Search Publications
An all-sky catalogue of stellar reddening values
Paunzen, E.; Prišegen, M.; Faltová, N. +1 more
Context. When observing astronomical objects, we have to deal with extinction (i.e. the absorption and scattering of the emitted radiation by dust and gas between the source and the observer). Interstellar extinction depends on the location of the object and the wavelength. The different extinction laws describing these effects are difficult to es…
Discovery of a hyperluminous quasar at z = 1.62 with Eddington ratio >3 in the eFEDS field confirmed by KOOLS-IFU on Seimei Telescope
Imanishi, Masatoshi; Ueda, Yoshihiro; Toba, Yoshiki +17 more
We report the discovery of a hyperluminous type 1 quasar (eFEDS J082826.9-013911; eFEDS J0828-0139) at
CLASH-VLT: Galaxy cluster MACS J0329–0211 and its surroundings using galaxies as kinematic tracers
Demarco, R.; Grillo, C.; Tozzi, P. +9 more
Context. The study of substructure is an important step in determining how galaxy clusters form. Aims. We aim to gain new insights into the controversial dynamical status of MACS J0329–0211 (MACS0329), a massive cluster at z = 0.4503 ± 0.0003, through a new analysis using a large sample of member galaxies as kinematic tracers. Methods. Our analysi…
Effects of Background Solar Wind and Drag Force on the Propagation of Coronal-mass-ejection-driven Shocks
Wood, Brian E.; Wu, Chin-Chun; Liou, Kan +1 more
The propagation of interplanetary shocks, particularly those driven by coronal mass ejections (CMEs), is still an outstanding question in heliophysics and space weather forecasting. Here, we address the effects of the ambient solar wind on the propagation of two similar CME-driven shocks from the Sun to Earth. The two shock events (CME03, 2010 Apr…
Discovery of 118 New Ultracool Dwarf Candidates Using Machine-learning Techniques
Tang, Shih-Yun; Meisner, Aaron M.; Kirkpatrick, J. Davy +45 more
We present the discovery of 118 new ultracool dwarf candidates, discovered using a new machine-learning tool, named SMDET, applied to time-series images from the Wide-field Infrared Survey Explorer. We gathered photometric and astrometric data to estimate each candidate's spectral type, distance, and tangential velocity. This sample has a photomet…
Exploring the relationship between X-ray binaries and compact star clusters (I): NGC 4490 and NGC 4214
Akyuz, A.; Aksaker, N.; Allak, S. +3 more
We conducted a study to investigate the relationship between X-ray binaries (XRBs) and compact star clusters in the nearby star-forming galaxies NGC 4490 and NGC 4214. By analysing archival data from Chandra, we identified a total of 32 XRBs with X-ray luminosities Lx > 1036 erg s-1 in both galaxies. Utilizing d…
An Unidentified Fermi Source Emitting Radio Bursts in the Galactic Bulge
Schinzel, F. K.; Bower, Geoffrey C.; Demorest, Paul B. +5 more
We report on the detection of radio bursts from the Galactic bulge using the real-time transient detection and localization system, realfast. The pulses were detected commensally on the Karl G. Jansky Very Large Array during a survey of unidentified Fermi γ-ray sources. The bursts were localized to subarcsecond precision using realfast fast-sample…
Suprathermal Outflowing H+ Ions in the Lobe Driven by an Interplanetary Shock: 1. An Observation Event
Mouikis, C. G.; Wang, Chih-Ping; Wang, Xueyi +2 more
To better understand how sharp changes in the solar wind and interplanetary magnetic field conditions affect the ionosphere outflows at high latitudes, we analyze an event observed on 17 July 2002 showing suprathermal (tens to hundreds of eV) outflowing H+ ions in the lobe driven by the impact of an interplanetary (IP) shock. A spacecra…
X-ray flux and spectral variability of the blazar OJ 287 with Suzaku
Gupta, Alok C.; Wiita, Paul J.; Xu, Haiguang +4 more
We present analyses of Suzaku XIS light curves and spectra of the BL Lac object OJ 287 with observations positioned primarily around proposed recurrent optical outbursts. The first two observations were performed in 2007 April 10-13 (epoch 1) and 2007 November 7-9 (epoch 2) that, respectively, correspond to a low and a high optical state and which…
Supervised star, galaxy, and QSO classification with sharpened dimensionality reduction
Trager, S. C.; Lourens, M. A. A.; Kim, Y. +2 more
Aims. We explored the use of broadband colors to classify stars, galaxies, and quasi-stellar objects (QSOs). Specifically, we applied sharpened dimensionality reduction (SDR)-aided classification to this problem, with the aim of enhancing cluster separation in the projections of high-dimensional data clusters to allow for better classification per…