The Chemodynamics of the Stellar Populations in M31 from APOGEE Integrated Light Spectroscopy

We present analysis of nearly 1,000 near-infrared, integrated light spectra from APOGEE in the inner $\sim$7 kpc of M31. We utilize full spectrum fitting with A-LIST simple stellar population spectral templates that represent a population of stars with the same age, [M/H], and [$\alpha$/M]. With this, we determine the mean kinematics, metallicities, $\alpha$ abundances, and ages of the stellar populations of M31's bar, bulge, and inner disk ($\sim$4-7 kpc). We find a non-axisymmetric velocity field in M31 resulting from the presence of a bar. The bulge of M31 is metal-poor relative to the disk ([M/H] = $-0.149^{+0.067}_{-0.081}$ dex), features minima in metallicity on either side of the bar ([M/H] $\sim$ -0.2), and is enhanced in $\alpha$ abundance ([$\alpha$/M] = $0.281^{+0.035}_{-0.038}$). The disk of M31 within $\sim$7 kpc is enhanced in both metallicity ([M/H] = $-0.023^{+0.050}_{-0.052}$) and $\alpha$ abundance ([$\alpha$/M] = $0.274^{+0.020}_{-0.025}$). Both of these structural components are uniformly old at $\simeq$ 12 Gyr. We find the metallicity increases with distance from the center of M31, with the steepest gradient along the disk major axis ($0.043\pm0.021$ dex/kpc). This gradient is the result of changing light contributions from the metal-poor bulge and metal-rich disk. The chemodynamics of stellar populations encodes information about a galaxy's chemical enrichment, star formation history, and merger history, allowing us to discuss new constraints on M31's formation. Our results provide a stepping stone between our understanding of the Milky Way and other external galaxies

Catalog of Integrated-light Star Cluster Light Curves in TESS

We present the first integrated-light, TESS-based light curves for star clusters in the Milky Way, Small Magellanic Cloud, and Large Magellanic Cloud. We explore the information encoded in these light curves, with particular emphasis on variability. We describe our publicly available package elk , which is designed to extract the light curves by applying principal component analysis to perform background light correction and incorporating corrections for TESS systematics, allowing us to detect variability on timescales shorter than ∼10 days. We perform a series of checks to ensure the quality of our light curves, removing observations where systematics are identified as dominant features, and deliver light curves for 348 previously cataloged open and globular clusters. Where TESS has observed a cluster in more than one observing sector, we provide separate light curves for each sector (for a total of 2204 light curves). We explore in detail the light curves of star clusters known to contain high-amplitude Cepheid and RR Lyrae variable stars, and we confirm that the variability of these known variables is still detectable when summed together with the light from thousands of other stars. We also demonstrate that even some low-amplitude stellar variability is preserved when integrating over a stellar population

ReveaLLAGN 0: First look at JWST MIRI data of Sombrero and NGC 1052

International audienceWe present the first results from the Revealing Low-Luminosity Active Galactic Nuclei (ReveaLLAGN) survey, a JWST survey of seven nearby LLAGNs. We focus on two observations with the Mid-Infrared Instrument (MIRI)'s Medium-Resolution Spectrometer of the nuclei of NGC 1052 and Sombrero (NGC 4594/M104). We also compare these data to public JWST data of higher-luminosity AGNs, NGC 7319 and NGC 7469. JWST clearly separates the AGN spectrum from the galaxy light even in Sombrero, the faintest target in our survey; the AGN components have very red spectra. We find that the emission-line widths in both NGC 1052 and Sombrero increase with increasing ionization potential, with FWHM > 1000 km s‑1 for lines with ionization potential ≳ 50 eV. These lines are also significantly blueshifted in both LLAGNs. The high-ionization-potential lines in NGC 7319 show neither broad widths nor significant blueshifts. Many of the lower-ionization-potential emission lines in Sombrero show significant blue wings extending >1000 km s‑1. These features and the emission-line maps in both galaxies are consistent with outflows along the jet direction. Sombrero has the lowest-luminosity high-ionization-potential lines ([Ne V] and [O IV]) ever measured in the mid-infrared, but the relative strengths of these lines are consistent with higher-luminosity AGNs. On the other hand, the [Ne V] emission is much weaker relative to the [Ne III] and [Ne II] lines of higher-luminosity AGNs. These initial results show the great promise that JWST holds for identifying and studying the physical nature of LLAGNs