J/A+A/625/A94 YSOs in early-type dwarf galaxies (Hamraz+, 2019)
Young stellar populations in early-type dwarf galaxies;
occurrence, radial extent, and scaling relations.
Hamraz E., Peletier R. F., Khosroshahi H. G., Valentijn E. A.,
den Brok M., Venhola A.
<Astron. Astrophys. 625, A94 (2019)>
=2019A&A...625A..94H 2019A&A...625A..94H (SIMBAD/NED BibCode)
ADC_Keywords: Clusters, galaxy ; Galaxies, photometry
Keywords: galaxies: clusters: general - galaxies: dwarf - galaxies: photometry -
galaxies: star formation - galaxies: evolution - Galaxy: center
Abstract:
To understand the stellar population content of dwarf early-type
galaxies (dEs) and its environmental dependence, we compare the slopes
and intrinsic scatter of color-magnitude relations (CMRs) for three
nearby clusters, Fornax, Virgo and Coma. Additionally we present and
compare internal color profiles of these galaxies to identify central
blue regions with younger stars.
We use the imaging of the HST/ACS Fornax cluster in the magnitude
range of -18:7≤Mg0≤-16:0, to derive magnitudes, colors and color
profiles, which we compare with literature measurements from the
HST/ACS Virgo and Coma Cluster Survey. We benefit HST accuracy to
investigate and parameterize the (g'-z') color profiles of these dEs.
Based on analysis of the color profiles, we report a large number of
dEs with young stellar populations in their center in all three
clusters. While for Virgo and Coma the number of blue-cored dEs is
found to be 85%±2% and 53%±3% respectively, for Fornax, we find
that all galaxies have a blue core.We show that bluer cores reside in
fainter dEs, similar to the trend seen in nucleated dEs. We find no
correlation between the luminosity of the galaxy and the size of its
blue core. Moreover, a comparison of the CMRs of the three clusters
shows that the scatter in Virgo's CMR is considerably larger than in
the Fornax and Coma clusters. Presenting adaptive smoothing we show
that the galaxies on the blue side of the CMR often show evidence for
dust extinction, which strengthens the interpretation that the bluer
colors are due to young stellar populations. We also find that
outliers on the red side of the CMR are more compact than expected for
their luminosity. We find several of these red outliers in Virgo,
often close to more massive galaxies. No red outlying compact
early-types are found in Fornax and Coma in this magnitude range while
we find three in the Virgo cluster. We show that the CMR of the Fornax
and Virgo clusters are slightly bluer than that of Coma. We suggest
that the large number of outliers and larger scatter found for the
Virgo cluster CMR is a result of Virgos different assembly history.
Description:
Table 2: Determined Parameters of the dEs in Fornax such as effective
radii, colors, total magnitudes. The magnitudes and colors have been
corrected for galactic reddening.
Table 4: Parameters of the color profiles of the dEs in the Fornax
cluster.
Table 5: Parameters of the color profiles of the dEs in the Virgo
cluster.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table2.dat 40 26 Photometric parameters of dEs in Fornax
table4.dat 35 26 Color profiles of dEs in Fornax
table5.dat 36 54 Color profiles of dEs in Virgo
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See also:
VII/180 : Galaxies in Fornax Cluster & 5 nearby groups (Ferguson+ 1990)
J/A+A/296/319 : Fornax cluster early-type galaxies (D'Onofrio+, 1995)
J/A+A/463/503 : Early-type dwarf galaxies in Fornax cluster (Mieske+, 2007)
J/A+A/620/A165 : Fornax Deep Survey with VST. V. dwarf galaxies (Venhola+ 2018)
J/AJ/90/1681 : The Virgo Cluster Catalog (VCC) (Binggeli+, 1985)
J/A+A/526/A114 : Kinematic profiles of Virgo early-type galaxies (Toloba+ 2011)
J/A+A/538/A69 : Virgo early-type galaxies optical properties (Lieder+, 2012)
Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 6 A6 --- FCC Name of the object (FCCNNN)
8- 11 F4.1 arcsec Re(g) Effective radius in g-band
13- 16 F4.1 arcsec Re(z) Effective radius in z-band
18- 21 F4.2 mag g-z (g-z) color in 1"<r<Re
23- 26 F4.2 mag e_g-z Error of (g-z) color
28- 33 F6.2 mag gMAG Absolute Magnitude in g filter
35- 40 F6.2 mag zMAG Absolute Magnitude in z filter
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Byte-by-byte Description of file:table4.dat
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Bytes Format Units Label Explanations
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1- 6 A6 --- FCC Name of the object (FCCNNN)
8- 10 I3 pc CoreRad Size of the blue/red core
12- 16 F5.2 --- XOuterFit Average excess light in the center (G1)
18- 22 F5.2 --- XCMR Average excess light from the CMR (G1)
24- 29 F6.3 --- Slope ?=-9.999 Slope of the fitted line
31- 35 F5.3 --- e_Slope ?=9.999 Error of Slope
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Byte-by-byte Description of file: table5.dat
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Bytes Format Units Label Explanations
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1- 7 A7 --- VCC Name of the object (VCCNNNN)
9- 11 I3 pc CoreRad ?=999 Size of the blue/red core
13- 17 F5.2 --- XOuterFit ?=-9.99 Average excess light in the center (G1)
19- 23 F5.2 --- XCMR Average excess light from the CMR (G1)
25- 30 F6.3 --- Slope ?=-9.999 Slope of the fitted line
32- 36 F5.3 --- e_Slope ?=9.999 Error of Slope
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Global notes:
Note (G1): Please see the paper for the formula of XOuterFit and XCMR.
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Acknowledgements:
Elaheh Hamraz, hamraz(at)astro.rug.nl
(End) Patricia Vannier [CDS] 03-May-2019