Search Publications
Everything that glitters is not gold: V1315 Cas is not a dormant black hole
Guenther, E. W.; Shenar, T.; Boffin, H. M. J. +11 more
The quest for quiet or dormant black holes has been ongoing since several decades. Ellipsoidal variables possibly indicate the existence of a very high-mass invisible companion and are thought to be one of the best ways to find such dormant black holes. This, however, is not a panacea as we show here with one example. We indeed report the discover…
The Initial Mass Function and Other Stellar Properties Across the Core of the Hydra I Cluster
Feldmeier-Krause, A.; Freedman, W. L.; Lonoce, Ilaria
The Hydra I cluster offers an excellent opportunity to study and compare the relic old stellar populations in the core of its two brightest galaxies. In addition, the differing kinematics of the two galaxies allows a test of the local validity of general scaling relations. In this work, we present a direct comparison employing full spectral fittin…
Planar Magnetic Structures Downstream of Coronal Mass Ejection-driven Shocks in the Inner Heliosphere
Xu, Qi; Feng, Xueshang; Shen, Zhenning +7 more
Planar magnetic structures (PMSs), characterized by interplanetary magnetic field vectors remaining parallel to a specific plane, are commonly observed in the solar wind, especially in the sheath region of interplanetary coronal mass ejections (ICMEs). In this study, PMS events in the 2 hr regions downstream of ICME-driven shocks were investigated…
Scaling slowly rotating asteroids with stellar occultations
Geier, S.; Urbanik, M.; Pál, A. +176 more
Context. As evidenced by recent survey results, the majority of asteroids are slow rotators (spin periods longer than 12 h), but lack spin and shape models because of selection bias. This bias is skewing our overall understanding of the spins, shapes, and sizes of asteroids, as well as of their other properties. Also, diameter determinations for l…
Generating Photospheric Vector Magnetograms of Solar Active Regions for SOHO/MDI Using SDO/HMI and BBSO Data with Deep Learning
Xu, Yan; Jing, Ju; Wang, Haimin +6 more
Solar activity is often caused by the evolution of solar magnetic fields. Magnetic field parameters derived from photospheric vector magnetograms of solar active regions (ARs) have been used to analyze and forecast eruptive events, such as solar flares and coronal mass ejections. Unfortunately, the most recent Solar Cycle 24 was relatively weak wi…
Ion Energization and Thermalization in Magnetic Reconnection Exhaust Region in the Solar Wind
Verscharen, Daniel; He, Jiansen; Fedorov, Andrey +7 more
Plasma energization and thermalization in magnetic reconnection is an important topic in astrophysical studies. We select two magnetic reconnection exhausts encountered by Solar Orbiter and analyze the associated ion heating in the kinetic regime. Both cases feature asymmetric plasma merging in the exhaust and anisotropic heating. For a quantitati…
Automated classification of Chandra X-ray point sources using machine learning methods
Bhattacharyya, Sudip; Kumaran, Shivam; Mandal, Samir +1 more
A large number of unidentified sources found by astronomical surveys and other observations necessitate the use of an automated classification technique based on machine learning (ML) methods. The aim of this paper is to find a suitable automated classifier to identify the point X-ray sources in the Chandra Source Catalogue (CSC) 2.0 in the catego…
PENELLOPE. V. The magnetospheric structure and the accretion variability of the classical T Tauri star HM Lup
Kóspál, Á.; Alcalá, J. M.; Manara, C. F. +9 more
HM Lup is a young M-type star that accretes material from a circumstellar disk through a magnetosphere. Our aim is to study the inner disk structure of HM Lup and to characterize its variability. We used spectroscopic data from HST/STIS, X-shooter, and ESPRESSO taken in the framework of the ULLYSES and PENELLOPE programs, together with photometric…
Photospheric and Chromospheric Magnetic Field Evolution during the X1.6 Flare in Active Region NOAA 12192
Guglielmino, S. L.; Romano, P.; Zuccarello, F. +2 more
We report on observations acquired by the Interferometric Bidimensional Spectropolarimeter (IBIS) during SOL2014-10-22T14:02, an X1.6 flare that occurred in active region NOAA 12192, taken in the Fe I 617.30 nm and Ca II 854.2 nm line profiles. We analyze polarization signatures in the Stokes profiles of the two lines across one of the flare ribbo…
Slowly rotating close binary stars in Cassini states
Fuller, Jim; Felce, Catherine
Recent asteroseismic measurements have revealed a small population of stars in close binaries, containing primaries with extremely slow rotation rates. Such stars defy the standard expectation of tidal synchronization in such systems, but they can potentially be explained if they are trapped in a spin-orbit equilibrium known as Cassini state 2 (CS…