Search Publications
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…
MHD simulation of the solar wind flow around the coma of comet Churyumov-Gerasimenko during Rosetta's flyby
Baranov, V. B.; Alexashov, D. B.; Lebedev, M. G.
The magnetohydrodynamic (MHD) model of the interaction between the solar wind and a cometary ionosphere is applied to investigate certain peculiar features of the solar wind flow around comet Churyumov-Gerasimenko during Rosetta's flyby at this comet. The model accounts for photoionization of the neutral component of the cometary outflow and the r…
A method to analyse velocity structure
Arnold, Becky; Goodwin, Simon P.
We present a new method of analysing and quantifying velocity structure in star-forming regions suitable for the rapidly increasing quantity and quality of stellar position-velocity data. The method can be applied to data in any number of dimensions, does not require the centre or characteristic size (e.g. radius) of the region to be determined, a…
Early science with the Large Millimetre Telescope: new mm-wave detections of circumstellar discs in IC 348 from LMT/AzTEC
Gutermuth, Robert A.; Lane, James; Wilson, Grant W. +2 more
We present the most complete sample of mm measurements of protoplanetary discs in the star-forming region IC 348 to date. New observations from the Large Millimetre Telescope and the 1.1 mm camera AzTEC are combined with literature results in order to characterize the disc population as relating to both stellar properties within the IC 348 region …