Search Publications
Concurrence of a Kelvin-Helmholtz instability and Kármán vortex street in the Sun's corona
Long, David M.; Fu, Hui; Li, Bo +4 more
Context. Instabilities are crucial to understanding the mass transportation and energy transformation in the solar atmosphere. Observations of the concurrence among the Kelvin-Helmholtz instability (KHI) and Kármán vortex street (KVS) in conditions as extreme as the Sun's corona have yet to be reported.
Aims: We aim to find evidence of a conc…
First r-process enhanced star confirmed as a member of the Galactic bulge
Schultheis, M.; Ryde, N.; Rich, R. M. +4 more
Aims: Stars with strong enhancements of r-process elements are rare and tend to be metal-poor, generally with [Fe/H] < −2 dex, and located in the halo. In this work, we aim to investigate a candidate r-process enriched bulge star with a relatively high metallicity of [Fe/H] ~ − 0.65 dex and to compare it with a previously published r-rich …
The Effelsberg survey of FU Orionis and EX Lupi objects. II. H2O maser observations
Menten, K. M.; Ábrahám, P.; Kóspál, Á. +7 more
Context. FU Orionis (FUor) and EX Lupi (EXor) type objects are two groups of peculiar and rare pre-main sequence low-mass stars that are undergoing powerful accretion outbursts during their early stellar evolution. Although water masers are widespread in star-forming regions and serve as powerful probes of mass accretion and ejection on small scal…
Systematics of planetary ephemeris reference frames inferred from pulsar timing astrometry
Liu, N.; Zhu, Z.; Liu, J. -C. +2 more
Aims: This study aims to investigate the systematic errors in planetary ephemeris reference frames through pulsar timing observations.
Methods: We used the published data sets from several pulsar timing arrays and performed timing analyses for each pulsar using different planetary ephemerides retrieved from the Jet Propulsion Laboratory'…
Transient obscuration event captured in NGC 3227. IV. Origin of the obscuring cloud variability
Kriss, G. A.; Bianchi, S.; Ebrero, J. +13 more
Context. Obscuration events in type I active galactic nuclei (AGN) have been detected more frequently in recent years. The strong flux decrease in the soft X-ray band between observations has been caused by clouds with large column densities transiting our line of sight (LOS) and covering the central AGN. Another event has been captured in NGC 322…
Inaccuracies and biases of the Gaussian size deconvolution for extracted sources and filaments
Men'shchikov, A.
A simple Gaussian size deconvolution method is routinely used to remove the blur of observed images caused by insufficient angular resolutions of existing telescopes, thereby to estimate the physical sizes of extracted sources and filaments. To ensure that the physical conclusions derived from observations are correct, it is necessary to know the …
Toward more accurate RR Lyrae metallicities
Kovacs, Geza; Jurcsik, Johanna
By using a large sample of fundamental mode RR Lyrae stars with published spectroscopic iron abundances and gravities, we point out the importance of correcting these abundances by using more accurate temporal gravities. For the 197 stars with multiple spectra, overall we find [Fe/H] standard deviations of 0.167 (as published), 0.145 (shifted by d…
Accelerated particle beams in a 3D simulation of the quiet Sun. Lower atmospheric spectral diagnostics
Rouppe van der Voort, L.; Carlsson, M.; Gudiksen, B. V. +2 more
Context. Nanoflare heating through small-scale magnetic reconnection events is one of the prime candidates to explain heating of the solar corona. However, direct signatures of nanoflares are difficult to determine, and unambiguous observational evidence is still lacking. Numerical models that include accelerated electrons and can reproduce flarin…
Polarimetry of the potential binary supermassive black hole system in J1430+2303
Antonucci, R.; Blinov, D.; Liodakis, I. +6 more
Context. The growth of supermassive black holes (SMBHs) through merging has long been predicted but its detection remains elusive. However, a promising target has been discovered in the Seyfert-1 galaxy J1430+2303, where two SMBHs may be about to merge.
Aims: If a binary system truly lies at the center of J1430+2303, the usual symmetry expect…
Magnetic reconnection as an erosion mechanism for magnetic switchbacks
Horbury, T. S.; Louarn, P.; Owen, C. J. +3 more
Context. Magnetic switchbacks are localised polarity reversals in the radial component of the heliospheric magnetic field. Observations from Parker Solar Probe (PSP) have shown that they are a prevalent feature of the near-Sun solar wind. However, observations of switchbacks at 1 au and beyond are less frequent, suggesting that these structures ev…