J/ApJ/765/154 RR Lyrae stars in the Catalina Sky Survey (Drake+, 2013)
Evidence for a Milky Way tidal stream reaching beyond 100 kpc.
Drake A.J., Catelan M., Djorgovski S.G., Torrealba G., Graham M.J.,
Mahabal A., Prieto J.L., Donalek C., Williams R., Larson S.,
Christensen E., Beshore E.
<Astrophys. J., 765, 154 (2013)>
=2013ApJ...765..154D 2013ApJ...765..154D
ADC_Keywords: Stars, variable ; Photometry ; Stars, distances
Keywords: galaxies: stellar content; Galaxy: formation; Galaxy: halo;
Galaxy: stellar content; Galaxy: structure; stars: variables: RR Lyrae
Abstract:
We present the analysis of 1207 RR Lyrae found in photometry taken by
the Catalina Survey's Mount Lemmon telescope. By combining accurate
distances for these stars with measurements for ∼14000 type-ab
RR Lyrae from the Catalina Schmidt telescope, we reveal an extended
association that reaches Galactocentric distances beyond 100kpc and
overlaps the Sagittarius stream system. This result confirms earlier
evidence for the existence of an outer halo tidal stream resulting
from a disrupted stellar system. By comparing the RR Lyrae source
density with that expected based on halo models, we find the detection
has ∼8σ significance. We investigate the distances, radial
velocities, metallicities, and period-amplitude distribution of the
RR Lyrae. We find that both radial velocities and distances are
inconsistent with current models of the Sagittarius stream. We also
find tentative evidence for a division in source metallicities for the
most distant sources. Following prior analyses, we compare the
locations and distances of the RR Lyrae with photometrically selected
candidate horizontal branch stars and find supporting evidence that
this structure spans at least 60° of the sky. We investigate the
prospects of an association between the stream and the unusual
globular cluster NGC 2419.
Description:
The Catalina Sky Survey began in 2004 and uses three telescopes to
cover the sky between declination -75° and +65° in order to
discover Near-Earth Objects (NEOs) and Potential Hazardous Asteroids
(Larson et al. 2003DPS....35.3604L 2003DPS....35.3604L). The three telescopes are each
considered sub-surveys. These consist of the Catalina Schmidt Survey
(CSS), the Mount Lemmon Survey (MLS), and the Siding Spring Survey
(SSS).
In Paper I (Drake et al. 2013, J/ApJ/763/32), we concentrated on
analyzing RRab data from the CSS sub-survey. In this paper we mainly
work with data observed by the MLS 1.5m telescope.
After removing non-RRL sources the final set of MLS RRL consists of
1207 stars (of which 538 are new) and is presented in Table 1. The new
RRab's found in CSS data re-analysis are given in Table 2.
The SEKBO survey discovered 2016 candidate RR Lyrae in a survey
covering 1675deg2 along the ecliptic (Keller et al. 2008,
J/ApJ/678/851). In Table 4, we present all the new SEKBO RRL found
using Catalina data (including RRL candidates where the period is
uncertain). This table contains 263 RRab, 282 RRc, and 11 RRd
candidates.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 103 1207 RRab from Mount Lemmon Survey (MLS)
table2.dat 108 2040 RRab from Catalina Schmidt Survey (CSS)
table4.dat 59 551 RR Lyrae from SEKBO survey
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See also:
B/vsx : AAVSO International Variable Star Index VSX (Watson+, 2006-2014)
II/294 : The SDSS Photometric Catalog, Release 7 (Adelman-McCarthy+, 2009)
J/ApJS/213/9 : Catalina Surveys periodic variable stars (Drake+, 2014)
J/ApJ/763/32 : I. Galactic halo type-ab RR Lyraes from CSS (Drake+, 2013)
J/ApJ/756/23 : V phot. follow-up of RR Lyrae from SEKBO (Akhter+, 2012)
J/AJ/144/114 : Radial velocities of 6 field RR Lyrae (Sesar+, 2012)
J/MNRAS/422/2116 : BHB and RR Lyrae towards Anticentre and NGP (Kinman+, 2012)
J/ApJ/708/717 : Light curve templates of RR Lyrae stars (Sesar+, 2010)
J/ApJ/696/870 : Catalina Real-time Transient Survey (CRTS) (Drake+, 2009)
J/ApJ/691/306 : Phot. of RR Lyrae candidates in Virgo stream (Prior+, 2009)
J/AcA/59/1 : VI light curves of LMC RR Lyrae stars (Soszynski+, 2009)
J/AJ/136/1645 : Spectroscopy of bright QUEST RR Lyrae stars (Vivas+, 2008)
J/ApJ/678/865 : LONEOS-I RR Lyrae stars (Miceli+, 2008)
J/ApJ/678/851 : RR Lyrae survey in the Galactic Halo (Keller+, 2008)
J/AJ/132/1202 : RRL in Northern Sky Variability Survey (Kinemuchi+, 2006)
J/AJ/132/714 : QUEST RR Lyrae survey. II. Halo overdensities (Vivas+, 2006)
J/PASP/109/524 : Light Curves for 40 RR Lyraes (Layden 1997)
http://www.sdss3.org/ : SDSS-III home page
http://crts.caltech.edu/ : CRTS survey home page
Byte-by-byte Description of file: table[12].dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 3 A3 --- Srv Name of survey: MLS = Mount Lemmon Survey,
CSS = Catalina Schmidt Survey
4 A1 --- --- [_]
5- 20 A16 --- Name Identification of RRab star (JHHMMSS.s+DDMMSS)
<[DCD2013] MLS JHHMMSS.s+DDMMSS> or
<[DCD2013] CSS JHHMMSS.s+DDMMSS> in Simbad
22- 30 F9.5 deg RAdeg Right Ascension in decimal degrees (J2000)
32- 40 F9.5 deg DEdeg Declination in decimal degrees (J2000)
42- 46 F5.2 mag <Vmag> [11.5/21.2] Average magnitude from Fourier
light curve fit
48- 55 F8.6 d Per [0.26/0.95] Period of RRab star
57- 60 F4.2 mag Vamp [0.2/1.9] Fourier fit amplitude to observed
variation
62- 64 I3 --- Nph [42/464] Number of photometric observations
66- 71 F6.2 kpc Dist [1.4/123] Heliocentric distance of star
73- 77 F5.3 mag Av [0.01/4.7] V band extinction (1)
79-106 A28 --- OName Alternative identifier if known
108 A1 --- f_Per [ab] Flag: a=uncertain period,
b=candidate Blazkho RR Lyrae
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Note (1): Based on the Schlegel, Finkbeiner & Davis (1998ApJ...500..525S 1998ApJ...500..525S)
reddening map.
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Byte-by-byte Description of file: table4.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 12 A12 --- objID SEKBO survey identifier (1)
14- 22 F9.5 deg RAdeg Right Ascension in decimal degrees (J2000)
24- 32 F9.5 deg DEdeg Declination in decimal degrees (J2000)
34- 38 F5.2 mag <Vmag> [13.6/20.2] Average magnitude from the AFD fit (2)
40- 48 F9.7 d Per [0.25/0.82]? Period
50- 53 F4.2 mag Vamp [0.1/1.4]? Amplitude of AFD fit (2)
55- 59 A5 --- Type Type of RR Lyrae (RRab, RRc or RRd;
a "?" indicates an uncertain classification)
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Note (1): Southern Edgeworth-Kuiper Belt Object (SEKBO) survey, as in
Keller et al. 2008 (J/ApJ/678/851), <[KMP2008] NNNNNN.NNNN> in Simbad
Note (2): AFD software (Torrealba et al., in prep.).
Magnitude from AFD if a period is found, weighted mean value otherwise.
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History:
From electronic version of the journal
Reference:
Drake et al. Paper I. 2013ApJ...763...32D 2013ApJ...763...32D Cat. J/ApJ/763/32
(End) Greg Schwarz [AAS], Emmanuelle Perret [CDS] 05-Nov-2014