J/A+A/539/A138 RR Lyr variable stars in M32 (Fiorentino+, 2012)
The ancient population of M 32: RR Lyrae variable stars confirmed.
Fiorentino G., Contreras Ramos R., Tolstoy E., Clementini G., Saha A.
<Astron. Astrophys. 539, A138 (2012)>
=2012A&A...539A.138F 2012A&A...539A.138F
ADC_Keywords: Galaxies, nearby ; Stars, variable ; Photometry, HST
Keywords: Local Group - stars: variables: RR Lyrae -
galaxies: individual: M 31 - stars: horizontal-branch -
galaxies: individual: M 32
Abstract:
Using archival multi-epoch ACS/WFC images in the F606W and F814W
filters of a resolved stellar field in Local Group dwarf elliptical
galaxy M 32 we have made an accurate Colour-Magnitude Diagram and a
careful search for RR Lyr variable stars. We identified 416 bona fide
RR Lyr stars over our field of view, and their spatial distribution
shows a rising number density towards the centre of M 32. These new
observations clearly confirm the tentative result of Fiorentino et al.
(2010ApJ...708..817F 2010ApJ...708..817F), on a much smaller field of view, associating an
ancient population of RR Lyr variables to M 32. We associate at least
83 RR Lyr stars in our field to M 32.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table2.dat 82 416 The RR Lyr variable stars we have identified
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Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 4 A4 --- Name Variable name, VNNN (1)
6 I1 h RAh Right ascension (J2000)
8- 9 I2 min RAm Right ascension (J2000)
11- 17 F7.4 s RAs Right ascension (J2000)
19 A1 --- DE- Declination sign (J2000)
20- 21 I2 deg DEd Declination (J2000)
23- 24 I2 arcmin DEm Declination (J2000)
26- 31 F6.3 arcsec DEs Declination (J2000)
33- 37 F5.3 d Per Period
39- 42 A4 --- Type RR Lyrae type (2)
44- 49 F6.3 mag <F606W> Light-curve weighted mean magnitude calibrated
in HST VEGAMAG
51- 55 F5.3 mag Vamp Amplitude in filter F606W
57- 62 F6.3 mag <F814W> light-curve weighted mean magnitude calibrated
in HST VEGAMAG for 2-filter RR Lyrae and
from Dolphot output for 1-filter RR Lyrae
64- 68 F5.3 mag Iamp ?=- Amplitude in filter F814W
(only available for 2-filter RR Lyrae)
70- 75 F6.3 mag <V0mag> ?=- Dereddened mean magnitude <F606W> (3)
77- 82 F6.3 mag <I0mag> ? Dereddened mean magnitude <F814W> (3)
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Note (1): The RR Lyrae have been named using their increasing distance from
the centre of M 32 (RA: 10.67375, DE: 40.8652777800)
Note (2): Pulsation mode RRab corresponds to fundamental and RRc to
first-overtone pulsators.
Note (3): transformed in Johnson-Cousins photometric system obtained
following the prescriptions by Sirianni et al. (2005PASP..117.1049S 2005PASP..117.1049S).
Only available for 2-filter RR Lyrae.
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Acknowledgements:
Giuliana Fiorentino, stregaccia30(at)gmail.com
(End) Patricia Vannier [CDS] 24-Jan-2012