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J/AJ/144/186   Variables in LMC globular clusters. II. NGC 1786   (Kuehn+, 2012)

Variable stars in Large Magellanic Cloud globular clusters. II. NGC 1786. Kuehn C.A., Smith H.A., Catelan M., Pritzl B.J., De Lee N., Borissova J. <Astron. J., 144, 186 (2012)> =2012AJ....144..186K
ADC_Keywords: Magellanic Clouds ; Clusters, globular ; Stars, variable ; Photometry, UBV Keywords: Magellanic Clouds - stars: horizontal-branch - stars: variables: general - stars: variables: RR Lyrae Abstract: This is the second in a series of papers studying the variable stars in Large Magellanic Cloud globular clusters. The primary goal of this series is to study how RR Lyrae stars in Oosterhoff-intermediate systems compare to their counterparts in Oosterhoff I/II systems. In this paper, we present the results of our new time-series B-V photometric study of the globular cluster NGC 1786. A total of 65 variable stars were identified in our field of view. These variables include 53 RR Lyraes (27 RRab, 18 RRc, and 8 RRd), 3 classical Cepheids, 1 Type II Cepheid, 1 Anomalous Cepheid, 2 eclipsing binaries, 3 Delta Scuti/SX Phoenicis variables, and 2 variables of undetermined type. Photometric parameters for these variables are presented. We present physical properties for some of the RR Lyrae stars, derived from Fourier analysis of their light curves. We discuss several different indicators of Oosterhoff type which indicate that the Oosterhoff classification of NGC 1786 is not as clear cut as what is seen in most globular clusters. Description: A total of 57 V and 56 B images were obtained using the SOAR (Southern Astrophysical Research) Optical Imager (SOI) (5.2*5.2arcmin field of view) on the SOAR 4m telescope in 2007 November and 2008 February while 43 V and 42 B images were obtained using ANDICAM (A Novel Dual Imaging CAMera; 6*6arcmin field of view) on the SMARTS (Small and Moderate Aperture Research Telescope System) 1.3m telescope operated by the SMARTS consortium (www.astro.yale.edu/smarts) from 2006 September to 2007 January. Table 1 lists the UT dates and times of each observation, which telescope it was on, the filter, and the seeing. File Summary:
FileName Lrecl Records Explanations
ReadMe 80 . This file table1.dat 44 198 Observing log table2.dat 109 57 Photometric parameters for variables in NGC 1786, excluding RRd stars table3.dat 103 8 Photometric parameters for the RRd variables in NGC 1786 table4.dat 68 8843 Photometry of the variable stars
See also: VII/239 : History and Accurate Positions for the NGC/IC Objects (Corwin, 2004) J/AJ/142/107 : Variable stars in NGC 1466 (Kuehn+, 2011) J/MNRAS/405/839 : Spectroscopy of globular clusters (Sharina+, 2010) J/AcA/60/1 : VI light curves of LMC delta Scuti stars (Poleski+, 2010) J/AcA/59/1 : VI light curves of LMC RR Lyrae stars (Soszynski+, 2009) J/AcA/58/293 : Type-II and anomalous Cepheids in LMC (Soszynski+, 2008) J/AcA/58/163 : VI light curves of LMC classical Cepheids (Soszynski+, 2008) J/ApJS/161/304 : Star clusters in Milky Way & satellites (McLaughlin+, 2005) J/AcA/53/93 : OGLE RR Lyrae in LMC (Soszynski+, 2003) Byte-by-byte Description of file: table1.dat
Bytes Format Units Label Explanations
1- 10 A10 "Y:M:D" Obs.date UT date of observation 12- 21 A10 "h:m:s" Obs.time UT time of observation 23 A1 --- Flt [BV] Filter (B or V) 25- 29 F5.1 s Exp Exposure time 31- 37 F7.5 arcsec Seeing Seeing 39- 44 A6 --- Tel Telescope (SOAR or SMARTS) (G1)
Byte-by-byte Description of file: table2.dat
Bytes Format Units Label Explanations
1 A1 --- --- [V] 2- 3 I02 --- Vno Variable number 5- 9 A5 --- n_Vno [Field BL] Peculiarity (1) 11- 12 I2 h RAh Hour of Right Ascension (J2000) 14- 15 I2 min RAm Minute of Right Ascension (J2000) 17- 20 F4.1 s RAs Second of Right Ascension (J2000) 22 A1 --- DE- Sign of the Declination (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_Type [?] Variable of undetermined type 36- 46 A11 --- Type Variable type (RRab, RRc, Delta Scuti, AC, Ceph, T2Ceph, Eclipse) (2) 48- 56 F9.6 d Per Period 58- 60 F3.1 d Per2 ? Second value of period (3) 62- 65 F4.2 mag Vamp ? Amplitude in V band 67- 71 F5.3 mag Bamp ? Amplitude in B band 73- 78 F6.3 mag <Vmag> ? Intensity-weighted V mean magnitude 80- 85 F6.3 mag <Bmag> ? Intensity-weighted B mean magnitude 87- 91 F5.3 mag <B-V> ? Magnitude-weighted mean B-V color index 93- 97 A5 --- Type2 OGLE-III variable type (G2) 99-103 I5 --- OGLE ? Optical Gravitational Lensing Experiment-III (OGLE-III) database number 105-109 I5 --- OGLE2 ? Other OGLE-III database number (5)
Note (1): Flag on Name as follows: Field = Large Magellanic Cloud (LMC) field star. The location of NGC 1786 near the center of the LMC means that some of the RR Lyrae stars likely belong to the field population of the LMC and not to the cluster. BL = Possible Blazhko star (see Section 3.2. for more details). Note (2): Variable type as follows: AC = Anomalous Cepheid; Ceph = classical Cepheid; T2Ceph = Type II Cepheid; Eclipse = Eclipsing binary. RRab = RR Lyrae RRab; RRc = RR Lyrae RRc. Note (3): We dit not have enough observations to definitively determine periods of the two eclipsing binaries V31 and V34. Note (5): OGLE-III RR LYR-02746 was classified as an RRd star by Soszynski et al. (2009, cat. J/AcA/59/1) but is only slightly separated on the sky from OGLE-III RRLYR-02743 (∼0.15arcsec) and these can potentially be a single star. Our photometry only found one variable star at this location, V24.
Byte-by-byte Description of file: table3.dat
Bytes Format Units Label Explanations
1 A1 --- --- [V] 2- 3 I02 --- Vno Variable number 5- 6 I2 h RAh Hour of Right Ascension (J2000) 8- 9 I2 min RAm Minute of Right Ascension (J2000) 11- 14 F4.1 s RAs Second of Right Ascension (J2000) 16 A1 --- DE- Sign of the Declination (J2000) 17- 18 I2 deg DEd Degree of Declination (J2000) 20- 21 I2 arcmin DEm Arcminute of Declination (J2000) 23- 26 F4.1 arcsec DEs Arcsecond of Declination (J2000) 28- 30 A3 --- Type [RRd] Variable type 32- 37 F6.4 d P0 Fundamental mode period 39- 44 F6.4 d P1 First overtone period 46- 51 F6.4 d P1/P0 Period ratio 53- 56 F4.2 mag Vamp0 ? Fundamental mode amplitude in V band 58- 61 F4.2 mag Vamp1 ? First overtone amplitude in V band 63- 66 F4.2 mag Bamp0 ? Fundamental mode amplitude in B band 68- 71 F4.2 mag Bamp1 ? First overtone amplitude in B band 73- 78 F6.3 mag <Vmag> ? Intensity-weighted V mean magnitude 80- 85 F6.3 mag <Bmag> ? Intensity-weighted B mean magnitude 87- 91 F5.3 mag <B-V> ? Magnitude-weighted B-V mean color index 93- 97 A5 --- Type2 OGLE-III variable type (G2) 99-103 I5 --- OGLE Optical Gravitational Lensing Experiment-III (OGLE-III) database number
Byte-by-byte Description of file: table4.dat
Bytes Format Units Label Explanations
1 A1 --- --- [V] 2- 3 I02 --- Vno Variable number 5 A1 --- Flt [BV] Filter (B or V) 7- 20 F14.6 d HJD Heliocentric Julian Date 22- 28 F7.5 --- Phase Phase (1) 30- 35 F6.3 mag mag ? Magnitude in Flt (2) 37- 46 F10.3 --- dflux ? Differential flux in Flt (2) 48- 52 F5.3 mag e_mag ? Error in mag 54- 61 F8.3 --- e_dflux ? Error in dflux 63- 68 A6 --- Tel Telescope (SOAR or SMARTS) (G1)
Note (1): Computed such that maximum light occurs at phase 0. Note (2): For the nine RR Lyrae stars (V15 in filter B, V16, V53, V57, V59, V63-V66) that were only found by the image subtraction package ISIS (the location of these stars in the extremely crowded center of the cluster did not allow Daophot light curves to be obtained), brightness is expressed in the form of differential flux.
Global notes: Note (G1): Telescope as follows: SOAR = Southern Astrophysical Research 4m telescope; SMARTS = Small & Moderate Aperture Research Telescope System 1.3m telescope (operated by the SMARTS consortium, http://www.astro.yale.edu/smarts). Note (G2): Variable type from OGLE-III as follows: ACEP = Anomalous Cepheid (Soszynski et al., 2008, cat. J/AcA/58/293); CEP = Cepheid (Soszynski et al., 2008, cat. J/AcA/58/163); DSCT = Delta Scuti (Poleski et al., 2010, cat. J/AcA/60/1); RRLYR = RR Lyrae (Soszynski et al., 2009, cat. J/AcA/59/1); T2CEP = Type II Cepheid (Soszynski et al., 2008, cat. J/AcA/58/293).
History: From electronic version of the journal References: Kuehn et al., Paper I, 2011AJ....142..107K, Cat. J/AJ/142/107 Kuehn et al., Paper III, 2013AJ....145..160K, Cat. J/AJ/145/160
(End) Greg Schwarz [AAS], Sylvain Guehenneux [CDS] 10-Jan-2014
The document above follows the rules of the Standard Description for Astronomical Catalogues.From this documentation it is possible to generate f77 program to load files into arrays or line by line

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