J/ApJ/829/26 Variable stars in the field of Andromeda XXV. III. (Cusano+, 2016)
Variable stars and stellar populations in Andromeda XXV.
III. A central cluster or the galaxy nucleus?
Cusano F., Garofalo A., Clementini G., Cignoni M., Federici L., Marconi M.,
Ripepi V., Musella I., Testa V., Carini R., Faccini M.
<Astrophys. J., 829, 26-26 (2016)>
=2016ApJ...829...26C 2016ApJ...829...26C (SIMBAD/NED BibCode)
ADC_Keywords: Galaxies, nearby ; Photometry, UBV ; Stars, variable
Keywords: galaxies: dwarf; galaxies: individual: Andromeda XXV;
Local Group; stars: distances; stars: variables: general;
techniques: photometric
Abstract:
We present B and V time series photometry of Andromeda XXV, the third
galaxy in our program on the Andromeda's satellites, which we have
imaged with the Large Binocular Cameras of the Large Binocular
Telescope. The field of Andromeda XXV is found to contain 62 variable
stars, for which we present light curves and characteristics of the
light variation (period, amplitudes, variability type, mean
magnitudes, etc.). The sample includes 57 RR Lyrae variables (46
fundamental-mode-RRab, and 11 first-overtone-RRc, pulsators), 3
anomalous Cepheids, 1 eclipsing binary system, and 1 unclassified
variable. The average period of the RRab stars (<Pab≥0.60
σ=0.04d) and the period-amplitude diagram place Andromeda XXV in
the class of the Oosterhoff-Intermediate objects. From the average
luminosity of the RR Lyrae stars we derive for the galaxy a distance
modulus of (m-M)0=24.63±0.17mag. The color-magnitude diagram
reveals the presence in Andromeda XXV of a single, metal-poor
([Fe/H]=-1.8dex) stellar population as old as ∼10-12Gyr, traced by a
conspicuous red giant branch and the large population of RR Lyrae
stars. We discovered a spherically shaped high density of stars near
the galaxy center. This structure appears to be at a distance
consistent with Andromeda XXV and we suggest it could either be a star
cluster or the nucleus of Andromeda XXV. We provide a summary and
compare the number and characteristics of the pulsating stars in the
M31 satellites analyzed so far for variability.
Description:
A total of 85 B and 87 V images, each of 400s exposure, were obtained
with the Large Binocular Cameras (LBC) of the Large Binocular
Telescope (LBT) of a region of 23'x23' centered on And XXV
(RA=00:30:08.9, DEC=+46:51:07, J2000.0) from the 18th to the 24th of
2011 October.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table2.dat 79 62 Identification and properties of the variable
stars detected in And XXV
fig1.dat 25 8380 Photometric data behind Figure 1 light curves
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See also:
V/143 : Revised Bologna Catalog of M31 clusters, V.5 (Galleti+ 2012)
J/MNRAS/437/2307 : LMC anomalous Cepheid Ks light curves (Ripepi+, 2014)
J/ApJ/779/7 : dSph satellites of M31. I. Variables in And XIX (Cusano+, 2013)
J/MNRAS/435/1928 : Dwarf galaxy planes in Local Group (Pawlowski+, 2013)
J/ApJ/776/80 : PAndAS view of Andromeda satellites. I. (Martin+, 2013)
J/ApJ/768/172 : Kinematic analysis of red giant in M31 dSphs (Collins+, 2013)
J/ApJ/758/11 : Bayesian distances to M31 satellites (Conn+, 2012)
J/AJ/138/184 : RR Lyrae stars in 2 fields in M31 spheroid (Sarajedini+, 2009)
J/AJ/129/2232 : Variable stars in And I and And III (Pritzl+, 2005)
J/A+A/421/937 : Metal abundances of LMC RR Lyrae (Gratton+, 2004)
J/AJ/127/2738 : ACS VI photometry of M31 halo RR Lyrea (Brown+, 2004)
Byte-by-byte Description of file: table2.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 3 A3 --- Name Variable star identifier (V1 to V63)
5- 5 A1 --- f_Name Star flag (1)
7- 8 I2 h RAh [0] Hour of right ascension (J2000)
10- 11 I2 min RAm [29/30] Minute of right ascension (J2000)
13- 18 F6.3 s RAs Second of right ascension (J2000)
20- 20 A1 --- DE- [+] Sign of the declination (J2000)
21- 22 I2 deg DEd [46] Degree of declination (J2000)
24- 25 I2 arcmin DEm [41/57] Arcminute of declination (J2000)
27- 31 F5.2 arcsec DEs Arcsecond of declination (J2000)
33- 38 A6 --- Type Variable Type, ? = uncertain type
40- 46 F7.5 d Per [0.2/1.4] Period
48- 54 F7.3 d Epoch Epoch (max); HJD-2455000
56- 60 F5.2 mag <Bmag> [21.4/26] LBT/LBC intensity-weighted mean B band
magnitude
62- 67 F6.3 mag <Vmag> [19.9/25.6] LBT/LBC intensity-weighted mean
V band magnitude
69- 73 F5.3 mag Amp-B [0.2/2] Amplitude of the B band light variation
75- 79 F5.3 mag Amp-V [0.1/1.4] Amplitude of the V band light variation
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Note (1): Variable Star Flag as follows:
1 = star located within once the galaxy half-light radius;
2 = star located within twice the galaxy half-light radius;
3 = star located beyond twice the galaxy half-light radius;
f = field variable star; also beyond twice the galaxy half-light radius.
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Byte-by-byte Description of file: fig1.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 3 A3 --- Name Variable star identifier as in table 2
5 A1 --- Filt [B,V] Filter used
7- 17 F11.5 d HJD [55852.6/55859] Observation date, HJD-2400000
19- 25 F7.4 mag mag [19.8/26.7] Photometric magnitude in filter
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History:
From electronic version of the journal
References:
Cusano et al. Paper I: And XIX 2013ApJ...779....7C 2013ApJ...779....7C Cat. J/ApJ/779/7
Cusano et al. Paper II: And XXI 2015ApJ...806..200C 2015ApJ...806..200C
Cusano et al. Paper III: And XXV 2016ApJ...829...26C 2016ApJ...829...26C This Catalog
(End) Prepared by [AAS], Emmanuelle Perret [CDS] 13-Dec-2016