J/MNRAS/442/3544 Kinematic tracers in Umbrella galaxy (NGC4651) (Foster+, 2014)
Kinematics and simulations of the stellar stream in the halo of the
Umbrella galaxy.
Foster C., Lux H., Romanowsky A.J., Martinez-Delgado D., Zibetti S.,
Arnold J.A., Brodie J.P., Ciardullo R., Gabany R.J., Merrifield M.R.,
Singh N., Strader J.
<Mon. Not. R. Astron. Soc., 442, 3544-3564 (2014)>
=2014MNRAS.442.3544F 2014MNRAS.442.3544F
ADC_Keywords: Galaxies, photometry ; Clusters, globular ; H II regions ;
Planetary nebulae ; Photometry, SDSS
Keywords: galaxies: individual: NGC 4651 - galaxies: interactions -
galaxies: kinematics and dynamics
Abstract:
We study the dynamics of faint stellar substructures around the
Umbrella Galaxy, NGC 4651, which hosts a dramatic system of streams
and shells formed through the tidal disruption of a nucleated dwarf
elliptical galaxy. We elucidate the basic characteristics of the
system (colours, luminosities, stellar masses) using multiband
Subaru/Suprime-Cam images. The implied stellar mass ratio of the
ongoing merger event is ∼1:50. We identify candidate kinematic
tracers (globular clusters, planetary nebulae, HII regions) and follow
up a subset with Keck/DEIMOS (DEep Imaging Multi-object Spectrograph)
spectroscopy to obtain velocities. We find that 15 of the tracers are
likely associated with halo substructures, including the probable
stream progenitor nucleus. These objects delineate a kinematically
cold feature in position-velocity phase space. We model the stream
using single test particle orbits, plus a rescaled pre-existing
N-body simulation. We infer a very eccentric orbit with a period of
∼0.35Gyr and turning points at ∼2-4 and ∼40kpc, implying a recent
passage of the satellite through the disc, which may have provoked the
visible disturbances in the host galaxy. This work confirms that the
kinematics of low surface brightness substructures can be recovered
and modelled using discrete tracers - a breakthrough that opens up a
fresh avenue for unravelling the detailed physics of minor merging.
Description:
In an effort to better define the properties of the faint
substructures, new images were obtained on the nights of 2011 January
3 and 4 in photometric conditions using the Suprime-Cam wide-field
camera (34x27arcmin2 field of view) on the 8.2m Subaru telescope.
NGC 4651 was imaged under 0.9, 0.6 and 0.9 arcsec seeing in the
g'-band (1300s), r'-band (500s) and i'-band (505s) filters,
respectively, using a preset dithering pattern that offset successive
images in order to compensate for gaps between Suprime-Cam's 10 CCDs
(laid out in a 5x2 xrid). An [OIII] narrow-band image (4860s) was
also acquired for HII region and PN candidate selection, under
1.2-arcsec seeing.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table2.dat 91 810 Catalog of photometrically selected globular
cluster candidates
table3.dat 91 64 Catalog of photometrically selected HII region
candidates
table4.dat 91 39 Catalog of photometrically selected planetary
nebula candidates
table5.dat 100 46 Summary of measured kinematic tracers
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Byte-by-byte Description of file: table2.dat table3.dat table4.dat
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Bytes Format Units Label Explanations
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1- 10 A10 --- Name Candidate name
11 A1 --- n_Name [*] * for spectroscopically confirmed
13- 14 I2 h RAh Right ascension (J2000)
16- 17 I2 min RAm Right ascension (J2000)
19- 24 F6.3 s RAs Right ascension (J2000)
26 A1 --- DE- Declination sign (J2000)
27- 28 I2 deg DEd Declination (J2000)
30- 31 I2 arcmin DEm Declination (J2000)
33- 38 F6.3 arcsec DEs Declination (J2000)
40- 45 F6.3 mag gmag ?=- Subaru/Suprime g magnitude (not for PN)
47- 52 F6.3 mag e_gmag ?=- rms uncertainty on gmag
54- 59 F6.3 mag rmag ?=- Subaru/Suprime r magnitude (not for PN)
61- 65 F5.3 mag e_rmag ?=- rms uncertainty on rmag
67- 72 F6.3 mag imag ?=- Subaru/Suprime i magnitude (not for PN)
74- 78 F5.3 mag e_imag ?=- rms uncertainty on imag
80- 85 F6.3 mag m5007 [21/29]?=- Subaru/Suprime [OIII] (5007Å)
magnitude
87- 91 F5.3 mag e_m5007 ?=- rms uncertainty on m5007
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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- 6 A6 --- Type Type (Nuclei, PNe, HII or GCs)
8- 18 A11 --- Name Name
20- 21 I2 h RAh Right ascension (J2000)
23- 24 I2 min RAm Right ascension (J2000)
26- 30 F5.2 s RAs Right ascension (J2000)
32 A1 --- DE- Declination sign (J2000)
33- 34 I2 deg DEd Declination (J2000)
36- 37 I2 arcmin DEm Declination (J2000)
39- 42 F4.1 arcsec DEs Declination (J2000)
44- 47 I4 km/s Vobs Observed heliocentric corrected recession
velocity
49- 50 I2 km/s e_Vobs rms uncertainty on Vobs
51 A1 --- n_Vobs [a] a: measured from the higher resolution
long-slit spectrum (1)
52- 56 F5.2 mag gmag ?=- Subaru/Suprime-Cam foreground extinction
corrected g' magnitude
58- 61 F4.2 mag e_gmag ?=- rms uncertainty on gmag
62 A1 --- n_gmag [c] c: photometry affected by crowding (1)
64- 68 F5.2 mag rmag ?=- Subaru/Suprime-Cam foreground extinction
corrected r' magnitude
70- 73 F4.2 mag e_rmag ?=- rms uncertainty on rmag
74 A1 --- n_rmag [c] c: photometry affected by crowding (1)
76- 80 F5.2 mag imag ?=- Subaru/Suprime-Cam foreground extinction
corrected i' magnitude
82- 85 F4.2 mag e_imag ?=- rms uncertainty on imag
86 A1 --- n_imag [c] c: photometry affected by crowding (1)
88- 91 F4.1 mag m5007 ?=- Subaru/Suprime-Cam foreground extinction
corrected [OIII] (5007Å) magnitude
93- 95 F3.1 mag e_m5007 ? rms uncertainty on m5007
96 A1 --- n_m5007 [b] identified by eye on image (1)
98-100 A3 --- Disc [Yes/No] whether or not the kinematics are
consistent with the disc of NGC 4651
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Note (1): Notes as follows:
a = measured from the higher resolution long-slit spectrum
b = identified by eye on image
c = photometry affected by crowding
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History:
From electronic version of the journal
(End) Patricia Vannier [CDS] 05-Mar-2015