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1. The Southern Stellar Stream Spectroscopic Survey ( S 5 ): Chemical Abundances of Seven Stellar Streams

   https://doi.org/10.3847/1538-3881/abacb6  

   Ji, Alexander P. ; Li, Ting S. ; Hansen, Terese T. ; Casey, Andrew R. ; Koposov, Sergey E. ; Pace, Andrew B. ; Mackey, Dougal ; Lewis, Geraint F. ; Simpson, Jeffrey D. ; Bland-Hawthorn, Joss ; et al ( October 2020 , The Astronomical Journal)

   null (Ed.)
2. Stellar population models based on the SDSS-IV MaStar library of stellar spectra. I. Intermediate-age/old models.

   https://doi.org/10.1093/mnras/staa1489  

   Maraston, C ; Hill, L ; Thomas, D ; Yan, R ; Chen, Y ; Lian, J ; Parikh, T ; Neumann, J ; Meneses-Goytia, S ; Bershady, M ; et al ( June 2020 , Monthly Notices of the Royal Astronomical Society)

   We use the first release of the SDSS/MaStar stellar library comprising ∼9000, high S/N spectra, to calculate integrated spectra of stellar population models. The models extend over the wavelength range 0.36-1.03 μm and share the same spectral resolution (R~1800) and flux calibration as the SDSS-IV/MaNGA galaxy data. The parameter space covered by the stellar spectra collected thus far allows the calculation of models with ages and chemical composition in the range t>200 Myr, -2 < [Z/H] < + 0.35, which will be extended as MaStar proceeds. Notably, the models include spectra for dwarf Main Sequence stars close to the core H-burning limit, as well spectra for cold, metal-rich giants. Both stellar types are crucial for modelling λ >0.7μm absorption spectra. Moreover, a better parameter coverage at low metallicity allows the calculation of models as young as 500 Myr and the full account of the Blue Horizontal Branch phase of old populations. We present models adopting two independent sets of stellar parameters (Teff, logg, [Z/H]). In a novel approach, their reliability is tested ’on the fly’ using the stellar population models themselves. We perform tests with Milky Way and Magellanic Clouds globular clusters, finding that the new models recover their ages and metallicities remarkably well, with systematics as low as a few per cent for homogeneous calibration sets. We also fit a MaNGA galaxy spectrum, finding residuals of the order of a few per cent comparable to the state-of-art models, but now over a wider wavelength range. 

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3. New Star Observations with NuSTAR : Flares from Young Stellar Objects in the ρ Ophiuchi Cloud Complex in Hard X-Rays

   https://doi.org/10.3847/1538-4357/ab2e0d  

   Vievering, Juliana T. ; Glesener, Lindsay ; Grefenstette, Brian W. ; Smith, David M. ( September 2019 , The Astrophysical Journal)
4. Grids of stellar models with rotation: VI. Models from 0.8 to 120 M ⊙ at a metallicity Z = 0.006

   https://doi.org/10.1051/0004-6361/202141222  

   Eggenberger, Patrick ; Ekström, Sylvia ; Georgy, Cyril ; Martinet, Sébastien ; Pezzotti, Camilla ; Nandal, Devesh ; Meynet, Georges ; Buldgen, Gaël ; Salmon, Sébastien ; Haemmerlé, Lionel ; et al ( August 2021 , Astronomy & Astrophysics)

   null (Ed.)

   Context. Grids of stellar models, computed with the same physical ingredients, allow one to study the impact of a given physics on a broad range of initial conditions and they are a key ingredient for modeling the evolution of galaxies. Aims. We present here a grid of single star models for masses between 0.8 and 120 M ⊙ , with and without rotation for a mass fraction of heavy element Z  = 0.006, representative of the Large Magellanic Cloud (LMC). Methods. We used the GENeva stellar Evolution Code. The evolution was computed until the end of the central carbon-burning phase, the early asymptotic giant branch phase, or the core helium-flash for massive, intermediate, and low mass stars, respectively. Results. The outputs of the present stellar models are well framed by the outputs of the two grids obtained by our group for metallicities above and below the one considered here. The models of the present work provide a good fit to the nitrogen surface enrichments observed during the main sequence for stars in the LMC with initial masses around 15 M ⊙ . They also reproduce the slope of the luminosity function of red supergiants of the LMC well, which is a feature that is sensitive to the time-averaged mass loss rate over the red supergiant phase. The most massive black hole that can be formed from the present models at Z  = 0.006 is around 55 M ⊙ . No model in the range of mass considered will enter into the pair-instability supernova regime, while the minimal mass to enter the region of pair pulsation instability is around 60 M ⊙ for the rotating models and 85 M ⊙ for the nonrotating ones. Conclusions. The present models are of particular interest for comparisons with observations in the LMC and also in the outer regions of the Milky Way. We provide public access to numerical tables that can be used for computing interpolated tracks and for population synthesis studies. 

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5. The H α luminosity and stellar mass dependent clustering of star-forming galaxies at 0.7 < z < 1.5 with 3D- HST

   https://doi.org/10.1093/mnras/stac1889  

   Clontz, Callie ; Wake, David ; Zheng, Zheng ( July 2022 , Monthly Notices of the Royal Astronomical Society)

   We present measurements of the dependence of the clustering amplitude of galaxies on their star formation rate (SFR) and stellar mass (M*) at 0.7 < z < 1.5 to assess the extent to which environment affects these properties. While these relations are well determined in the local Universe, they are much more poorly known at earlier times. For this analysis, we make use of the near-infrared HST WFC3 grism spectroscopic data in the five CANDELS fields obtained as part of the 3D-HST survey. We make projected two-point correlation function measurements using ∼6000 galaxies with accurate redshifts, M*, and H α luminosities. We find a strong dependence of clustering amplitude on H α luminosity and thus SFR. However, at fixed M*, the clustering dependence on H α luminosity is largely eliminated. We model the clustering of these galaxies within the halo occupation distribution framework using the conditional luminosity function model and the newly developed conditional stellar mass and H α luminosity distribution model. These show that galaxies with higher SFRs tend to live in higher mass haloes, but this is largely driven by the relationship between SFR and M*. Finally, we show that the small residual correlation between clustering amplitude and H α luminosity at fixed M* is likely being driven by a broadening of the SFR–M* relationship for satellite galaxies.

    

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