J/A+A/465/357 Stroemgren photometry in the Draco dSph galaxy (Faria+, 2007)
The usage of Stroemgren photometry in studies of local group dwarf spheroidal
galaxies. Application to Draco: a new catalogue of Draco members and a study of
the metallicity distribution function and radial gradients.
Faria D., Feltzing S., Lundstroem I., Gilmore G., Wahlgren G.M.,
Ardeberg A., Linde P.
<Astron. Astrophys., 465, 357-373 (2007)>
=2007A&A...465..357F 2007A&A...465..357F
ADC_Keywords: Galaxies, nearby ; Photometry, uvby ; Abundances, [Fe/H]
Keywords: galaxies: dwarf - galaxies: individual: Draco dSph -
galaxies: individual: UGC 10822 - galaxies: stellar content -
galaxies: photometry - Local Group
Abstract:
In this paper we demonstrate how Stroemgren uvby photometry can be
efficiently used to: 1. identify red giant branch stars that are
members in a dwarf spheroidal galaxy; 2. derive age-independent
metallicities for the same stars and quantify the associated errors.
Stroemgren uvby photometry in a 11'x22' field centered on the
Draco dwarf spheroidal galaxy was obtained using the Isaac Newton
Telescope on La Palma. Members of the Draco dSph galaxy were
identified using the surface gravity sensitive c1 index which
discriminates between red giant and dwarf stars. Thus enabling us to
distinguish the (red giant branch) members of the dwarf spheroidal
galaxy from the foreground dwarf stars in our galaxy. The method is
evaluated through a comparison of our membership list with membership
classifications in the literature based on radial velocities and
proper motions. The metallicity sensitive m1 index was used to derive
individual and age-independent metallicities for the members of the
Draco dSph galaxy. The derived metallicities are compared to studies
based on high resolution spectroscopy and the agreement is found to be
very good.
Description:
The Draco dSph galaxy was observed during five nights in March 2000 at
the 2.5m Isaac Newton Telescope (INT) on La Palma using the Wide
Field Camera (WFC).
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table2.dat 37 43 List of the photometry used for the standard stars
(from Schuster & Nissen, 1988A&AS...73..225S 1988A&AS...73..225S)
table6.dat 124 169 Draco RGB stars
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See also:
J/AJ/110/2131 : M/L for Draco and UMi. I. (Armandroff+ 1995)
J/AJ/121/841 : RV photometry of Draco dwarf spheroidal galaxy (Piatek+, 2001)
J/AJ/123/2511 : RV photometry of Draco dwarf spheroidal galaxy (Piatek+, 2002)
J/ApJS/145/245 : SDSS stars in Draco dwarf spheroidal galaxy (Rave+, 2003)
J/AJ/127/861 : RR Lyrae in Draco dSph (Bonanos+, 2004)
J/A+A/442/165 : Draco dSph late-type stars IJKs photometry (Cioni+, 2005)
Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 13 A13 --- Name Name
14- 19 F6.3 mag y0 Dereddened Stroemgren y magnitude
21- 25 F5.3 mag (b-y)0 Dereddened Stroemgren b-y colour index
27- 31 F5.3 mag (m1)0 Dereddened Stroemgren m1 index
33- 37 F5.3 mag (c1)0 Dereddened Stroemgren c1 index
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Byte-by-byte Description of file: table6.dat
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Bytes Format Units Label Explanations
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1- 4 I4 --- [FFL2007] Sequential number
6- 10 A5 --- OName Stetson number (1)
12- 19 F8.3 pix xpos X pixel position on the CCD
21- 28 F8.3 pix ypos Y pixel position on the CCD
30- 38 F9.7 arcmin oRA Offset in right ascension (2)
40- 48 F9.7 arcmin oDE Offset in declination (2)
50- 55 F6.3 mag ymag Stroemgren y magnitude (3)
57- 61 F5.3 mag e_ymag rms uncertainty on ymag
63- 68 F6.3 mag bmag Stroemgren b magnitude (3)
70- 74 F5.3 mag e_bmag rms uncertainty on bmag
76- 81 F6.3 mag vmag Stroemgren v magnitude (3)
83- 87 F5.3 mag e_vmag rms uncertainty on vmag
89- 94 F6.3 mag umag Stroemgren u magnitude (3)
96-100 F5.3 mag e_umag rms uncertainty on umag
102-106 F5.2 [Sun] [Fe/H] Metallicity derived in this paper using the
m1 index
108-111 F4.2 [Sun] e_[Fe/H] rms uncertainty on [Fe/H]
113-116 F4.2 --- Pmem ? Membership probability (4)
118-124 F7.2 km/s RV ? Radial velocity from Kleyna et al.
(2002, Cat. J/MNRAS/330/792)
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Note (1): Designation from Stetson's photometric catalog, available at
http://www2.cadc-ccda.hia-iha.nrc-cnrc.gc.ca/community/STETSON/standards/
Note (2): Offset from the center od the Draco dSph galaxy,
RA=17:20:12, DE=+57:54:55.0, J2000
Note (3): Not corrected for reddening.
Note (4): Membership probability based on proper motions given in Stetson
(1980AJ.....85..387S 1980AJ.....85..387S).
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History:
From electronic version of the journal
* 19-Nov-2007: Original version in ftp
* 13-Dec-2007: All positions corrected in table6
(End) Patricia Vannier [CDS] 09-Oct-2007