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J/MNRAS/398/1757    RR Lyraes in SDSS stripe 82              (Watkins+, 2009)

Substructure revealed by RR Lyraes in SDSS stripe 82. Watkins L.L., Evans N.W., Belokurov V., Smith M.C., Hewett P.C., Bramich D.M., Gilmore G.F., Irwin M.J., Vidrih S., Wyrzykowski L., Zucker D.B. <Mon. Not. R. Astron. Soc., 398, 1757-1770 (2009)> =2009MNRAS.398.1757W
ADC_Keywords: Stars, variable ; Photometry, SDSS Keywords: catalogues - astrometry - stars: variables: other - Galaxy: halo - Galaxy: stellar content - Galaxy: structure Abstract: We present an analysis of the substructure revealed by RR Lyraes in Sloan Digital Sky Survey Stripe 82, which covers 2.5° in declination on the celestial equator over the right ascension range α=20.7h to 3.3h. We use the new public archive of light-motion curves in Stripe 82, published by Bramich et al. in 2008 (Cat. V/141), to identify a set of high-quality RR Lyrae candidates. Period estimates are determined to high accuracy using a string-length method. A subset of 178 RR Lyraes with spectrally derived metallicities are employed to derive metallicity-period-amplitude relations, which are then used, together with archive magnitude data and light-curve Fourier decomposition, to estimate metallicities and hence distances for the entire sample. The RR Lyraes lie 5-115kpc from the Galactic Centre, with distance estimates accurate to ∼8%. The RR Lyraes are further divided into subsets of 316 RRab types and 91 RRc types based on their period, colour and metallicity. We fit a smooth density law to the distribution as a simple representation of the data. For Galactocentric radii 5-25kpc the number density of RR Lyraes falls as r-2.4, but beyond 25kpc, the number density falls much more steeply, as r-4.5. However, we stress that in practice the density distribution is not smooth, but dominated by clumps and substructure. Samples of 55 and 237 RR Lyraes associated with the Sagittarius Stream and the Hercules-Aquila Cloud, respectively, are identified. Hence, ∼70% of the RR Lyraes in Stripe 82 belong to known substructure, and the sharp break in the density law reflects the fact that the dominant substructure in Stripe 82 - the Hercules-Aquila Cloud and the Sagittarius Stream - lie within 40kpc. In fact, almost 60% of all the RR Lyraes in Stripe 82 are associated with the Hercules-Aquila Cloud alone, which emphasizes the cloud's pre-eminence. Additionally, evidence of a new and distant substructure - the Pisces Overdensity - is found, consisting of 28 faint RR Lyraes centred on Galactic coordinates (l∼80°, b~-55°), with distances of ∼80kpc. The total stellar mass in the Pisces Overdensity is ∼104M and its metallicity is [Fe/H]~-1.5. Description: In this paper, we select first the variable objects in Stripe 82 and then the subset of RR Lyraes, using the Bramich et al. (2008MNRAS.386..887B, Cat. V/141) light-motion curve catalogue (LMCC) and HLC. We make a selection of the variable objects and an identification of RR Lyrae stars. File Summary:
FileName Lrecl Records Explanations
ReadMe 80 . This file vars.dat 137 21939 Variable star-like objects in SDSS Stripe 82 lyraes.dat 228 407 RR Lyraes in SDSS Stripe 82
See also: V/141 : Light-Motion Curve Catalogue (LMCC) in Stripe 82 (Bramich+ 2008) Byte-by-byte Description of file: vars.dat
Bytes Format Units Label Explanations
1- 31 A31 --- LC Lightcurve name (in the LMCC and HLC from Bramich et al. 2008MNRAS.386..887B, Cat. V/141) 34- 35 I2 h RAh Right ascension (J2000) 37- 38 I2 min RAm Right ascension (J2000) 40- 43 F4.1 s RAs Right ascension (J2000) 46 A1 --- DE- Declination sign (J2000) 47- 48 I2 deg DEd Declination (J2000) 50- 51 I2 arcmin DEm Declination (J2000) 53- 54 I2 arcsec DEs Declination (J2000) 57- 62 F6.3 mag umag Apparent u band magnitude 65- 69 F5.3 mag e_umag Uncertainty in umag 72- 77 F6.3 mag gmag Apparent g band magnitude 80- 84 F5.3 mag e_gmag Uncertainty in gmag 87- 92 F6.3 mag rmag Apparent r band magnitude 95- 99 F5.3 mag e_rmag Uncertainty in rmag 102-107 F6.3 mag imag Apparent i band magnitude 110-114 F5.3 mag e_imag Uncertainty in imag 117-122 F6.3 mag zmag Apparent z band magnitude 125-129 F5.3 mag e_zmag Uncertainty in zmag 132-137 F6.4 d Per [0.21/0.82]?=0 Period of variability (1)
Note (1): Periods are given for objects determined to be RR Lyraes. For all other objects, periods are given as 0.
Byte-by-byte Description of file: lyraes.dat
Bytes Format Units Label Explanations
1- 31 A31 --- LC Lightcurve name (in the LMCC and HLC from Bramich et al. 2008MNRAS.386..887B, Cat. V/141) 34- 35 I2 h RAh Right ascension (J2000) 37- 38 I2 min RAm Right ascension (J2000) 40- 43 F4.1 s RAs Right ascension (J2000) 46 A1 --- DE- Declination sign (J2000) 47- 48 I2 deg DEd Declination (J2000) 50- 51 I2 arcmin DEm Declination (J2000) 53- 54 I2 arcsec DEs Declination (J2000) 57- 62 F6.3 mag umag Apparent u-band magnitude 65- 69 F5.3 mag e_umag Uncertainty in umag 72- 77 F6.3 mag gmag Apparent g-band magnitude 80- 84 F5.3 mag e_gmag Uncertainty in gmag 87- 92 F6.3 mag rmag Apparent r-band magnitude 95- 99 F5.3 mag e_rmag Uncertainty in rmag 102-107 F6.3 mag imag Apparent i-band magnitude 110-114 F5.3 mag e_imag Uncertainty in imag 117-122 F6.3 mag zmag Apparent z-band magnitude 125-129 F5.3 mag e_zmag Uncertainty in zmag 132-137 F6.4 d Per [0.21/0.82] Period of variability 140-141 A2 --- RR RR Lyrae type (ab or c) 144-147 F4.2 mag gAmp [0.1/0.8] g-band amplitude 150-153 F4.2 mag rAmp [0.1/0.6] r-band amplitude 156-160 F5.2 [Sun] [Fe/H] [-3.1/-0.8] Metallicity 163-166 F4.2 [Sun] e_[Fe/H] [0.2/0.9] Uncertainty in [Fe/H] 169-172 F4.2 mag zMAG [0.11/1.1] z-band absolute magnitude 175-180 F6.2 kpc Dist [4/108] Heliocentric distance 183-187 F5.2 kpc e_Dist [0.1/58] Uncertainty in Dist 190-196 F7.2 --- gcsq [19/2006] g-band χ-squared 199-205 F7.2 --- rcsq [8.67/1494.85] r-band χ-squared 208-211 F4.2 mag grms [0.1/0.56] g-band RMS 214-217 F4.2 mag rrms [0.07/0.41] r-band RMS 220-224 F5.2 --- Lg [2.56/33.92] g-band Stetson index 227-228 A2 --- Assoc Association (1)
Note (1): Associations are: HA = associated with Hercules-Aquila Cloud SS = Sagittarius Stream PI = Pisces Overdensity -- = no association
Acknowledgements: Dan Bramich, dan.bramich(at)hotmail.co.uk
(End) Patricia Vannier [CDS] 05-Oct-2015
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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