J/AJ/117/2868 BV photometry in M2 (NGC 7089) (Lee+, 1999)
BV photometry of RR Lyrae variables in the globular cluster M2 (NGC 7089).
Lee J.-W., Carney B.W.
<Astron. J. 117, 2868 (1999)>
=1999AJ....117.2868L 1999AJ....117.2868L
ADC_Keywords: Stars, variable ; Photometry, CCD ; Photometry, UBV
Keywords: globular clusters: individual (NGC 7089) - RR Lyrae variable -
stars: horizontal-branch
Abstract:
We present BV CCD photometry for 30 RR Lyrae variables, including 13
newly discovered, in the Oosterhoff type II globular cluster M2. New
light curves and ephemerides are presented. Our observations cover
magnitudes ranging from the red giant branch tip to ∼3mag below the
turnoff, allowing us to determine accurate fundamental photometric
parameters. With the discovery of new RR Lyrae variables, the mean
periods of the RRab and RRc variables are <Pab≥0.685±0.022days
and <Pc≥0.333±0.013days, respectively. The number ratio of the
RRc type variables to the total number of RR Lyrae type variables is
n(c)/n(ab+c)=0.40. The RR Lyrae pulsational mode transition occurs
between the fundamental period of 0.528-days and 0.556-days. From star
counts along the horizontal branch (HB), we obtain two HB color
distribution indices, (B-R)/(B+V+R)=0.92 and B2/(B+V+R)=0.46. The
period-change rates are also derived. The mean period-change rate from
six RRab variables is <β≥0.06±0.04days/Myr, which agrees well
with the predictions of Lee's 1991 model. Our color-magnitude diagram
shows a very extended blue HB tail, and there are no significant blue
HB gaps in M2.
Objects:
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RA (2000) DE Designation(s)
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21 33 29.3 -00 49 23 M 2 = NGC 7089
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table2.dat 37 19229 Color-magnitude diagram data
table3.dat 75 30 Parameters for M2 RR Lyrae variables
table4.dat 54 4200 RR Lyrae data
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See also:
V/97 : Updated 3rd Cat Variable Stars in Globular Clusters (Clement+ 1997)
Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 5 I5 --- LC Identification number
(Cl* NGC 7089 LC NNNNN in Simbad)
7- 14 F8.3 pix Xpos X position (1)
16- 23 F8.3 pix Ypos Y position (1)
25- 30 F6.3 mag B-V B-V colour index
32- 37 F6.3 mag Vmag V magnitude
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Note (1): 1pix=0.68".
Plate centered on the cluster (RA=21h33min, DE=-0°49', J2000.0)
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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- 7 A7 --- Name RR Lyrae name (G1)
9- 17 F9.7 d Per Period
19- 32 F14.6 d Ep0 Epoch at φ=0.00
34- 38 F5.3 mag AV Absorption in V band
40- 44 F5.3 mag AB Absorption in B band
46- 51 F6.3 mag <Vmag> Magnitude-weighted integrated V magnitude
53- 58 F6.3 mag <Bmag> Magnitude-weighted integrated B magnitude
60- 65 F6.3 mag <Vint> Intensity-weighted integrated V magnitude
67- 72 F6.3 mag <Bint> Intensity-weighted integrated B magnitude
74- 75 A2 --- Class [ab c] RR Lyrae class
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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- 7 A7 --- Name RR Lyrae name (G1)
9- 24 F16.8 d HJD Heliocentric Julian date
26- 31 F6.4 --- Phase [0/1] Phase
33- 39 F7.4 mag Vmag V magnitude
41- 46 F6.4 mag B-V B-V colour index
48- 54 F7.4 mag Bmag B magnitude
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Global notes:
Note (G1): VNN = Cl* NGC 7089 SAW VNNN in Simbad
LCNNNN = Cl* NGC 7089 LC NNNNN in Simbad
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History: From AJ electronic version
(End) James Marcout, Patricia Bauer [CDS] 14-Sep-1999