J/MNRAS/480/669 Variable stars in the SMCNOD (Prudil+, 2018)
Photometric study of the SMCNOD using variable stars from the OGLE-IV survey.
Prudil Z., Grebel E.K., Dekany I., Smolec R.
<Mon. Not. R. Astron. Soc., 480, 669-680 (2018)>
=2018MNRAS.480..669P 2018MNRAS.480..669P (SIMBAD/NED BibCode)
ADC_Keywords: Magellanic Clouds ; Stars, variable ; Photometry
Keywords: galaxies: Magellanic Clouds - stars: variables: RR Lyrae -
stars: variables: Cepheids
Abstract:
We present a study of a recently discovered stellar overdensity near
the northern edge of the Small Magellanic Cloud (SMCNOD). We exploited
variable stars from the fourth release of the Optical Gravitational
Lensing Experiment. We used mainly pulsating variable stars and
investigated their potential association with the SMCNOD using their
spatial distribution and distances. We found four rather spatially
concentrated anomalous Cepheids and eight evenly dispersed RR Lyrae
stars to be most likely members of this overdensity. The anomalous
Cepheids inside the SMCNOD trace possible intermediate-age population
with ages ranging between 2 and 4.5Gyr. The age distribution of
anomalous Cepheids seems to be in a good agreement with the age
distribution of anomalous Cepheids in the SMC. Using empirical
relations for RR Lyrae stars, we determined the median metallicity for
a possible old population in the SMCNOD to be
[Fe/H]SMCNOD=-1.71±0.21dex, which is in agreement with median
metallicity of the old SMC population. The density profile for
anomalous Cepheids shows a small anomaly at the position of the
SMCNOD, on the other hand, RR Lyrae variables show no such deviation.
The probability of finding the observed number of variable stars at
the location of the SMCNOD by chance is very low for anomalous
Cepheids (0.7 per cent) but high for RR Lyrae stars (13.0 per cent).
Based on its variable stars content, we thus confirm the presence of a
modest overdensity in intermediate-age stars in the SMCNOD and
conclude that it probably has its origin in the SMC rather than to be
the remnant of an accreted dwarf galaxy.
Description:
A study of a recently discovered stellar overdensity near the northern
edge of the Small Magellanic Cloud (SMCNOD) is presented.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
acsmcnod.dat 37 115 Anomalous Cepheids in SMCNOD (table 2)
rrsmcnod.dat 47 2991 RR Lyraes in SMCNOD (table 4)
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See also:
J/AcA/65/233 : OGLE Magellanic Clouds anomalous Cepheids (Soszynski+, 2015)
J/AcA/65/297 : OGLE4 LMC and SMC Cepheids (Soszynski+, 2015)
J/AcA/66/131 : VI light curves of SMC and LMC RR Lyrae (Soszynski+, 2016)
Byte-by-byte Description of file: acsmcnod.dat
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Bytes Format Units Label Explanations
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1- 3 I3 --- ID [1/119] OGLE identifier,
OGLE SMC-ACEP-NNN
5- 6 A2 --- mode [F 1O] Pulsation mode,
F (fundamental) 1O (first overtone)
8- 16 F9.5 deg RAdeg [] Right ascension (J2000)
18- 26 F9.5 deg DEdeg Declination (J2000)
28- 32 F5.2 kpc d Distance
34- 37 F4.2 kpc e_d Uncertainty on distance
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Byte-by-byte Description of file: rrsmcnod.dat
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Bytes Format Units Label Explanations
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1- 4 I4 --- ID [1/6567] OGLE identifier,
OGLE SMC-RRLYR-NNNN in Simbad
6- 14 F9.5 deg RAdeg [] Right ascension (J2000)
16- 24 F9.5 deg DEdeg Declination (J2000)
26- 31 F6.2 kpc d Distance
33- 36 F4.2 kpc e_d Uncertainty on distance
38- 42 F5.2 --- [Fe/H] Metallicity
44- 47 F4.2 --- e_[Fe/H] Uncertainty on metallicity
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Acknowledgements:
Zdenek Prudil, prudilz(at)ari.uni-heidelberg.de
(End) Zdenek Prudil [ARI, Germany], Patricia Vannier [CDS] 07-Mar-2020