5.3 mag e_Ksmag rms uncertainty on Ksmag
53- 57 F5.3 mag J-H Flux-weighted mean J-H colour index
59- 63 F5.3 mag H-Ks Flux-weighted mean H-Ks colour index
65- 69 F5.3 mag J-Ks Flux-weighted mean J-Ks colour index
71- 78 F8.4 d Per Period
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Note (1): Stars cep003 to cep018 used in solutions.
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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- 3 A3 --- --- [cep]
4- 6 I03 --- cep [1/101] Cepheid number
7 A1 --- Rem [abc] Cepheid in overlapping fields (1)
9- 18 F10.5 d HJD Heliocentric Julian date (HJD-2450000)
20- 25 F6.3 mag Jmag ?=- J magnitude
27- 31 F5.3 mag e_Jmag ?=- rms uncertainty on Jmag
33- 38 F6.3 mag Hmag ?=- H magnitude
40- 44 F5.3 mag e_Hmag ?=- rms uncertainty on Hmag
46- 51 F6.3 mag Ksmag ?=- Ks magnitude
53- 57 F5.3 mag e_Ksmag ?=- rms uncertainty on Ksmag
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Note (1): Notes as follows:
a = cep004 in both overlapping fields 1 and 3
b = cep014 in both overlapping fields 1 and 3
c = cep018 in both overlapping fields 1 and 3
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History:
From electronic version of the journal
(End) Patricia Vannier [CDS] 08-Mar-2013