Search Publications
Photometric variable stars in the young open cluster NGC 6823
Chen, W. P.; Bhatt, B. C.; Pandey, J. C. +8 more
We present stellar variability towards the young open cluster NGC 6823. Time series V- and I-band CCD photometry led to identification and characterization of 88 variable stars, of which only 14 have been previously recognized. We ascertain the membership of each variable with optical UBVI and infrared photometry, and with Gaia EDR3 parallax and p…
The source of electrons at comet 67P
Nilsson, H.; Goetz, C.; Henri, P. +8 more
We examine the origin of electrons in a weakly outgassing comet, using Rosetta mission data and a 3D collisional model of electrons at a comet. We have calculated a new data set of electron-impact ionization (EII) frequency throughout the Rosetta escort phase, with measurements of the Rosetta Plasma Consortium's Ion and Electron Sensor (RPC/IES). …
Solar active region magnetic parameters and their relationship with the properties of halo coronal mass ejections
Moon, Y. -J.; Shanmugaraju, A.; Ebenezer, E. +2 more
The coronal mass ejections (CMEs) from the sun consist of the plasma and strong magnetic fields (∼4-5 G at 1.3 R⊙) and generally, the fast CMEs are often associated with energetic particles of energy few hundreds of MeV. When the fast CMEs are ejected towards the Earth, they can disrupt the flow of solar wind in the heliosphere and impa…
Investigating starburst-driven neutrino emission from galaxies in the Great Observatories All-Sky LIRG Survey
Privon, G. C.; van Eijndhoven, N.; Merckx, Y. +3 more
We present a phenomenological framework for starburst-driven neutrino production via proton-proton collisions and apply it to (ultra)luminous infrared galaxies (U/LIRGs) in the Great Observatories All-Sky LIRG Survey (GOALS). The framework relates the infrared luminosity of a GOALS galaxy, derived from consistently available Herschel Space Observa…
The HARPS search for southern extra-solar planets. XLVII. Five Jupiter-mass planets in long-period orbits, one highly irradiated Neptune, one brown dwarf, and five stellar binaries
Bouchy, F.; Moutou, C.; Queloz, D. +10 more
Context. The long-term ongoing HARPS radial velocity survey of extra-solar planets initiated in 2003 provides a unique data set with a 19-yr baseline that allows the detection of long-period exoplanets, brown dwarfs, and low-mass binaries.
Aims: Our aim is to detect and characterise long-period companions around main sequence stars (spectral …
Chemodynamical ages of small-scale kinematic structures of the galactic disc in the solar neighbourhood from 250 000 K and M dwarfs
Lépine, Sébastien; Medan, Ilija
We combine photometric metallicities with astrometry from Gaia DR3 to examine the chemodynamic structure of ~250 000 K dwarfs in the solar neighbourhood (SN). In kinematics, we observe ridges/clumps of 'kinematic groups', like studies of more massive main-sequence stars. Here, we note clear differences in both metallicity and vertical velocity as …
Ultraluminous quasars at high redshift show evolution in their radio-loudness fraction in both redshift and ultraviolet luminosity
D'Eugenio, Francesco; Norris, Ray P.; Onken, Christopher A. +1 more
We take a sample of 94 ultraluminous, optical quasars from the search of over 14 486 deg2 by Onken et al. in the range 4.4 < redshift < 5.2 and match them against the Rapid ASKAP Continuum Survey (RACS) observed on the Australian Square Kilometre Array Pathfinder (ASKAP). From this most complete sample of the bright end of the red…
Hubble Space Telescope Proper Motion Measurements of Supernova Remnant N132D: Center of Expansion and Age
Blair, William P.; Law, Charles J.; Morse, Jon A. +8 more
We present proper motion measurements of the oxygen-rich ejecta of the LMC supernova remnant N132D using two epochs of Hubble Space Telescope Advanced Camera for Surveys data spanning 16 years. The proper motions of 120 individual knots of oxygen-rich gas were measured and used to calculate a center of expansion (CoE) of α = 5h25m<…
Behaviour of 27-Day and 13.5-Day Periodicities in Galactic Cosmic Particles as Observed by Spacecraft and Neutron Monitors During Different Solar Polarity Cycles
Kotzé, Pieter
An analysis has been made of the behaviour of the 27-day and 13.5-day periodicities in proton, C, and O galactic-cosmic-ray (GCR) particles at different energies as observed by the Advanced Composition Explorer (ACE) and SOHO (Solar and Heliospheric Observatory) spacecraft during both Solar Cycles 23 and 24. In addition, the behaviour of the 27-da…
Wrinkles in Time. I. Rapid Rotators Found in High-eccentricity Orbits
Rampalli, Rayna; Curtis, Jason L.; Newton, Elisabeth R. +2 more
Recent space-based missions have ushered in a new era of observational astronomy, where high-cadence photometric light curves for thousands to millions of stars in the solar neighborhood can be used to test and apply stellar age-dating methods, including gyrochronology. Combined with precise kinematics, these data allow for powerful new insights i…