J/A+A/501/949 Star cluster properties in five spiral galaxies (Mora+, 2009)
Imaging of star clusters in unperturbed spiral galaxies with the Advanced Camera
for Surveys.
II. A comparison of star cluster systems in five late type spirals.
Mora M.D., Larsen S.S, Kissler-Patig M., Brodie J.P., Richtler T.
<Astron. Astrophys. 501, 949 (2009)>
=2009A&A...501..949M 2009A&A...501..949M
ADC_Keywords: Galaxies, photometry
Keywords: galaxies: star clusters - galaxies: photometry
Abstract:
Aims: Our goal is to investigate the formation of star clusters in
relatively unperturbed environments. To do this, we studied the five
nearby spiral galaxies: NGC 45, NGC 1313, NGC 4395, NGC 5236, and NGC
7793.
Methods: We obtained images of the galaxies and their star cluster
systems in UBVI using the Advanced Camera for Surveys (ACS) and the
Wide Field Planetary Camera 2 (WFPC2) on board the Hubble Space
Telescope. From a comparison of the broad-band colours with simple
stellar population (SSP) models, we derived individual properties for
each galaxy for the clusters such such as masses, ages, and sizes, as
well as global star cluster system properties such as the age
distribution, luminosity function, and disruption time for clusters.
Results. We identified about 600 star cluster candidates in the five
galaxies, typically spanning ages from 3.9Myr up to 1Gyr and masses
from 102M☉ up to 105M☉. We used the cluster age
distribution to reconstruct the recent star formation history of each
galaxy and observed significant variations from galaxy to galaxy. We
went on to derive the luminosity function of the young star clusters
and found slopes around α~-2 (similar to the ones found in
previous studies) and the brightest star cluster magnitudes consistent
with a random sampling of the luminosity function without involving an
upper luminosity cut off. Finally, the sample includes only a handful
of old globular clusters in each galaxy from which we derive low
globular cluster specific frequencies.
Description:
The galaxies were observed with the HST ACS Wide Field Channel and the
WFPC2.
File Summary:
--------------------------------------------------------------------------------
FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
table.dat 251 580 Derived star cluster properties for all galaxies
--------------------------------------------------------------------------------
See also:
J/A+A/464/495 : UBVI photometry of NGC 45 star clusters (Mora+, 2007)
Byte-by-byte Description of file: table.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 13 A13 --- Name Cluster ID (1)
15- 16 I2 h RAh Hour Right Ascension J2000 (hours)
17 A1 --- --- [:]
18- 19 I2 min RAm Right Ascension J2000 (minutes)
20 A1 --- --- [:]
21- 27 F7.4 s RAs Right Ascension J2000 (seconds)
29 A1 --- DE- Declination J2000 (sign)
30- 31 I2 deg DEd Declination J2000 (degrees)
32 A1 --- --- [:]
33- 34 I2 arcmin DEm Declination J2000 (minutes)
35 A1 --- --- [:]
36- 41 F6.3 arcsec DEs Declination J2000 (seconds)
43- 50 F8.3 pix Xpos X position on the CCD according to the image
52- 59 F8.3 pix Ypos Y position on the CCD according to the image
61- 66 F6.3 mag Bmag B(F435W) photometry
68- 72 F5.3 mag e_Bmag Photometry error of F435W (Sigma_F435W)
74- 79 F6.3 mag Vmag V(F555W) photometry
81- 85 F5.3 mag e_Vmag Photometry error of F555W (Sigma_F555W)
87- 92 F6.3 mag Imag I(F814W) photometry
94- 98 F5.3 mag e_Imag Photometry error of F814W (Sigma_F814W)
100-105 F6.3 mag Umag U(F336W) photometry
107-111 F5.3 mag e_Umag Photometry error of F336W (Sigma_F336W)
113-119 F7.3 pix BfwhmS FWHM in pixels measured in the B(F435W)
images according to SExtractor
121-127 F7.3 pix Bfwhm FWHM in pixels measured in the B(F435W)
images according to ISHAPE
129-135 F7.3 pix Vfwhm FWHM in pixels measured in the V(F555W)
images according to ISHAPE
137-143 F7.3 pix Ifwhm FWHM in pixels measured in the I(F814W)
images according to ISHAPE
145-149 F5.3 mag E(B-V)1 Color excess calculated with Z=0.004 GALEV
151-155 F5.3 mag E(B-V)2 Color excess calculated with Z=0.008 GALEV
157-161 F5.3 mag E(B-V)3 Color excess calculated with Z=0.02 GALEV
163-167 F5.3 mag E(B-V)4 Color excess calculated with Z=0.05 GALEV
169-173 F5.3 mag E(B-V)5 Color excess calculated with Z=0.004 Girardi
175-179 F5.3 mag E(B-V)6 Color excess calculated with Z=0.019 Girardi
181-185 F5.3 [yr] Age1 log(Age) calculated with Z=0.004 GALEV
187-191 F5.3 [yr] Age2 log(Age) calculated with Z=0.008 GALEV
193-197 F5.3 [yr] Age3 log(Age) calculated with Z=0.02 GALEV
199-203 F5.3 [yr] Age4 log(Age) calculated with Z=0.05 GALEV
205-209 F5.3 [yr] Age5 log(Age) calculated with Z=0.004 Girardi
211-215 F5.3 [yr] Age6 log(Age) calculated with Z=0.019 Girardi
217-221 F5.3 [solMass] Mass1 log(Mass) calculated with Z=0.004 GALEV
223-227 F5.3 [solMass] Mass2 log(Mass) calculated with Z=0.008 GALEV
229-233 F5.3 [solMass] Mass3 log(Mass) calculated with Z=0.02 GALEV
235-239 F5.3 [solMass] Mass4 log(Mass) calculated with Z=0.05 GALEV
241-245 F5.3 [solMass] Mass5 log(Mass) calculated with Z=0.004 Girardi
247-251 F5.3 [solMass] Mass6 log(Mass) calculated with Z=0.019 Girardi
--------------------------------------------------------------------------------
Note (1): Galaxy ID: NameFieldN
--------------------------------------------------------------------------------
Acknowledgements:
Marcelo Mora, mmora(at)dfa.uv.cl
References:
Mora et al., Paper I 2007A&A...464..495M 2007A&A...464..495M, Cat. J/A+A/464/495
(End) M.D. Mora [Univ. de Valparaiso], Francois Ochsenbein [CDS] 28-Jul-2009