J/AJ/154/85 CTIO/DECam photometry of RR Lyrae stars in M5 (Vivas+, 2017)
Absolute magnitudes and colors of RR Lyrae stars in DECam passbands from
photometry of the globular cluster M5.
Vivas A.K., Saha A., Olsen K., Blum R., Olszewski E.W., Claver J.,
Valdes F., Axelrod T., Kaleida C., Kunder A., Narayan G., Matheson T.,
Walker A.
<Astron. J., 154, 85-85 (2017)>
=2017AJ....154...85V 2017AJ....154...85V (SIMBAD/NED BibCode)
ADC_Keywords: Clusters, globular ; Stars, nearby ; Stars, variable ;
Photometry, ugriz
Keywords: dust, extinction - globular clusters: individual: M5 -
stars: distances - stars: variables: RR Lyrae
Abstract:
We characterize the absolute magnitudes and colors of RR Lyrae stars
in the globular cluster M5 in the ugriz filter system of the Dark
Energy Camera (DECam). We provide empirical period-luminosity (P-L)
relationships in all five bands based on 47 RR Lyrae stars of the type
ab and 14 stars of the type c. The P-L relationships were found to be
better constrained for the fundamental-mode RR Lyrae stars in the riz
passbands, with dispersions of 0.03, 0.02 and 0.02mag, respectively.
The dispersion of the color at minimum light was found to be small,
supporting the use of this parameter as a means to obtain accurate
interstellar extinctions along the line of sight up to the distance of
the RR Lyrae star. We found a trend of color at minimum light with a
pulsational period that, if taken into account, brings the dispersion
in color at minimum light to 0.016 mag for the (r-i), (i-z), and (r-z)
colors. These calibrations will be very useful for using RR Lyrae
stars from DECam observations as both standard candles for distance
determinations and color standards for reddening measurements.
Description:
Observations were obtained during 2013 (2013 Jun 7-9, and 2013 Jun 21)
and 2014 (2014 Mar 7-9) with the Dark Energy Camera (DECam) imager on
the 4m Blanco Telescope at Cerro Tololo Inter-American Observatory
(CTIO), Chile. Repeated DECam images of a field centered on M5
(R.A.=15:18:33.2, decl.=+02:04:51.7, J2000.0) were obtained using the
u,g,r,i, and z filters. The large field of view (FOV) of DECam
(2.2°) easily covers the whole globular cluster with only the
central CCDs of the camera.
A total of 66 RR Lyrae stars and 1 SX Phe were recognized in the field
of M5. The individual measurements for the periodic variable stars are
provided in Table2. In Table3, we present the list of periodic
variable stars.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table2.dat 34 14516 Individual measurements in ugriz of the
periodic variables in the field of M5
table3.dat 127 67 Periodic variable stars identified in the M5 field
table4.dat 89 54701 Photometry within a radius of 17.7' from the
center of M5
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See also:
VII/202 : Globular Clusters in the Milky Way (Harris, 1997)
J/ApJ/834/160 : ugriz colors of RR Lyrae stars in SDSS Stripe 82 (Ngeow+, 2017)
J/other/ApSS/361.175 : M5 RR Lyr and HB VI light curves (Arellano Ferro+, 2016)
J/ApJS/213/9 : Catalina Surveys periodic variable stars (Drake+, 2014)
J/ApJ/765/154 : RR Lyrae stars in the Catalina Sky Survey (Drake+, 2013)
J/ApJ/763/32 : Galactic halo RRab stars from CSS (Drake+, 2013)
J/ApJ/632/266 : WFPC2 photometry of the globular cluster M5 (Layden+, 2005)
Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 6 I6 --- Star [16339/139277] Identification number
8- 19 F12.6 d MJD Modified Julian Date
21 A1 --- Flt [ugriz] Filter (CTIO/DECam u, g, r, i, or z)
23- 28 F6.3 mag mag [14.11/20.74] Apparent magnitude in Flt
30- 34 F5.3 mag e_mag [0.01/0.159] Error in mag
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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 --- Star [16339/139277] Identification number
8- 9 I2 h RAh Hour of Right Ascension (J2000)
11- 12 I2 min RAm Minute of Right Ascension (J2000)
14- 18 F5.2 s RAs Second of Right Ascension (J2000)
20 A1 --- DE- Sign of the Declination (J2000)
21- 22 I2 deg DEd Degree of Declination (J2000)
24- 25 I2 arcmin DEm Arcminute of Declination (J2000)
27- 30 F4.1 arcsec DEs Arcsecond of Declination (J2000)
32- 38 F7.5 d Per [0.089/0.85] Period
40- 45 A6 --- Type Type of periodic variable (RR Lyrae ab,
RR Lyrae c, or SX Phe)
47- 51 F5.2 mag [15.1/20] Mean magnitude in u band (1)
53- 57 F5.2 mag [14.7/19.4] Mean magnitude in g band (1)
59- 63 F5.2 mag [14.6/19.3] Mean magnitude in r band (1)
65- 69 F5.2 mag [14.6/19.3] Mean magnitude in i band (1)
71- 75 F5.2 mag [14.5/19.2] Mean magnitude in z band (1)
77- 81 F5.2 mag uref [15.5/20.6]? Magnitude at minimum light in u band
(uref) (2)
83- 87 F5.2 mag gref [15/19.8]? Magnitude at minimum light in g band
(gref) (2)
89- 93 F5.2 mag rref [14.7/19.5]? Magnitude at minimum light in r band
(rref) (2)
95- 99 F5.2 mag iref [14.6/19.4]? Magnitude at minimum light in i band
(iref) (2)
101-105 F5.2 mag zref [14.65/19.35]? Magnitude at minimum light in z
band (zref) (2)
107-127 A21 --- OName Other name
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Note (1): The reported mean magnitudes are not plain averages but were obtained
by integrating the best fitted template of the light curve in intensity
units, and transforming back to magnitudes. This method of calculating the
mean magnitudes avoids the biases toward minimum magnitudes (because the RR
Lyrae stars spend most of their pulsation cycle time at minimum light) as
well as those biases that may appear as a result of unevenly sampled light
curves.
Note (2): Measured as explained in Section 5.
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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- 6 I6 --- Star [18709/120853] Identification number
8- 16 F9.5 deg RAdeg Right Ascension in decimal degrees (J2000)
18- 24 F7.5 deg DEdeg Declination in decimal degrees (J2000)
26- 31 F6.3 mag [12.45/21.61]? Mean magnitude in u band
33- 37 F5.3 mag e_ [0.002/0.44]? Standard deviation in
(σu) (1)
39- 44 F6.3 mag [11.95/22.43]? Mean magnitude in g band
46- 50 F5.3 mag e_ [0.001/0.36]? Standard deviation in
(σg) (1)
52- 57 F6.3 mag [11.4/22.8]? Mean magnitude in r band
59- 63 F5.3 mag e_ [0.001/0.31]? Standard deviation in
(σr) (1)
65- 70 F6.3 mag [11.7/22.1]? Mean magnitude in i band
72- 76 F5.3 mag e_ [0.001/0.3]? Standard deviation in
(σi) (1)
78- 83 F6.3 mag [11.2/21.5]? Mean magnitude in z band
85- 89 F5.3 mag e_ [0.001/0.68]? Standard deviation in
(σz) (1)
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Note (1): Refers to the standard deviation of the mean of all the measurements
for a star in each filter.
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History:
From electronic version of the journal
(End) Prepared by [AAS]; Sylvain Guehenneux [CDS] 13-Nov-2017