J/MNRAS/491/5693 Globular clusters in NGC 5907's stellar stream (Alabi+, 2020)
Globular clusters in the stellar stream surrounding the Milky Way analogue
NGC 5907.
Alabi A.B., Forbes D.A., Romanowsky A.J., Brodie J.P.
<Mon. Not. R. Astron. Soc., 491, 5693-5701 (2020)>
=2020MNRAS.491.5693A 2020MNRAS.491.5693A (SIMBAD/NED BibCode)
ADC_Keywords: Galaxies ; Clusters, globular ; Radial velocities ;
Photometry, ugriz ; Spectra, optical
Keywords: galaxies: evolution - galaxies: individual NGC 5907 -
galaxies: interactions
Abstract:
We study the globular clusters (GCs) in the spiral galaxy NGC 5907
well-known for its spectacular stellar stream - to better understand
its origin. Using wide-field Subaru/Suprime-Cam gri images and deep
Keck/DEIMOS multi-object spectroscopy, we identify and obtain the
kinematics of several GCs superimposed on the stellar stream and the
galaxy disc. We estimate the total number of GCs in NGC 5907 to be
154±44, with a specific frequency of 0.73±0.21. Our analysis also
reveals a significant, new population of young star cluster candidates
found mostly along the outskirts of the stellar disc. Using the
properties of the stream GCs, we estimate that the disrupted galaxy
has a stellar mass similar to the Sagittarius dwarf galaxy accreted by
the Milky Way, i.e. ∼108M☉.
Description:
The imaging used for this work was obtained using the wide-field
Suprime-Cam imager on the 8.2m Subaru telescope with the SDSS gri
filters under photometric conditions (0.6"-0.9" seeing). Details of
the observations and data reduction are explained in Laine et al.
(2016AJ....152...72L 2016AJ....152...72L). The imager has a total field of view of
34arcsecx27arcsec with a pixel scale of 0.2" per pixel.
Using our point-source catalogue, we identified target point-sources
for follow-up spectroscopy with the DEIMOS spectrograph on the Keck II
telescope. We obtained three masks; one along with the bright NE loop,
one covering the E1 and E2 loops of Martinez-Delgado et al.
(2008ApJ...689..184M 2008ApJ...689..184M), with the last mask positioned along the disc of
NGC 5907. Data were obtained on the nights of 2013 April 10, 2016
March 10, and 2017 April 27 for a total of 6.5h. We used both the
600lines/mm grating (centred on 6700Å) and the 1200lines/mm grating
(centred on 7800Å). Spectra were reduced using the SPEC2D pipeline
and the same procedure as successfully applied during the SLUGGS
survey (e.g. Pota et al. 2013MNRAS.428..389P 2013MNRAS.428..389P, Cat. J/MNRAS/428/389;
Forbes et al. 2017AJ....153..114F 2017AJ....153..114F, Cat. J/AJ/153/114). We measured
line-of-sight velocities from the CaT and Hα spectral features
with FXCOR in IRAF using stellar templates from the MILES spectral
library (Vazdekis et al. 2016MNRAS.463.3409V 2016MNRAS.463.3409V).
We provide a complete summary of all the various classes of
point-sources detected in this work in Table 2.
Objects:
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RA (ICRS) DE Designation(s)
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15 15 53.68 +56 19 43.8 NGC5907 = 2MASX J15155368+5619438
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table2.dat 95 420 Summary of GCs, young star clusters, stars and
galaxies in the field of NGC 5907
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Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 14 A14 --- Name Object name (NGC5907_GCNNNN, NGC5907_YCNN,
NGC5907_StarNN or NGC5907_GalN)
16- 25 F10.6 deg RAdeg Right ascension (J2000)
27- 35 F9.6 deg DEdeg Declination (J2000)
37- 42 F6.3 mag gmag Subaru/SuprimeCam g-band magnitude corrected
for Galactic extinction
44- 48 F5.3 mag e_gmag Error on gmag
50- 55 F6.3 mag rmag Subaru/SuprimeCam r-band magnitude corrected
for Galactic extinction
57- 61 F5.3 mag e_rmag Error on rmag
63- 68 F6.3 mag imag Subaru/SuprimeCam i-band magnitude corrected
for Galactic extinction
70- 74 F5.3 mag e_imag Error on imag
76- 80 F5.2 mag g-i Subaru/SuprimeCam g-i colour index
82- 87 F6.3 mag r-i Subaru/SuprimeCam r-i colour index
89- 92 I4 km/s RV ? Radial velocity
94- 95 I2 km/s e_RV ? Error on RV
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History:
From electronic version of the journal
(End) Ana Fiallos [CDS] 23-Feb-2023