J/AcA/63/429 VI light curves of 10 variables in NGC288 (Arellano Ferro+, 2013)
Variable Stars in the Globular Cluster NGC 288: [Fe/H] and distance.
Arellano Ferro A,, Bramich D.M., Giridhar S., Figuera Jaimes R., Kains N.,
Kuppuswamy K.
<Acta Astron. 63, 429 (2013)>
=2013AcA....63..429A 2013AcA....63..429A
ADC_Keywords: Clusters, globular ; Stars, variable ; Photometry, CCD
Keywords: globular clusters: individual: NGC 288 - stars: variables: RR Lyrae -
stars: variables: delta Scuti
Abstract:
A search for variable stars in the globular cluster NGC 288 was
carried out using a time-series of CCD images in the V and I filters.
The photometry of all stellar sources in the field of view of our
images, down to V∼19mag, was performed using difference image analysis
(DIA). For stars of∼15mag, measurement accuracies of ∼8mmag and
∼10mmag were achieved for V and I respectively. Three independent
search strategies were applied to the 5525 light curves but no new
variables were found above the threshold limits characteristic of our
data set. The use of older data from the literature combined with the
present data allowed the refinement of the periods of all known
variables. Fourier light curve decomposition was performed for the
RRab and the RRc stars to obtain an estimate of
[Fe/H]ZW=-1.62±0.02 (statistical) ±0.14 (systematic). A true
distance modulus of 14.768±0.003mag (statistical) ±0.042mag
(systematic), or a distance of 8.99±0.01kpc (statistical) ±0.17kpc
(systematic) was calculated from the RRab star. The RRc star predicts
a discrepant distance about one kiloparsec shorter but it is possibly
a Blazhko variable. An independent distance from the P-L relationship
for SX Phe stars leads to a distance of 8.9±0.3kpc. The SX Phe stars
V5 and V9 are found to be double mode pulsators.
Description:
Standard and instrumental magnitudes in the Johnson-Kron Cousins V,I
filters are listed for 10 variables in the globular cluster NGC 288.
Epoch of mid-exposure and magnitude uncertainties are also listed.
For completeness, also listed are the reference flux [ADU/s], the
differential flux [ADU/s] and the photometric scale factor p(t), and
their uncertainties.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table3.dat 93 10 General data for all of the confirmed variables
in NGC 288 in the FoV of our images
table2.dat 80 3539 VI CCD photometry of variable stars in NGC 288
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See also:
J/A+AS/125/337 : New variables in NGC 288 (Kaluzny+ 1997)
J/AJ/106/1024 : BV photometry in NGC 288 (Bergbusch 1993)
J/AJ/122/2569 : VI photometry of NGC 288, 362 and 1851 (Bellazzini+, 2001)
Byte-by-byte Description of file: table3.dat
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Bytes Format Units Label Explanations
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1- 3 A3 --- Name Variable name <Cl* NGC 288 Saw VNN> in Simbad
5- 10 A6 --- Type Variable type (RRab/c, SR, SX Phe or E)
12- 17 F6.3 mag Vmag Johnson V magnitude
19- 24 F6.3 mag Imag ?=- Cousins I magnitude
26 A1 --- l_AV [~] Limit flag on AV
27- 31 F5.3 mag AV Amplitude in V band
33 A1 --- l_AI [~] Limit flag on AI
34- 37 F4.2 mag AI ?=- Amplitude in I band
39- 48 F10.8 d Per ?=- Period from this paper
50- 58 F9.4 d HJDmax Date of maximum (HJD-2450000)
59 A1 --- n_HJDmax [b] b: HJDmax contains time of minimum light
60- 68 F9.5 d Perl Period from literature
69 A1 --- n_Per [a] a: Period from Oosterhoff
(1943BAN.....9..397O 1943BAN.....9..397O)
71- 72 I2 h RAh Right Ascension (J2000.0)
74- 75 I2 min RAm Right Ascension (J2000.0)
77- 81 F5.2 s RAs Right Ascension (J2000.0)
83 A1 --- DE- Declination sign (J2000.0)
84- 85 I2 deg DEd Declination (J2000.0)
87- 88 I2 arcmin DEm Declination (J2000.0)
90- 93 F4.1 arcsec DEs Declination (J2000.0)
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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 --- Name Variable star number, VNN
5 A1 --- Flt [VI] Filter
7- 19 F13.5 d HJD Heliocentric Julian day
21- 26 F6.3 mag magstd Standard magnitude
28- 33 F6.3 mag maginst Instrumental magnitude
35- 39 F5.3 mag e_magstd Error on the magnitude
41- 49 F9.3 s-1 Fref Reference flux (in ADU/s)
51- 56 F6.3 s-1 e_Fref Error on the reference flux (in ADU/s)
58- 66 F9.3 s-1 DFlux Differential flux (in ADU/s)
68- 73 F6.3 s-1 e_DFlux Error on the differential flux (in ADU/s)
75- 80 F6.4 --- p Photometric scale factor
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Acknowledgements:
Armando Arellano Ferro, armando(at)astro.unam.mx
References:
Kaluzny, CCD photometry of NGC 288 variable stars, 1996A&AS..120...83K 1996A&AS..120...83K
(End) A. Arellano Ferro [IA-UNAM, Mexico], P. Vannier [CDS] 15-Jan-2014