The abundances of highly siderophile elements (HSE) in planetary mantles and achondrites potentially provide important constraints on several aspects of planet formation, including the nature and composi-tion of late accreted materials. Here, we experimentally and systematically assess the distribution of the HSE between silicate melts, sulfide and/or metal liquids at the highly to moderately reduced conditions thought to have characterized Earth accretion. The results show that the chalcophile behavior of all ele-ments, except for Re, is strongly decreased at low FeO and/or high S concentrations in the silicate melt. There are considerable differences between how FeO and/or S contents of the silicate melt affect the D values of the various HSE, with the largest effects observed for Pd, Pt, Ir and Au. If liquid metal is Si -rich and S-poor, the siderophile behavior of the HSE mimics that in the presence of sulfide liquids, but with an offset due to differences in HSE activities in metal and sulfide liquids.Using our new experimental data, we quantify the relative effects of O in sulfide and S in silicate melt on the sulfide liquid-silicate melt partitioning behavior of the HSE using a thermodynamic approach. The resulting expressions were used to model the distribution of the HSE in highly reduced and differentiated EH-and EL chondritic parent bodies and during differentiation of the aubrite parent body. Our results show that even with their strongly decreased chalcophile and siderophile behavior at highly reduced con-ditions, HSE abundances in the mantles of these parent bodies remain extremely low. However, if such bodies accreted to Earth, any residual metal present in the parent body mantle and subsequently retained in Earth's mantle would dramatically affect HSE abundances and produce chondritic ratios, making it impossible to track the potential accretion of a large reduced impactor to the BSE using HSE abundance systematics. In terms of the aubrite parent body, our results confirm previous hypotheses related to the importance of (un)differentiated core forming metals in establishing the HSE contents of unbrecciated aubrites. Finally, our results confirm that sulfides are likely a minor source of HSE abundances in aubrites, particularly for Re, consistent with sample observations.(c) 2022 Elsevier Ltd. All rights reserved.

Using Hubble Space Telescope ACS/WFC data we present the photometry and spatial distribution of resolved stellar populations of four fields within the extended ultraviolet disc (XUV disc) of M83. These observations showa clumpy distribution of main-sequence stars and a mostly smooth distribution of red giant branch stars. We constrain the upper end of the initial mass function (IMF) in the outer disc using the detected population of main-sequence stars and an assumed constant star formation rate (SFR) over the last 300 Myr. By comparing the observed main-sequence luminosity function to simulations, we determine the best-fitting IMF to have a power-law slope alpha=-2.35 +/- 0.3 and an upper mass limit M-u = 25(-3)(+17) M-circle dot. This IMF is consistent with the observed H alpha emission, which we use to provide additional constraints on the IMF. We explore the influence of deviations from the constant SFR assumption, finding that our IMF conclusions are robust against all but strong recent variations in SFR, but these are excluded by causality arguments. These results, along with our similar studies of other nearby galaxies, indicate that some XUV discs are deficient in high-mass stars compared to a Kroupa IMF. There are over one hundred galaxies within 5 Mpc, many already observed with HST, thus allowing a more comprehensive investigation of the IMF, and how it varies, using the techniques developed here.

apply the near-infrared J-region asymptotic giant branch (JAGB) method, recently introduced by Madore & Freedman, to measure the distances to 14 nearby galaxies out to 4 Mpc. We use the geometric detached eclipsing binary (DEB) distances to the LMC and SMC as independent zero-point calibrators. We find excellent agreement with previously published distances based on the tip of the red giant branch (TRGB): the JAGB distance determinations (including the LMC and SMC) agree in the mean to within Delta(JAGB-TRGB) = +0.025 +/- 0.013.mag, just over 1%, where the TRGB I-band zero-point is M-I = -4.05 mag. With further development and testing, the JAGB method has the potential to provide an independent calibration of Type Ia supernovae, especially with the James Webb Space Telescope. The JAGB stars (with M-J = -6.20 mag) can be detected farther than the fainter TRGB stars, allowing greater numbers of calibrating galaxies for the determination of H-0. Along with the TRGB and Cepheids, JAGB stars are amenable to theoretical understanding and further refined empirical calibration. A preliminary test shows little dependence, if any, of the JAGB magnitude on metallicity of the parent galaxy. These early results suggest that the JAGB method has considerable promise for providing high-precision distances to galaxies in the local universe that are independent of distances derived from the Leavitt Law and/or the TRGB method, and it has numerous and demonstrable advantages over the possible use of Mira variables.

A near-infrared, color-selected subset of carbon-rich asymptotic giant branch (C-AGB) stars is found to have tightly constrained luminosities in the near-infrared J band. Based on JK photometry of some 3300 C-AGB stars in the bar of the Large Magellanic Cloud (LMC) we find that these stars have a constant absolute magnitude of < M-J > = -6.22 mag, adopting the detached eclipsing binary (DEB) distance to the LMC of 18.477 +/- 0.004 (stat) +/- 0.026 (sys). Undertaking a second, independent calibration in the Small Magellanic Cloud, which also has a DEB geometric distance, we find < M-J > = - 6.18. 0.01 (stat) +/- 0.05.(sys) mag. For the LMC the scatter is +/- 0.27 mag for single-epoch observations, (falling to +/- 0.15 mag for multiple observations averaged over a window of more than one year). We provisionally adopt < M-J > = -6.20 mag +/- 0.01.(stat) +/- 0.04.(sys) mag for the mean absolute magnitude of these stars. Applying this calibration to stars recently observed in the galaxy NGC.253, we determine a distance modulus of 27.66 +/- 0.01(stat) +/- 0.04 mag (syst), corresponding to a distance of 3.40 +/- 0.06 Mpc.(stat). This is in excellent agreement with the average tip of the red giant branch (TRGB) distance modulus of 27.68 +/- 0.05 mag, assuming M-I = -4.05 mag for the TRGB zero-point.

We consider the application of the tip of the red giant branch (TRGB) in the optical and in the near-infrared for the determination of distances to nearby galaxies. We analyze ACS VI (F555W and F814W) data and self-consistently cross-calibrate WFC3-IR JH (F110W and F120W) data using an absolute magnitude calibration ofM(I) = -4.05 mag as determined in the Large Magellanic Cloud using detached eclipsing binary star geometric parallaxes. We demonstrate how the optical and near-infrared calibrations of the TRGB method are mathematically self-consistent, and illustrate the mathematical basis and relations among these multiwavelength calibrations. We go on to present a method for determining the reddening, extinction, and the true modulus to the host galaxy using multiwavelength data. The power of the method is that with high-precision data, the reddening can be determined using the TRGB stars themselves, and decreases the systematic (albeit generally small) uncertainty in distance due to reddening for these halo stars.

Context. Malin 1 is the largest known low surface brightness (LSB) galaxy, the archetype of so-called giant LSB galaxies. The structure and origin of such galaxies are still poorly understood, especially because of the lack of high-resolution kinematics and spectroscopic data.Aims. We use emission lines from spectroscopic observations of Malin 1 aiming to bring new constraints on the internal dynamics and star formation history of Malin 1.Methods. We extracted a total of 16 spectra from different regions of Malin 1 and calculated the rotational velocities of these regions from the wavelength shifts and star formation rates from the observed H alpha emission line fluxes. We compared our data with existing data and models for Malin 1.Results. For the first time we present the inner rotation curve of Malin 1, characterised in the radial range r < 10 kpc by a steep rise in the rotational velocity up to at least 350 km s(-1) (with a large dispersion), which had not been observed previously. We used these data to study a suite of new mass models for Malin 1. We show that in the inner regions dynamics may be dominated by the stars (although none of our models can explain the highest velocities measured) but that at large radii a massive dark matter halo remains necessary. The H alpha fluxes derived star formation rates are consistent with an early-type disc for the inner region and with the level found in extended UV galaxies for the outer parts of the giant disc of Malin 1. We also find signs of high metallicity but low dust content for the inner regions.

The local determination of the Hubble constant sits at a crossroad. Current estimates of the local expansion rate of the universe differ by about 1.7 sigma, derived from the Cepheid- and TRGB-based calibrations, applied to Type Ia supernovae. To help elucidate possible sources of systematic error causing the tension, we show in this study the recently developed distance indicator, the J-region Asymptotic Giant Branch (JAGB) method, can serve as an independent cross-check and comparison with other local distance indicators. Furthermore, we make the case that the JAGB method has substantial potential as an independent, precise, and accurate calibrator of Type Ia supernovae for the determination of H-0. Using the Local Group galaxy Wolf-Lundmark-Melotte (WLM), we present distance comparisons between the JAGB method, a TRGB measurement at near-infrared (JHK) wavelengths, a TRGB measurement in the optical I band, and a multiwavelength Cepheid period-luminosity relation determination. We find

The recently developed J-region asymptotic giant branch (JAGB) method has extraordinary potential as an extragalactic standard candle, capable of calibrating the absolute magnitudes of locally accessible Type Ia supernovae, thereby leading to an independent determination of the Hubble constant. Using Gaia Early Data Release 3 (EDR3) parallaxes, we calibrate the zero-point of the JAGB method, based on the mean luminosity of a color-selected subset of carbon-rich AGB stars. We identify Galactic carbon stars from the literature and use their near-infrared photometry and Gaia EDR3 parallaxes to measure their absolute J-band magnitudes. Based on these Milky Way parallaxes we determine the zero-point of the JAGB method to be M ( J ) = -6.14 +/- 0.05 (stat) +/- 0.11 (sys) mag. This Galactic calibration serves as a consistency check on the JAGB zero-point, agreeing well with previously published, independent JAGB calibrations based on geometric, detached eclipsing binary distances to the LMC and SMC. However, the JAGB stars used in this study suffer from the high parallax uncertainties that afflict the bright and red stars in EDR3, so we are not able to attain the higher precision of previous calibrations, and ultimately will rely on future improved DR4 and DR5 releases.

The J-region asymptotic giant branch (JAGB) method is a new standard candle that is based on the stable intrinsic J-band magnitude of color-selected carbon stars, and has a precision comparable to other primary distance indicators such as Cepheids and the TRGB. We further test the accuracy of the JAGB method in the Local Group galaxy M33. M33's moderate inclination, low metallicity, and nearby proximity make it an ideal laboratory for tests of systematics in local distance indicators. Using high-precision optical BVI and near-infrared JHK photometry, we explore the application of three independent distance indicators: the JAGB method, the Cepheid Leavitt law, and the TRGB. We find: mu (0)(TRGB( I )) = 24.72 +/- 0.02 (stat) +/- 0.07 (sys) mag, mu (0)(TRGB(NIR)) = 24.72 +/- 0.04 (stat) +/- 0.10 (sys) mag, mu (0)(JAGB) = 24.67 +/- 0.03 (stat) +/- 0.04 (sys) mag, and mu (0)(Cepheid) = 24.71 +/- 0.04 (stat) +/- 0.01 (sys) mag. For the first time, we also directly compare a JAGB distance using ground-based and space-based photometry. We measure mu (0)(JAGB(F110W)) = 24.71 +/- 0.06 (stat) +/- 0.05 (sys) mag using the (F814W-F110W) color combination to effectively isolate the JAGB stars. In this paper, we measure a distance to M33 accurate to 2% and provide further evidence that the JAGB method is a powerful extragalactic distance indicator that can effectively probe a local measurement of the Hubble constant using spaced-based observations. We expect to measure the Hubble constant via the JAGB method in the near future, using observations from the James Webb Space Telescope.

The current Cepheid-calibrated distance ladder measurement of H (0) is reported to be in tension with the values inferred from the cosmic microwave background (CMB), assuming standard cosmology. However, some tip of the red giant branch (TRGB) estimates report H (0) in better agreement with the CMB. Hence, it is critical to reduce systematic uncertainties in local measurements to understand the Hubble tension. In this paper, we propose a uniform distance ladder between the second and third rungs, combining Type Ia supernovae (SNe Ia) observed by the Zwicky Transient Facility (ZTF) with a TRGB calibration of their absolute luminosity. A large, volume-limited sample of both calibrator and Hubble flow SNe Ia from the same survey minimizes two of the largest sources of systematics: host-galaxy bias and nonuniform photometric calibration. We present results from a pilot study using the existing TRGB distance to the host galaxy of ZTF SN Ia SN 2021rhu (aka ZTF21abiuvdk) in NGC7814. Combining the ZTF calibrator with a volume-limited sample from the first data release of ZTF Hubble flow SNe Ia, we infer H (0) = 76.94 +/- 6.4 km s(-1) Mpc(-1), an 8.3% measurement. The error budget is dominated by the single object calibrating the SN Ia luminosity in this pilot study. However, the ZTF sample includes already five other SNe Ia within similar to 20 Mpc for which TRGB distances can be obtained with the Hubble Space Telescope. Finally, we present the prospects of building this distance ladder out to 80 Mpc with James Webb Space Telescope observations of more than 100 ZTF SNe Ia.