Search Publications
Flares during eclipses of high-mass X-ray binary systems Vela X-1, 4U 1700-37, and LMC X-4
Paul, Biswajit; Paul, K. T.; Jithesh, V. +2 more
In eclipsing X-ray binary systems, the direct X-ray emission is blocked by the companion star during the eclipse. We observe only reprocessed emission that contains clues about the environment of the compact object and its chemical composition, ionization levels, etc. We have found flares in some X-ray binaries during their eclipses. The study of …
Asymmetry of the spectral lines of the coronal hole and quiet Sun in the transition region
Kayshap, Pradeep; Safari, Hossein; Hosseini, Razieh +1 more
The asymmetry of line profiles, i.e. the secondary component, is crucial to understanding the energy release of coronal holes (CH), quiet Sun (QS), and bright points (BPs). We investigate the asymmetry of Si IV 1393.75 Å of the transition-region (TR) line recorded by Interface Region Imaging Spectrograph (IRIS) and co-spatial-temporal Atmospheric …
The STATiX pipeline for the detection of X-ray transients in three dimensions
Georgakakis, A.; Pierre, M.; Georgantopoulos, I. +3 more
The recent serendipitous discovery of a new population of short duration X-ray transients, thought to be associated with collisions of compact objects or stellar explosions in distant galaxies, has motivated efforts to build up statistical samples by mining X-ray telescope archives. Most searches to date, however, do not fully exploit recent devel…
A cautionary lesson from Gaia systematics: the mono-metallic globular cluster NGC 5904
Bianchini, Paolo; Mastrobuono-Battisti, Alessandra
The study of the chemistry of the stellar populations in globular clusters (GCs) is a fundamental task to unveil their formation in the high-redshift universe and to reconstruct the build-up of our Galaxy. Using metallicity estimates from BP/RP low-resolution Gaia DR3 spectra, a recent work presented the surprizing detection of two stellar populat…
Concurrent kink and sausage waves in a crescent-shaped structure over a limb prominence
Ghiasi, Maryam; Dadashi, Neda; Ebadi, Hossein
A Crescent-shaped prominence Structure (CS) over the solar west limb is studied using Extreme Ultra-Violet (EUV) Imaging Spectrometer/Hinode and Atmospheric Imaging Assembly (AIA)/Solar Dynamics Observatory (SDO). First, the time-varying positions of the top and bottom borders of the CS, along with its central axis, are derived. Time evolutions of…
Mutual occurrence ratio of planets - I. New clues to reveal origins of hot and warm Jupiter from the RV sample
Zhang, Hui; Zhou, Ji-Lin; Su, Xiang-Ning
Many studies have analysed planetary occurrence rates and their dependence on the host's properties to provide clues to planet formation, but few have focused on the mutual occurrence ratio of different kinds of planets. Such relations reveal whether and how one type of planet evolves into another, e.g. from a cold Jupiter (CJ) to a warm Jupiter (…
Looking for timing variations in the transits of 16 exoplanets
Aksaker, N.; Southworth, J.; Mancini, L. +27 more
We update the ephemerides of 16 transiting exoplanets using our ground-based observations, new Transiting Exoplanet Survey Satellite data, and previously published observations including those of amateur astronomers. All these light curves were modelled by making use of a set of quantitative criteria with the EXOFAST code to obtain mid-transit tim…
The stellar 'Snake' - II. The mass function
Qiu, Dan; Bird, Sarah A.; Yang, Xiang-Ming +8 more
We present a comprehensive investigation on the mass function (MF) of a snake-like stellar structure in the solar neighbourhood, building on our previous discovery. To ensure the reliability of the data, we reselect the member stars of the Stellar 'Snake' in the latest Gaia Data Release 3 using the same approach as the initial series of articles. …
Parsec-scale evolution of the gigahertz-peaked spectrum quasar PKS 0858 - 279
Kovalev, Y. Y.; Perucho, M.; Kosogorov, N. A. +1 more
We conducted multi-epoch, multifrequency parsec-scale studies on the gigahertz-peaked spectrum quasar PKS 0858 - 279 with the Very Long Baseline Array (VLBA). Our observations on 2005 November 26 elucidated a weak core, characterized by an inverted spectrum, and a distinctly bent jet that exhibited a notable bright feature in its Stokes I emission…
Revisiting the accretion disc spectra of dwarf novae and nova-like variables: implications for the standard disc model
Pringle, J. E.; Naylor, T.; Zsidi, Gabriella +1 more
Accretion discs are fundamental to much of astronomy. They can occur around stars, both young and old, around compact objects they provide a window into the extremes of physics, and around supermassive black holes in galaxy centres, they generate spectacular luminosities that can outshine the entire galaxy. However, our understanding of the inner …