J/AJ/110/2747 Stars in Sculptor dwarf spheroidal galaxy (Schweitzer+ 1995)
The absolute proper motion and a membership survey of the Sculptor dwarf
spheroidal galaxy
Schweitzer A.E., Cudworth K.M., Majewski S.R., Suntzeff N.B.
<Astron. J. 110, 2747 (1995)>
=1995AJ....110.2747S 1995AJ....110.2747S
ADC_Keywords: Proper motions ; Cross identifications
Abstract:
Using 26 plates taken over the course of more than half a century, we
present proper motions and photometry for 1177 stars in the central
region of the Sculptor dwarf spheroidal galaxy, down to a limiting
magnitude of V∼20.25 at the level of the horizontal branch. The
proper-motion cleaned color-magnitude diagram retained a broad giant
branch, further supporting an intrinsic spread in metallicity. We
determined an absolute proper motion for Sculptor, relative to
background galaxies, of mu_alpha=+0.036±0.022arcsec/century and
mu_delta=0.043±0.025arcsec/century after correcting for the LSR and
peculiar solar motions. Our proper-motion uncertainty is similar to or
smaller than those obtained by different groups for other distant
satellites of the Galaxy. When combined with Sculptor's distance and
radial velocity, this measurement shows the dwarf spheroidal to have a
space velocity of roughly 220±125km/s. Although our measurement is
less than twice its uncertainty, the direction of Sculptor's motion is
significant because it rules out motion along the Magellanic Stream. A
2.5 sigma error allows for motion in a direction toward the Fornax
dwarf spheroidal galaxy, so Sculptor remains a possible member of the
proposed Fornax-Leo-Sculptor stream.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table3.dat 114 1183 Sculptor photometry, membership probabilities,
positions, and proper motions
table4.dat 90 34 Photometry and positions of possible variable
stars in Sculptor
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Byte-by-byte Description of file: table3.dat table4.dat
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Bytes Format Units Label Explanations
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1- 5 I5 --- SCMS Identification from this study
7- 10 I4 --- V78 ? ID from Van Agt, 1978PDDO....3..205V 1978PDDO....3..205V
12- 17 A6 --- H65 ID from Hodge, 1965ApJ...142.1390H 1965ApJ...142.1390H
19- 21 I3 --- KD77 ? ID from Kunkel & Demers, 1977ApJ...214...21K 1977ApJ...214...21K
23- 25 I3 --- FBM82 ? ID from Frogel et al., 1982ApJ...252..133F 1982ApJ...252..133F
31- 35 F5.2 mag Vmag V magnitude
37- 41 F5.2 mag B-V B-V color index
43- 45 I3 % PMemb *? Probability of membership
47- 54 F8.1 arcsec Xpos X coordinate relative to dSph center
56- 63 F8.1 arcsec Ypos Y coordinate relative to dSph center
66- 68 I3 h RAh Right Ascension (J2000)
70- 71 I2 min RAm Right Ascension (J2000)
73- 77 F5.2 s RAs Right Ascension (J2000)
80 A1 --- DE- Declination sign (J2000)
81- 82 I2 deg DEd Declination (J2000)
84- 85 I2 arcmin DEm Declination (J2000)
87- 90 F4.1 arcsec DEs Declination (J2000)
92- 97 I6 10-2mas/yr pmX ? Relative proper motion
99-102 I4 10-2mas/yr e_pmX ? Standard error in pmX
104-109 I6 10-2mas/yr pmY ? Relative proper motion
111-114 I4 10-2mas/yr e_pmY ? Standard error in pmY
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Note on PMemb:
Probability of membership, only for table3.dat. The background galaxies,
for which the stellar profile-fitting photometry may be unreliable, are
listed at the beginning with a membership probability of -1.
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Origin: AAS CD-ROM series, Volume 7, 1996 Lee Brotzman [ADS] 14-Jul-1996
(End) [CDS] 30-Jan-1997