Astrophys. J., 855, 43-43 (2018/March-1)
Discovery of distant RR Lyrae stars in the Milky Way using DECam.
MEDINA G.E., MUNOZ R.R., VIVAS A.K., CARLIN J.L., FORSTER F., MARTINEZ J., GALBANY L., GONZALEZ-GAITAN S., HAMUY M., DE JAEGER T., MAUREIRA J.C. and MARTIN J.S.
Abstract (from CDS):
We report the discovery of distant RR Lyrae stars, including the most distant known in the Milky Way, using data taken in the g-band with the Dark Energy Camera as part of the High cadence Transient Survey (HiTS; 2014 campaign). We detect a total of 173 RR Lyrae stars over a ∼120 deg2 area, including both known RR Lyrae and new detections. The heliocentric distances dH of the full sample range from 9 to >200 kpc, with 18 of them beyond 90 kpc. We identify three sub-groups of RR Lyrae as members of known systems: the Sextans dwarf spheroidal galaxy, for which we report 46 new discoveries, and the ultra-faint dwarf galaxies Leo IV and Leo V. Following an MCMC methodology, we fit spherical and ellipsoidal profiles of the form ρ(R) ∼ Rn to the radial density distribution of RR Lyrae in the Galactic halo. The best fit corresponds to the spherical case, for which we obtain a simple power-law index of n=-4.17–0.20+0.18, consistent with recent studies made with samples covering shorter distances. The pulsational properties of the outermost RR Lyrae in the sample (dH > 90 kpc) differ from the ones in the halo population at closer distances. The distribution of the stars in a period-amplitude diagram suggest they belong to Oosterhoff-intermediate or Oosterhoff II groups, similar to what is found in the ultra-faint dwarf satellites around the Milky Way. The new distant stars discovered represent an important addition to the few existing tracers of the Milky Way potential in the outer halo.
© 2018. The American Astronomical Society. All rights reserved.
Galaxy: halo - Galaxy: stellar content - Galaxy: structure - stars: variables: RR Lyrae
VizieR on-line data:
<Available at CDS (J/ApJ/855/43): table1.dat table5.dat table6.dat>
Tables 1+5+6: HiTS JHHMMSS+DDMMSS N=173.
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