Search Publications
OGLE-ing the Magellanic System: RR Lyrae Stars in the Bridge
Udalski, Andrzej; Mróz, Przemek; Szymański, Michał K. +12 more
We use the extended and updated Optical Gravitational Lensing Experiment (OGLE) Collection of Variable Stars to thoroughly analyze the distribution of RR Lyrae stars in the Magellanic Bridge. We use photometric metallicities to derive the absolute Wesenheit magnitude and individual distance of each RR Lyrae star. We confirm results from our earlie…
The Slow Heartbeats of an Ultraluminous X-Ray Source in NGC 3621
Salvaterra, R.; Tiengo, A.; Marelli, M. +6 more
We report on the results of X-ray observations of 4XMM J111816.0-324910, a transient ultraluminous X-ray source located in the galaxy NGC 3621. This system is characterized by a transient nature and marked variability with a characteristic timescale of ≈3500 s, in contract with other ultraluminous X-ray sources, which in the vast majority show lim…
A high-precision abundance analysis of the nuclear benchmark star HD 20
Grebel, Eva K.; Hanke, Michael; Hansen, Camilla Juul +4 more
Metal-poor stars with detailed information available about their chemical inventory pose powerful empirical benchmarks for nuclear astrophysics. Here we present our spectroscopic chemical abundance investigation of the metal-poor ([Fe/H] = -1.60 ± 0.03 dex), r-process-enriched ([Eu/Fe] = 0.73 ± 0.10 dex) halo star
SS433: A massive X-ray binary in an advanced evolutionary stage
Cherepashchuk, Anatol; Postnov, Konstantin; Molkov, Sergey +2 more
INTEGRAL IBIS/ISGRI 18-60 keV observations of SS433 performed in 2003-2011 enabled for the first time the hard X-ray phase-resolved orbital and precessional light curves and spectra to be constructed. The spectra can be fitted by a power-law with photon index ≃ 3.8 and remain almost constant while the X-ray flux varies by a factor of a few. This s…
Matched Photometric Catalogs of GALEX UV Sources with Gaia DR2 and SDSS DR14 Databases (GUVmatch)
Bianchi, Luciana; Shiao, Bernard
We have matched the ultraviolet (UV) sources in GUVcat_AIS with optical databases that have similar depth and wide sky coverage. GUVcat_AIS has Galaxy Evolution Explorer (GALEX) far-UV (FUV, λeff ∼ 1528 Å) and near-UV (NUV, λeff ∼ 2310 Å) photometry of ≈83 million sources, covering 24,788 square degrees of the sky, with a typ…
The Metallicity Gradient and Complex Formation History of the Outermost Halo of the Milky Way
Yoon, Jinmi; Beers, Timothy C.; Placco, Vinicius M. +1 more
We present an examination of the metallicity distribution function of the outermost stellar halo of the Galaxy based on an analysis of both local (within 4 kpc of the Sun, ∼16,500 stars) and non-local (∼21,700 stars) samples. These samples were compiled using spectroscopic metallicities from the Sloan Digital Sky Survey and photometric metalliciti…
The AGN fuelling/feedback cycle in nearby radio galaxies - III. 3D relative orientations of radio jets and CO discs and their interaction
Davis, Timothy A.; Bureau, Martin; Paladino, Rosita +4 more
This is the third paper of a series exploring the multifrequency properties of a sample of eleven nearby low-excitation radio galaxies (LERGs) in the southern sky. We are conducting an extensive study of different galaxy components (stars, dust, warm and cold gas, radio jets) with the aim of better understanding the AGN fuelling/feedback cycle in …
Helium abundances and its radial gradient from the spectra of H II regions and ring nebulae of the Milky Way
Méndez-Delgado, J. E.; Arellano-Córdova, K. Z.; García-Rojas, J. +2 more
We determine the radial abundance gradient of helium in the disc of the Galaxy from published spectra of 19 H II regions and ring nebulae surrounding massive O-type stars. We revise the Galactocentric distances of the objects considering Gaia DR2 parallaxes (Gaia Collaboration 2018) and determine the physical conditions and the ionic abundance of …
The SOFIA Massive (SOMA) Star Formation Survey. III. From Intermediate- to High-mass Protostars
Yang, Yao-Lun; Tanaka, Kei E. I.; Zhang, Yichen +9 more
We present $\sim 10\mbox{--}40\,\mu {\rm{m}}$ SOFIA-FORCAST images of 14 intermediate-mass protostar candidates as part of the SOFIA Massive (SOMA) Star Formation Survey. We build spectral energy distributions, also using archival Spitzer, Herschel, and IRAS data. We then fit the spectral energy distributions with radiative transfer models of Zhan…
Heating at the Remote Footpoints as a Brake on Jet Flows along Loops in the Solar Atmosphere
Fu, Hui; Li, Bo; Xia, Lidong +3 more
We report on observations of a solar jet propagating along coronal loops taken by the Solar Dynamics Observatory, the Interface Region Imaging Spectrograph, and the 1 m New Vacuum Solar Telescope. The ejecta of the jet consist of multithermal components and propagate with a speed greater than 100 km s-1. Brightenings are found in the re…