| Title | Variable Stars in the Fornax dSph Galaxy. II. Pulsating Stars below the Horizontal Branch |
| Authors | Poretti, Ennio; Clementini, Gisella; Held, Enrico V.; Greco, Claudia; Mateo, Mario; Dell'Arciprete, Luca; Rizzi, Luca; Gullieuszik, Marco; Maio, Marcella |
| Bibcode | 2008ApJ...685..947P Search ADS ↗ |
| Abstract | We have carried out an intensive survey of the northern region of the Fornax dwarf spheroidal galaxy with the aim of detecting the galaxy's short-period pulsating stars (P < 0.25 days). Observations collected over three consecutive nights with the Wide Field Imager of the 2.2 m MPI telescope at ESO allowed us to detect 85 high-amplitude (0.20-1.00 mag in B light) variable stars with periods in the range from 0.046 to 0.126 days, similar to SX Phoenicis stars in Galactic metal-poor stellar populations. The plots of the observed periods vs. the B and V magnitudes show a dispersion largely exceeding the observational errors. To disentangle the matter, we separated the first-overtone from the fundamental-mode pulsators and tentatively identified a group of subluminous variables, about 0.35 mag fainter than the others. Their nature as either metal-poor intermediate-age stars or stars formed by the merging of close binary systems is discussed. The rich sample of the Fornax variables also led us to reconstruct the period-luminosity relation for short-period pulsating stars. An excellent linear fit, MV = - 1.83(+/- 0.08) - 3.65(+/- 0.07) log PF, was obtained using 153 δ Scuti and SX Phoenicis stars in a number of different stellar systems. Based on observations collected at ESO, La Silla, Chile, Proposal 68.A-0281. |
| Objects | 4 Objects Search NED ↙ |
