J/AJ/131/375 Photometry and velocities of Sculptor dSph giants (Westfall+, 2006)
Exploring halo substructure with giant stars. VIII. The extended structure of the Sculptor dwarf spheroidal galaxy. Westfall K.B., Majewski S.R., Ostheimer J.C., Frinchaboy P.M., Kunkel W.E., Patterson R.J., Link R. <Astron. J., 131, 375-406 (2006)> =2006AJ....131..375W
ADC_Keywords: Galaxies, nearby ; Radial velocities ; Photometry Keywords: galaxies: dwarf - galaxies: halos - galaxies: individual (Sculptor) - galaxies: photometry - galaxies: structure - Local Group Abstract: We explore the spatial distribution of stars in the Sculptor dwarf spheroidal (dSph) galaxy over an area of 7.82deg2, including coverage of the central region but extending mostly south and east of the dSph core. Two methods are used to identify stars that are most likely associated with the dSph, and these filtered samples of stars are used to map its spatial structure. First, following the method of previous contributions in this series, we utilize Washington M, T2+DDO51 photometry to identify red giant branch (RGB) star candidates with approximately the same distance and metallicity as the Sculptor dSph. Second, a prominent blue horizontal branch (BHB) population provides a fairly populous and pure sample of Sculptor stars having broadband colors unlike the bulk of the Galactic field star population. A spectroscopically observed subset of Sculptor candidate stars (147 total stars: ∼5% of all Sculptor candidates and ∼10% of Sculptor giant candidates) yields a systemic heliocentric velocity for the system of vhel=110.43±0.79km/s, in good agreement with previous studies. Description: A mosaic of the Sculptor dSph was created via CCD imaging undertaken over the course of six observing runs at the Swope 1m telescope located at Las Campanas Observatory, between 1999 Aug and 2001 Nov. Spectra for this study were obtained using the HYDRA multifiber system at the Blanco 4m telescope at the Cerro Tololo Inter-American Observatory (CTIO) during UT 2000 November 10-12 and 2001 October 7-10. Spectra were also obtained with the Magellan Inamori Kyocera Echelle (MIKE) slit spectrograph mounted on the Magellan II (Clay) 6.5m telescope at Las Campanas Observatory on the nights of UT 2004 January 27-28 and December 30-31. File Summary:
FileName Lrecl Records Explanations
ReadMe 80 . This file table2.dat 121 36 Adopted radial velocities for multiple observations table4.dat 112 179 Heliocentric radial velocities of selected stars
See also: J/ApJ/705/328 : Abundance measurements in Sculptor dSph (Kirby+, 2009) J/AJ/130/1065 : Members of the Sculptor dSph galaxy (Coleman+, 2005) J/MNRAS/363/734 : Sculptor dSph variables metal abundances (Clementini+, 2005) J/AJ/128/245 : M giant stars in the Sagittarius dwarf galaxy (Majewski+, 2004) J/AJ/110/2747 : Stars in Sculptor dwarf spheroidal galaxy (Schweitzer+ 1995) Byte-by-byte Description of file: table2.dat
Bytes Format Units Label Explanations
1- 8 I8 --- ID Source identification 10- 15 F6.2 km/s HRV Average heliocentric velocity 17- 21 F5.2 km/s e_HRV Standard deviation in HRV 23- 28 F6.2 km/s HRV1 Heliocentric velocity of 1st observation 30- 33 F4.2 --- CCP1 Magnitude of the 1st observation XC peak (G1) 35 I1 --- q_Obs1 Quality (Q) of 1st observation (G1) 37- 46 A10 "YYYY/MM/DD" Obs1 UT date of 1st observation 48- 53 F6.2 km/s HRV2 Heliocentric velocity of 2nd observation 55- 58 F4.2 --- CCP2 Magnitude of the 2nd observation XC peak (G1) 60 I1 --- q_Obs2 Quality (Q) of 2nd observation (G1) 62- 71 A10 "YYYY/MM/DD" Obs2 UT date of 2nd observation 73- 78 F6.2 km/s HRV3 ? Heliocentric velocity of 3rd observation 80- 83 F4.2 --- CCP3 ? Magnitude of the 3rd observation XC peak (G1) 85 I1 --- q_Obs3 ? Quality (Q) of 3rd observation (G1) 87- 96 A10 "YYYY/MM/DD" Obs3 ? UT date of 3rd observation 98-103 F6.2 km/s HRV4 ? Heliocentric velocity of 4th observation 105-108 F4.2 --- CCP4 ? Magnitude of the 4th observation XC peak (G1) 110 I1 --- q_Obs4 ? Quality (Q) of 4th observation (G1) 112-121 A10 "YYYY/MM/DD" Obs4 ? UT date of 4th observation
Byte-by-byte Description of file: table4.dat
Bytes Format Units Label Explanations
1- 8 I8 --- ID Source identification 10- 11 I2 h RAh Hour of Right Ascension (J2000) 13- 14 I2 min RAm Minute of Right Ascension (J2000) 16- 20 F5.2 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- 43 A10 "YYYY/MM/DD" Obs ? UT date of observation (1) 45- 49 F5.2 mag Mmag Washington M filter magnitude 51- 54 F4.2 mag e_Mmag Uncertainty in Mmag 56- 59 F4.2 mag M-T2 Washington (M-T2) color index 61- 64 F4.2 mag e_M-T2 Uncertainty in M-T2 66- 70 F5.2 mag M-D51 Washington (M-DD051) color index 72- 75 F4.2 mag e_M-D51 Uncertainty in M-D51 77- 83 F7.2 km/s HRV Heliocentric velocity 85- 88 F4.2 km/s e_HRV ? The 1σ error in HRV (2) 90- 93 F4.2 --- CCP ? Magnitude of the XC peak (G1) 95 I1 --- q_Obs ? Quality (Q) (G1) 97-104 F8.4 arcmin Dist Elliptical distance (3) 106 A1 --- P [Y/N] Satisfies the photometric criterion 108 A1 --- f_P Remarks on the photometric selection (4) 110 A1 --- V [Y/N] Satisfies the radial velocity criterion 112 A1 --- f_V [j] Remarks on the velocity selection (4)
Note (1): Dates for stars multiply observed by us are given in Table 2. Note (2): Errors from literature stars, calculated for multiply observed stars as: (∑[1/ε(vi)2])-1/2. Errors for stars observed by us on Nov 2000, Oct 2001, Jan 2004, and Dec 2004 are adopted as 10, 4, 1.5, and 2.5km/s, respectively. Note (3): Assuming the mean ellipticity for the samples fit in Section 5.2. Note (4): Flag as follows: e = Star selected as giant candidate but fell redward of our RGB/RHB selection at the bright end. f = Previously observed star that is consistent with our photometric candidate constraints but does not satisfy our χ morphological constraint. g = Photometrically selected BHB candidate. h = Star fell redward of our BHB selection. i = Star fell blueward of our 2CD selection limit. j = Mean HRV inconsistent with Sculptor but at least one individual observation was consistent.
Global notes: Note (G1): Velocities are determined via a modified version of the cross-correlation (XC) technique developed initially by Tonry & Davis (1979AJ.....84.1511T); the methology is described by Majewski et al. 2004 (Paper VI, see Cat. J/AJ/128/245). The qualities are gauged by the strength (as compared to secondary peaks) and symmetry of the XC peak on a scale Q=1 (lowest) to Q=7 (highest) quality.
History: From electronic version of the journal References: Majewski et al. Paper I. 2000AJ....120.2550M Majewski et al. Paper II. 2000AJ....119..760M Kundu et al. Paper III. 2002ApJ...576L.125K Palma et al. Paper IV. 2003AJ....125.1352P Cat. J/AJ/125/1352 Crane et al. 2003ApJ...594L.119C Rocha-Pinto et al. 2004ApJ...615..732R Majewski et al. Paper VI. 2005AJ....130.2677M Cat. J/AJ/130/2677 Munoz et al. 2005ApJ...631L.137M Munoz et al. 2006ApJ...650L..51M Sohn et al. Paper X. 2007ApJ...663..960S Cat. J/ApJ/663/960 Munoz et al. Paper XI. 2006ApJ...649..201M
(End) Greg Schwarz [AAS], Emmanuelle Perret [CDS] 27-Jun-2011
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