J/A+A/574/A15 RR Lyrae in omega Cen (Fernandez-Trincado+, 2015)
Searching for tidal tails around ω Centauri using RR Lyrae stars.
Fernandez-Trincado J.G., Vivas A.K., Mateu C.E., Zinn R., Robin A.C.,
Valenzuela O., Moreno E., Pichardo B.
<Astron. Astrophys., 574, A15 (2015)>
=2015A&A...574A..15F 2015A&A...574A..15F (SIMBAD/NED BibCode)
ADC_Keywords: Clusters, globular; Stars, variable ; Photometry, VRI
Keywords: stars: variables: RR Lyrae - stars: kinematics and dynamics -
globular clusters: individual: omega Centauri -
globular clusters: individual: NGC 5139 - stars: horizontal-branch
Abstract:
We present a survey of RR Lyrae stars in an area of 50deg2 around
the globular cluster ω Centauri, aimed at detecting debris
material from the alleged progenitor galaxy of the cluster. We
detected 48 RR Lyrae stars, only 11 of which have been previously
reported. Ten of the eleven previously known stars were found inside
the tidal radius of the cluster. The rest were located outside the
tidal radius up to distances of ∼6-degrees from the center of the
cluster. Several of these stars are located at distances similar to
that of ω Centauri. We investigate the probability that they may
have been stripped off the cluster. To do this, we studied their
properties (mean periods) by calculating the expected halo and
thick-disk population of RR Lyrae stars in this part of the sky,
analyzing the radial velocity of a sub-sample of the RR Lyrae stars,
and finally, studying the probable orbits of this sub-sample around
the Galaxy. The results of these investigations do not support the
scenario that there is significant tidal debris around ω
Centauri, which confirms previous studies on the region. It is
puzzling that tidal debris has been found elsewhere but not near the
cluster itself.
Description:
The techniques used for this survey are similar to those used
extensively by our group in studies of RR Lyrae stars in the galactic
halo and the Canis Major over density with the QUEST1 camera. The
photometric survey was carried out using the QUEST camera at the 1.0m
Jurgen Stock telescope (1.5m Schmidt camera) at the National
Astronomical Observatory of Llano del Hato, Venezuela. The QUEST
camera is a mosaic of 16 CCDs (charge-coupled devices), with a field
of view of 2.3x2.5deg2. Each detector has 2048x2048pixels of 15um,
resulting in an angular resolution of 1-arcsec/pix.
File Summary:
--------------------------------------------------------------------------------
FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
table12.dat 118 50 RR Lyrae stars (No. 1-48, table1) and photometric
parameters for stars No 49 and 50 (table 2)
--------------------------------------------------------------------------------
See also:
J/A+AS/105/145 : RR Lyr stars of omega Cen (Petersen 1994)
J/A+AS/125/343 : OGLE RR Lyr stars in omega Cen (Kaluzny+ 1997)
J/A+A/424/1101 : Variable Stars in the field of ω Cen (Kaluzny+, 2004)
Byte-by-byte Description of file: table12.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 2 I2 --- ID Sequential number, [FVM2015] NN in Simbad
3 A1 --- n_ID [a] a: two periods reported for these stars
(see text)
5- 14 F10.6 deg RAdeg Right ascension (J2000)
16- 25 F10.6 deg DEdeg Declination (J2000)
27- 28 I2 --- Nobs Number of observation
30- 31 A2 --- VType RR Lyrae type
33- 39 F7.5 d Per Period
41- 47 F7.5 d Per2 ? Second period
49- 52 F4.2 mag Amp Amplitude of variation
54- 66 F13.5 d HJD ? Heliocentric Julian date at maximum light
68- 72 F5.2 mag <Vmag> ?=- Mean V magnitude
74- 77 F4.2 mag e_<Vmag> ? rms uncertainty on <Vmag>
79- 83 F5.2 mag <Imag> ?=- Mean I magnitude
85- 88 F4.2 mag e_<Imag> ? rms uncertainty on <Imag>
90- 94 F5.3 mag E(B-V) ? Reddening
96- 99 F4.1 kpc Dist ? Heliocentric distance
101-103 F3.1 kpc e_Dist ? rms uncertainty on Dist
105-107 F3.1 deg theta ? Angular distance from the center of omega Cen
109-111 I3 km/s RV ?=- Radial velocity
113-114 I2 km/s e_RV ? rms uncertainty on RV
116-118 I3 --- IDC01 ? ID number in Clement et al.
(2001AJ....122.2587C 2001AJ....122.2587C),
Cl* NGC 5139 SAW VNNN in Simbad
--------------------------------------------------------------------------------
History:
From electronic version of the journal
(End) Patricia Vannier [CDS] 17-Jan-2017