J/ApJ/727/9 The RR Lyrae population of NGC 6101 (Cohen+, 2011)
The unusual RR Lyrae population of NGC 6101.
Cohen R.E., Sarajedini A., Kinemuchi K., Leiton R.
<Astrophys. J., 727, 9 (2011)>
=2011ApJ...727....9C 2011ApJ...727....9C
ADC_Keywords: Photometry, UBV ; Stars, variable ; Clusters, globular
Keywords: Galaxy: kinematics and dynamics - stars: variables: RR Lyrae -
globular clusters: individual (NGC 6101) - stars: horizontal-branch -
Abstract:
We use V-band time-series data to analyze the RR Lyrae (RRL)
population of the Galactic globular cluster NGC 6101. Using template
fitting, we have discovered seven new RRL stars and confirmed 10
candidates. We find unusually long mean periods for the RRL of
<Pab≥0.803 days and <Pc≥0.393 days, and an atypically high ratio
of n(c)/n(ab+c)=0.82. Based on our derived mean properties of the RRL,
NGC 6101 is Oosterhoff type II, consistent with the cluster
metallicity but intriguing with respect to its kinematics.
Description:
Our ground-based observations of NGC 6101 were obtained at Cerro
Tololo Inter-American Observatory with the Yale 1.0m telescope,
operated by the Small and Moderate Aperture Research Telescope System
consortium, on the nights of 2008 July 14-19, in V and B filters.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table2.dat 64 17 NGC 6101 RR Lyrae properties
table3.dat 54 10811 Photometry of NGC 6101
table4.dat 28 646 Time series
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See also:
J/other/PASA/29.72 : RR Lyrae in NGC 6101 (Fitzgerald+, 2012)
J/A+A/380/478 : BVI photometry in NGC 6101 (Marconi+, 2001)
J/A+AS/145/451 : Nearby GCs photometric catalog (Rosenberg+, 2000)
Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 3 A3 --- VID RR Lyrae name (V1 to V22) (G1)
5- 6 I2 h RAh [16] Hour of right ascension (J2000)
8- 9 I2 min RAm [24/26] Minute of right ascension (J2000)
11- 14 F4.1 s RAs Second of right ascension (J2000)
16 A1 --- DE- [-] Sign of declination (J2000)
17- 18 I2 deg DEd [72] Degree of declination (J2000)
20- 21 I2 arcmin DEm [7/16] Arcminute of declination (J2000)
23- 26 F4.1 arcsec DEs Arcsecond of declination (J2000)
28- 32 F5.3 d Per [0.32/0.913] Period
34- 38 F5.3 mag AV [0.1/0.722] Extinction
40- 45 F6.3 mag <Vmag> [16.224/16.686] Mean V-band magnitude
47- 51 F5.3 mag B-V Mean (B-V) color index
53- 57 F5.2 [Sun] [Fe/H] [-2.28/-0.81] Fe/H abundance (1)
59- 62 A4 --- Type RR Lyrae type (RRab or RRc)
64 A1 --- u_Type [b] Uncertain classification (2)
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Note (1): Based on Fourier decomposition or template fitting as described in
Section 4.3.
Note (2): Classification somewhat uncertain, see Section 3.3 for a discussion.
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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- 6 I6 --- ID [1/11032] Object identification number,
<[CSK2011] NNNNN> in Simbad
8- 15 F8.3 pix Xpix X pixel coordinate (1)
17- 24 F8.3 pix Ypix Y pixel coordinate (1)
26- 32 F7.4 mag <Bmag> Mean B band magnitude
34- 39 F6.4 mag e_<Bmag> The 1σ uncertainty in <Bmag>
41- 47 F7.4 mag <Vmag> Mean V band magnitude
49- 54 F6.4 mag e_<Vmag> The 1σ uncertainty in <Vmag>
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Note (1): We matched our photometry to that of Marconi et al., 2001 (M01;
Cat. J/A+A/380/478) to compare our results. Since M01 only provide
their positions in pixel coordinates, we matched our coordinate system
to theirs using the geomap and geoxytran tasks in IRAF by visually
cross-referencing a small set of bright (V<18) stars between images.
The resulting transformation, with an rms value of 0.11 pixels, was
then applied to the rest of the stars.
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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 --- VID RR Lyrae name (V1 to V22) (G1)
5 A1 --- F [BV] Filter used in the observation
7- 14 F8.5 d JD Julian Date (JD-2454600)
16- 21 F6.3 mag mag Observed magnitude in Filter
23- 28 F6.4 mag e_mag Error in mag
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Global notes:
Note (G1): The designations are from Liller (1981AJ.....86.1204L 1981AJ.....86.1204L;
<Cl* NGC 6101 SAW VNN> in Simbad) and, in order to avoid confusion
with their field variables V11-V15, we have designated our seven new
variables V16-V22.
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History:
From electronic version of the journal
(End) Greg Schwarz [AAS], Emmanuelle Perret [CDS] 17-Aug-2012