J/AJ/127/2738 ACS VI photometry of M31 halo RR Lyrae (Brown+, 2004)
RR Lyrae stars in the Andromeda halo from deep imaging with the
Advanced Camera for Surveys.
Brown T.M., Ferguson H.C., Smith E., Kimble R.A., Sweigart A.V.,
Renzini A., Rich R.M.
<Astron. J., 127, 2738-2752 (2004)>
=2004AJ....127.2738B 2004AJ....127.2738B
ADC_Keywords: Stars, variable ; Photometry
Keywords: galaxies: evolution - galaxies: halos - galaxies: individual (M31) -
galaxies: stellar content - stars: variables: other
Abstract:
We present a complete census of RR Lyrae stars in a halo field of the
Andromeda galaxy. These deep observations, taken as part of a program
to measure the star formation history in the halo, spanned a period of
41 days with sampling on a variety of timescales, enabling the
identification of short- and long-period variables. Although the
long-period variables cannot be fully characterized within the time
span of this program, the enormous advance in sensitivity provided by
the Advanced Camera for Surveys on the Hubble Space Telescope allows
accurate characterization of the RR Lyrae population in this field. We
find 29 RRab stars with a mean period of 0.594 days, 25 RRc stars with
a mean period of 0.316 days, and one RRd star with a fundamental
period of 0.473 days and a first-overtone period of 0.353 days. These
55 RR Lyrae stars imply a specific frequency SRR∼5.6, which is large
given the high mean metallicity of the halo, but not surprising given
that these stars arise from the old, metal-poor tail of the
distribution.
Description:
Using the Wide Field Camera on the ACS, we obtained deep optical
images of a 3.5'x3.7' field along the southeast minor axis of the M31
halo, at J2000.0 RA=00:46:07, DE=+40:42:34.
From 2002 December 2 to 2003 January 11, we obtained 39.1hr of images
in the F606W filter (broad V) and 45.4hr in the F814W filter (I).
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 59 55 RR Lyrae properties
table2.dat 28 12870 RR Lyrae photometry
table3.dat 28 60 Positions of other variables
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See also:
J/A+A/402/113 : (RI)c photometry of variables in M31 (Joshi+, 2003)
J/AJ/124/234 : M31 outer halo UBVRI phot. and metallicity (Reitzel+, 2002)
J/AJ/125/1298 : C star population in outer disk of M31 (Battinelli+, 2003)
J/MNRAS/351/1071 : POINT-AGAPE Survey. M31 variables (An+, 2004)
Byte-by-byte Description of file: table1.dat table3.dat
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Bytes Format Units Label Explanations
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1- 4 A4 --- [BFS2004] Variable number, VNNN
6- 7 I2 h RAh Right ascension (J2000.0)
9- 10 I2 min RAm Right ascension (J2000.0)
12- 16 F5.2 s RAs Right ascension (J2000.0)
18 A1 --- DE- Declination sign (J2000.0)
19- 20 I2 deg DEd Declination (J2000.0)
22- 23 I2 arcmin DEm Declination (J2000.0)
25- 28 F4.1 arcsec DEs Declination (J2000.0)
30- 34 F5.3 d Per ? Period (only in table1.dat)
36- 40 F5.2 mag <F606W> ? F606W (V) mean magnitude (only in table1.dat)
42- 46 F5.2 mag <F814W> ? F814W (I) mean magnitude (only in table1.dat)
48- 51 F4.2 mag AF606W ? Absorption in F606W band (only in table1.dat)
53- 56 F4.2 mag AF814W ? Absorption in F814W band (only in table1.dat)
58- 59 A2 --- Type ? [abcd ] RR Lyrae class (only in table1.dat)
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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 --- [BFS2004] Variable number, VNNN
6- 16 F11.5 d MJD Modified Julian Date (JD-2400000.5)
18- 22 A5 --- Band Filter (F606W or F814W)
24- 28 F5.2 mag mag ?=99.99 Magnitude in Band
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History:
From electronic version of the journal
(End) Greg Schwarz [AAS], Patricia Vannier [CDS] 08-Jul-2004