J/MNRAS/382/1947 CT1 photometry in NGC 1399 and NGC 4486 (Forte+, 2007)
A quantitative link between globular clusters and the stellar haloes in
elliptical galaxies.
Forte J.C., Faifer F., Geisler D.
<Mon. Not. R. Astron. Soc., 382, 1947-1964 (2007)>
=2007MNRAS.382.1947F 2007MNRAS.382.1947F
ADC_Keywords: Galaxies, photometry ; Clusters, globular ; Photometry, CMT1T2V
Keywords: galaxies: general - galaxies: haloes - galaxies: star clusters -
globular clusters: individual: NGC 1399 -
globular clusters: individual: NGC 4486
Abstract:
This paper explores the quantitative connection between globular
clusters and the diffuse stellar population of the galaxies they are
associated with. Both NGC 1399 and NGC 4486 (M87) are well suited for
this kind of analysis due to their large globular cluster populations.
The main assumption of our Monte Carlo based models is that each
globular cluster is formed along with a given diffuse stellar mass
that shares the same spatial distribution, chemical composition and
age. The main globular cluster subpopulations, that determine the
observed bimodal colour distribution, are decomposed avoiding a priori
parametric (e.g. Gaussian) fits and using a new colour
(C-T1)-metallicity relation. The eventual detectability of a blue tilt
in the colour-magnitude diagrams of the blue globular cluster
subpopulation is also addressed.
Description:
Photometric observations were carried out with the Mayall and Blanco
4-m telescopes at KPNO and CTIO, respectively, and 2048x2048 CCDs,
with a pixel scale of 0.43". The C filter from the Washington System
and the RKC filter of the Kron-Cousins system were used at both
telescopes. As noted by Geisler (1996AJ....111..480G 1996AJ....111..480G) this last filter
is comparable to the T1 filter in the Washington system although much
more efficient in terms of transmission. In what follows, we keep the
T1 denomination for our red magnitudes.
Objects:
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RA (2000) DE Designation(s)
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03 38 29.32 -35 27 00.7 NGC 1399 = LEDA 13418
12 30 49.42 +12 23 28.0 NGC 4486 = M 87
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 38 6825 Photometric data: NGC 1399
table2.dat 38 8477 Photometric data: NGC 4486
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See also:
J/ApJ/559/812 : Globular cluster system in M87 (Hanes+, 2001)
J/ApJ/513/733 : Globular cluster system in M87 (Kundu+, 1999)
Byte-by-byte Description of file: table[12].dat
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Bytes Format Units Label Explanations
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1- 6 I6 --- [FFG2007] Identification number within the cluster (1)
8- 13 F6.1 arcsec Xpos X position (2)
15- 20 F6.1 arcsec Ypos Y position (2)
22- 26 F5.2 mag T1mag T1 magnitude
28- 32 F5.2 mag C-T1 C-T1 colour index
35- 38 F4.2 --- Rnd Roundness parameter (3)
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Note (1): Objects identified in Simbad as
[FFG2007] NGC 1399 NNNNNN in table1
[FFG2007] NGC 4486 NNNNNN in table2
Note (2): Coordinates are referred to the galaxy centres. 1pix=0.43". North
is to the right-hand side and east is up for NGC 1399 (table1) North
is up and east is to the left-hand side for NGC 4486 (table2)
Note (3): Roundness parameter, which is zero for a perfectly-round
object and 1 or higher for an elongated object.
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History:
From electronic version of the journal
(End) Patricia Vannier [CDS] 22-Apr-2008