Search Publications
Low-frequency pulse profile variation in PSR B2217+47: evidence for echoes from the interstellar medium
Kramer, M.; Pilia, M.; Grießmeier, J. -M. +17 more
We have observed a complex and continuous change in the integrated pulse profile of PSR B2217+47, manifested as additional components trailing the main peak. These transient components are detected over 6 yr at 150 MHz using the LOw Frequency ARray (LOFAR), but they are not seen in contemporaneous Lovell observations at 1.5 GHz. We argue that prop…
Spectroscopic diagnostics of dust formation and evolution in classical nova ejecta
Shore, Steven N.; Mason, Elena; De Gennaro Aquino, Ivan +1 more
A fraction of classical novae form dust during the early stages of their outbursts. The classical CO nova V5668 Sgr (Nova Sgr. 2015b) underwent a deep photometric minimum about 100 days after outburst that was covered across the spectrum. A similar event was observed for an earlier CO nova, V705 Cas (Nova Cas 1993) and a less optically significant…
Properties of the inner penumbral boundary and temporal evolution of a decaying sunspot
Gömöry, P.; Jurčák, J.; Kuckein, C. +3 more
Context. It has been empirically determined that the umbra-penumbra boundaries of stable sunspots are characterized by a constant value of the vertical magnetic field.
Aims: We analyzed the evolution of the photospheric magnetic field properties of a decaying sunspot belonging to NOAA 11277 between August 28-September 3, 2011. The observation…
A new method for probing magnetic field strengths from striations in the interstellar medium
Federrath, Christoph; Tassis, Konstantinos; Schneider, Nicola +1 more
Recent studies of the diffuse parts of molecular clouds have revealed the presence of parallel, ordered low-density filaments termed striations. Flows along magnetic field lines, Kelvin-Helmholtz instabilities and hydromagnetic waves are amongst the various formation mechanisms proposed. Through a synergy of observational, numerical, and theoretic…
Cresting the wave: proper motions of the Eastern Banded Structure
Belokurov, Vasily; Koposov, Sergey E.; Deason, Alis J.
We study the kinematic properties of the Eastern Banded Structure (EBS) and Hydra I overdensity using exquisite proper motions derived from the Sloan Digital Sky Survey (SDSS) and Gaia source catalogue. Main sequence turn-off stars in the vicinity of the EBS are identified from SDSS photometry; we use the proper motions and, where applicable, spec…
Mapping Excitation in the Inner Regions of the Planetary Nebula NGC 5189 Using HST WFC3 Imaging
Karovska, Margarita; Montez, Rodolfo, Jr.; Maksym, W. Peter +1 more
The planetary nebula (PN) NGC 5189 around a Wolf-Rayet [WO] central star demonstrates one of the most remarkable complex morphologies among PNe with many multiscale structures, showing evidence of multiple outbursts from an asymptotic giant branch (AGB) progenitor. In this study, we use multiwavelength Hubble Space Telescope Wide Field Camera 3 ob…
Thirty-fold: Extreme Gravitational Lensing of a Quiescent Galaxy at z = 1.6
Brammer, G.; Toft, S.; Richard, J. +4 more
We report the discovery of eMACSJ1341-QG-1, a quiescent galaxy at z = 1.594 located behind the massive galaxy cluster eMACSJ1341.9-2442 (z = 0.835). The system was identified as a gravitationally lensed triple image in Hubble Space Telescope images obtained as part of a snapshot survey of the most X-ray luminous galaxy clusters at z > 0.5 and s…
The Pleiades apex and its kinematical structure
Yadav, R. K. S.; Vereshchagin, S. V.; Chupina, N. V. +4 more
A study of cluster characteristics and internal kinematical structure of the middle-aged Pleiades open star cluster is presented. The individual star apexes and various cluster kinematical parameters including the velocity ellipsoid parameters are determined using both Hipparcos and Gaia data. Modern astrometric parameters were taken from the Gaia…
V1224 Cas: An EL CVn-type Eclipsing Binary Consisting of a Helium White Dwarf Precursor and a Delta Scuti Pulsator
Deng, Licai; Zhang, Xiaobin; Wang, Kun +3 more
We report the discovery of a new eclipsing EL CVn-type binary, consisting of a δ Sct-type pulsator and a thermally bloated low-mass pre-He white dwarf (WD). Spectroscopy and time-series BV photometry of V1224 Cas were carried out. The spectroscopy reveals a spectral type of A3 for the star. Light curve modeling indicates that V1224 Cas is a short-…
Equatorial Oscillation and Planetary Wave Activity in Saturn's Stratosphere Through the Cassini Epoch
Fletcher, L. N.; Flasar, F. M.; Spiga, A. +4 more
Thermal infrared spectra acquired by Cassini/Composite InfraRed Spectrometer (CIRS) in limb-viewing geometry in 2015 are used to derive 2-D latitude-pressure temperature and thermal wind maps. These maps are used to study the vertical structure and evolution of Saturn's equatorial oscillation (SEO), a dynamical phenomenon presenting similarities w…