The Local Volume HI Survey

ESO 245-G007 (HIPASS J0150-44) also known as the Phoenix Dwarf Galaxy, is a member of the Local Group (D_TRGB = 420 ± 10 kpc). Its distance has been well constrained by several authors (e.g., Young et al. 2007). Our ATCA HI mosaic of ESO 245-G007 is shown in Fig. 6, revealing an extended HI cloud embracing the stellar core to the south-west. We detect HI emission from about -40 to -8 km/s, no clear velocity gradient is seen. The HI emission associated with the Phoenix galaxy is also clearly detected in the re-calibrated HIPASS data. Phoenix is likely a transitional dwarf galaxy as previously suggested by Young & Lo (1997), St-Germain et al. (1999) and Young et al. (2007) who carry out detailed studies of its HI emission. Martinez-Delgado et al. (1999) investigate the stellar content of the Phoenix Dwarf Galaxy and find a predominantly old population oriented north−south and a more compact, young population aligned east−west; the latter shows an asymmetry in its distribution with more blue stars in the south-western part of the galaxy. Later stellar velocity measurements of -13 ± 9 km/s (Gallart et al. 2001, Irwin & Tolstoy 2002) confirmed that the HI cloud is indeed associated with the galaxy. Young et al. (2007) use deep VLA HI data of Phoenix to investigate mechanisms which may transform gas-rich irregulars into gas-poor dwarf spheroidal galaxies. As the HI cloud is associated with the most recent star formation in Phoenix, they suggest that the gas expulsion may have been caused by winds from supernovae. Using our ATCA maps we measure an HI flux density of F_HI = 2.3 Jy km/s, corresponding to an HI mass of M_HI ~ 10⁵ M_☉. For comparison, St-Germain et al. (1999) measure F_HI = 4.0 Jy km/s with the ATCA, while Young et al. (2007) measure F_HI = 2.95 ± 0.10 Jy km/s with the VLA (single pointing).

Reference: Koribalski et al. 2018 * LVHIS database * LVHIS homepage * next