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J/AJ/110/2166       Variables in Sextans dSph galaxy (Mateo+ 1995)

Variable Stars in the Sextans Dwarf Spheroidal Galaxy Mateo M.,Fischer P.,Krzeminski W. <Astron. J. 110, 2166 (1995)> =1995AJ....110.2166M (SIMBAD/NED BibCode)
ADC_Keywords: Stars, variable ; Photometry, CCD Abstract: We describe a survey for variable stars in the Sextans dwarf spheroidal (dSph) galaxy based on the analysis of 113 B and 48 V CCD images of four fields covering a total area of 18'x18'. We have identified 44 variables: 36 RR Lyr star, 6 anomalous Cepheids, one long-period red variable, all probable members of Sextans, and one foreground contact binary. We have used the pulsating stars to derive a true distance modulus of 19.67±0.15 for Sextans (or D=86±6kpc), where the error is primarily due to uncertainties in the luminosity-metallicity relation for RR Lyr stars. Based on our new data we conclude that [Fe/H]_Sex=-1.6±0.2, somewhat higher than the value from Suntzeff et al. (1993ApJ...418..208S) obtained from the analysis of fiber spectroscopy of the near-IR Calcium triplet. We present a new deep color-magnitude diagram for Sextans which reveals the presence of anomalous Cepheids in the galaxy. This young population may represent as much as 25% of the total stellar content of Sextans. We find a surprisingly strong correlation between the frequency of anomalous Cepheids in dSph galaxies and galaxian luminosity and speculate on the possible origin of this strange effect. The RR Lyr stars in Sextans do not exhibit the Oosterhoff dichotomy observed in globular clusters and in the Galactic halo field. File Summary:
FileName Lrecl Records Explanations
ReadMe 80 . This file table2 65 161 Log of Sextans observations table8 38 1038 B-band photometry of the Sextans variables table9 38 560 V-band photometry of the Sextans variables table10 72 2852 Photometry of non-variable stars in the deep Sextans images
Byte-by-byte Description of file: table2
Bytes Format Units Label Explanations
1- 3 I3 --- Frame Frame number 6- 13 A8 "DD/MM/YY" Date UT Date of observation 16- 17 I2 h UTmidh Time of mid-exposure 19- 20 I2 min UTmidm Time of mid-exposure 22- 23 I2 s UTmids Time of mid-exposure 26- 30 F5.1 s Exp Exposure time 33- 37 F5.3 --- AirMass Air-mass at mid-exposure 40- 53 F14.6 --- HJD_mid HJD of mid exposure, epoch 2448000 56- 58 F3.1 arcsec Seeing Seeing 61- 62 A2 --- Field Field, NE, NW, SE, SW 65 A1 --- Filt Filter, V or B
Byte-by-byte Description of file: table8
Bytes Format Units Label Explanations
1- 3 A3 --- Star Variable star number, V1, V2, ... V46 5- 18 F14.6 --- HJD Heliocentric Julian Date of observation 21- 26 F6.3 mag Bmag B magnitude 28- 32 F5.3 mag e_Bmag B magnitude error 34- 38 F5.3 --- Phase *[0/1[? Pulsation or orbital phase
Note for Phase: Pulsation or orbital phase calculated with the ephemerides in Table 4 of the printed paper. The phasing is defined so that phase zero corresponds to minimum light. No phase information is given for V16, V23, V35, or V46 because reliable periods could not be determined for these stars. Byte-by-byte Description of file: table9
Bytes Format Units Label Explanations
1- 3 A3 --- Star Variable star number, V1, V2, ... V46 5- 18 F14.6 --- HJD Heliocentric Julian Date of observation 21- 26 F6.3 mag Vmag V magnitude 28- 32 F5.3 mag e_Vmag V magnitude error 34- 38 F5.3 --- Phase *[0/1[? Pulsation or orbital phase
Note for Phase: Pulsation or orbital phase calculated with the ephemerides in Table 4 of the printed paper. The phasing is defined so that phase zero corresponds to minimum light. No phase information is given for V16, V23, V35, or V46 because reliable periods could not be determined for these stars. Byte-by-byte Description of file: table10
Bytes Format Units Label Explanations
1- 4 I4 --- Star Star number 6- 9 I4 pix Xpos X coordinate 11- 14 I4 pix Ypos Y coordinate 17- 18 A2 --- Field Field, NE, NW, SE, SW 21- 22 I2 h RAh Right ascension J2000 24- 25 I2 min RAm Right ascension J2000 27- 31 F5.2 s RAs Right ascension J2000 33 A1 --- DE- Declination sign 34 I1 deg DEd Declination, J2000 (always "1") 36- 37 I2 arcmin DEm Declination, J2000 39- 43 F5.2 arcsec DEs Declination, J2000 46- 51 F6.3 mag Vmag V magnitude 54- 58 F5.3 mag e_Vmag V magnitude error 60- 65 F6.3 mag B-V B-V color 68- 72 F5.3 mag e_B-V B-V color error
Origin: AAS CD-ROM series, Volume 5, 1995 Lee Brotzman [ADS] 03-Nov-1995
(End) Patricia Bauer [CDS] 24-Oct-1996
The document above follows the rules of the Standard Description for Astronomical Catalogues.From this documentation it is possible to generate f77 program to load files into arrays or line by line

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