J/AJ/121/841 RV photometry of Draco dwarf spheroidal galaxy (Piatek+, 2001) ================================================================================ Stars of the Draco dwarf spheroidal galaxy beyond its measured tidal boundary. Piatek S., Pryor C., Armandroff T.E., Olszewski E.W. =2001AJ....121..841P ================================================================================ ADC_Keywords: Galaxies, photometry ; Photometry, CCD Keywords: galaxies: dwarf - galaxies: individual (Draco) - galaxies: stellar content - galaxies: structure - Local Group Abstract: We report R- and V-band photometry derived from CCD imaging for objects in nine fields in and around the Draco dwarf spheroidal galaxy. The most distant fields are about 1.3{deg} from the center. We use these data to search for Draco stars outside of its measured tidal boundary. The search involves three methods: (1) plotting color-magnitude diagrams for individual fields, for sections of fields, and for combined fields and sections - a colour-magnitude diagram can reveal a population of Draco stars by the presence of the expected principal sequences; (2) measuring field-to-field fluctuations in the surface density of objects located near the Draco principal sequences in the color-magnitude diagram; (3) measuring intrafield fluctuations in the surface density of those objects. We find evidence for the presence of Draco stars immediately beyond the measured tidal boundary of Draco and place an upper limit on the number of such stars in more distant fields that lie close to the extension of its major axis. The best evidence is the presence of the Draco principal sequences in the color-magnitude diagram for some combined fields and sections of fields. The measurements of the field-to-field fluctuations in the stellar surface density confirm this result. File Summary: -------------------------------------------------------------------------------- FileName Lrecl Records Explanations -------------------------------------------------------------------------------- ReadMe 80 . This file table1.dat 94 10 Information about fields table4.dat 99 71519 R and V Photometry of Draco -------------------------------------------------------------------------------- See also: J/AJ/110/2131 : M/L for Draco and UMi. I. (Armandroff+ 1995) J/MNRAS/330/792 : Radial velocity in Draco (Kleyna+, 2002) J/AJ/123/2511 : Draco dwarf spheroidal galaxy RV photometry (Piatek+, 2002) Byte-by-byte Description of file: table1.dat -------------------------------------------------------------------------------- Bytes Format Units Label Explanations -------------------------------------------------------------------------------- 1- 7 A7 --- Field Field designation (1) 9- 18 A10 "YYYY/MM/DD" Date Observation date 21- 22 I2 h RAh Right ascension (J2000) 24- 25 I2 min RAm Right ascension (J2000) 27- 31 F5.2 s RAs Right ascension (J2000) 33 A1 --- DE- Declination sign (J2000) 34- 35 I2 deg DEd Declination (J2000) 37- 38 I2 arcmin DEm Declination (J2000) 40- 44 F5.2 arcsec DEs Declination (J2000) 46- 52 F7.4 deg GLON Galactic longitude 54- 60 F7.4 deg GLAT Galactic latitude 62 I1 --- o_TexpV Number of expositions in V band 63 A1 --- --- [x] 64- 67 I4 s TexpV Time of each expositions in V band 69 I1 --- o_TexpR Number of expositions in R band 70 A1 --- --- [x] 71- 74 I4 s TexpR Time of each expositions in R band 76- 79 F4.2 pix FWHMV ? FWHM in V band 81- 84 F4.2 pix e_FWHMV ? rms uncertainty on FWHMV 86- 89 F4.2 pix FWHMR ? FWHM in R band 91- 94 F4.2 pix e_FWHMR ? rms uncertainty on FWHMR -------------------------------------------------------------------------------- Note (1): E1(tie) overlaps the C0 and E1 fields. -------------------------------------------------------------------------------- Byte-by-byte Description of file: table4.dat -------------------------------------------------------------------------------- Bytes Format Units Label Explanations -------------------------------------------------------------------------------- 1- 9 A9 --- [PPA2001] Star designation, WWN NNNNN (1) 11- 18 F8.3 pix Xpix X pixel coordinate on the R frame 20- 27 F8.3 pix Ypix Y pixel coordinate on the R frame 29- 30 I2 h RAh Right Ascension (J2000) 32- 33 I2 min RAm Right Ascension (J2000) 35- 39 F5.2 s RAs Right Ascension (J2000) 40 A1 --- DE- Declination sign (J2000) 41- 42 I2 deg DEd Declination (J2000) 44- 45 I2 arcmin DEm Declination (J2000) 47- 51 F5.2 arcsec DEs Declination (J2000) 53- 59 F7.4 mag Rmag R band magnitude 61- 66 F6.4 mag e_Rmag Uncertainty in Rmag 68- 74 F7.4 mag Vmag V band magnitude 76- 81 F6.4 mag e_Vmag Uncertainty in Vmag 83- 89 F7.4 --- Chi Average robust measure of {chi}^2^ 91- 98 F8.4 --- Sharp Average sharpness value of object (2) -------------------------------------------------------------------------------- Note (1): The Simbad designation is: [PPA2001] WWN NNNNN, with WWN the field name and NNNNN the star number in the field. Note (2): If Sharp is close to 0, the object is likely to be a star; if it is significantly less than 0, the object is probably a corrupted pixel; and, if it is significantly larger than zero, the object is likely to be a galaxy or unresolved double star. -------------------------------------------------------------------------------- History: From electronic version of the journal ================================================================================ (End) Greg Schwarz [AAS], Patricia Bauer [CDS] 24-Apr-2001