J/MNRAS/375/831 Draco MegaCam, INT and HST photometry (Segall+, 2007)
Draco, a flawless dwarf galaxy.
Segall M., Ibata R.A., Irwin M.J., Martin N.F., Chapman S.
<Mon. Not. R. Astron. Soc., 375, 831-842 (2007)>
=2007MNRAS.375..831S 2007MNRAS.375..831S
ADC_Keywords: Galaxies, photometry
Keywords: galaxies: dwarf - galaxies: structure - dark matter
Abstract:
The Draco dwarf spheroidal galaxy (dSph), with its apparent immense
mass-to-light ratio and compact size, holds many clues to the nature
of the enigmatic dark matter. Here we present deep photometric studies
of this dwarf galaxy, undertaken with the MegaCam Camera at the
Canada-France-Hawaii Telescope, the Wide Field Camera at the Isaac
Newton Telescope and the Wide Field and Planetary Camera onboard the
Hubble Space Telescope (HST). The new photometric data cover the
entirety of the galaxy, and reach i'=24.5 at 50 per cent
completeness, significantly deeper than previous panoramic studies,
allowing searches for tidal disturbances of much lower surface
brightness than has been possible before. With these improved
statistics, we find no evidence for asymmetric disturbances or tidal
tails that possess more than 3 per cent of the stars found within the
centre of the galaxy. We find that the central stellar density, as
probed by the HST data, rises into the central 0.5arcmin.
Uncertainties in the position of the centroid of the galaxy do not
allow us to determine whether the apparent flattening of the profile
interior to 0.5arcmin is reliable or not. Draco is therefore a
flawless dwarf galaxy, featureless and apparently unaffected by
Galactic tides.
Description:
The Draco dSph galaxy was observed with the wide-field MegaCam camera
at the Canada-France-Hawaii Telescope (CFHT) in service mode during the
2004A and 2005A observing seasons. MegaCam is a mosaic of 364612x2048
EEV chips, offering a field of ∼0.96x0.94deg2.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table2.dat 73 1100913 MegaCam catalogue
table3.dat 56 271194 INT catalogue
table5.dat 79 3182 HST catalogue
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See also:
J/AJ/121/841 : RV photometry of Draco dwarf spheroidal galaxy (Piatek+, 2001)
J/AJ/110/2131 : M/L for Draco and UMi. I. (Armandroff+ 1995)
Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 2 I2 h RAh Right ascension (J2000.0)
4- 5 I2 min RAm Right ascension (J2000.0)
7- 11 F5.2 s RAs Right ascension (J2000.0)
12 A1 --- DE- Declination sign (J2000.0)
13- 14 I2 deg DEd Declination (J2000.0)
16- 17 I2 arcmin DEm Declination (J2000.0)
19- 22 F4.1 arcsec DEs [0/60] Declination (J2000.0)
24- 29 F6.3 mag gmag ?=0.000 MegaCam g magnitude in AB system (G1)
32- 36 F5.3 mag e_gmag ?=0.000 rms uncertainty on gmag
38- 39 I2 --- cg Classification parameter in g band (G2)
41- 46 F6.3 mag rmag ?=0.000 MegaCam r magnitude in AB system (G1)
49- 53 F5.3 mag e_rmag ?=0.000 rms uncertainty on rmag
55- 56 I2 --- cr Classification parameter in r band (G2)
58- 63 F6.3 mag imag ?=0.000 MegaCam i magnitude in AB system (G1)
66- 70 F5.3 mag e_imag ?=0.000 rms uncertainty on imag
72- 73 I2 --- ci Classification parameter in i band (G2)
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Byte-by-byte Description of file: table3.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 2 I2 h RAh Right ascension (J2000.0)
4- 5 I2 min RAm Right ascension (J2000.0)
7- 11 F5.2 s RAs Right ascension (J2000.0)
12 A1 --- DE- Declination sign (J2000.0)
13- 14 I2 deg DEd Declination (J2000.0)
16- 17 I2 arcmin DEm Declination (J2000.0)
19- 22 F4.1 arcsec DEs [0/60] Declination (J2000.0)
24- 29 F6.3 mag Vmag ?=0.000 INT V magnitude converted into the
MegaCam AB system (G1)
32- 36 F5.3 mag e_Vmag ?=0.000 rms uncertainty on Vmag
38- 39 I2 --- cV Classification parameter in V band (G2)
41- 46 F6.3 mag imag ?=0.000 INT i magnitude converted into the
MegaCam AB system (G1)
49- 53 F5.3 mag e_imag ?=0.000 rms uncertainty on imag
55- 56 I2 --- ci Classification parameter in i band (G2)
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Byte-by-byte Description of file: table5.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 2 I2 h RAh Right ascension (J2000.0)
4- 5 I2 min RAm Right ascension (J2000.0)
7- 11 F5.2 s RAs Right ascension (J2000.0)
13 A1 --- DE- Declination sign (J2000.0)
14- 15 I2 deg DEd Declination (J2000.0)
17- 18 I2 arcmin DEm Declination (J2000.0)
20- 23 F4.1 arcsec DEs [0/60] Declination (J2000.0)
25- 30 F6.3 mag Vmag ?=0.000 HST V (F606W) magnitude
33- 37 F5.3 mag e_Vmag ?=0.000 rms uncertainty on Vmag
40- 44 F5.3 --- Chi2V Chi2 value of PSF fit for V band
46- 51 F6.3 --- Vsharp Profile shape (sharpness) for V band
53- 58 F6.3 mag imag ?=0.000 HST i (F814W) magnitude
61- 65 F5.3 mag e_imag ?=0.000 rms uncertainty on imag
68- 72 F5.3 --- Chi2i Chi2 value of PSF fit for i band
74- 79 F6.3 --- isharp Profile shape (sharpness) for i band
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Global notes:
Note (G1): Magnitude values of 0.000 indicate that no measurement was possible.
Note (G2): A classification index of 1 corresponds to a likely galaxy,
-1, ..., -9 to a point sources (in order of decreasing confidence
of stellarity), and 0 to an artefact or noise
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Nomeclature note:
Galaxies identified as [SII2007] JHHMMSS.ss+DDMMSS.s in Simbad
History:
From electronic version of the journal
(End) Patricia Vannier [CDS] 21-Dec-2007