Distance to the Sagittarius Dwarf Galaxy using MACHO Project RR Lyrae stars

Abstract

We derive the distance to the northern extension of the Sagittarius (Sgr) dwarf spheroidal galaxy from 203 Sgr RR0 Lyrae stars found in the MACHO database. Their distances are determined differentially with respect to 288 Galactic Bulge RR0 Lyrae stars also found in the MACHO data. We find a distance modulus difference of 2.41 mags at $l$ = 5${}^{\circ }$ and $b$ = -8${}^{\circ }$ and that the extension of the Sgr galaxy towards the galactic plane is inclined toward us. Assuming ${\mathrm{R}}_{\mathrm{GC}}$ = 8 kpc, this implies the distance to these stars is $(m-M{)}_0$ = 16.97 $\pm$ 0.07 mags, which corresponds to D = 24.8 $\pm$ 0.8 kpc. Although this estimate is smaller than previous determinations for this galaxy and agrees with previous suggestions that Sgr's body is truly closer to us, this estimate is larger than studies at comparable galactic latitudes.

accepted in AJ

References in corpus (7)

• The ACS Survey of Galactic Globular Clusters: M54 and Young Populations in the Sagittarius Dwarf Spheroidal Galaxy
• Tracing the long bar with red-clump giants
• The Overdensity in Virgo, Sagittarius Debris, and the Asymmetric Spheroid
• The distance to the Galactic Centre based on Population-II Cepheids and RR Lyrae stars
• RR Lyrae stars in Galactic globular clusters. VI. The Period-Amplitude relation
• Metallicity Analysis of MACHO Galactic Bulge RR0 Lyrae stars from their Lightcurves
• The Extinction Toward the Galactic Bulge from RR Lyrae Stars