J/ApJ/756/23 V-band photometric follow-up of RR Lyrae from SEKBO (Akhter+, 2012)
Probing the stellar halo of the Milky Way with the SEKBO RR Lyrae survey.
Akhter S., Da Costa G.S., Keller S.C., Schmidt B.P.
<Astrophys. J., 756, 23 (2012)>
=2012ApJ...756...23A 2012ApJ...756...23A
ADC_Keywords: Photometry, UBV ; Stars, variable ; Milky Way ; Stars, halo
Keywords: Galaxy: halo; Galaxy: structure; stars: Population II;
stars: variables: RR Lyrae
Abstract:
We investigate the steepening of the power-law slope beyond the
Galactocentric radius of R∼45kpc in the RR Lyrae (RRL) space density
distribution found by Keller et al. (2008, Cat. J/ApJ/678/851). They
identified 2016 RRL candidates derived from the analysis of archival
observations of the Southern Edgeworth-Kuiper Belt Object (SEKBO)
survey. Our aim is to verify the completeness of RRLs and ultimately
the space density distribution function given by Keller et al. We
followed up on a subset of 137 candidates with a range of magnitudes
(V∼14-20) using the Faulkes Telescope (FT) database and confirmed 57
candidates as real RRLs. A cross-match between SEKBO RRL survey and
Sloan Digital Sky Survey Data Release-7 (SDSS DR-7) revealed 272 RRL
candidates in common. Applying the color selection criteria proposed
by Ivezić et al. (2005AJ....129.1096I 2005AJ....129.1096I) resulted in 193 likely RRLs.
The completeness as a function of magnitude was calculated empirically
from the combined set of SEKBO RRL candidates from current FT data,
SDSS cross-matched data, and the Prior et al. catalog (2009,
Cat. J/ApJ/691/306). This resulted in a spatial density distribution
characterized by two power laws with a break radius R within a range
between 45kpc and 50kpc, similar to the results of Keller et al. We
find the power-law slopes for the inner halo as ninner=-2.78±0.02
and for the outer halo as nouter=-5.0±0.2.
Description:
For the current investigation, 207 fields containing SEKBO (Southern
Edgeworth-Kuiper Belt Object) candidates with magnitudes 14<V<20 were
followed up photometrically using images from the database of Faulkes
telescopes (North and South) observations. The fields cover all R.A.
and -28°>DEC>20°. Data were taken, using the Bessell-V filter,
from 2008 September to 2010 June. The observations were taken at
irregular time intervals and many objects have images separated by
3-10 months.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table2.dat 89 57 Positions and derived parameters for confirmed
RR Lyrae variables
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See also:
J/MNRAS/427/3374 : QUEST RR Lyrae Survey III. Low Galactic lat. (Mateu+, 2012)
J/ApJ/731/4 : Galactic halo as seen by the CFHTLS (Sesar+, 2011)
J/ApJ/714/663 : Stellar density map of the Milky Way (de Jong+, 2010)
J/ApJ/708/717 : Light curve templates of RR Lyrae stars (Sesar+, 2010)
J/ApJ/691/306 : Phot. of RR Lyrae candidates in Virgo stream (Prior+, 2009)
J/ApJ/678/865 : LONEOS-I RR Lyrae stars (Miceli+, 2008)
J/ApJ/678/851 : RR Lyrae survey in the Galactic Halo (Keller+, 2008)
J/AJ/136/1645 : Spectroscopy of bright QUEST RR Lyrae stars (Vivas+, 2008)
J/MNRAS/375/1381 : Kinematics of RR Lyr and HB stars in NGP (Kinman+, 2007)
J/AJ/127/1158 : QUEST RR Lyrae Survey first catalog (Vivas+, 2004)
J/AJ/115/193 : RR Lyrae V light curves (Layden, 1998)
J/AcA/48/113 : OGLE RR Lyrae VI photometry (Udalski, 1998)
J/A+AS/113/483 : Phot. and radial velocity of RRLyr stars (Carrillo+ 1995)
Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 11 A11 --- [KMP2008] Object identification
13- 14 I2 h RAh Hour of Right Ascension (J2000)
16- 17 I2 min RAm Minute of Right Ascension (J2000)
19- 23 F5.2 s RAs Second of Right Ascension (J2000)
25 A1 --- DE- Sign of the Declination (J2000)
26- 27 I2 deg DEd Degree of Declination (J2000)
29- 30 I2 arcmin DEm Arcminute of Declination (J2000)
32- 36 F5.2 arcsec DEs Arcsecond of Declination (J2000)
38- 42 A5 --- Class RR Lyrae classification ("RRLab" or "RRLc")
44- 45 I2 --- Nobs [5/27] Number of observations
47- 51 F5.2 mag Vmag2 [15/19.8] V band magnitude from Keller et al.
(SEKBO survey; 2008, Cat. J/ApJ/678/851)
53- 58 F6.3 mag Vmag [15.1/19.8]? V band magnitude from the
current study (FT data)
60- 65 F6.3 mag Vdiff [-0.5/0.3]? V band magnitude difference
(VSEKBO-VFT)
67- 71 F5.3 d Per [0.2/0.8] Period from the current study
73- 77 F5.3 mag Vamp [0.3/1.4] V band amplitude from the current
study
79- 83 F5.3 d Per2 [0.2/0.7]? Period from Prior et al. (P09;
2009, Cat. J/ApJ/691/306)
85- 89 F5.3 mag Vamp2 [0.3/1.2]? V band amplitude from P09
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History:
From electronic version of the journal
(End) Greg Schwarz [AAS], Emmanuelle Perret [CDS] 14-Mar-2014