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Spectroscopic Distance, Mass, and Age Estimations for APOGEE DR17
Brownstein, Joel R.; Stassun, Keivan G.; Holtzman, Jon A. +3 more
We derive distances and masses of stars from the Sloan Digital Sky Survey (SDSS) Apache Point Observatory Galactic Evolution Experiment Data Release 17 using simple neural networks. Training data for distances comes from Gaia EDR3, supplemented by literature distances for star clusters. For masses, the network is trained using asteroseismic masses…
GHOST commissioning science results - II: a very metal-poor star witnessing the early galactic assembly
Hayes, Christian R.; Sestito, Federico; Jensen, Jaclyn +25 more
This study focuses on Pristine$\_180956.78$-294759.8 (hereafter P180956, [Fe/H] = -1.95 ± 0.02), a star selected from the Pristine Inner Galaxy Survey (PIGS), and followed-up with the recently commissioned Gemini High-resolution Optical SpecTrograph (GHOST) at the Gemini South telescope. The GHOST spectrograph's high efficiency in the blue spectra…
Probing the physics of star formation (ProPStar). I. First resolved maps of the electron fraction and cosmic-ray ionization rate in NGC 1333
Caselli, Paola; Chen, Mike; Neri, Roberto +11 more
Context. Electron fraction and cosmic-ray ionization rates in star-forming regions are important quantities in astrochemical modeling and are critical to the degree of coupling between neutrals, ions, and electrons, which regulates the dynamics of the magnetic field. However, these are difficult quantities to estimate.
Aims: We aim to derive …
Unveiling energy pathways in AGN accretion flows with the warm corona model for the soft excess
Bianchi, S.; Petrucci, P. -O.; De Marco, B. +9 more
The soft excess in active galactic nuclei (AGNs) may arise through a combination of relativistic reflection and the effects of a warm corona at the surface of the accretion disc. Detailed examination of the soft excess can therefore constrain models of the transport and dissipation of accretion energy. Here, we analyse 34 XMM-Newton observations f…
BUFFALO/Flashlights: Constraints on the abundance of lensed supergiant stars in the Spock galaxy at redshift 1
Koekemoer, Anton M.; Mahler, Guillaume; Richard, Johan +28 more
In this work, we present a constraint on the abundance of supergiant (SG) stars at redshift z ≈ 1, based on recent observations of a strongly lensed arc at this redshift. First we derived a free-form model of MACS J0416.1-2403 using data from the Beyond Ultra-deep Frontier Fields and Legacy Observations (BUFFALO) program. The new lens model is bas…
The JWST-SUSPENSE Ultradeep Spectroscopic Program: Survey Overview and Star Formation Histories of Quiescent Galaxies at 1 < z < 3
Barro, Guillermo; Franx, Marijn; Muzzin, Adam +19 more
We present an overview and first results from the Spectroscopic Ultradeep Survey Probing Extragalactic Near-infrared Stellar Emission (SUSPENSE), executed with NIRSpec on JWST. The primary goal of the SUSPENSE program is to characterize the stellar, chemical, and kinematic properties of massive quiescent galaxies at cosmic noon. In a single deep N…
Evolutionary Map of the Universe (EMU): A pilot search for diffuse, non-thermal radio emission in galaxy clusters with the Australian SKA Pathfinder
Botteon, A.; Riseley, C. J.; Norris, R. P. +10 more
Clusters of galaxies have been found to host Mpc-scale diffuse, non-thermal radio emission in the form of central radio halos and peripheral relics. Turbulence and shock-related processes in the intra-cluster medium are generally considered responsible for the emission, though details of these processes are still not clear. The low surface brightn…
The Orbital Geometries and Stellar Obliquities of Exoplanet-hosting Multistar Systems
Vanderburg, Andrew; Rice, Malena; Gerbig, Konstantin
The current orbital geometries of exoplanet systems offer a fossilized record of the systems' dynamical histories. A particularly rich set of dynamical mechanisms is available to exoplanets residing in multistar systems, which may have their evolution shaped by the gravitational influence of bound stellar companions. In this work, we examine the j…
Extremely strong C IV λ1550 nebular emission in the extremely low-metallicity star-forming galaxy J2229+2725
Schaerer, D.; Thuan, T. X.; Izotov, Y. I. +2 more
Using Hubble Space Telescope/Cosmic Origins Spectrograph observations of one of the most metal-poor dwarf star-forming galaxies (SFGs) in the local Universe, J2229+2725, we have discovered an extremely strong nebular C IV λλ1549, 1551 emission-line doublet, with an equivalent width of 43 Å, several times higher than the value observed so far in lo…
Asteroseismology of the young open cluster NGC 2516. I. Photometric and spectroscopic observations
Li, Gang; Bedding, Timothy R.; Aerts, Conny +8 more
Context. Asteroseismic modelling of isolated stars presents significant challenges due to the difficulty in accurately determining stellar parameters, particularly the stellar age. These challenges can be overcome by observing stars in open clusters whose coeval members share an initial chemical composition. The light curves from the all-sky surve…