J/A+A/555/A36 VrI light curves of NGC7099 variables (Kains+, 2013)
Estimating the parameters of globular cluster M 30 (NGC 7099) from time-series
photometry.
Kains N., Bramich D.M., Arellano Ferro A., Figuera Jaimes R.,
Jorgensen U.G., Giridhar S., Alsubai K.A., Andersen J.M., Bozza V.,
Browne P., Burgdorf M., Calchi Novati S., Damerdji Y., Diehl C., Dodds P.,
Dominik M., Elyiv A., Fang X.-S., Giannini E., Gu S.-H., Hardis S.,
Harpsoe K., Hinse T.C., Hornstrup A., Hundertmark M., Jessen-Hansen J.,
Juncher D., Kerins E., Kjeldsen H., Korhonen H., Liebig C., Lund M.N.,
Lundkvist M., Mancini L., Martin R., Mathiasen M., Penny M.T., Rabus M.,
Rahvar S., Ricci D., Sahu K., Scarpetta G., Skottfelt J., Snodgrass C.,
Southworth J., Surdej J., Tregloan-Reed J., Vilela C., Wertz O., Williams A.
(The MiNDSTEp consortium)
<Astron. Astrophys. 555, A36 (2013)>
=2013A&A...555A..36K 2013A&A...555A..36K
ADC_Keywords: Clusters, globular ; Stars, variable ; Photometry, CCD
Keywords: stars: variables: general - stars: variable: RR Lyrae -
globular clusters: individual: NGC 7099
Abstract:
We present the analysis of 26 nights of V and I time-series
observations from 2011 and 2012 of the globular cluster M 30
(NGC 7099). We used our data to search for variable stars in this
cluster and refine the periods of known variables; we then used our
variable star light curves to derive values for the cluster's
parameters.
We used difference image analysis to reduce our data to obtain
high-precision light curves of variable stars. We then estimated the
cluster parameters by performing a Fourier decomposition of the light
curves of RR Lyrae stars for which a good period estimate was
possible. We also derive an estimate for the age of the cluster by
fitting theoretical isochrones to our colour-magnitude diagram (CMD).
Out of 13 stars previously catalogued as variables, we find that only
4 are bona fide variables.
We detect two new RR Lyrae variables, and confirm two additional
RR Lyrae candidates from the literature. We also detect four other new
variables, including an eclipsing blue straggler system, and an
SX Phoenicis star. This amounts to a total number of confirmed
variable stars in M 30 of 12. We perform Fourier decomposition of the
light curves of the RR Lyrae stars to derive cluster parameters using
empirical relations. We find a cluster metallicity
[Fe/H]ZW=-2.01±0.04, or [Fe/H]UVES=-2.11±0.06, and a distance
of 8.32±0.20kpc (using RR0 variables), 8.10 kpc (using one RR1
variable), and 8.35±0.42kpc (using our SX Phoenicis star detection
in M 30). Fitting isochrones to the CMD, we estimate an age of
13.0±1.0Gyr for M 30.
Description:
V and I time-series photometry and difference imaging parameters
for all confirmed variables in NGC 7099.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
stars.dat 113 12 Data for all confirmed variable stars in NGC7099
(tables 3 and 5 of the paper)
table2.dat 83 9654 V and I lightcurves
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See also:
J/other/MmSAI/20.63 : M30 V1-V3 variable light curves (Rosino, 1949)
J/A+A/313/129 : M30 blue stars positions and magnitudes (Burgarella+ 1996)
J/AJ/116/1757 : M30 UBV photometry (Guhathakurta+, 1998)
J/ApJ/518/262 : CCD VIc Photometry of M30 stars (Sandquist+, 1999)
J/ApJ/657/286 : Chandra X-ray sources in M30 (NGC 7099) (Lugger+, 2007)
J/MNRAS/413/1275 : VrI light curves of NGC6981 variables (Bramich+, 2011)
J/A+A/548/A92 : VrI light curves of NGC1904 variables (Kains+, 2012)
Byte-by-byte Description of file: stars.dat
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Bytes Format Units Label Explanations
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1- 3 A3 --- VName Variable name, VNN,
<Cl* NGC 7099 SAW VNN> in Simbad
4 A1 --- n_VName [bc] Individual notes on variables (1)
6- 7 I2 h RAh Right ascension (J2000)
9- 10 I2 min RAm Right ascension (J2000)
12- 16 F5.2 s RAs Right ascension (J2000)
18 A1 --- DE- Declination sign (J2000)
19- 20 I2 deg DEd Declination (J2000)
22- 23 I2 arcmin DEm Declination (J2000)
25- 28 F4.1 arcsec DEs Declination (J2000)
30- 38 F9.4 d Ep Epoch (HJD-2450000)
40- 48 F9.7 d Per Period
50- 58 F9.7 d Per1 ?=- Rosino (1949, J/other/MmSAI/20.63) period
59 A1 --- n_Per1 [a] Note on Per1 (2)
61- 65 F5.3 d Per2 ?=- Pietrukowicz et al. (2004AcA....54...19P 2004AcA....54...19P)
period (3)
67- 71 F5.2 mag <Vmag> Mean V magnitude (4)
73- 77 F5.2 mag <Imag> ? Mean I magnitude (4)
79 A1 --- l_Vamp [~] Limit flag on Vamp
80- 83 F4.2 mag Vamp Amplitude in V band
85- 88 F4.2 mag Iamp ?=- Amplitude in I band
90-113 A24 --- VType Variable type
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Note (1): Notes on VName as follows:
b = The period given for V4 is that of the sinusoidal variations seen during
the quiescent part of the light curve, and the mean magnitudes are also
those during quiescent phase; outburst mean magnitudes are given in the
text
c = For V19, the mean magnitudes are overestimated and amplitudes are
underestimated due to blending, as discussed in the text
Note (2): Note on Per1 as follows:
a = Rosino (1961, Contr. Asiago-Padova, 117) revised the period of
V1 to 0.743608d.
Note (3): V15 = Cl* NGC 7099 PK 2 and V19 = Cl* NGC 7099 PK 3.
Note (4): intensity-weighted mean magnitudes for RR Lyrae,
inverse-variance-weighted mean magnitudes for other variables.
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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 --- VName Variable name, VNN
5 A1 --- Filter [VI] Observation filter
7- 19 F13.5 d HJD Heliocentric Julian date
21- 26 F6.3 mag mag.s Standard magnitude
28- 33 F6.3 mag mag.i Instrumental magnitude
35- 39 F5.3 mag e_mag.i Error on the magnitude
41- 49 F9.3 1/s Fref Reference flux (in ADU/s)
51- 56 F6.3 1/s e_Fref Error on the reference flux (in ADU/s)
58- 68 F11.3 1/s DFlux Differential flux (in ADU/s)
70- 76 F7.3 1/s e_DFlux Error on the differential flux (in ADU/s)
78- 83 F6.4 --- p Photometric scale factor
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History:
* 30-Dec-2013: On-line version
* 15-Jul-2014: Units of Fref and DFlux corrected in 5*s-1
(instead of s-1), from author
* 17-Jul-2014: Table2 corrected (units in s-1 with corresponding values),
from author
Acknowledgements:
Noe Kains, nkains(at)eso.org
(End) Noe Kains [ESO], Patricia Vannier [CDS] 15-May-2013