adsabs/SciX_UAT_keywords huggingface dataset:
ELemental abundances of Planets and brown dwarfs Imaged around Stars (ELPIS). I. Potential Metal Enrichment of the Exoplanet AF Lep b and a Novel Retrieval Approach for Cloudy Self-luminous Atmospheres

AF Lep A+b is a remarkable planetary system hosting a gas-giant planet that has the lowest dynamical mass among directly imaged exoplanets. We present an in-depth analysis of the atmospheric composition of the star and planet to probe the planet's formation pathway. Based on new high-resolution spectroscopy of AF Lep A, we measure a uniform set of stellar parameters and elemental abundances (e.g., [Fe/H] = -0.27 ± 0.31 dex). The planet's dynamical mass ( ${2.8}_{-0.5}^{+0.6}$ M Jup) and orbit are also refined using published radial velocities, relative astrometry, and absolute astrometry. We use petitRADTRANS to perform chemically consistent atmospheric retrievals for AF Lep b. The radiative-convective equilibrium temperature profiles are incorporated as parameterized priors on the planet's thermal structure, leading to a robust characterization for cloudy self-luminous atmospheres. This novel approach is enabled by constraining the temperature-pressure profiles via the temperature gradient $(d\mathrm{ln}T/d\mathrm{ln}P)$ , a departure from previous studies that solely modeled the temperature. Through multiple retrievals performed on different portions of the 0.9-4.2 μm spectrophotometry, along with different priors on the planet's mass and radius, we infer that AF Lep b likely possesses a metal-enriched atmosphere ([Fe/H] > 1.0 dex). AF Lep b's potential metal enrichment may be due to planetesimal accretion, giant impacts, and/or core erosion. The first process coincides with the debris disk in the system, which could be dynamically excited by AF Lep b and lead to planetesimal bombardment. Our analysis also determines T eff ≈ 800 K, $\mathrm{log}(g)\approx 3.7$ dex, and the presence of silicate clouds and disequilibrium chemistry in the atmosphere. Straddling the L/T transition, AF Lep b is thus far the coldest exoplanet with suggested evidence of silicate clouds.

Keywords: exoplanet formation; exoplanet atmospheres; exoplanet atmospheric composition; extrasolar gaseous giant planets; stellar abundances
Gamma-Ray Emission of 60Fe and 26Al Radioactivity in Our Galaxy

The isotopes 60Fe and 26Al originate from massive stars and their supernovae, reflecting ongoing nucleosynthesis in the Galaxy. We studied the gamma-ray emission from these isotopes at characteristic energies 1173, 1332, and 1809 keV with over 15 yr of SPI data, finding a line flux in 60Fe combined lines of $(0.31\pm 0.06)\times {10}^{-3}\,\mathrm{ph}\,{\mathrm{cm}}^{-2}\,{{\rm{s}}}^{-1}$ and the Al line flux of $(16.8\pm 0.7)\times {10}^{-4}\,\mathrm{ph}\,{\mathrm{cm}}^{-2}\,{{\rm{s}}}^{-1}$ above the background and continuum emission for the whole sky. Based on the exponential disk grid maps, we characterize the emission extent of 26Al to find scale parameters ${R}_{0}={7.0}_{-1.0}^{+1.5}$ and ${z}_{0}={0.8}_{-0.2}^{+0.3}$ kpc; however, the 60Fe lines are too weak to spatially constrain the emission. Based on a point-source model test across the Galactic plane, the 60Fe emission would not be consistent with a single strong point source in the Galactic center or somewhere else, providing a hint of a diffuse nature. We carried out comparisons of emission morphology maps using different candidate source tracers for both 26Al and 60Fe emissions and suggest that the 60Fe emission is more likely to be concentrated toward the Galactic plane. We determine the 60Fe/26Al γ-ray flux ratio at 18.4% ± 4.2% when using a parameterized spatial morphology model. Across the range of plausible morphologies, it appears possible that 26Al and 60Fe are distributed differently in the Galaxy. Using the best-fitting maps for each of the elements, we constrain flux ratios in the range 0.2-0.4. We discuss the implications for massive star models and their nucleosynthesis.

Keywords: gamma-rays; gamma-ray astronomy; gamma-ray sources
Constraints on the Epoch of Reionization with Roman Space Telescope and the Void Probability Function of Lyα Emitters

We use large simulations of Lyα emitters with different fractions of ionized intergalactic medium to quantify the clustering of Lyα emitters as measured by the void probability function (VPF), and how it evolves under different ionization scenarios. We quantify how well we might be able to distinguish between these scenarios with a deep spectroscopic survey using the future Nancy Grace Roman Space Telescope. Because Roman will be able to carry out blind spectroscopic surveys of Lyα emitters continuously between 7 < z < 12 to sensitivities of at least 10-17 erg s-1 over a wide field of view, it can measure the epoch of reionization as well as the pace of ionization of the intergalactic medium (IGM). We compare deep Roman surveys covering roughly 1, 4, and 16 deg2, and quantify what constraints on reionization the VPF may find for these surveys. A survey of 1 deg2 would distinguish between very late reionization and early reionization to 3σ near z = 7.7 with the VPF. The VPF of a 4 deg2 survey can distinguish between slow versus fast, as well as early versus late, reionization at >3σ-4σ at several redshifts between 7 < z < 9. However, a survey of 13-16 deg2 would allow the VPF to give several robust constraints (>5-8σ) across the epoch of reionization, and would yield a detailed history of the reionization of the IGM and its effect on Lyα emitter clustering.

Keywords: reionization; clustering; astronomical simulations; lyman-alpha galaxies
Reconstructing the XUV Spectra of Active Sun-like Stars Using Solar Scaling Relations with Magnetic Flux

The Kepler space telescope and Transiting Exoplanet Survey Satellite unveiled that Sun-like stars frequently host exoplanets. These exoplanets are subject to fluxes of ionizing radiation in the form of X-ray and extreme-ultraviolet (EUV) radiation that may cause changes in their atmospheric dynamics and chemistry. While X-ray fluxes can be observed directly, EUV fluxes cannot be observed because of severe interstellar medium absorption. Here we present a new empirical method to estimate the whole stellar X-ray plus EUV (XUV) and far-UV (FUV) spectra as a function of total unsigned magnetic fluxes of stars. The response of the solar XUV and FUV spectrum (0.1-180 nm) to the solar total unsigned magnetic flux is investigated by using the long-term Sun-as-a-star data set over 10 yr, and the power-law relation is obtained for each wavelength with a spectral resolution of 0.1-1 nm. We applied the scaling relations to active young Sun-like stars (G dwarfs), EK Dra (G1.5V), π 1 Uma (G1.5V), and κ 1 Ceti (G5V) and found that the observed spectra (except for the unobservable longward EUV wavelength) are roughly consistent with the extension of the derived power-law relations with errors of an order of magnitude. This suggests that our model is a valuable method to derive the XUV/FUV fluxes of Sun-like stars, including the EUV band mostly absorbed at wavelengths longward of 36 nm. We also discuss differences between the solar extensions and stellar observations at wavelengths in the 2-30 nm band and conclude that simultaneous observations of magnetic and XUV/FUV fluxes are necessary for further validations.

Keywords: solar x-ray emission; extreme ultraviolet astronomy; solar extreme ultraviolet emission; solar coronal heating; stellar x-ray flares; stellar coronae; solar ultraviolet emission; solar active region magnetic fields; solar active regions; magnetic fields; magnetic variable stars; starspots
A Sanity Check for Planets around Evolved Stars

We present the radius-period plot for exoplanet candidates around giant stars. The diagram contains two distinct regions. While planets of giants with radii smaller than 21 R⊙ exhibit a wide range of orbital periods, there is evidently a lack of both relatively short-period (≤300 days) and long-period (≥800 days) planets around bigger stars. In other words, planets around K giants all have similar orbital periods above a certain stellar radius, presumably pointing out a new phenomenon which preferably occurs in stars with radii larger than ~21 R⊙. So far, it is speculative if we are seeing rotational modulation due to some kind of surface structure or an unprecedented form of nonradial stellar oscillations. Consequently, the radius is the second key parameter for giants apart from the stellar mass. Thus, we propose the radius-period plot as a tool to check the plausibility of planetary companions around more challenging host stars by taking into account their stellar identity (e.g., stellar radius and metallicity) to exclude intrinsic stellar variability.

Keywords: exoplanet catalogs; exoplanet systems; exoplanets; planet hosting stars; evolved stars; g giant stars; k giant stars
Characterization and Optimization of Skipper CCDs for the SOAR Integral Field Spectrograph

We present results from the characterization and optimization of Skipper charge-coupled devices (CCDs) for use in a focal plane prototype for the Southern Astrophysical Research Integral Field Spectrograph (SIFS). We tested eight Skipper CCDs and selected six for SIFS based on performance results. The Skipper CCDs are 6k × 1k, 15 μm pixels, thick, fully depleted, p-channel devices that have been thinned to ∼250 μm, backside processed, and treated with an anti-reflective coating. We demonstrate a single-sample readout noise of <4.3 e‑ rms pixel‑1 in all amplifiers. We optimize the readout sequence timing to achieve a readout noise of 0.5 e‑ rms pixel‑1 after 74 non-destructive measurements, which can be accomplished in a region covering 5% of the detector area in a readout time of <4 minutes. We demonstrate single-photon-counting in all 24 amplifiers (four amplifiers per detector) with a readnoise of σ N ∼ 0.18 e‑ rms pixel‑1 after N samp = 400 samples, and we constrain the degree of nonlinearity to be ≲1% at low signal levels (0 e‑ to 50 e‑). Clock-induced charge (CIC) remains an important issue when the Skipper CCD is configured to provide a large full-well capacity. We achieve a CIC rate of <1.45 × 10‑3 e‑ pixel‑1 frame‑1 for a full-well capacity of ∼900 e‑, which increases to a CIC rate of ∼3 e‑ pixel‑1 frame‑1 for full-well capacities ∼40,000–65,000 e‑. We also perform conventional CCD characterization measurements such as charge transfer inefficiency (3.44 × 10‑7 on average), dark current (∼2 × 10‑4 e‑ pixel‑1 s‑1), photon transfer curves, cosmetic defects (<0.45% "bad" pixels), and charge diffusion (point-spread function < 7.5 μm) to verify that these properties are consistent with expectations from conventional p-channel CCDs used for astronomy. Furthermore, we provide the first measurements of the brighter-fatter effect and absolute quantum efficiency (≳80% between 450 and 980 nm; ≳90% between 600 and 900 nm) using Skipper CCDs.

Keywords: ccd observation; astronomical detectors; spectroscopy
Supernova Magnitude Evolution and PAge Approximation

The evidence of environmental dependence of SN Ia luminosity has inspired recent discussion about whether the late-universe cosmic acceleration is still supported by supernova data. We adopt the ΔHR/Δage parameter, which describes the dependence of supernova absolute magnitude on the age of supernova progenitor, as an additional nuisance parameter. Using the Pantheon supernova data, a lower bound ≥12 Gyr on the cosmic age, and a Gaussian prior H0=70± 2 km s-1 Mpc-1 on the Hubble constant, we reconstruct the cosmic expansion history. Within the flat Λ cold dark matter framework, we still find a 5.6σ detection of cosmic acceleration. This is because a matter-dominated decelerating universe would be too young to accommodate observed old stars with age ≳12 Gyr. A decelerating but non-flat universe is marginally consistent with the data, however, only in the presence of a negative spatial curvature ∼2 orders of magnitude beyond the current constraint from cosmic microwave background data. Finally, we propose a more general parameterization based on the cosmic age (PAge), which is not directly tied to the dark energy concept and hence is ideal for a null test of the cosmic acceleration. We find that, for a magnitude evolution rate ΔHR/Δage ≲ 0.3 mag/5.3 Gyr, a spatially flat and decelerating PAge universe is fully consistent with the supernova data and the cosmic age bound, and has no tension with the geometric constraint from the observed cosmic microwave background acoustic angular scales.

Keywords: cosmology; observational cosmology; dark energy; cosmological constant experiments
New Photometric Calibration of the Wide Field Camera 3 Detectors

We present a new photometric calibration of the WFC3-UVIS and WFC3-IR detectors based on observations collected from 2009 to 2020 for four white dwarfs-namely, GRW +70 5824, GD 153 , GD 71 , G191B2B-and a G-type star, P330E. These calibrations include recent updates to the Hubble Space Telescope primary standard white dwarf models and a new reference flux for Vega. Time-dependent inverse sensitivities for the two WFC3-UVIS chips, UVIS1 and UVIS2, were calculated for all 42 full-frame filters after accounting for temporal changes in the observed count rates with respect to a reference epoch in 2009. We also derived new encircled energy values for a few filters and improved sensitivity ratios for the two WFC3-UVIS chips by correcting for sensitivity changes with time. Updated inverse sensitivity values for the 20 WFC3-UVIS quad filters and 15 WFC3-IR filters were derived by using the new models for the primary standards, the new Vega reference flux, and, in the case of the IR detector, new flat fields. However, these values do not account for any sensitivity changes with time. The new calibration provides a photometric internal precision better than 0.5% for the wide-, medium-, and narrowband WFC3-UVIS filters; 5% for the quad filters; and 1% for the WFC3-IR filters. As of 2020 October 15, an updated set of photometric keywords were populated in the WFC3 image headers.

Keywords: ccd photometry; spectrophotometric standards; flux calibration; photometric systems; astronomical instrumentation; hubble space telescope; hst photometry
SN 2013aa and SN 2017cbv: Two Sibling Type Ia Supernovae in the Spiral Galaxy NGC 5643

We present photometric and spectroscopic observations of SN 2013aa and SN 2017cbv, two nearly identical type Ia supernovae (SNe Ia) in the host galaxy NGC 5643. The optical photometry has been obtained using the same telescope and instruments used by the Carnegie Supernova Project. This eliminates most instrumental systematics and provides light curves in a stable and well-understood photometric system. Having the same host galaxy also eliminates systematics due to distance and peculiar velocity, providing an opportunity to directly test the relative precision of SNe Ia as standard candles. The two SNe have nearly identical decline rates, negligible reddenings, and remarkably similar spectra, and, at a distance of ∼20 Mpc, they are ideal potential calibrators for the absolute distance using primary indicators such as Cepheid variables. We discuss to what extent these two SNe can be considered twins and compare them with other supernova "siblings" in the literature and their likely progenitor scenarios. Using 12 galaxies that hosted two or more SNe Ia, we find that when using SNe Ia, and after accounting for all sources of observational error, one gets consistency in distance to 3%.

Keywords: distance indicators; type ia supernovae; interstellar dust extinction; galaxy distances
TEMPLATES: Characterization of a Merger in the Dusty Lensing SPT0418–47 System

We present JWST and Atacama Large Millimeter/submillimeter Array (ALMA) imaging for the lensing system SPT0418‑47, which includes a strongly lensed, dusty, star-forming galaxy at redshift z = 4.225 and an associated multiply imaged companion. The JWST NIRCam and MIRI imaging observations presented in this paper were acquired as part of the Early Release Science program Targeting Extremely Magnified Panchromatic Lensed Arcs and Their Extended Star formation (TEMPLATES). This data set provides robust mutiwavelength detections of stellar light in both the main (SPT0418A) and companion (SPT0418B) galaxies, while the ALMA detection of [C II] emission confirms that SPT0418B lies at the same redshift as SPT0418A. We infer that the projected physical separation of the two galaxies is 4.42 ± 0.05 kpc. We derive total magnifications of μ = 29 ± 1 and μ = 4.1 ± 0.7 for SPT0418A and SPT0418B, respectively. We use both PROSPECTOR and CIGALE to derive stellar masses. We find that SPT0418A has a stellar mass of ${M}_{* }={3.4}_{-0.6}^{+1.1}\times {10}^{10}{M}_{\odot }$ from PROSPECTOR or M * = 1.5 ± 0.3 × 1010 M ⊙ from CIGALE. The stellar mass ratio of SPT0418A and SPT0418B is roughly between 4 and 7 ( ${4.2}_{-1.6}^{+1.9}$ for PROSPECTOR and 7.5 ± 3.7 for CIGALE). We see evidence of extended structure associated with SPT0418A that is suggestive of a tidal feature. These features, along with the close projected proximity, imply that the system is interacting. Interestingly, the star formation rates and stellar masses of both galaxies are consistent with the main sequence of star-forming galaxies at this epoch, indicating that this ongoing interaction has not noticeably elevated the star formation levels.

Keywords: high-redshift galaxies; strong gravitational lensing; galaxy mergers; einstein rings
SPT-CL J2215-3537: A Massive Starburst at the Center of the Most Distant Relaxed Galaxy Cluster

We present the discovery of the most distant, dynamically relaxed cool core cluster, SPT-CL J2215-3537 (SPT2215), and its central brightest cluster galaxy (BCG) at z = 1.16. Using new X-ray observations, we demonstrate that SPT2215 harbors a strong cool core with a central cooling time of 200 Myr (at 10 kpc) and a maximal intracluster medium cooling rate of 1900 ± 400 M ⊙ yr-1. This prodigious cooling may be responsible for fueling the extended, star-forming filaments observed in Hubble Space Telescope imaging. Based on new spectrophotometric data, we detect bright [O II] emission in the BCG, implying an unobscured star formation rate (SFR) of ${320}_{-140}^{+230}$ M ⊙ yr-1. The detection of a weak radio source (2.0 ± 0.8 mJy at 0.8 GHz) suggests ongoing feedback from an active galactic nucleus (AGN), though the implied jet power is less than half the cooling luminosity of the hot gas, consistent with cooling overpowering heating. The extreme cooling and SFR of SPT2215 are rare among known cool core clusters, and it is even more remarkable that we observe these at such high redshift, when most clusters are still dynamically disturbed. The high mass of this cluster, coupled with the fact that it is dynamically relaxed with a highly isolated BCG, suggests that it is an exceptionally rare system that must have formed very rapidly in the early universe. Combined with the high SFR, SPT2215 may be a high-z analog of the Phoenix cluster, potentially providing insight into the limits of AGN feedback and star formation in the most massive galaxies.

Keywords: galaxy clusters; high-redshift galaxy clusters; starburst galaxies; star formation; intracluster medium; cooling flows
Proposed Resolution to the Solar Open Magnetic Flux Problem

The solar magnetic fields emerging from the photosphere into the chromosphere and corona are comprised of a combination of closed (field lines with both ends rooted at the Sun) and open (field lines with only one end at the Sun) fields. Since the early 2000s, the magnitude of total unsigned open magnetic flux estimated by coronal models has been in significant disagreement with in situ spacecraft observations, especially during solar maximum. Estimates of total open unsigned magnetic flux using coronal hole observations (e.g., using extreme ultraviolet or helium (He) I) are in general, in average agreement with the coronal model results and thus show similar disagreements with in situ observations. This paper provides a brief overview of the problem, summarizes the proposed explanations for the discrepancies, and presents results that strongly support the explanation that the discrepancy is due to dynamics at the open-closed boundary. These results are derived from the determination of the total unsigned open magnetic flux, utilizing the Wang–Sheeley–Arge model at a particular spatial resolution and different field-line tracing methods. One of these methods produces excellent agreement with in situ observations. Our results imply that strong magnetic fields in close proximity to active regions and residing near the boundaries of mid-latitude coronal holes are the primary source of the missing open flux. Furthermore, the results outlined here resolve many of the seemingly contradictory facts that have made the open-flux problem so difficult.

Keywords: solar magnetic fields; solar corona; interplanetary magnetic fields
Comet A117uUD Goes Interstellar after Encountering Saturn in 2022

Small solar system bodies may reach hyperbolic orbits after a close interaction with a giant planet. Comet C/1980 E1 (Bowell), with a current value of the eccentricity of 1.057733 ± 0.000008, reached its present-day path after a close encounter with Jupiter in 1980. Comet A117uUD was found by ATLAS South Africa on 2024 June 14. Its current orbit determination, based on 142 observations for a data-arc span of 31 days, places A117uUD among the bodies following hyperbolic orbits (19.51σ, eccentricity of 1.037 ± 0.002). However, it did not come from interstellar space. Here, we show that it reached its current hyperbolic trajectory after a close encounter with Saturn in 2022.

Keywords: solar system; comets
The Zwicky Transient Facility Census of the Local Universe. I. Systematic Search for Calcium-rich Gap Transients Reveals Three Related Spectroscopic Subclasses

Using the Zwicky Transient Facility alert stream, we are conducting a large spectroscopic campaign to construct a complete, volume-limited sample of transients brighter than 20 mag, and coincident within 100″ of galaxies in the Census of the Local Universe catalog. We describe the experiment design and spectroscopic completeness from the first 16 months of operations, which have classified 754 supernovae. We present results from a systematic search for calcium-rich gap transients in the sample of 22 low-luminosity (peak absolute magnitude M > -17), hydrogen-poor events found in the experiment. We report the detection of eight new events, and constrain their volumetric rate to ≳15% ± 5% of the SN Ia rate. Combining this sample with 10 previously known events, we find a likely continuum of spectroscopic properties ranging from events with SN Ia-like features (Ca-Ia objects) to those with SN Ib/c-like features (Ca-Ib/c objects) at peak light. Within the Ca-Ib/c events, we find two populations distinguished by their red (g - r ≈ 1.5 mag) or green ( $g-r\approx 0.5$ mag) colors at the r-band peak, wherein redder events show strong line blanketing features and slower light curves (similar to Ca-Ia objects), weaker He lines, and lower [Ca II]/[O I] in the nebular phase. We find that all together the spectroscopic continuum, volumetric rates, and striking old environments are consistent with the explosive burning of He shells on low-mass white dwarfs. We suggest that Ca-Ia and red Ca-Ib/c objects arise from the double detonation of He shells, while green Ca-Ib/c objects are consistent with low-efficiency burning scenarios like detonations in low-density shells or deflagrations.

Keywords: supernovae; compact objects; white dwarf stars