Search Publications
Predicting CME arrival time through data integration and ensemble learning
Xu, Yan; Jing, Ju; Wang, Haimin +7 more
The Sun constantly releases radiation and plasma into the heliosphere. Sporadically, the Sun launches solar eruptions such as flares and coronal mass ejections (CMEs). CMEs carry away a huge amount of mass and magnetic flux with them. An Earth-directed CME can cause serious consequences to the human system. It can destroy power grids/pipelines, sa…
Dynamical parallax, physical parameters, and evolutionary status of the components of the bright eclipsing binary α Draconis
Bodensteiner, J.; Bowman, D. M.; Tkachenko, A. +13 more
Aims: Both components of the bright eclipsing binary α Dra have been resolved using long baseline interferometry and the secondary component has been shown to contribute approximately 15% of the total flux; however, a spectroscopic detection of the companion star has so far been unsuccessful. We aim for a firm spectroscopic detection of the s…
On the Origin of the Dichotomy of Stellar Activity Cycles
Corsaro, Enrico; Bonanno, Alfio
The presence of possible correlations between stellar rotation rate Ω and the frequency of the activity cycle ω cyc is still much debated. We implement a new Bayesian classification algorithm based on a simultaneous regression analysis of multiple scaling laws and we demonstrate the existence of two different scalings in the ${\mathrm{l…
Lithium on the lower red giant branch of five Galactic globular clusters
Salaris, M.; Pancino, E.; Monaco, L. +3 more
Context. Lithium is one of the few elements produced during Big Bang nucleosynthesis in the early universe. Moreover, its fragility makes it useful as a proxy for stellar environmental conditions. As such, the lithium abundance in old systems is at the core of various astrophysical investigations.
Aims: Stars on the lower red giant branch are…
Asteroid astrometry by stellar occultations: Accuracy of the existing sample from orbital fitting
Tanga, P.; Spoto, F.; Herald, D. +2 more
Context. The technique of stellar occultations, greatly enhanced by the publication of the Gaia data releases, permits not only the determination of asteroid size and shape, but also the retrieval of additional, very accurate astrometry, with a possible relevant impact on the study of dynamical properties. The use of Gaia as reference catalogue an…
The GALAH Survey: A New Sample of Extremely Metal-poor Stars Using a Machine-learning Classification Algorithm
Lewis, Geraint F.; Spitler, Lee R.; Ting, Yuan-Sen +21 more
Extremely metal-poor (EMP) stars provide a valuable probe of early chemical enrichment in the Milky Way. Here we leverage a large sample of ~600,000 high-resolution stellar spectra from the GALAH survey plus a machine-learning algorithm to find 54 candidates with estimated [Fe/H] ≤-3.0, six of which have [Fe/H] ≤-3.5. Our sample includes ~20% main…
Asteroid phase curves using sparse Gaia DR2 data and differential dense light curves
Shevchenko, V.; Kwiatkowski, T.; Oszkiewicz, D. +10 more
The amount of sparse asteroid photometry being gathered by both space- and ground-based surveys is growing exponentially. This large volume of data poses a computational challenge owing to both the large amount of information to be processed and the new methods needed to combine data from different sources (e.g. obtained by different techniques, i…
Optical Light Curve of 4FGL J0935.3+0901: A Flaring Black Widow Candidate
Halpern, Jules P.
I obtained time-series photometry of the compact binary candidate for the Fermi source 4FGL J0935.3+0901. Superposed on the 2.44 hr orbital modulation are day-to-day variations and frequent flaring as seen in several redback and black widow millisecond pulsars (MSPs). The short orbital period favors a black widow. While the modulation of ≤1 mag is…
Photometric properties of nuclear star clusters and their host galaxies in the Fornax cluster
Janz, Joachim; Peletier, Reynier F.; Salo, Heikki +2 more
Aims: We aim to investigate the relations between nuclear star clusters (NSCs) and their host galaxies and to offer a comparison between the structural properties of nucleated and non-nucleated galaxies. We also address the environmental influences on the nucleation of galaxies in the Fornax main cluster and the Fornax A group.
Methods: …
The Factory and the Beehive. IV. A Comprehensive Study of the Rotation X-Ray Activity Relation in Praesepe and the Hyades
Cargile, Phillip A.; Rampalli, Rayna; Law, Nicholas M. +7 more
X-ray observations of low-mass stars in open clusters are critical to understanding the dependence of magnetic activity on stellar properties and their evolution. Praesepe and the Hyades, two of the nearest, most-studied open clusters, are among the best available laboratories for examining the dependence of magnetic activity on rotation for stars…