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The Role of Spiral Arms in Galaxies
Calzetti, Daniela; Battisti, Andrew J.; Sun, Bingqing
We test the influence of spiral arms on the star formation activity of disk galaxies by constructing and fitting multiwavelength spectral energy distributions for the two nearby spiral galaxies NGC 628 and NGC 4321, at a spatial scale of 1–1.5 kpc. Recent results in the literature support the "gatherers" picture, i.e., that spiral arms gather mate…
Four-hundred Very Metal-poor Stars Studied with LAMOST and Subaru. III. Dynamically Tagged Groups and Chemodynamical Properties
Shi, Jianrong; Zhao, Gang; Chen, Yuqin +9 more
Very metal-poor (VMP) stars record the signatures of early accreted galaxies, making them essential tools for unraveling the early stages of Galaxy formation. Understanding the origin of VMP stars requires comprehensive studies of their chemical compositions and kinematics, which are currently lacking. Hence, we conduct a chemodynamical analysis o…
Age of Massive Galaxies at Redshift 8
López-Corredoira, M.; Melia, F.; Wei, J. -J. +1 more
Recent James Webb Space Telescope data analyses have shown that massive red galaxies existed at redshifts z ≳ 6, a discovery that is difficult to understand in the context of standard cosmology (ΛCDM). Here, we analyze these observations more deeply, by fitting a stellar population model to the optical and near-infrared photometric data. These fit…
Deep Chandra Observation of the Remarkable Ionization Cones of NGC 5252
Elvis, Martin; Guainazzi, Matteo; Bianchi, Stefano +4 more
Seyfert galaxy NGC 5252 harbors enormously extended ionization cones that have been previously detected in the optical and X-ray band, offering a unique opportunity to investigate the interaction between the central active galactic nucleus (AGN) and the surrounding gas in the AGN host galaxy. We present deep Chandra imaging spectroscopy of NGC 525…
HST astrometry of the closest brown dwarfs-II. Improved parameters and constraints on a third body
Apai, D.; Pourbaix, D.; Bedin, L. R. +5 more
Located at less than two pc away, Luhman 16 AB (WISE J104915.57-531906.1) is the closest pair of brown dwarfs and the third closest "stellar" system to Earth. An exoplanet candidate in the Luhman 16 binary system was reported in 2017 based on a weak astrometric signature in the analysis of 12 HST epochs. An additional epoch collected in 2018 and r…
Peering above the clouds of the warm Neptune GJ 436 b with CRIRES+
Gandhi, Siddharth; Snellen, Ignas A. G.; Grasser, Natalie +2 more
Context. Exoplanets with masses between Earth and Neptune are amongst the most commonly observed, yet their properties are poorly constrained. Their transmission spectra are often featureless, which indicate either high-altitude clouds or a high atmospheric metallicity. The archetypical warm Neptune GJ 436 b is such a planet showing a flat transmi…
HdC and EHe stars through the prism of Gaia DR3. Evolution of RV amplitude and dust formation rate with effective temperature
Tisserand, P.; Crawford, C. L.; Clayton, G. C. +3 more
Context. The Gaia DR3 release includes heliocentric radial velocity measurements and velocity variability indices for tens of millions of stars observed over 34 months.
Aims: In this study, we utilise these indices to investigate the intrinsic radial velocity variations of Hydrogen-deficient Carbon (HdC) stars and Extreme Helium (EHe) stars a…
JWST-FEAST: Feedback in Emerging extrAgalactic Star clusTers: Calibration of Star Formation Rates in the Mid-infrared with NGC 628
Östlin, Göran; Smith, Linda J.; Melinder, Jens +19 more
New JWST near-infrared imaging of the nearby galaxy NGC 628 from the JWST Cycle 1 program Feedback in Emerging extrAgalactic Star clusTers (JWST-FEAST) is combined with archival JWST mid-infrared imaging to calibrate the 21 µm emission as a star formation rate (SFR) indicator at ∼120 pc scales. The Paα (1.8756 µm) hydrogen recombinatio…
Comparing emission- and absorption-based gas-phase metallicities in GRB host galaxies at z = 2-4 using JWST
Tagliaferri, G.; Salvaterra, R.; D'Elia, V. +34 more
Much of what is known of the chemical composition of the universe is based on emission line spectra from star-forming galaxies. Emission-based inferences are, nevertheless, model-dependent and they are dominated by light from luminous star-forming regions. An alternative and sensitive probe of the metallicity of galaxies is through absorption line…
X-Ray Characterization of the Pulsar PSR J1849-0001 and Its Wind Nebula G32.64+0.53 Associated with TeV Sources Detected by H.E.S.S., HAWC, Tibet ASγ, and LHAASO
Woo, Jooyun; An, Hongjun; Mori, Kaya +6 more
We report on the X-ray emission properties of the pulsar PSR J1849-0001 and its wind nebula (PWN), as measured by Chandra, XMM-Newton, NICER, Swift, and NuSTAR. In the X-ray data, we detected the 38 ms pulsations of the pulsar up to ~60 keV with high significance. Additionally, we found that the pulsar's on-pulse spectral energy distribution displ…