J/ApJ/701/1323 Variable stars in Fornax dSph. III. (Greco+, 2009)
Variable stars in the Fornax dSph galaxy.
III. The globular cluster Fornax 5.
Greco C., Clementini G., Catelan M., Held E.V., Poretti E., Gullieuszik M.,
Maio M., Rest A., De Lee N., Smith H.A., Pritzl B.J.
<Astrophys. J., 701, 1323-1335 (2009)>
=2009ApJ...701.1323G 2009ApJ...701.1323G
ADC_Keywords: Photometry, UBV ; Stars, variable ; Clusters, globular
Keywords: galaxies: dwarf - galaxies: individual (Fornax) -
globular clusters: individual (Fornax 5) - stars: horizontal-branch -
stars: variables: other - techniques: photometric
Abstract:
We present a new study of the variable star population in globular
cluster 5 of the Fornax dSph, based on B and V time series photometry
obtained with the MagIC camera of the 6.5m Magellan Clay telescope and
complementary Hubble Space Telescope archive data. Light curves and
accurate periodicities were obtained for 30 RR Lyrae stars and one SX
Phoenicis variable. The RR Lyrae sample includes 15 fundamental-mode
pulsators, 13 first-overtone pulsators, one candidate double-mode
pulsator and one RR Lyrae star with uncertain type classification.
The average and minimum periods of the ab-type RR Lyrae stars,
<Pab≥0.590days, Pab,min=0.53297days and the position in the
horizontal branch type-metallicity plane, indicate that the cluster
has Oosterhoff-intermediate properties, basically confirming previous
indications by Mackey & Gilmore, although with some differences both
in the period and type classification of individual variables.
Description:
B, V time series photometry of For 5 was obtained over two consecutive
nights in November 2003 with the MagIC camera of the Magellan/Clay
6.5m telescope. Observations of For 4 were also obtained during the
same nights (see Paper I, Greco et al. 2007ApJ...670..332G 2007ApJ...670..332G).
In order to improve the light curve sampling and the period
definition, the Magellan data were complemented by the HST archival
data of HST Program 5917.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table2.dat 25 1758 V, B photometry of the For 5 variable stars with
light curves on a magnitude scale
table3.dat 102 31 Identification and properties of the For 5
variable stars
table4.dat 52 23 Cross-identification with MG03 study of the
variable stars in For 5 (2003MNRAS.345..747M 2003MNRAS.345..747M)
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See also:
J/ApJ/685/947 : SX Phe stars in Fornax. II. (Poretti+, 2008)
J/MNRAS/345/747 : RR Lyrae in 4 Fornax globular clusters (Mackey+, 2003)
J/AJ/123/840 : VI photometry of variable stars in Fornax (Bersier+, 2002)
J/AJ/111/1596 : BV photometry in Fornax globulars (Smith+ 1996)
Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 2 I2 --- ID Variable star identification number (G1)
4 A1 --- Filt [BV] Filter used in observation (B, V)
6- 19 F14.6 d HJD Heliocentric Julian Date of observation
21- 25 F5.2 mag mag Observed magnitude in Filt
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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 A1 --- --- [V]
2- 3 I2 --- ID Variable name (G1) (1)
5- 9 A5 --- Id Internal identification
11 I1 h RAh Hour of right ascension (J2000)
13- 14 I2 min RAm Minute of right ascension (J2000)
16- 20 F5.2 s RAs Second of right ascension (J2000)
22 A1 --- DE- Sign of declination (J2000)
23- 24 I2 deg DEd Degree of declination (J2000)
26- 27 I2 arcmin DEm Arcminute of declination (J2000)
29- 33 F5.2 arcsec DEs Arcsecond of declination (J2000)
35- 40 A6 --- Vtype Variable type (RR types or SX Phe)
42- 49 F8.6 d Per ? Pulsation period
50 A1 --- u_Per [:] Uncertainty flag on Per
52- 59 F8.3 d T0 ? Time of maximum light (JD-2450000)
60 A1 --- u_T0 [:] Uncertainty flag on T0
62- 66 F5.2 mag <Vmag> ? Intensity-averaged V-band magnitude
67 A1 --- u_<Vmag> [:] Uncertainty flag on <Vmag>
69- 70 I2 --- NV1 Number of phase points in the V band for
Magellan observations
71 A1 --- --- [+]
72- 73 I2 --- NV2 ? Number of phase points in the V band from
HST data
75- 79 F5.2 mag <Bmag> ? Intensity-averaged B-band magnitude
80 A1 --- u_<Bmag> [:] Uncertainty flag on <Bmag>
82- 83 I2 --- NB ? Number of phase points in the B band
85- 86 A2 --- l_Vamp [≥ ] Limit flag on Vamp
87- 90 F4.2 mag Vamp ? Amplitude of the light variation, AV
91 A1 --- u_Vamp [:] Uncertainty flag on Vamp
93- 94 A2 --- l_Bamp [≥ ] Limit flag on Bamp
95- 98 F4.2 mag Bamp ? Amplitude of the light variation, AB
100-102 A3 --- Notes [a-i, ] Notes (2)
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Note (1): Variable stars were assigned increasing numbers starting from the
cluster center, which was set at J024221.07-340607.5. Stars from V1 to
V28 are located within 45" from the For 5 center, hence are more
likely cluster members (see Section 4.4).
Note (2): Notes as follows:
b = Light curves from the Magellan observations (50-55 data points) are
available in differential flux only. Magnitudes, when available are only
from the HST dataset (10-14 data points). They were obtained through a
rough calibration of the HST F555W data done neglecting the color terms,
they provide only a crude estimate of the actual average magnitude of
these variable stars, which often have poor light curve coverage in the
HST dataset.
c = The light curve coverage of V1 and V6 in the HST dataset is not
sufficient to provide an estimate of the star average V magnitude.
d = V5 has no secure counterpart in the HST photometry.
e = Average magnitude and shape of the light curve are consistent with a
small amplitude RR Lyrae star, but the period definition is very
uncertain. A period of about 0.49 days phases the star light curve, a
shorter period around 0.34 days is also possible. MG03 derive for the
star a period of 0.394 but with large uncertainty. In Figure 4 the star
light curves were folded according to the period P=0.34 which is closer
to the value found by MG03.
f = Shape and amplitude of the light curve indicate a long period fundamental
mode RR Lyrae star, but the period definition is very uncertain. A period
around 0.68 days phases the light curve well but with a large gap around
the minimum light. Longer periods around 0.73 or 0.79 days are also
possible.
g = The scatter and specifically the two maxima slightly different in shape
observed in the light curves of V18 in two consecutive nights suggest
that the star could be a double-mode RR Lyrae variable.
h = These stars fall outside the FOV covered by the HST observations.
i = The HST photometry of V28 is systematically brighter than the Magellan
photometry.
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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 A1 --- --- [V]
2- 3 I2 --- ID Variable name (G1)
5- 9 A5 --- Id Internal identification
11- 17 A7 --- HST HST camera identification
19- 23 A5 --- OType Object type from this paper
25- 32 F8.6 d Per ? Period from this paper
33 A1 --- u_Per [:] Uncertainty flag on Per
35- 39 A5 --- [MG2003] Identification from Mackey et al., 2003
Cat. J/MNRAS/345/747 (MG03)
40 A1 --- f_[MG2003] [b] b: candidate variable according to MG03
Table 3
42- 45 A4 --- MGType Variability type in MG03 (RRab or RRc)
47- 51 F5.3 d MGPer ? Period in MG03
52 A1 --- u_MGPer [a] a: Uncertain period determination (MG03)
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Global notes:
Note (G1): Variable names are <[GCC2009] VNN> in Simbad.
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History:
From electronic version of the journal
References:
Greco et al. Paper I. 2007ApJ...670..332G 2007ApJ...670..332G
Poretti et al. Paper II. 2008ApJ...685..947P 2008ApJ...685..947P Cat. J/ApJ/685/947
(End) Greg Schwarz [AAS], Emmanuelle Perret [CDS] 22-Sep-2011