Search Publications
Outliers: multicolour photometry guiding the search for evolved binary systems in the globular cluster 47 Tucanae
Kepler, S. O.; Montgomery, M. H.; Winget, D. E. +11 more
We use Hubble Space Telescope multicolour photometry of the globular cluster 47 Tucanae to uncover a population of 24 objects with no previous classification that are outliers from the single-star model tracks in the colour-magnitude diagram and yet are likely cluster members. By comparing those sources with evolutionary models and X-ray source ca…
Photoionization modelling of the giant broad-line region in NGC 3998
Devereux, Nick
Prior high angular resolution spectroscopic observations of the Low-ionization nuclear emission-line region (Liner) in NGC 3998 obtained with the Space Telescope Imaging Spectrograph (STIS) aboard the Hubble Space Telescope (HST) revealed a rich UV-visible spectrum consisting of broad permitted and broad forbidden emission lines. The photoionizati…
Testing stellar proper motions of TGAS stars using data from the HSOY, UCAC5 and PMA catalogues
Akhmetov, V. S.; Fedorov, P. N.; Velichko, A. B.
We analyse the stellar proper motions from the Tycho-Gaia Astrometric Solution (TGAS) and those from the ground-based HSOY, UCAC5 and PMA catalogues derived by combining them with Gaia DR1 space data. Assuming that systematic differences in stellar proper motions of the two catalogues are caused by a mutual rigid-body rotation of the reference cat…
RR Lyrae variables in M31 and its satellites: an analysisof the galaxy's population
Sarajedini, Ata; Tanakul, Nahathai
We present an analysis of M31 RR Lyrae stars in six different fields using archival imaging from the Hubble Space Telescope. Published data for M31, M33, and several M31 dwarf spheroidal galaxies are also used to study the global properties of RR Lyrae in these systems. From the properties of RR Lyrae stars, we found that the majority of M31 and M…
The surface magnetic activity of the weak-line T Tauri stars TWA 9A and V1095 Sco
Donati, J. -F.; Hussain, G. A. J.; Wright, D. +5 more
We present a detailed analysis of high-resolution spectropolarimetric observations of the weak-line T Tauri stars (wTTSs) TWA 9A and V1095 Sco as part of a wider survey of magnetic properties and activity in weak-line T Tauri stars, called MaTYSSE (Magnetic Topologies of Young Stars and the Survival of close-in giant Exoplanets). Our targets have …
The big lobe of 67P/Churyumov-Gerasimenko comet: morphological and spectrophotometric evidences of layering as from OSIRIS data
Jorda, L.; Lamy, P. L.; Lara, L. M. +45 more
Between 2014 and 2016, ESA's Rosetta OSIRIS cameras acquired multiple-filters images of the layered nucleus of comet 67P/Churyumov-Gerasimenko, ranging from ultraviolet to near-infrared wavelengths. No correlation between layers disposition and surface spectral variegation has been observed so far. This paper investigates possible spectral differe…
A faint outburst of the accreting millisecond X-ray pulsar SAX J1748.9-2021 in NGC 6440
Mereghetti, S.; Sanna, A.; Di Salvo, T. +6 more
SAX J1748.9-2021 is an accreting X-ray millisecond pulsar observed in outburst five times since its discovery in 1998. In early October 2017, the source started its sixth outburst, which lasted only ∼13 days, significantly shorter than the typical 30 days duration of the previous outbursts. It reached a 0.3-70 keV unabsorbed peak luminosity of ∼3 …
Physical properties and optical-infrared transmission spectrum of the giant planet XO-1 b
Smith, A. M. S.; Mancini, L.; Madhusudhan, N. +3 more
We present 10 high-precision light curves of four transits in the XO-1 planetary system, obtained using u, g, r, redshifted H α, I, and z filters. We use these to measure the physical properties, orbital ephemeris, and a transmission spectrum of the planet covering the full optical wavelength range. We augment this with published HST/WFC3 observat…
Assessment of Phobos gravity field determination from both near polar and near equatorial orbital flyby data
Andert, T.; Li, F.; Yan, J. G. +5 more
The C20 and C22 coefficients of the Phobos gravity field are key parameters to constrain the internal structure of the Martian moon, but reliable observed values of these parameters are still missing. In this paper, we demonstrate, through a combination of forward and inverse modelling of simulated Doppler spacecraft tracking…
Narrow vs. broad-line Seyfert 1 galaxies: X-ray, optical, and mid-infrared AGN characteristics
Popović, Luka Č.; Lakićević, Maša; Kovačević-Dojčinović, Jelena
investigated narrow-line Seyfert 1 galaxies (NLS1s) at optical, mid-infrared (MIR), and X-ray wavelengths, comparing them to the broad-line active galactic nuclei (BLAGNs). We found that black hole mass, coronal line luminosities, X-ray hardness ratio and X-ray, and optical and MIR luminosities are higher for the BLAGNs than for NLS1s, while polic…