Search Publications
New hot subdwarf variables from the EC survey
Kilkenny, D.; Lynas-Gray, A. E.; Worters, H. L.
We present new results for hot subdwarf stars from the Edinburgh-Cape (EC) blue object survey. EC 03089-6421, an sdO star recently discovered to be a very rapid pulsator with periods near 31.1 and 34.2 s (29.2 and 32.1 mHz), is shown to have an even faster pulsation near 26.6 s (37.6 mHz) although all pulsations are variable in amplitude and effec…
The radial distribution of blue stragglers in Galactic globular cluster NGC 6656 - clues to the dynamical status
Yadav, R. K. S.; Singh, Gaurav
We present the dynamical status of the Galactic globular cluster NGC 6656 using the spatial distribution of blue straggler stars (BSSs). A combination of multi-wavelength high-resolution space- and ground-based data are used to cover a large cluster region. We determine the centre of gravity (Cgrav) and construct the projected density p…
Star formation and polycyclic aromatic hydrocarbons in ELAIS N1 galaxies as seen by AKARI
Burgarella, Denis; Oyabu, Shinki; Kaneda, Hidehiro +4 more
We have examined the relationship between star formation and polycyclic aromatic hydrocarbons (PAHs) in a variety of galaxies. PAHs are excited by the ultraviolet photons of young stars, but they are disassociated by strong UV radiation in starbursts. Therefore their emission (which is in the wavelength range covered by AKARI) can be used as a sta…
The Formation of CME from Coupling Fan-spine Magnetic System: A Difficult Journey
Yang, Jiayan; Hong, Junchao; Chen, Hechao +1 more
We present the eruption of a mini-filament that caused a large-scale complicated coronal mass ejection (CME) on 2014 March 28, using the high-resolution observations taken by the Solar Dynamic Observatory. Three-dimensional coronal magnetic field extrapolated from the nonlinear force-free field code reveals that the magnetic environment of the eru…
Solar-Related Variations of the Cloud Top Circulation Above Aphrodite Terra From VMC/Venus Express Wind Fields
Bertaux, J. -L.; Zasova, L. V.; Titov, D. V. +3 more
Winds derived by a digital tracking technique from ultraviolet (365 nm) images captured by the Venus Monitoring Camera (VMC) onboard the Venus Express spacecraft from 2006 to 2013 were used to study the atmospheric circulation at cloud top level (70 ± 2 km). This data set allows variations of the wind speed with both latitude and longitude to be s…
NSV 1440: first WZ Sge-type object in AM CVn stars and candidates
Nogami, Daisaku; Myers, Gordon; Monard, Berto +5 more
In 2015 and 2017, the AM CVn candidate NSV 1440 showed superoutbursts that had the characteristic features of WZ Sge-type dwarf novae (DNe). By analogy with hydrogen-rich cataclysmic variables (CVs), we can interpret these outbursts as "double superoutbursts" which are composed of a first superoutburst with early superhumps and a second superoutbu…
Radial Velocities, Space Motions, and Nearby Young Moving Group Memberships of Eleven Candidate Young Brown Dwarfs
Alam, Munazza K.; Faherty, Jacqueline K.; Cruz, Kelle L. +5 more
We present new radial velocity (RV) measurements for 11 candidate young very-low-mass stars and brown dwarfs, with spectral types from M7 to L7. Candidate young objects were identified by features indicative of low surface gravity in their optical and/or near-infrared spectra. RV measurements are derived from high-resolution (R =λ/Δλ = 20,000) J-b…
PPMXL and Gaia morphological analysis of Melotte 22 (Pleiades) and Melotte 25 (Hyades)
Elsanhoury, W. H.; Nouh, M. I.
In this article, we present a morphological study of two extended open clusters in the sky, Melotte 22 and Melotte 25 using J, H, and Ks photometry with Gaia DR2 and PPMXL proper motions. Various photometric and kinematic astrophysical parameters have been determined.
Based on proper motions of these clusters, we extract our member…Gaia 8: Discovery of a star cluster containing β Lyrae
Bastian, U.
Aims: The aim here is to try and clarify whether there are stars in the neighbourhood of β Lyrae which are physically connected to the famous prototype eclipsing binary.
Methods: We scrutinised the astrometric and photometric data (from HIPPARCOS and Gaia DR2) of stars in a limited sky field around β Lyrae.
Results: A star cluster o…
Quantifying the Influence of Key Physical Processes on the Formation of Emission Lines Observed by IRIS. I. Non-equilibrium Ionization and Density-dependent Rates
Testa, Paola; Bradshaw, Stephen J.
In the work described here, we investigate atomic processes leading to the formation of emission lines within the Interface Region Imaging Spectrograph wavelength range at temperatures near 105 K. We focus on (1) non-equilibrium and (2) density-dependent effects influencing the formation and radiative properties of S IV and O IV. These …