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Paper: |
TP-AGB Stars in M31: Results from PHAT |
Volume: |
497, Why Galaxies Care about AGB Stars III: A Closer Look in Space and Time |
Page: |
413 |
Authors: |
Girardi, L.; Beerman, L. C.; Boyer, M. L.; Dalcanton, J. J.; Dolphin, A.; Fouesnaeu, M.; Hamren, K.; Johnson, L. C.; Lang, D.; Lewis, A.; Marigo, P.; Rosenfield, P.; Senchyna, P.; Seth, A. C.; Veyette, M.; Weisz, D. R.; Williams, B. F. |
Abstract: |
The Panchromatic Hubble Andromeda Treasury (PHAT) is an HST multi-cycle
treasury program that mapped one-third of M31 from the UV through the
near-IR. It provides photometry in up to 6 filters for about 117 million
stars distributed across ∼20 kpc of the M31 disk, with a spatial
resolution comparable to that routinely attained for the Magellanic
Clouds from the ground. These data are revolutionising our view of the
spatial distribution of stars and dust across M31.
Here we present an overview of PHAT data and results, with a focus on
the thermally-pulsing asymptotic giant branch (TP-AGB) stars. We comment
on (1) the overall spatial distribution of TP-AGB stars as compared to
stars of the red giant branch (RGB); (2) the detection of a dramatic
drop in the C/M ratio toward the inner M31 disk; (3) the large population
of TP-AGB stars in star clusters; (4) an improved view of the planetary
nebula population; and (5) the unusual populations of UV-bright stars in
the M31 bulge, which correspond to either post-AGB or “failed-AGB” stars.
These rich datasets allow us to test the evolution of TP-AGB stars in a
metal-rich and star-forming environment, avoiding the incompleteness and
distance uncertainties that severely limit similar studies in the Milky
Way. |
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