J/ApJ/712/1259 LCID project. II. Variables in IC1613 (Bernard+, 2010)
The ACS LCID project.
II. Faint variable stars in the isolated dwarf irregular galaxy IC 1613.
Bernard E.J., Monelli M., Gallart C., Aparicio A., Cassisi S.,
Drozdovsky I., Hidalgo S.L., Skillman E.D., Stetson P.B.
<Astrophys. J., 712, 1259-1276 (2010)>
=2010ApJ...712.1259B 2010ApJ...712.1259B
ADC_Keywords: Photometry, HST ; Stars, variable ; Binaries, eclipsing ;
Galaxies, nearby
Keywords: binaries: eclipsing - galaxies: dwarf -
galaxies: individual (IC 1613) - Local Group -
stars: variables: Cepheids - stars: variables: RR Lyrae
Abstract:
We present the results of a new search for variable stars in the Local
Group (LG) isolated dwarf galaxy IC 1613, based on 24 orbits of F475W
and F814W photometry from the Advanced Camera for Surveys (ACS) on
board the Hubble Space Telescope. We detected 259 candidate variables
in this field, of which only 13 (all of them bright Cepheids) were
previously known. Out of the confirmed variables, we found 90 RR Lyrae
stars, 49 classical Cepheids (including 36 new discoveries), and 38
eclipsing binary stars for which we could determine a period. The RR
Lyrae include 61 fundamental (RRab) and 24 first-overtone (FO, RRc)
pulsators, and five pulsating in both modes simultaneously (RRd). As
for the majority of LG dwarfs, the mean periods of the RRab and RRc
(0.611 and 0.334 days, respectively) as well as the fraction of
overtone pulsators (fc=0.28) place this galaxy in the intermediate
regime between the Oosterhoff types. From their position on the
period-luminosity diagram and light-curve morphology, we can
unambiguously classify 25 and 14 Cepheids as fundamental and FO mode
pulsators, respectively. Another two are clearly second-overtone
Cepheids, the first ones to be discovered beyond the Magellanic
Clouds. Among the remaining candidate variables, five were classified
as δ-Scuti and five as long-period variables. Most of the others
are located on the main sequence, the majority of them likely
eclipsing binary systems, although some present variations similar to
pulsating stars.
Description:
This work is based on observations obtained with the ACS onboard the
HST of a field located about 5' west of the center of IC 1613. 24 HST
orbits were devoted to this galaxy. These were collected over about
2.4 consecutive days between 2006 August 28 and 30 in F475W and F814W.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table2.dat 61 6216 Photometry of the variable stars in IC1613:
HST bands
table3.dat 89 6216 Photometry of the variable stars in IC1613:
Johnson bands
table4.dat 120 182 Pulsation properties of variable stars in IC1613:
ACS field
table5.dat 46 77 Candidate variable stars in IC1613: ACS field
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See also:
B/gcvs : General Catalogue of Variable Stars (Samus+ 2007-2012)
B/hst : HST Archived Exposures Catalog (STScI, 2007)
J/ApJ/699/1742 : LCID project. I. Cetus and Tucana variables (Bernard+, 2009)
J/A+A/445/901 : BV(RI)c bands of Cepheids in IC 1613 (Antonello+, 2006)
J/AcA/51/221 : OGLE-II. Cepheids in IC 1613 (Udalski+, 2001)
J/A+A/367/759 : Variable stars in IC 1613 (Mantegazza+, 2001)
J/A+A/363/29 : Variable stars in IC 1613 (Antonello+, 2000)
Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 5 A5 --- [BMG2010] Object identification (VNNN or VCNNN)
7- 20 F14.6 d HJD-475 Heliocentric Julian Date at mid-exposure for
m475
22- 27 F6.3 mag m475 ?=99.999 The HST/ACS F475W magnitude
29- 33 F5.3 mag e_m475 ?=9.999 Error in m475
35- 48 F14.6 d HJD-814 Heliocentric Julian Date at mid-exposure for
m814
50- 55 F6.3 mag m814 ?=99.999 The HST/ACS F814W magnitude
57- 61 F5.3 mag e_m814 ?=9.999 Error in m814
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Byte-by-byte Description of file: table3.dat
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Bytes Format Units Label Explanations
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1- 5 A5 --- [BMG2010] Object identification (VNNN or VCNNN)
7- 20 F14.6 d HJD-B Heliocentric Julian Date at mid-exposure for B
22- 27 F6.3 mag Bmag ?=99.999 The Johnson B magnitude
29- 33 F5.3 mag e_Bmag ?=9.999 Error in Bmag
35- 48 F14.6 d HJD-V Heliocentric Julian Date at mid-exposure for V
50- 55 F6.3 mag Vmag ?=99.999 The Johnson V magnitude
57- 61 F5.3 mag e_Vmag ?=9.999 Error in Vmag
63- 76 F14.6 d HJD-I Heliocentric Julian Date at mid-exposure for I
78- 83 F6.3 mag Imag ?=99.999 The Johnson I magnitude
85- 89 F5.3 mag e_Imag ?=9.999 Error in Imag
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Byte-by-byte Description of file: table4.dat
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Bytes Format Units Label Explanations
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1- 4 A4 --- [BMG2010] Object identification (VNNN)
6- 9 A4 --- Type Variable classification (1)
11- 12 I2 h RAh Hour of right Ascension (J2000)
14- 15 I2 min RAm Minute of right Ascension (J2000)
17- 21 F5.2 s RAs Second of right Ascension (J2000)
23- 24 I2 deg DEd Degree of Declination (J2000)
26- 27 I2 arcmin DEm Arcminute of Declination (J2000)
29- 32 F4.1 arcsec DEs Arcsecond of Declination (J2000)
34 A1 --- u_Per [u] Indicates an uncertainty in period,
magnitudes, or amplitudes
36- 41 F6.3 d Per Period
43- 48 F6.3 [d] logP Logarithm of the Period
50- 55 F6.3 mag F475W Intensity-averaged HST/ACS F475W magnitude
57- 61 F5.3 mag F475amp The F475W amplitude
63- 68 F6.3 mag F814W Intensity-averaged HST/ACS F814W magnitude
70- 74 F5.3 mag F814amp The F814W amplitude
76- 81 F6.3 mag F475-814 Intensity-averaged F475W-F814W color index
83- 88 F6.3 mag Bmag Intensity-averaged B magnitude
90- 94 F5.3 mag Bamp The B amplitude
96-101 F6.3 mag Vmag Intensity-averaged V magnitude
103-107 F5.3 mag Vamp The V amplitude
109-114 F6.3 mag Imag Intensity-averaged I magnitude
116-120 F5.3 mag Iamp The I amplitude
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Note (1): Classification as follows:
ab = Fundamental mode RR Lyrae
c = First-overtone mode RR Lyrae
d = Double mode RR Lyrae
F = Fundamental mode Classical Cepheid
FO = First overtone Classical Cepheid
SO = Second overtone Classical Cepheid
Cep = Candidate Cepheid
EB = Eclipsing binary
dSct = Candidate delta-Scuti
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Byte-by-byte Description of file: table5.dat
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Bytes Format Units Label Explanations
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1- 5 A5 --- [BMG2010] Object identification (VCNNN)
7- 9 A3 --- Type Variable classification (1)
11- 12 I2 h RAh Hour of right Ascension (J2000)
14- 15 I2 min RAm Minute of right Ascension (J2000)
17- 21 F5.2 s RAs Second of right Ascension (J2000)
23- 24 I2 deg DEd Degree of Declination (J2000)
26- 27 I2 arcmin DEm Arcminute of Declination (J2000)
29- 32 F4.1 arcsec DEs Arcsecond of Declination (J2000)
34- 39 F6.3 mag m475 The HST/ACS F475W magnitude
41- 46 F6.3 mag m814 The HST/ACS F814W magnitude
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Note (1): Classification as follows:
MSV = Main-sequence variable candidate
RGV = Red giant variable candidate
ISV = Instability strip variable candidate
LPV = Candidate long-period variable candidate
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History:
From electronic version of the journal
References:
Bernard et al. Paper I. 2009ApJ...699.1742B 2009ApJ...699.1742B Cat. J/ApJ/699/1742
Monelli et al. Paper III. 2010ApJ...720.1225M 2010ApJ...720.1225M
Monelli et al. Paper IV. 2010ApJ...718..707M 2010ApJ...718..707M
Hidalgo et al. Paper V. 2011ApJ...730...14H 2011ApJ...730...14H
Monelli et al. Paper VI. 2010ApJ...722.1864M 2010ApJ...722.1864M
Monelli et al. Paper VII. 2012ApJ...744..157M 2012ApJ...744..157M
(End) Greg Schwarz [AAS], Emmanuelle Perret [CDS] 10-Apr-2012