We report the discovery of a significant and compact over-density of old and metal-poor stars in the fourth data release of the KiDS survey (DR4). The discovery is confirmed by deeper HSC-SSP data revealing the old main sequence turn-off of a stellar system located at a distance from the sun of D-circle dot= 145-(+14)(13) kpc in the direction of the Sextans constellation. The system has an absolute integrated magnitude (M-V = -3.9 +/- 0.4), half-light radius (r(h) = 193(-46)(+61) pc), and ellipticity (e = 0.46(-0.15)(+0.11)) values that are typical of ultra-faint dwarf galaxies (UFDs). The central surface brightness is near the lower limits of known local dwarf galaxies of a similar integrated luminosity, as expected for stellar systems that have escaped detection until now. The distance of the newly found system suggests that it is likely to be a satellite of our own Milky Way and we have thus tentatively named it Sextans II (KiDS-UFD-1).

New KiDS in town

Cignoni, Michele;
2024-01-01

Abstract

We report the discovery of a significant and compact over-density of old and metal-poor stars in the fourth data release of the KiDS survey (DR4). The discovery is confirmed by deeper HSC-SSP data revealing the old main sequence turn-off of a stellar system located at a distance from the sun of D-circle dot= 145-(+14)(13) kpc in the direction of the Sextans constellation. The system has an absolute integrated magnitude (M-V = -3.9 +/- 0.4), half-light radius (r(h) = 193(-46)(+61) pc), and ellipticity (e = 0.46(-0.15)(+0.11)) values that are typical of ultra-faint dwarf galaxies (UFDs). The central surface brightness is near the lower limits of known local dwarf galaxies of a similar integrated luminosity, as expected for stellar systems that have escaped detection until now. The distance of the newly found system suggests that it is likely to be a satellite of our own Milky Way and we have thus tentatively named it Sextans II (KiDS-UFD-1).
2024
Gatto, Massimiliano; Bellazzini, Michele; Tortora, Crescenzo; Ripepi, Vincenzo; Dall’Ora, Massimo; Cignoni, Michele; Kuijken, Konrad; Hildebrandt, Hendrik; Zhang, Shiyang; de Jong, Jelte; Napolitano, Nicola R.; Smith, Simon E. T.
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11568/1234467
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