J/ApJ/678/865 LONEOS-I RR Lyrae stars (Miceli+, 2008) ================================================================================ Evidence for distinct components of the galactic stellar halo from 838 RR Lyrae stars discovered in the LONEOS-I survey. Miceli A., Rest A., Stubbs C.W., Hawley S.L., Cook K.H., Magnier E.A., Krisciunas K., Bowell E., Koehn B. =2008ApJ...678..865M ================================================================================ ADC_Keywords: Stars, halo ; Stars, variable ; Photometry Keywords: galaxies: halos - galaxies: individual (Milky Way) - galaxies: structure Abstract: We present 838 ab-type RR Lyrae stars from the Lowell Observatory Near Earth Objects Survey Phase I (LONEOS-I). These objects cover 1430deg^2^ and span distances ranging from 3 to 30kpc from the Galactic center. Object selection is based on phased, photometric data with 28-50 epochs. We use this large sample to explore the bulk properties of the stellar halo, including the spatial distribution. The period-amplitude distribution of this sample shows that the majority of these RR Lyrae stars resemble Oosterhoff type I, but there is a significant fraction (26%) which have longer periods and appear to be Oosterhoff type II. We find that the radial distributions of these two populations have significantly different profiles ({rho}_OoI_~R^-2.26+/-0.07^ and {rho}_OoII_~R^-2.88+/-0.11^). This suggests that the stellar halo was formed by at least two distinct accretion processes and supports dual-halo models. Description: The LONEOS-I photometric variability database discussed in this paper consists of photometric data obtained between 1998 and 2000. Situated on the Anderson Mesa outside Flagstaff, Arizona, LONEOS is carried out with a 0.6m Schmidt telescope. It covers a large fraction of the sky, much of it imaged in multiple epochs (see Fig. 1). File Summary: -------------------------------------------------------------------------------- FileName Lrecl Records Explanations -------------------------------------------------------------------------------- ReadMe 80 . This file table1.dat 42 838 Properties of 838 LONEOS-I RR Lyrae sample -------------------------------------------------------------------------------- See also: J/AJ/132/714 : QUEST RR Lyrae survey. II. Halo overdensities (Vivas+, 2006) J/AJ/132/1202 : RR Lyrae in Northern Sky Variability Survey (Kinemuchi+, 2006) Byte-by-byte Description of file: table1.dat -------------------------------------------------------------------------------- Bytes Format Units Label Explanations -------------------------------------------------------------------------------- 1- 10 F10.6 deg RAdeg Right Ascension in decimal degrees (J2000) 12- 21 F10.6 deg DEdeg Declination in decimal degrees (J2000) 23- 27 F5.2 mag Mean LONEOS V band magnitude (1) 29- 36 F8.6 d Per Period 38- 42 F5.3 mag Amp Amplitude (2) -------------------------------------------------------------------------------- Note (1): Tied to the V_SDSS_ system (V_SDSS_ = r + 0.44(g-r) - 0.02) Note (2): Measured from minimum to maximum brightness as defined by the RR Lyrae template that best fit the lightcurve. -------------------------------------------------------------------------------- Nomenclature note: objects are designed by <[MRS2008] DDD.dddddd+DD.ddddddd> in Simbad. History: From electronic version of the journal ================================================================================ (End) Greg Schwarz [AAS], Emmanuelle Perret [CDS] 20-Sep-2010