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.
<Astron. J. 121, 841 (2001)>
=2001AJ....121..841P 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° 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:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 94 10 Information about fields
table4.dat 99 71519 R and V Photometry of Draco
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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
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Bytes Format Units Label Explanations
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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
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Note (1): E1(tie) overlaps the C0 and E1 fields.
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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- 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 χ2
91- 98 F8.4 --- Sharp Average sharpness value of object (2)
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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.
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History:
From electronic version of the journal
(End) Greg Schwarz [AAS], Patricia Bauer [CDS] 24-Apr-2001