J/AJ/154/263 NIR photometry of 77 RR Lyrae stars (Karczmarek+, 2017)
The Araucaria Project: the distance to the Fornax Dwarf Galaxy from
near-infrared photometry of RR Lyrae stars.
Karczmarek P., Pietrzynski G., Gorski M., Gieren W., Bersier D.
<Astron. J., 154, 263 (2017)>
=2017AJ....154..263K 2017AJ....154..263K (SIMBAD/NED BibCode)
ADC_Keywords: Galaxies, nearby ; Stars, variable ; Photometry, infrared
Keywords: galaxies: distances and redshift - galaxies: individual (Fornax) -
infrared: stars - stars: variables: RR Lyrae
Abstract:
We have obtained single-phase near-infrared (NIR) magnitudes in the J
and K bands for 77 RR Lyrae (RRL) stars in the Fornax Dwarf Spheroidal
Galaxy. We have used different theoretical and empirical NIR
period-luminosity-metallicity calibrations for RRL stars to derive
their absolute magnitudes, and found a true, reddening-corrected
distance modulus of 20.818±0.015(statistical)±0.116(systematic) mag.
This value is in excellent agreement with the results obtained within
the Araucaria Project from the NIR photometry of red clump stars
(20.858±0.013 mag), the tip of the red giant branch
(20.84±0.04±0.14 mag), as well as with other independent distance
determinations to this galaxy. The effect of metallicity and reddening
is substantially reduced in the NIR domain, making this method a
robust tool for accurate distance determination at the 5% level. This
precision is expected to reach the level of 3% once the zero points of
distance calibrations are refined thanks to the Gaia mission. NIR
period-luminosity-metallicity relations of RRL stars are particularly
useful for distance determinations to galaxies and globular clusters
up to 300 kpc, that lack young standard candles, like Cepheids.
Description:
NIR observations were conducted between 2008 October 7 and 2008 October 23
with the High Acuity Wide-field K-band Imager (HAWK-I) mounted in the
Nasmyth focus of UT4/VLT ESO 8 m telescope at Paranal, Chile. The
locations of four target fields in the Fornax galaxy (Figure 1) were
purposely chosen to overlap fields from the previous visual observations
of Bersier & Wood (2002, J/AJ/123/840). The HAWK-I field of view of
four 2048x2048 pixel detectors was about 7.5'x7.5' with a scale of
0.106 pixel-1. The fields were observed in J and Ks (further denoted
as K) wavebands, under photometric conditions (seeing range 0.4"-0.7").
Exposure times of 60 s per jitter were fixed for the J and K bands,
resulting in total integration times of 18 and 26 minutes per field,
respectively.
Objects:
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RA (ICRS) DE Designation(s)
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02 39 59.3 -34 26 57 Fornax Dwarf Galaxy = NAME Fornax Dwarf Spheroidal
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table4.dat 116 104 Cross-identification and main characteristics
of 77 RR Lyrae stars
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See also:
J/AJ/123/840 : VI photometry of variable stars in Fornax (Bersier+, 2002)
J/MNRAS/345/747 : RR Lyrae in 4 Fornax globular clusters (Mackey+, 2003)
J/ApJ/685/947 : SX Phe stars in Fornax. II. (Poretti+, 2008)
J/ApJ/701/1323 : Variable stars in Fornax dSph. III. (Greco+, 2009)
Byte-by-byte Description of file: table4.dat
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Bytes Format Units Label Explanations
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1- 3 A3 --- --- [FBW]
4- 19 A16 --- FBW Star identifier (FBW JHHMMSS.s+DDMMSS) (1)
21- 27 A7 --- Field HAWK-I field
29- 30 I2 h RAh Hour of Right ascension (J2000)
32- 33 I2 min RAm Minute of Right ascension (J2000)
35- 39 F5.2 s RAs Second of Right ascension (J2000)
41 A1 --- DE- Sign of the Declination (J2000)
42- 43 I2 deg DEd Degree of Declination (J2000)
45- 46 I2 arcmin DEm Arcminute of Declination (J2000)
48- 51 F4.1 arcsec DEs Arcsecond of Declination (J2000)
53- 59 F7.5 d Per [0.33563/0.6754] Pulsational period
61- 62 A2 --- RRtype [ab c] Type of RR Lyrae star (1)
64- 69 F6.3 mag Jmag [19.989/20.755] HAWK-I apparent magnitude in
J-band
71- 75 F5.3 mag e_Jmag [0.011/0.031] Uncertainty in Jmag
77- 82 F6.3 mag Ksmag [19.806/20.499] HAWK-I apparent magnitude in
Ks-band
84- 88 F5.3 mag e_Ksmag [0.027/0.055] Uncertainty in Ksmag
90-102 F13.5 d JD-J Julian date of J-band exposure
104-116 F13.5 d JD-Ks Julian date of Ks-band exposure
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Note (1): From Bersier & Wood (2002, J/AJ/123/840).
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History:
From electronic version of the journal
(End) Prepared by [AAS], Tiphaine Pouvreau [CDS] 29-Aug-2018