2019/09/17 by Brian D. Davis, Howard E. Bond, Robin Ciardullo +1 · 1 citation
Physics and Astronomy · #astro-ph.SR #astro-ph.GA
paper · pdf · doi:10.3847/1538-4357/ab44d4
18 pages, 5 figures, 4 tables
arxiv created 2019/09/17 · arxiv updated 2019/11/06
We use imaging and spectroscopy from the Hubble Space Telescope (HST) to examine the properties of a bright planetary nebula (PN) projected within M31's young open cluster B477-D075. We show that the probability of a chance superposition of the PN on the cluster is small, \lesssim2%. Moreover, the radial velocity of the PN is the same as that of the cluster within the measurement error of ∼10 km s-1. Given the expected ∼70 km s-1 velocity dispersion in this region, ∼8 kpc from M31's nucleus, the velocity data again make it extremely likely that the PN belongs to the cluster. Applying isochrone fitting to archival color-magnitude photometric data from the HST Advanced Camera for Surveys, we determine the cluster age and metallicity to be 290 Myr and Z = 0.0071, respectively, implying an initial mass of 3.38+0.03-0.02 M\odot for any PN produced by the cluster. From HST's Space Telescope Imaging Spectrograph observations and Cloudy photoionization modeling, we find that the PN is likely a Type I planetary, with a nitrogen abundance that is enhanced by ∼5-6 times over the solar value scaled to the cluster metallicity. If the PN is indeed a cluster member, these data present strong empirical evidence that hot-bottom burning occurs in AGB stars with initial masses as low as 3.4 M\odot.