The ACS Nearby Survey Treasury
ANGST (ACS Nearby Galaxy Survey Treasury) is a HST Treasury Proposal aimed to directly measure the star formation history (SFH) of a complete volume-limited sample of nearby galaxies. The sample includes 69 galaxies within 4 Mpc, covering a 104 range in their luminosities, including both isolated and close galaxies, great spirals, irregulars an dwarf spheroidals. ANGST is complemented by the archival proposal ANGRRR (Archive of Nearby Galaxies: Reduce, Reuse, Recycle).
ANGST/ANGRRR has so far provided homogeneous multicolor photometry for more than 14 million stars in 69 galaxies (Dalcanton et al. 2009). It has found that massive spirals such as M81 have formed most of their stars more than 7 Gyr ago (Williams et al. 2009). It has been verified the consistency between several SFH indicators for young populations (Gogarten et al. 2009). The data analyses are being performed using Padova stellar evolutionary models and new tables of bolometric corrections, colour-temperature relations, and extinction coefficients in the HST photometric systems (Girardi et al 2008).
As the main optical survey has finished, data analysis proceeds and is being complemented by a series of observations at other wavelengths. Particularly interesting are the extensions to near-infrared, which allow a complete census of the red supergiants and asymptotic giant branch stars in these galaxies.
People: L. Girardi
Collaboration: J. Dalcanton (PI, Univ. Washington, Seattle), plus the ANGST-ANGRRR team, J. Melbourne (Caltech) and P. Marigo (Padova Univ.)
Publications: Gogarten et al. (2009) ApJ 691,115; Williams et al. (2009), AJ 137,419; Girardi et al. (2008), PASP 120,583; Dalcanton et al. (2009), ApJ, accepted;