J/ApJ/861/23 RR Lyrae variables in the Crater II dwarf galaxy (Joo+, 2018)
RR Lyrae variables in the Crater II dwarf galaxy.
Joo S.-J., Kyeong J., Yang S.-C., Han S.-I., Sung E.-C., Kim D., Jeong H.,
Ree C.H., Rey S.-C., Jerjen H., Kim H.-S., Cha S.-M., Lee Y.
<Astrophys. J., 861, 23 (2018)>
=2018ApJ...861...23J 2018ApJ...861...23J
ADC_Keywords: Galaxies, photometry; Stars, variable; Photometry, UBV
Keywords: galaxies: dwarf ; galaxies: individual (Crater II) ; Local Group ;
stars: variables: RR Lyrae
Abstract:
We report the detection of RR Lyrae variable stars in Crater II, a
recently discovered large and diffuse satellite dwarf galaxy of the
Milky Way (MW). Based on B, V time-series photometry obtained with the
Korea Microlensing Telescope Network 1.6m telescope at Cerro Tololo
Inter-American Observatory, we identified 83 ab-type and 13 c-type
pulsators by fitting template light curves. The detected RR Lyrae
stars are centrally concentrated, which ensures that most of them are
members of Crater II. In terms of the distribution of RRab stars in
the period-amplitude diagram, Crater II is clearly different from
ultra-faint dwarf (UFD) galaxies, but very similar to the two
classical MW dwarf spheroidal (dSph) galaxies Draco and Carina with
Oosterhoff-intermediate (Oo-int) properties. Combined with the mean
period of ab-type variables (<Pab≥0.631±0.004days) and the c-type
fraction (∼0.14) in Crater II, this suggests an Oo-int classification
for Crater II and implies that its nature is more like a dSph rather
than a UFD. We also estimated the mean metallicity, reddening, and
distance of Crater II, from the photometric and pulsation properties
of the RR Lyrae stars. The stellar population model we have
constructed indicates that Crater II is dominated by an old
population, but is relatively younger than the oldest globular
clusters in the MW. With a lack of high-amplitude short-period RRab
stars, Crater II, like most of the other less massive dSphs, is
probably not a surviving counterpart of the major building blocks of
the MW halo.
Description:
Time-series B, V observations of the Crater II dwarf galaxy were
carried out using the Korea Microlensing Telescope Network (KMTNet)
1.6m telescope located at the Cerro Tololo Inter-American Observatory
(CTIO) during 2016 February 1-4, 6-10, and 2017 January 29-30 (UT).
Our observations covered a total area of ∼3°x3° with five
largely overlapping fields.
Objects:
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RA (ICRS) DE Designation(s) (Dist)
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11 49 14 -18 24.8 Crater II = NAME Crater II (112kpc)
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 109 97 Pulsation properties of RR Lyrae stars in Crater II
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See also:
I/315 : UCAC3 Catalogue (Zacharias+ 2009)
II/350 : VLT Survey Telescope ATLAS (Shanks+, 2015)
J/AJ/115/193 : RR Lyrae V light curves (Layden, 1998)
J/AJ/115/1856 : Dwarf Cepheids in Carina (Mateo+, 1998)
J/AJ/119/1760 : M54 and Sgr dSph VI photometry (Layden+, 2000)
J/AJ/124/1464 : Variable stars in Andromeda VI (Pritzl+, 2002)
J/AJ/129/267 : RR Lyrae variables in NGC 5272 (Cacciari+, 2005)
J/AJ/130/873 : BQS objects in the SDSS DR3 area (Jester+, 2005)
J/AJ/132/1361 : RR Lyrae variables in M33 (Sarajedini+, 2006)
J/MNRAS/380/281 : Faint galactic satellites spectrosc. survey (Martin+, 2007)
J/AJ/136/1921 : Variable stars of Draco dSph (Kinemuchi+, 2008)
J/ApJ/674/L81 : Variable stars in dwarf galaxy CVn I (Kuehn+, 2008)
J/AcA/58/293 : Type-II and anomalous Cepheids in LMC (Soszynski+, 2008)
J/MNRAS/397/1748 : Spectroscopic study of Segue 2 (Belokurov+, 2009)
J/MNRAS/398/1757 : RR Lyraes in SDSS stripe 82 (Watkins+, 2009)
J/ApJ/708/560 : Spectroscopy of UMa II and Coma Ber (Frebel+, 2010)
J/ApJ/723/1632 : Abundance spreads in Bootes I and Segue 1 (Norris+, 2010)
J/ApJ/724/799 : RR Lyrae variables in M33. II. (Yang+, 2010)
J/AJ/139/357 : Variable stars in NGC 5286 (Zorotovic+, 2010)
J/AJ/141/171 : RR Lyrae stars in M31 ultra-deep fields (Jeffery+, 2011)
J/ApJ/733/46 : Velocity measurements in Segue 1 (Simon+, 2011)
J/ApJ/756/108 : HST VI phot. of variable stars in Leo T (Clementini+, 2012)
J/ApJ/752/42 : BV time series in Ursa Major II (Dall'Ora+, 2012)
J/AJ/144/4 : Dwarf galaxies in the Local Group (McConnachie+, 2012)
J/ApJ/756/121 : Variable stars in Her dwarf galaxy (Musella+, 2012)
J/ApJ/756/79 : Optical phot. in 3 Local Group dwarf galaxies (Sand+, 2012)
J/ApJ/767/62 : RR Lyrae stars BV photometry in UMa I (Garofalo+, 2013)
J/ApJ/763/40 : UBVI data of GCs in the Fornax galaxy cluster (Kim+, 2013)
J/ApJ/767/134 : Abundances of red giants in UFD galaxies (Vargas+, 2013)
J/ApJ/793/135 : Positions and distances of RR Lyrae stars (Sesar+, 2014)
J/PASP/126/616 : Variable stars in Leo I dSph (Stetson+, 2014)
J/ApJ/784/76 : RR Lyrae in ESO294-G010 and ESO410-G005 (Yang+, 2014)
J/ApJ/781/22 : La Silla QUEST RR Lyrae star survey (Zinn+, 2014)
J/ApJ/814/71 : Carina project IX: UBVI data of variables (Coppola+, 2015)
J/ApJ/803/63 : gr photometry of stars in Kim 2 (Kim+, 2015)
J/ApJ/832/99 : HK', CN & CH indexes in NGC 362 & NGC 6723 (Lim+, 2016)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 3 A3 --- ID Variable identifier (V1 to V97);
<[JKY2018] NNN> in Simbad
5- 6 I2 h RAh [11] Hour of right ascension (J2000)
8- 9 I2 min RAm [46/54] Minute of right ascension (J2000)
11-15 F5.2 s RAs Second of right ascension (J2000)
17 A1 --- DE- [-] Sign of declination (J2000)
18-19 I2 deg DEd [17/19] Degree of declination (J2000)
21-22 I2 arcmin DEm Arcminute of declination (J2000)
24-28 F5.2 arcsec DEs Arcsecond of declination (J2000)
30-32 A3 --- Type RR Lyrae type ("ab": 83 occurrences,
"c": 13 occurrences or "ab?": 1 occurrence)
34-39 F6.4 d Per [0.2/0.8] Period
41-48 F8.4 d Epoch Epoch max; JD-2457000
50-55 F6.3 mag Bmean [20.9/21.7] Intensity-weighted mean B-band magnitude
57-62 F6.3 mag Vmean [20.5/21.4] Intensity-weighted mean V-band magnitude
64-66 I3 --- NB [36/142] Number of observations used in
our light curve analysis in B-band
68-70 I3 --- NV [36/145] Number of observations used in
our light curve analysis in V-band
72-76 F5.3 mag Bamp [0.2/1.5] Pulsation amplitude in B-band
78-82 F5.3 mag Vamp [0.2/1.1] Pulsation amplitude in V-band
84-109 A26 --- Note Note(s)
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History:
From electronic version of the journal
(End) Emmanuelle Perret [CDS] 10-Jul-2019