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J/MNRAS/261/657 Deep CCD photometry of the dwarf spheroidal gal (Demers 1993)
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Deep CCD photometry of the dwarf spheroidal galaxy Leo II.
Demers S., Irwin M.J
Mon. Not. R. Astron. Soc. 261, 657 (1993)
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Keywords: galaxies: individual: Leo II - Local Group -
galaxies: stellar content.
Abstract:
We present a deep colour-magnitude diagram of the central 7 x 7
arcmin2 region of Leo II. The diagram shows a well-defined giant
branch and a red horizontal branch, heavily populated on the red
side but extending far into the blue. Having a low metallicity
([Fe/H]=-1.9), the Leo II diagram is similar to those of outer
halo clusters suffering from the second-parameter syndrome. From
the mean apparent magnitude of candidate RR Lyrae stars,
(VHB) = 22.10, we estimate the distance of Leo II to be 215 kpc,
a value similar to previous estimates. A number of variable-star
candidates are identified and two new very red giants have been
found. Comparison with the other dwarf spheroidals of the Local
Group reveals that Leo II belongs to the group of four small and
faint dwarf spheroidal galaxies.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table3 32 2039 Stars brighter than V=22.5 in Leo II
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Table 1: Journal of observations.
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UT date fil- Exp. FWHM air-
(mid exposure) tre (s) (") mass
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08 44 26-3-1992 B 998 1.0 1.011
09 06 26-3-1992 B 998 1.0 1.002
09 23 26-3-1992 V 499 0.7 1.001
09 47 26-3-1992 V 499 0.7 1.009
11 00 26-3-1992 B 998 0.9 1.097
11 18 26-3-1992 V 499 0.8 1.137
11 32 26-3-1992 V 499 0.8 1.175
11 52 26-3-1992 B 998 1.0 1.240
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08 33 27-3-1992 V 600 1.0 1.015
08 53 27-3-1992 B 1200 1.0 1.005
09 18 27-3-1992 B 1200 0.9 1.002
09 54 27-3-1992 V 600 1.0 1.015
11 53 27-3-1992 B 1200 1.1 1.285
12 17 27-3-1992 B 1200 1.2 1.370
12 37 27-3-1992 V 600 1.5 1.480
12 52 27-3-1992 V 600 1.7 1.587
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Table 2: Coefficients determined from standards.
(lowercase letters refer to instrumental magnitudes,
uppercase letters refer to standard magnitudes)
X = airmass, k"_bv=-0.03
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v = alpha_v + V + beta_v(B-V) + k_v.X
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Night1 Night2 Adopted
alpha_v -0.706 -0.676 -0.69l +/-0.022
beta_v 0.0059 0.0108 0.0083 +/-0.0035
k_v 0.248 0.258 0.253 +/-0.007
rms of resid. 0.039 0.037
number 36 36
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b-v = [alpha_bv + beta_bv(B-V)][1-k"_bv] + k'_bv.X
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Night1 Night2 Adopted
alpha_bv 0.589 0.514 0.537 +/-0.03l
beta_bv 0.967 0.971 0.968 +/-0.009
k'_bv 0.058 0.088 0.085 +/-0.022
rms of resid. 0.029 0.033 0.034
number 33 34 67
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Table 4: Magnitudes and colours of carbon and very red stars.
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No. id V B-V
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1
2 2508 20.19 1.50
3 730 19.43 2.46
4 2697 19.82 2.12
5 2387 l9.70 1.61
6 1592 18.79 1.85
7 1574 19.37 1.64
- 339 19.39 1.83
- 786 l9.l6 1.67
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Table 5: Properties of dwarf spheroidal galaxies.
(Core and Tidal radii as defined by King models)
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Name Mv ref d ref rc rt ref
kpc pc pc
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Fornax -13.7 (1) 132 (6) 640 4100 (10)
Leo I -12.0 (2) 270 (2) 350 1100 (11)
And I -11.7 (1) 720 (7) 500 2800 (1)
And II -11.7 (1) 720 (7) 330 3600 (1)
Sculptor -10.7 (1) 80 (8) 210 2200 (12)
And III -10.2 (1) 720 (7) 300 1300 (1)
Sextans -10.0 (1) 87 (9) 380 2300 (13)
Phoenix - 9.9 (3) 415 (3)
Leo II - 9.9 (4) 215 (4) 210 625 (14)
Carina - 9.4 (5) 100 (5) 200 600 (5)
Ursa Minor - 8.9 (3) 65 (5) 150 900 (5)
Draco - 8.5 (5) 75 (5) 150 450 (5)
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References:
(1) Caldwell et al. (1992), AJ 103, 840
(2) Lee et al. (1992), in 11th Santa-Cruz Workshop in Astron. Astrophys.,
"The Globular Cluster Galaxy Connection"
(3) van de Rydt, Demers & Kunkel (1991), AJ 102, 130
(4) this paper;
(5) Aaronson (1986), in "Stellar Populations", Cambridge Univ. Press, 45
(6) Demers, Kunkel & Grondin (1990), PASP 102, 632
(7) Welch et al. (1986), ApJ 305, 583
(8) Kunkel & Demers (1977), ApJ 214, 21
(9) Mateo et al. (1991), AJ 101, 892
(10) Eskridge (1988), AJ 95, 1706
(11) Hodge (1963), AJ 68, 470
(12) Eskridge (1988b)
(13) Irwin et al. (1990), MNRAS 244, 16P
(14) Demers & Harris (1983), AJ 88, 329
Byte-by-byte Description of file: table3
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Bytes Format Units Label Explanations
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1- 4 I4 --- Id Sequence number
7- 10 I4 pix x Position along X axis (ESE)
12- 15 I4 pix y Position along Y axis (NNW)
18- 22 F5.2 mag V magnitude
24- 28 F5.2 mag B-V color
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History: Keypunched at CDS
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(End) James Marcout, Francois Ochsenbein [CDS] 02-Jun-1994