Search Publications
Probing inhomogeneity in the helium ionizing UV background
Kim, Tae-Sun; Syphers, David; Pieri, Matthew M. +1 more
We present an analysis combining the simultaneous measurement of intergalactic absorption by hydrogen ({{H {I}}}), helium ({{He {II}}}), and oxygen ({{O {VI}}}) in UV and optical quasar spectra. The combination of the {{H {I}}} and {{He {II}}} Lyman-alpha forests through η (the ratio of column densities of singly ionized helium to neutral hydrogen…
Optical observations and CYCLOPS post-shock region modelling of the polar V348 Pav
Belloni, Diogo; Rodrigues, Claudia V.; Diaz, Marcos P. +3 more
Post-shock regions (PSR) of polar cataclysmic variables (CVs) produce most of their luminosity and give rise to high circular polarization in optical wavelengths and strong variability on the white dwarf (WD) rotation period, which are distinctive features of these systems. To investigate the polar candidate V348 Pav, we obtained a comprehensive o…
Unveiling the nature of candidate high-mass young stellar objects in the Magellanic Clouds with near-IR spectroscopy
Meixner, Margaret; Reiter, Megan; Nayak, Omnarayani +1 more
As nearby neighbours to the Milky Way, the Large and Small Magellanic Clouds (LMC and SMC) provide a unique opportunity to study star formation in the context of their galactic ecosystems. Thousands of young stellar objects (YSOs) have been characterized with large-scale Spitzer and Herschel surveys. In this paper, we present new near-IR spectrosc…
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…