J/AJ/161/120 gri photometry for 73 stars in NGC419 (Martinez-Vazquez+, 2021)
Short-period variability in the globular cluster NGC419 and the SMC field.
Martinez-Vazquez C.E., Salinas R., Vivas A.K.
<Astron. J., 161, 120 (2021)>
=2021AJ....161..120M 2021AJ....161..120M
ADC_Keywords: Clusters, globular; Stars, variable; Photometry, VRI
Keywords: Globular star clusters ; Delta Scuti variable stars ;
Small Magellanic Cloud ; Variable stars
Abstract:
Delta Scuti (δSct) stars have been extensively studied in our
Galaxy but far less in extragalactic systems. Here we study the
population of δSct variables in NGC419, an intermediate-age
globular cluster of the Small Magellanic Cloud (SMC), using g, r, and
i Gemini-S/Gemini Multi-Object Spectrograph (GMOS) time-series
observations. Our goal is to study the role of such variables in the
cluster extended main-sequence turnoff (MSTO). We report the discovery
of 54 δSct stars and three eclipsing binaries in the NGC419
field. We find only a handful of the δSct stars at the MSTO of
NGC419, while the majority are fainter, indicating that the cluster is
younger (≲1.2Gyr) than previously thought. Considering their radial
distribution, we identify only six δSct stars as probable
members of NGC419, while the 48 remaining are likely δSct stars
of the SMC field. Cluster δSct stars appear close to the red
edge of the MSTO, supporting the idea that the extended MSTO has its
origin in an age spread. The 48 field δSct stars represent the
largest detection of δSct stars made in the SMC. The period
distribution of these newly detected δSct stars
(0.04day≲P≲0.15day) is similar to that detected in other systems.
The amplitude distribution (0.05mag≲Δr≲0.60mag) is likely
biased because of the lack of low-amplitude stars. We finally use the
δSct stars to calculate distances using different
period-luminosity relations. The average distance moduli obtained are
18.76±0.14mag for NGC419 and 18.86±0.11mag for the SMC field,
which agree with previous measurements.
Description:
Time-series imaging of NGC419 was obtained with the Gemini
Multi-Object Spectrograph (GMOS) mounted at the Gemini-S telescope at
Cerro Pachon, Chile. Observations were carried out on the nights of
2017 September 14, 22, and 27 as part of the Fast Turnaround program
GS-2017B-FT-2. Observations were obtained with 2x2 binning, resulting
in a pixel scale of 0.16pixel/arcsec. Images were obtained in Sloan
Digital Sky Survey (SDSS) g, r, and i, with 11, 112, and 7 frames in
total and exposure times of 120, 90, and 80s, respectively, reaching a
signal-to-noise ratio (S/N) ∼50 at the level of the main-sequence
turnoff (MSTO).
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table3.dat 126 73 Position and mean pulsation properties of the
variables stars detected and discovered in
NGC419
table4.dat 81 8050 Photometry of the variable stars in NGC 419
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See also:
J/A+AS/122/131 : Delta Scuti rotational velocities and Teff (Solano+ 1997)
J/AJ/115/193 : RR Lyrae V light curves (Layden, 1998)
J/A+AS/144/469 : Delta Scuti stars (Rodriguez+, 2000)
J/AJ/132/1630 : CaII spectro. in Magellanic Cloud clusters (Grocholski+, 2006)
J/AJ/131/895 : Stars in the Carina dwarf spheroidal galaxy (Koch+, 2006)
J/MNRAS/389/678 : Catalogue of extended objects Magellanic Clouds (Bica+, 2008)
J/AJ/136/1039 : CaII index of SMC red giant branch stars (Carrera+, 2008)
J/AJ/135/836 : Calcium triplet index in LMC stars (Carrera+, 2008)
J/AJ/136/1703 : Ridgelines of six intermediate-age SMC clusters (Glatt+, 2008)
J/ApJ/685/947 : SX Phe stars in Fornax. II. (Poretti+, 2008)
J/AJ/140/328 : LMC High-amplitude delta Scuti stars (Garg+, 2010)
J/AcA/60/1 : VI light curves of LMC delta Scuti stars (Poleski+, 2010)
J/MNRAS/419/342 : SX Phe stars in globular clusters (Cohen+, 2012)
J/ApJ/779/102 : Metallicities of RGB stars in dwarf galaxies (Kirby+, 2013)
J/AJ/145/160 : Variables LMC globular clusters. III. Reticulum (Kuehn+, 2013)
J/ApJS/208/9 : Intrinsic colors and temperatures of PMS stars (Pecaut+, 2013)
J/AJ/146/141 : BV photometry of dwarf Cepheids in Carina (Vivas+, 2013)
J/ApJ/780/59 : Araucaria project: eclipsing binaries in SMC (Graczyk+, 2014)
J/ApJ/814/71 : Carina project IX: UBVI data Carina variables (Coppola+, 2015)
J/AcA/65/233 : OGLE Magellanic Clouds anomalous Cepheids (Soszynski+, 2015)
J/AcA/65/297 : OGLE4 LMC and SMC Cepheids (Soszynski+, 2015)
J/MNRAS/462/4349 : Variable stars in Sculptor dSph (Martinez-Vazquez+, 2016)
J/AcA/66/421 : Eclipsing binaries in the Magellanic System (Pawlak+, 2016)
J/AcA/66/131 : VI light curves of SMC and LMC RR Lyrae (Soszynski+, 2016)
J/MNRAS/473/3131 : VMC survey. XXVI. SMC RR Lyrae stars (Muraveva+, 2018)
J/AJ/155/183 : Properties of variables in the NGC 1846 field (Salinas+, 2018)
J/AJ/157/35 : Population pulsating variable stars in Sextans (Vivas+, 2019)
Byte-by-byte Description of file: table3.dat
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Bytes Format Units Label Explanations
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1- 3 A3 --- ID Variable identifier
4 A1 --- f_ID [*] Flag means Aδ Scuti star within 2rh of
NGC 419 (6 occurrences)
7- 15 F9.6 deg RAdeg [16.92/17.23] Right Ascension (J2000)
17- 26 F10.6 deg DEdeg [-72.93/-72.83] Declination (J2000)
28- 32 F5.2 mag rmag [16.07/22.37] Weighted intensity-average r band
magnitude (1)
34- 38 F5.2 mag gmag [16.39/22.63] Weighted intensity-average g band
magnitude (1)
40- 44 F5.2 mag imag [16.07/22.43] Weighted intensity-average i band
magnitude (1)
46- 49 F4.1 --- RoMS [1.6/84.6] The robust median statistic value
51- 55 F5.1 --- J [2.2/122.1] Welch-Stetson variability index
57 A1 --- Type Variable type (2)
59- 67 F9.5 d Per [0.03/251] Period
68 A1 --- u_Per [:] Uncertainty flag on Period
70- 74 F5.2 mag rint [18.8/22.5]? Intensity-averaged r band magnitude
(3)
75 A1 --- u_rint [:] Uncertainty flag on rint
77 A1 --- l_Delr Limit flag on Delr
78- 81 F4.2 mag Delr [0.05/0.76]? r band amplitude
82 A1 --- u_Delr [:] Uncertainty flag on Delr
84- 88 F5.2 mag gint [18.65/22.7]? Intensity-averaged g band magnitude
(3)
89 A1 --- u_gint [:] Uncertainty flag on gint
91- 94 F4.2 mag Delg [0.01/1.45]? g band amplitude
95 A1 --- u_Delg [:] Uncertainty flag on Delg
97-101 F5.2 mag iint [19.06/22.52]? Intensity-averaged i band magnitude
(3)
102 A1 --- u_iint [:] Uncertainty flag on iint
104-107 F4.2 mag Deli [0/0.8]? i band amplitude
108 A1 --- u_Deli [:] Uncertainty flag on Deli
110-126 A17 --- OGLE Previous name; OGLE identifier
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Note (1): Calculated from the individual measurements.
Note (2): Types as follows:
C = Cepheid (10 occurrences)
D = δScuti (54 occurrences)
E = Eclipsing binary (9 occurrences)
Note (3): Obtained by fitting the light curves with the
Layden+, 1998, J/AJ/115/193 templates.
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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- 3 A3 --- ID Variable identifier
5- 14 F10.4 d MJDr [58010/58024] Modified Julian Date of r band
observation at mid-exposure
16- 22 F7.3 mag rmag [16.03/22.97] Apparent r band magnitude
24- 29 F6.3 mag e_rmag [0.001/0.6] Uncertainty in rmag
31- 40 F10.4 d MJDg [58010/58024]? Modified Julian Date of g band
observation at mid-exposure
42- 48 F7.3 mag gmag [16.33/23.14]? Apparent g band magnitude
50- 55 F6.3 mag e_gmag [0.001/0.2]? Uncertainty in gmag
57- 66 F10.4 d MJDi [58010/58024]? Modified Julian Date of i band
observation at mid-exposure
68- 74 F7.3 mag imag [15.91/23.19]? Apparent i band magnitude
76- 81 F6.3 mag e_imag [0/0.26]? Uncertainty in imag
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History:
From electronic version of the journal
(End) Prepared by [AAS], Coralie Fix [CDS], 26-Apr-2021