Search Publications
Envelopes and vertical amplitudes of disc-crossing orbits
Vieira, Ronaldo S. S.; Ramos-Caro, Javier
We recently found that regular orbits in axially symmetric galactic discs have their envelopes Z(R) accurately described by the relation Z(R)∝[ΣI(R)]-1/3, if their amplitudes are comparable to the disc thickness, where ΣI is the surface density of the disc (integrated over its whole vertical range). Moreover, the u…
Magnetic fields and extraordinarily bright radio emission in the X-ray faint galaxy group MRC 0116 + 111
Böhringer, H.; Simionescu, A.; Mernier, F. +4 more
MRC 0116 + 111 is a nearby (z = 0.132) poor galaxy group, which was previously known for exhibiting a bright diffuse radio emission with no central point-like source, presumably related to a past activity of the active galactic nucleus (AGN) in its central cD galaxy. Here, we present an X-ray observation (∼30 ks of cleaned XMM-Newton/EPIC exposure…
Two merging galaxy clusters with very hot shock fronts observed shortly before pericentric passage
Lopes, P. A. A.; Laganá, T. F.; Machado, R. E. G. +2 more
We present a detailed analysis of two merging clusters, from XMM-Newton X-ray archival data: PLCKESZ G036.7+14.9 (z = 0.15; hereafter G036) and PLCK G292.5+22.0 (z = 0.30; hereafter G292). We notice that the intracluster medium (ICM) is heated as a result of the merger, and we find evidence for a merger shock in the region between both subcluster …
The influence of dark matter halo on the stellar stream asymmetry via dynamical friction
Kipper, Rain; Tenjes, Peeter; Tuvikene, Taavi +2 more
We study the effect of dynamical friction on globular clusters (GCs) and on the stars evaporated from the GCs (stellar streams) moving in the Galactic halo. Due to dynamical friction, the position of a GC as a stream progenitor starts to shift with respect to its original position in the reference frame of initial GC orbit. Therefore the stars tha…
Variation of mass accretion rate on to the white dwarf in the dwarf nova VW Hyi in quiescence
Ishida, Manabu; Hayashi, Takayuki; Nakaniwa, Nozomi +1 more
We have analysed a series of Suzaku data and one data set of XMM-Newton of the SU UMa type dwarf nova VW Hyi in optical quiescence. The observed spectra in the 0.2-10 keV band are moderately well represented by multitemperature thermal plasma emission models with a maximum temperature of 5-9 keV and bolometric luminosity of (2.4-5.2) × 1030
TYC 8606-2025-1: a mild barium star surrounded by the ejecta of a very late thermal pulse
Fossati, L.; Gvaramadze, V. V.; Grebel, E. K. +4 more
We report the discovery of a spiral-like nebula with the Wide-field Infrared Survey Explorer and the results of optical spectroscopy of its associated star TYC 8606-2025-1 with the Southern African Large Telescope. We find that TYC 8606-2025-1 is a G8 III star of ≈ 3 M_{⊙ }, showing a carbon depletion by a factor of 2 and a nitrogen enhancement by…
A classifier to detect elusive astronomical objects through photometry
Vig, S.; Ghosh, S. K.; Bhavana, D. +1 more
The application of machine learning principles in the photometric search of elusive astronomical objects has been a less-explored frontier of research. Here, we have used three methods, the neural network and two variants of k-nearest neighbour, to identify brown dwarf candidates using the photometric colours of known brown dwarfs. We initially ch…
V1082-Sgr: A magnetic cataclysmic variable with a lobe-filling companion star
Xu, Xiaojie; Shao, Yong; Li, Xiang-Dong
V1082 Sgr is a cataclysmic variable with accretion luminosity above 1034 erg s-1, indicating a mass-transfer rate above 10^{-9} M_{⊙ } yr-1. However, its K-type companion was suggested to be underfilling its Roche lobe (RL), making the high mass-transfer rate a mystery. In this work we propose a possible model to e…
Optical IFU spectroscopy of a bipolar microquasar jet in NGC 300
Maccarone, T. J.; Motch, C.; Knigge, C. +9 more
We recently reported the discovery of a candidate jet-driving microquasar (S10) in the nearby spiral galaxy NGC 300. However, in the absence of kinematic information, we could not reliably determine the jet power or the dynamical age of the jet cavity. Here, we present optical Multi Unit Spectroscopic Explorer (MUSE) integral field unit (IFU) obse…
Observational constraints on the magnetic field of the bright transient Be/X-ray pulsar SXP 4.78
Tsygankov, Sergey S.; Lutovinov, Alexander A.; Poutanen, Juri +4 more
We report results of the spectral and timing analysis of the Be/X-ray pulsar SXP 4.78 using the data obtained during its recent outburst with NuSTAR, Swift, Chandra, and NICER observatories. Using an overall evolution of the system luminosity, spectral analysis, and variability power spectrum we obtain constraints on the neutron star magnetic fiel…