J/ApJ/842/120 Large spectrosc. survey of Palomar 5 stellar stream (Ibata+, 2017)
Feeling the pull: a study of natural galactic accelerometers.
II. Kinematics and mass of the delicate stellar stream of the
Palomar 5 globular cluster.
Ibata R.A., Lewis G.F., Thomas G., Martin N.F., Chapman S.
<Astrophys. J., 842, 120-120 (2017)>
=2017ApJ...842..120I 2017ApJ...842..120I (SIMBAD/NED BibCode)
ADC_Keywords: Clusters, globular ; Radial velocities ; Spectra, infrared ;
Photometry, ugriz
Keywords: Galaxy: halo; globular clusters: individual: Palomar 5
Abstract:
We present two spectroscopic surveys of the tidal stellar stream of
the Palomar 5 globular cluster undertaken with the VLT/FLAMES and
AAT/AAOmega instruments. We use these data in conjunction with
photometric data presented in the previous contribution in this series
to classify the survey stars in terms of their probability of
belonging to the Palomar 5 stellar stream. We find that
high-probability candidates are only found in a very narrow spatial
interval surrounding the locus of the stream on the sky. PanSTARRS
RRLyrae stars in this region of the sky are also distributed in a
similar manner. The absence of significant "fanning" of this stellar
stream confirms that Palomar 5 does not follow a chaotic orbit.
Previous studies have found that Palomar 5 is largely devoid of
low-mass stars, and we show that this is true also of the stellar
populations along the trailing arm out to 6°. Within this region,
which contains 73% of the detected stars, the population is
statistically identical to the core, implying that the ejection of the
low-mass stars occurred before the formation of the stream. We also
present an updated structural model fit to the bound remnant, which
yields a total mass of 4297±98M☉ and a tidal radius
0.145±0.009kpc. We estimate the mass of the observed system
including the stream to be 12200±400M☉, and the initial mass
to have been ∼47000±1500M☉.
Description:
The present contribution builds upon the survey of Paper I (Ibata+,
2016,J/ApJ/819/1). In addition to the deep CFHT photometry, in Paper I
we also presented shallower KPNO photometry of this system using the
M-band filter (approximately V) and the intermediate-band "DDO 51"
filter (central wavelength 5145.2Å, FWHM=162.9Å) which covers
the Mg b triplet.
Here we present a large spectroscopic survey of the stellar stream.
On 2009 June 23-27, we used the FLAMES multiobject spectrograph on the
8m VLT to observe 35 fields along the Palomar 5 stellar stream.
The high-resolution setting HR21 was used, which straddles the CaII
triplet feature and covers the spectral region between 8484Å and
9001Å with a resolution of R=16200. Each field consisted of 3x600s
exposures.
The FLAMES fields are fully contained within the CFHT survey region
(see Figure 1), and yielded a total of 1327 stars.
We also observed 15 fields with the AAOmega multiobject spectrograph
at the 4m Australian Astronomical Telescope on the nights of 2006
June 13-18.
The 1700D grating was used to measure the spectral region between
∼8400Å and ∼8850Å, at a resolution of 0.24Å/pixel. In each
field, three exposures of 1800s were combined.
Selecting good quality stars from both data sets (S/N>40 for FLAMES,
S/N>30 for AAOmega), we obtain 45 stars in common. The velocity
difference between the two samples is vFLAMES-vAAO=3.73±1.89km/s,
and we used this mean offset to put the AAO velocities onto the FLAMES
zero point.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table2.dat 59 154 Kinematic catalog
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See also:
V/147 : The SDSS Photometric Catalogue, Release 12 (Alam+, 2015)
J/MNRAS/365/1357 : Absolute mag. of Globular Cluster (Di Criscienzo+, 2006)
J/ApJ/738/186 : HST and DEIMOS measurements of NGC 2419 stars (Ibata+, 2011)
J/ApJ/776/26 : RRab stars in the Orphan stream distances (Sesar+, 2013)
J/ApJ/817/73 : QSOs & RRL* in Pan-STARRS1 3π Data (Hernitschek+ 2016)
J/ApJ/819/1 : Wide-field photometry of the GC Palomar 5 (Ibata+, 2016)
J/ApJ/823/157 : LOS vel. & [Fe/H] of Pal 5 tidal stream (Ishigaki+, 2016)
J/A+A/601/A41 : Palomar 5 abundance analysis (Koch+, 2017)
Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 2 I2 h RAh Hour of Right Ascension (J2000)
4- 5 I2 min RAm Minute of Right Ascension (J2000)
7- 12 F6.3 s RAs Second of Right Ascension (J2000)
14 A1 --- DE- Sign of the Declination (J2000)
15- 16 I2 deg DEd Degree of Declination (J2000)
18- 19 I2 arcmin DEm Arcminute of Declination (J2000)
21- 25 F5.2 arcsec DEs Arcsecond of Declination (J2000)
27- 32 F6.3 mag g0mag [15.7/19.8] CFHT/MegaCam g magnitude,
extinction corrected;
as in Paper I (Ibata+, 2016, J/ApJ/819/1)
34- 38 F5.3 mag (g-r)0 [0.4/0.8] g-r color index, extinction corrected
40- 46 F7.2 km/s HRV [-282/250] Heliocentric radial velocity
48- 51 F4.2 km/s e_HRV [0.5/5] Uncertainty in HRV
53- 57 F5.3 --- PMemb [0.2/1] Membership probability (1)
59 A1 --- Inst Instrument flag (F=VLT/FLAMES; A=AAT/AAOmega)
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Note (1): Here we present the cleanest sample, using all of the RGB membership
criteria, with PMemb=PRGBxPDDO51xPBS12xP[Fe/H]>0.2
(BS12 = Battaglia & Starkenburg 2012A&A...539A.123B 2012A&A...539A.123B).
This sample consists of 154 stars, of which 116 have velocities in the
range -80km/s < ν < -40km/s; 72 of these stars were not previously
known to be kinematic stream members.
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History:
From electronic version of the journal
References:
Ibata et al. 2016ApJ...819....1I 2016ApJ...819....1I Paper I. Cat. J/ApJ/819/1
Ibata et al. 2017ApJ...842..120I 2017ApJ...842..120I Paper II. This catalog
(End) Prepared by [AAS], Emmanuelle Perret [CDS] 06-Feb-2018