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X-ray analysis of the accreting supermassive black hole in the radio galaxy PKS 2251+11
Tombesi, F.; Panessa, F.; Bruni, G. +2 more
Context. We have investigated the dichotomy between jetted and non-jetted active galactic nuclei (AGNs), focusing on the fundamental differences of these two classes in the accretion physics onto the central supermassive black hole (SMBH). We tested the validity of the unification model of AGNs through the characterization of the mutual interactio…
Parameter estimation for scarce stellar populations
Bitsakis, T.; Bruzual, G.; Cervantes Sodi, B. +1 more
We present a Bayesian method to determine simultaneously the age, metallicity, distance modulus, and interstellar reddening by dust of any resolved stellar population, by comparing the observed and synthetic colour magnitude diagrams on a star by star basis, with no need to bin the data into a carefully selected magnitude grid. We test the method …
Reprint of "Evidence for color dichotomy in the primordial Neptunian Trojan population"
Smith, M.; D'Andrea, C. B.; Abbott, T. M. C. +45 more
In the current model of early Solar System evolution, the stable members of the Jovian and Neptunian Trojan populations were captured into resonance from the leftover reservoir of planetesimals during the outward migration of the giant planets. As a result, both Jovian and Neptunian Trojans share a common origin with the primordial disk population…
A Recipe for Finding Stellar Radii, Temperatures, Surface Gravities, Metallicities, and Masses Using Spectral Lines
Gray, David F.; Kaur, Taranpreet
A recipe based on physical principles employs the observed equivalent widths of 10 spectral lines to model the photosphere of a target star. Coupled with the visual magnitude and an absolute flux calibration, the recipe yields the angular radius, effective temperature, surface gravity, and metallicity. With the addition of a parallax, a linear rad…
Optical Spectrum of Distant OH/IR Star V1648 Aql (IRAS 19386+0155)
Klochkova, V. G.; Tavolzhanskaya, N. S.
We present an optical spectrum of the star V1648 Aql (IRAS19386+0155) obtained at the 6-m SAO RAS telescope with a spectral resolution of R ≥ 60 000. Heliocentric radial velocity was measured from numerous metal absorptions is Vr = 10.18 ± 0.05 km s-1 (VLSR = 18.1 km s-1). We determined the atmospheric, …
ALMA, ATCA, and Spitzer Observations of the Luminous Extragalactic Supernova SN 1978K
Kotak, R.; Ryder, S. D.; Smith, I. A. +2 more
Only three extragalactic supernovae have been detected at late times at millimeter wavelengths: SN 1987A, SN 1978K, and SN 1996cr. SN 1978K is a remarkably luminous Type IIn supernova that remains bright at all wavelengths 40 years after its explosion. Here, we present Atacama Large Millimeter/submillimeter Array (ALMA) observations taken in 2016 …
Kinetic Theory of Ion Acoustic Waves Observed at Comet 67P/Churyumov-Gerasimenko
Rehman, Saeed ur; Shah, Asif; Haque, Qamar ul
This work presents the resonance interaction of ion acoustic waves with the cometary plasma as observed at comet 67P/Churyumov-Gerasimenko. The plasma is comprised of cold, warm, and suprathermal electron populations and water ions such that the quasineutrality is satisfied. The cold electron population is found to play a dominant role in the damp…
Absolute parameters of young stars: HX Velorum
Demircan, O.; Özkardeş, B.; Erdem, A. +4 more
We present combined photometric and spectroscopic analyses of the southern multiple star HX Vel. High-resolution spectra of this system were taken at the University of Canterbury Mt. John Observatory in the years 2009-2015. Absolute parameters for HX Vel tend to confirm its young and near-main-sequence nature. We specify the main adopted parameter…
A high signal-to-noise HST spectrum towards J1009+0713: precise absorption measurements in the CGM of two galaxies
Nicastro, Fabrizio; Mathur, Smita; Weinberg, David H. +6 more
High signal-to-noise spectra towards background quasars are crucial for uncovering weak absorption in the circumgalactic medium (CGM) of intervening galaxies, such as the diagnostic lines of N V that provide insight to the ionization process of warm gas but typically have low equivalent widths. We present a new spectrum from the Hubble Space Teles…
Exploring the Asymmetry of the Solar Corona Electron Density with Very Long Baseline Interferometry
Pavlov, Dmitry; Melnikov, Alexey; Aksim, Dan +1 more
The Sun’s corona has interested researchers for multiple reasons, including the search for a solution to the famous coronal heating problem and a purely practical consideration of predicting geomagnetic storms on Earth. There exist numerous different theories regarding the solar corona; therefore, it is important to be able to perform comparative …