Search Publications
A distortion solution for the Bok telescope with four CCD chips
Wang, N.; Peng, Q. Y.; Zhou, X. +2 more
The Beijing-Arizona Sky Survey (BASS) is an imaging survey that uses the 2.3-m Bok telescope at Kitt Peak. In order to realize the astrometric potential of the Bok telescope and improve the astrometry of BASS, a distortion solution for the Bok telescope is needed. In the past, we used a single lookup table to correct all the positional errors. How…
Soft and hard X-ray dips in the light curves of γ Cassiopeiae
Smith, M. A.; Lopes de Oliveira, R.
The available six archival XMM-Newton observations of the anomalous X-ray emitter γ Cas (B0.5 IVe) have been surveyed for the presence of soft X-ray `dips' in X-ray light curves. In addition to discovering such events in the soft band (≤2 keV), we show that sometimes they are accompanied by minor, nearly simultaneous dips in the hard X-ray band. H…
A likely runaway star cluster in the outer disc of the Large Magellanic Cloud
Grebel, Eva K.; Piatti, Andrés E.; Salinas, Ricardo
We present results from photometric and spectroscopic data obtained with SOAR and Gemini observatory facilities in the field of a recently discovered star cluster. The cluster, projected towards the Eastern side of the outer disc of the Large Magellanic Cloud (LMC), was originally placed nearly 10 kpc behind the LMC with an age and metallicity typ…
On the structure of the Pleiades cluster
Krełowski, J.; Galazutdinov, G. A.; Strobel, A. +2 more
The data available on the distances (both from Gaia DR2 and those determined from interstellar Ca II lines) to the brightest stars in the Pleiades (`Seven Sisters' and their `parents') suggest that these stars highly likely do not form a compact cluster but are localized in front of the main (Pleiades) cluster - at a distance close to that given b…
On the geometry of the X-ray emission from pulsars: the changing aspect of the Be/X-ray pulsar SXP348
Zezas, A.; Coe, M. J.; Laycock, S. G. T. +2 more
The X-ray source SXP348 is a high-mass X-ray binary system in the Small Magellanic Cloud. Since its 1998 discovery by BeppoSAX, this pulsar has exhibited a spin period of ∼340-350 s. In an effort to determine the orientation and magnetic geometry of this source, we used our geometric model Polestar to fit 71 separate pulse profiles extracted from …
NGC 7457: evidence for merger-driven cylindrical rotation in disc galaxies
Peletier, R. F.; Falcón-Barroso, J.; Aguerri, J. A. L. +7 more
We construct Schwarzschild orbit-based models of NGC 7457, known as a peculiar low-mass lenticular galaxy. Our best-fitting model successfully retrieves most of the unusual kinematics behaviours of this galaxy, in which, the orbital distribution of stars is dominated by warm and hot orbits. The reconstructed surface brightness of the hot component…
The HST Large Programme on NGC 6752. I. Serendipitous discovery of a dwarf Galaxy in background
Salaris, M.; Apai, D.; Anderson, J. +12 more
As part of a large Hubble Space Telescope investigation aiming at reaching the faintest stars in the Galactic globular cluster NGC 6752, an Advanced Camera for Surveys/Wide Field Channel field was the subject of deep optical observations reaching magnitudes as faint as V ∼ 30. In this field, we report the discovery of Bedin I, a dwarf spheroidal g…
High-velocity runaway binaries from supernovae in triple systems
Li, Jiao; Jia, Shi; Gao, Yan
Recent studies on hypervelocity stars (HVSs) have generated a need to understand the high velocity limits of binary systems. If runaway binary systems with high movement speeds well in excess of 200 km s-1 were to exist, it would have implications on how HVS candidates are selected, and our current understanding of how they form needs t…
An unusually large gaseous transit in a debris disc
Wahhaj, Zahed; Kennedy, Grant M.; Godoy, Nicolás +9 more
We present the detection of an unusually large transient gas absorption in several ionized species in the debris disc star HD 37306 using high-resolution optical spectra. We have been analysing a large sample of debris discs searching for circumstellar gas absorptions aiming to determine the frequency of gas in debris discs. HD 37306 stood out sho…
The case for a high-redshift origin of GRB 100205A
Cenko, S. B.; Lyman, J. D.; Berger, E. +15 more
The number of long gamma-ray bursts (GRBs) known to have occurred in the distant Universe (z > 5) is small (∼15); however, these events provide a powerful way of probing star formation at the onset of galaxy evolution. In this paper, we present the case for GRB 100205A being a largely overlooked high-redshift event. While initially noted as a h…