J/ApJ/855/43 Distant RR Lyrae stars discovered with HiTS (Medina+, 2018)
Discovery of distant RR Lyrae stars in the Milky Way using DECam.
Medina G.E., Munoz R.R., Vivas A.K., Carlin J.L., Forster F., Martinez J.,
Galbany L., Gonzalez-Gaitan S., Hamuy M., de Jaeger T., Maureira J.C.,
Martin J.S.
<Astrophys. J., 855, 43 (2018)>
=2018ApJ...855...43M 2018ApJ...855...43M
ADC_Keywords: Stars, variable; Stars, distances; Milky Way; Photometry, UBV
Keywords: Galaxy: halo ; Galaxy: stellar content ; Galaxy: structure ;
stars: variables: RR Lyrae
Abstract:
We report the discovery of distant RR Lyrae stars, including the most
distant known in the Milky Way, using data taken in the g-band with
the Dark Energy Camera as part of the High cadence Transient Survey
(HiTS; 2014 campaign). We detect a total of 173 RR Lyrae stars over a
∼120deg2 area, including both known RR Lyrae and new detections. The
heliocentric distances dH of the full sample range from 9 to >200kpc,
with 18 of them beyond 90kpc. We identify three sub-groups of RR Lyrae
as members of known systems: the Sextans dwarf spheroidal galaxy, for
which we report 46 new discoveries, and the ultra-faint dwarf galaxies
Leo IV and Leo V. Following an MCMC methodology, we fit spherical and
ellipsoidal profiles of the form ρ(R)∼Rn to the radial density
distribution of RR Lyrae in the Galactic halo. The best fit
corresponds to the spherical case, for which we obtain a simple
power-law index of n=-4.17-0.20+0.18, consistent with recent
studies made with samples covering shorter distances. The pulsational
properties of the outermost RR Lyrae in the sample (dH>90kpc) differ
from the ones in the halo population at closer distances. The
distribution of the stars in a period-amplitude diagram suggest they
belong to Oosterhoff-intermediate or Oosterhoff II groups, similar to
what is found in the ultra-faint dwarf satellites around the Milky
Way. The new distant stars discovered represent an important addition
to the few existing tracers of the Milky Way potential in the outer
halo.
Description:
The High Cadence Transient Survey (HiTS; Forster+ 2016ApJ...832..155F 2016ApJ...832..155F)
is a deep optical campaign carried out with the Dark Energy Camera
(DECam) mounted at the prime focus of the Blanco 4m telescope at Cerro
Tololo Inter-American Observatory (CTIO).
The observations used for the current work took place between UT 2014
February 28 and March 4 (five consecutive nights). Forty fields were
observed with a cadence of 2 hours, 4 times per night in the g-band.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 58 18 Most distant RR Lyrae stars (dH>90kpc)
table5.dat 77 65 RR Lyrae stars found in the Sextans dSph by the
High Cadence Transient Survey (HiTS)
table6.dat 64 108 Full list of the RRLs presented in this work,
excluding the candidates in the Sextans dSph galaxy
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See also:
J/AJ/110/2166 : Variables in Sextans dSph galaxy (Mateo+ 1995)
J/AJ/126/2840 : BVI CCD photometry of Sextans dSph galaxy (Lee+, 2003)
J/AJ/127/1158 : QUEST RR Lyrae Survey first catalog (Vivas+, 2004)
J/ApJS/162/1 : MUSYC: optical source catalog (Gawiser+, 2006)
J/AJ/132/714 : QUEST RR Lyrae survey. II. Halo overdensities (Vivas+, 2006)
J/ApJ/678/851 : RR Lyrae survey in the Galactic Halo (Keller+, 2008)
J/MNRAS/398/1757 : RR Lyraes in SDSS stripe 82 (Watkins+, 2009)
J/ApJ/708/717 : Light curve templates of RR Lyrae stars (Sesar+, 2010)
J/ApJ/731/4 : Galactic halo as seen by the CFHTLS (Sesar+, 2011)
J/ApJ/756/23 : V-band follow-up of RR Lyrae from SEKBO (Akhter+, 2012)
J/AJ/144/4 : Dwarf galaxies in the Local Group (McConnachie+, 2012)
J/ApJ/763/32 : Galactic halo RRab stars from CSS (Drake+, 2013)
J/ApJ/765/154 : RR Lyrae stars in the Catalina Sky Survey (Drake+, 2013)
J/AJ/146/101 : LINEAR. III. Periodic variables (Palaversa+, 2013)
J/ApJ/776/26 : RRab stars in the Orphan stream distances (Sesar+, 2013)
J/AJ/146/21 : LINEAR. II. Catalog of RR Lyrae stars (Sesar+, 2013)
J/ApJS/213/9 : Catalina Surveys periodic variable stars (Drake+, 2014)
J/ApJ/781/22 : La Silla QUEST RR Lyrae star survey --Region I (Zinn+, 2014)
J/ApJ/788/105 : XSTPS RR Lyrae in the north Galactic cap (Faccioli+, 2014)
J/ApJ/793/135 : Positions and distances of RR Lyrae stars (Sesar+, 2014)
J/A+A/574/A15 : RR Lyrae in omega Cen (Fernandez-Trincado+, 2015)
J/ApJ/829/108 : Kinematic data of Galactic globular clusters (Eadie+, 2016)
J/MNRAS/460/30 : gi photometry of Sextans dSph galaxy stars (Roderick+, 2016)
J/ApJ/831/165 : RR Lyrae as tracers in Virgo overdensity region (Vivas+, 2016)
J/MNRAS/469/3688 : CSS Periodic Variable Star Catalogue (Drake+, 2017)
J/ApJ/844/L4 : PS1 RRab for tracing outer Virgo overdensity (Sesar+, 2017)
J/ApJ/849/150 : RR Lyrae candidates in the MW outer halo (Cohen+, 2017)
J/AJ/153/179 : VVV Survey RR Lyr stars in Galactic plane (Minniti+, 2017)
J/AJ/153/204 : RR Lyrae stars from the PS1 3π survey (Sesar+, 2017)
J/AJ/154/85 : CTIO/DECam photometry of RR Lyrae stars in M5 (Vivas+, 2017)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 4 A4 --- --- [HiTS]
5- 17 A13 --- HiTS RR Lyrae identifier (HHMMSS+DDMMSS; J2000)
19- 27 F9.5 deg RAdeg [155/173.3] Right ascension (J2000)
29- 36 F8.5 deg DEdeg [-10/2.3] Declination (J2000)
38- 41 F4.1 mag gmagAvg [20.4/22.8] g-band mean AB magnitude
43- 47 F5.1 kpc Dist [92.5/262.2] Heliocentric distance (dH)
49- 52 F4.1 kpc e_Dist [4/24.3] Uncertainty in Dist
54- 55 A2 --- Type RR Lyrae type ("ab" or "c")
57- 58 I2 --- Nobs [18/22] Number of observations
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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- 4 A4 --- --- [HiTS]
5- 17 A13 --- HiTS RR Lyrae identifier (HHMMSS+DDMMSS; J2000)
19- 27 F9.5 deg RAdeg [152/154.2] Right ascension (J2000)
29- 36 F8.5 deg DEdeg [-2.6/-0.6] Declination (J2000)
38- 41 F4.1 mag gmagAvg [20/20.6] g-band mean AB magnitude
43- 49 F7.5 d Per [0.3/0.8] Period
51- 54 F4.2 mag Amp [0.4/1.2] Amplitude
56- 57 I2 kpc Dist [76/90] Heliocentric distance (dH)
59- 60 A2 -- Type RR Lyrae type ("ab" or "c")
62- 63 I2 -- Nobs [20/38] Number of observations
65- 77 A13 -- pID Previous ID (1)
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Note (1): Stars with prefixes V and C are taken from Amigo Fuentes+ (Amigo
Fuentes P., Catelan M. and Zoccali M. 2012 PhD thesis, Univ. Catolica
de Chile), with the former corresponding to detections made by Mateo+
(1995, J/AJ/110/2166 ; <[MFK95] VNN> in Simbad). The RRLs with prefixes LSQ
are stars from LSQ (Zinn+ 2014, J/ApJ/781/22 ; <[ZHV2014] NNNN> in Simbad),
and the ones labeled as VV, VI and MV are from Lee+ (2003, J/AJ/126/2840 ;
<[LPP2003] {VV/VI/MV} NN> in Simbad).
Stars with MV come from Mateo+ (1995, J/AJ/110/2166) as well.
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Byte-by-byte Description of file: table6.dat
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Bytes Format Units Label Explanations
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1- 4 A4 --- --- [HiTS]
5- 17 A13 --- HiTS RR Lyrae identifier (HHMMSS+DDMMSS; J2000)
19- 27 F9.5 deg RAdeg [149.6/174.5] Right ascension (J2000)
29- 36 F8.5 deg DEdeg [-10/3.1] Declination (J2000)
38- 41 F4.1 mag gmagAvg [15.5,22.8] g-band mean AB magnitude
43- 48 F6.4 d Per [0.2/0.9] Period
50- 53 F4.2 mag Amp [0.1/1.5] Amplitude
55- 57 I3 kpc Dist [9/262] Heliocentric distance (dH)
59- 60 A2 -- Type RR Lyrae type ("ab" or "c")
62- 64 I3 -- Nobs [16/38] Number of observations
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Acknowledgements:
Gustavo Medina [Departamento de Astronomia, Universidad de Chile]
History:
From electronic version of the journal -
In table 5, pID for HiTS101401-014046 has been corrected for V43, MV09 and
pID for HiTS101403-013845 has been corrected for V44; after verifications
by the author.
(End) Prepared by [AAS], Emmanuelle Perret [CDS] 16-Nov-2018