We report on the detection of a population of Red Clump (RC) stars probably associated with the recently discovered stellar system Boötes III. The RC is identified as a 3σ peak in the luminosity function (LF) of colour-selected stars extracted from the Sloan Digital Sky Survey data base. The peak is consistently detected in the g,r,i and z LFs at the expected luminosity of a typical RC at the distance of Boötes III. Moreover, the stars around the LF peak show a maximum of surface density nearly coincident with the reported centre of the system. Assuming that the detected feature is the genuine RC of Boötes III, we find that the system has the horizontal branch morphology typical of old and metal-poor dwarf spheroidals, it has an integrated magnitude MV ~= -5.8 +/- 0.5 and an ellipticity ɛ ~ 0.5, quite typical of the recently identified new class of very faint dwarf galaxies.
Red Clump stars in the Boötes III stellar system
CORRENTI, MATTEO;FERRARO, FRANCESCO ROSARIO
2009
Abstract
We report on the detection of a population of Red Clump (RC) stars probably associated with the recently discovered stellar system Boötes III. The RC is identified as a 3σ peak in the luminosity function (LF) of colour-selected stars extracted from the Sloan Digital Sky Survey data base. The peak is consistently detected in the g,r,i and z LFs at the expected luminosity of a typical RC at the distance of Boötes III. Moreover, the stars around the LF peak show a maximum of surface density nearly coincident with the reported centre of the system. Assuming that the detected feature is the genuine RC of Boötes III, we find that the system has the horizontal branch morphology typical of old and metal-poor dwarf spheroidals, it has an integrated magnitude MV ~= -5.8 +/- 0.5 and an ellipticity ɛ ~ 0.5, quite typical of the recently identified new class of very faint dwarf galaxies.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
