J/A+A/448/983 VIJsKs photometry in AM 1339-445 and AM1343-452 (Rejkuba+, 2006)
Dwarf elliptical galaxies in Centaurus A group: stellar populations in
AM 1339-445 and AM1343-452.
Rejkuba M., Da Costa G.S., Jerjen, H., Zoccali, M., Binggeli B.
<Astron. Astrophys. 448, 983 (2006)>
=2006A&A...448..983R 2006A&A...448..983R
ADC_Keywords: Galaxies, nearby ; Photometry, CCD ; Populations, stellar
Keywords: galaxies: dwarf - galaxies: stellar content -
galaxies: evolution - Stars: AGB and post-AGB
Abstract:
We study the red giant populations of two dwarf elliptical (dE)
galaxies, AM 1339-445 and AM 1343-452. The galaxies are members of
the Centaurus A group (D∼3.8Mpc), and are classified as outlying
(R∼350kpc) satellites of Cen A. The analysis is based on near-IR
photometry for individual red giant stars, derived from images
obtained with ISAAC on the VLT, and on optical V and I photometry,
derived from WFPC2 images retrieved from the HST science archive.
The data enable us to investigate the stellar populations of these
galaxies in the vicinity of the red giant branch (RGB) tip. In both
systems we find stars above the RGB tip, which we interpret as
intermediate-age upper-AGB stars. Their luminosities suggest ages of
approximately 6.5±1 and 4±1Gyr as estimates for the epoch of the
last episode of significant star formation in these systems. In both
cases the number of upper-AGB stars suggests that ∼15% of the total
stellar population is in the form of intermediate-age stars.
Description:
The catalogues of the upper red giant stars in AM 1339-445 and
AM 1343-452 are based on ground-based observations obtained in near-IR
Js and Ks bands with ISAAC at VLT and on space-based archival optical
V and I data from WFPC2 at HST. The Ks observations were taken in two
different epochs. The combined optical and near-IR catalogues contain
all the stellar sources detected both in ISAAC array and WF3 chip of
the WFPC2, which was centered on each galaxy.
Table 2 lists V, I, Js and the average Ks magnitudes of 275 stars in
AM 1339-445.
Table 3 lists V, I, Js and the average Ks magnitudes of 190 stars in
AM 1343-452.
The magnitudes have not been corrected for extinction. For each
magnitude we list magnitude errors as given by photometric packages,
HSTphot and DAOPHOT, used to obtain optical and near-IR photometry,
respectively.
Objects:
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RA (2000) DE Designation(s) (File)
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13 42 05.8 -45 12 21 AM 1339-445 = [KK98a] 211 (table2.dat)
13 46 18.8 -45 41 05 AM 1343-452 = [KK98a] 217 (table3.dat)
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table2.dat 66 275 VIJsKs photometry for 275 stars in AM 1339-445
table3.dat 66 190 VIJsKs photometry for 190 stars in AM 1343-452
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Byte-by-byte Description of file: table2.dat table3.dat
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Bytes Format Units Label Explanations
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1- 4 I4 --- Seq Identification number
6- 11 F6.2 pix Xpos X coordinate on WF3 chip (1)
13- 18 F6.2 pix Ypos Y coordinate on WF3 chip (1)
20- 25 F6.3 mag Vmag WFPC2 V (520.2nm) magnitude
27- 31 F5.3 mag e_Vmag Error in V magnitude
33- 38 F6.3 mag Imag WFPC2 I (820.3nm) magnitude
40- 44 F5.3 mag e_Imag Error in I magnitude
46- 50 F5.2 mag Jsmag ISAAC Js (1.24um) magnitude
52- 55 F4.2 mag e_Jsmag Error in Js magnitude
57- 61 F5.2 mag Ksmag ISAAC Ks (2.16um) magnitude
63- 66 F4.2 mag e_Ksmag Error in Ks magnitude
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Note (1): Origin and orientation (1pix=0.0996" for the two tables):
-- table2.dat (AM 1339-452):
Orientation: 139.312
The origin is at the lower left corner of the image
RA and DE of pixel (1.0,1.0): RA=13:42:10.407, DE=-45:12:21.18
-- table3.dat (AM1343-452):
Orientation: 150.02
The origin is at the lower left corner of the image
RA and DE of pixel (1.0,1.0): RA=13:46:21.916, DE=-45:41:17.58
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Acknowledgements: Marina Rejkuba, mrejkuba(at)eso.org
(End) Marina Rejkuba [ESO, Germany], Patricia Vannier [CDS] 01-Dec-2005