J/A+A/330/423 Early-type galaxies kinematics (Rampazzo+ 1998)
Testing the physical reality of binaries and compact groups.
Properties of early-type galaxies in groups with diffuse X-ray emission
Rampazzo R., Covino S., Trinchieri G., Reduzzi L.
<Astron. Astrophys. 330, 423 (1998)>
=1998A&A...330..423R 1998A&A...330..423R (SIMBAD/NED BibCode)
ADC_Keywords: Galaxies, optical ; X-ray sources
Keywords: galaxies: elliptical and lenticular - galaxies: interactions -
galaxies: kinematics and dynamics - galaxies: photometry -
X-rays: galaxies
Abstract:
We present data on the stellar kinematics of the brightest ellipticals
in HCG 62, HCG 68, NGC 2300 groups. Moreover, we report on ASCA GIS as
well as optical observations of the early-type member of the pair
K 416 (NGC 5480/5481) similar, in many respects, to the dominant pair in
the NGC 2300 group. The kinematics of HCG 62a/b and HCG 68a/b indicate
that they are not interacting pairs. HCG 62a is instead possibly
interacting with HCG 62c, as suggested by their morphology (see Mendes
de Oliveira and Hickson 1994), In contrast to the results for the NGC
2300/2276 group, ASCA observations indicate a significant absence of
hot gas in the K 416 system. Whether the NGC 2300 multiplet is viewed
as a loose group or as a massive E+S pair, it is clear that similar
morphological entities do not always show similar X-ray properties.
Under the hypothesis that diffuse X-ray emission marks the group
potential, we consider the possibility that K 416 is an unbound
encounter. In this scenario, morphological distortions are indicative
of the ongoing interaction, but are only circumstantially correlated
with the physical reality of a pair/multiplet as a bound system.
Objects:
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RA (2000) DE Designation(s)
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12 53 05.8 -09 12 16 HCG 62a
12 53 04.4 -09 11 56 HCG 62b
13 53 26.5 +40 16 59 HCG 68a = NGC 5353
13 53 26.6 +40 18 09 HCG 68b = NGC 5354
07 32 36.0 +85 43 00 NGC 2300
14 06 22.0 +50 43 30 NGC 5480 = K72 416a
14 06 42.0 +50 45 00 NGC 5481 = K72 416b
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
tables.tex 80 136 LaTeX version of the tables
tables.ps 72 364 Post-Script version
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Table1: ASCA upper limits of X-ray emission from K 416 members
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Object Counts/s F(0.3-10keV) L(0.3-10keV) F(0.3-2.4keV) L(0.3-2.4keV) Detector
10-3
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NGC 5480 <1.4 <1.0 <0.2 <0.5 <0.1 GIS 2
NGC 5480 <3.0 <1.7 <0.3 <0.9 <0.2 GIS 3
NGC 5481 <1.4 <0.9 <0.2 <0.8 <0.2 GIS 2
NGC 5481 <2.6 <1.4 <0.3 <1.2 <0.3 GIS 3
Extended <3.3 <2.0 <0.4 <1.9 <0.4 GIS 2
Emission <5.0 <2.6 <0.5 <2.4 <0.5 GIS 3
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Note : Flux are in 10-13erg/s/cm2, luminosities are in
10+41erg/s/h50. 3σ upper limits have been calculated in a
circle of 25 for the two galaxies and of 75 for the extended emission,
as explained in the text. Fluxes are derived assuming a thermal
bremsstrahlung model with kT=5keV for NGC 5480 and a Raymond Smith
plasma model with kT=1keV and abundance = 0.5 solar for NGC 5481 and
the extended source. NH = 1.41x1020cm-2 has been taken from
Stark et al. (1992ApJS...79...77S 1992ApJS...79...77S). A distance of 40 h-150 Mpc is
assumed
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Table2: Main kinematics data
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Object other name Vhel σ0 Type
km/s km/s
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NGC 2300 2003±34 330 (1) E2
HCG 62a 4279±25 246±24 E3
HCG 62b 3542±25 272±26 S0
HCG 68a NGC 5353 2250±22 361±22 S0
HCG 68b NGC 5354 2570±17 241±22 E2
K 416b NGC 5481 2033±13 185±14 E3
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Note(1): The central velocity dispersion of NGC 2300 is extrapolated.
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Table3: Positions and parameters of the fit of X-ray spectra of unknown sources
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Object RA (2000) DE Counts/s γ norm. XI2 bins Flux Camera
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Unknown source 1 14 05 12 50 42 29 GIS 2
+0.2
14 05 04 50 41 36 4.4±0.5 2.3 9.4 0.8 15 4.7 GIS 3
-0.8
Unknown source 2 14 05 37 50 56 51 GIS 2
+0.9
14 05 29 50 56 11 4.0±0.4 1.8 6.8 0.8 16 3.7 GIS 3
-0.3
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Notes: Counts/s an norm. are in 10-3
The flux (0.3-10keV) is in 10-13erg/s/cm2
GIS 3 spectra were tentatively fitted with a power law, γ, and
interstellar absorption, NH = 0 and 1.1x1021cm-2 respectively for
the source 1 and 2. The errors are computed on two degrees of freedom
90% confidence interval.
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Acknowledgements: Roberto Rampazzo
(End) Patricia Bauer [CDS] 20-Jan-1998