Search Publications
Sudden and steady orbital period changes across six classical Nova Eruptions: the end of hibernation and two serious challenges for the magnetic braking model of cataclysmic variable evolution
Schaefer, Bradley E.
I report on two new measures of the sudden change in the orbital period (P) across the nova eruption (ΔP) and the steady period change in quiescence (\dot{P}) for classical novae (CNe) RR Pic and HR Del, bringing a total of six such measures for CNe, all in a final report of my large and long observing program. The fractional changes (ΔP/P) in par…
A disc reflection model for ultra-soft narrow-line Seyfert 1 galaxies
Fabian, Andrew C.; Reynolds, Christopher S.; Jiang, Jiachen +2 more
We present a detailed analysis of the XMM-Newton observations of five narrow-line Seyfert 1 galaxies (NLS1s). They all show very soft continuum emission in the X-ray band with a photon index of Γ ≳ 2.5. Therefore, they are referred to as 'ultra-soft' NLS1s in this paper. By modelling their optical/UV-X-ray spectral energy distribution (SED) with a…
Deflection of the hypervelocity stars by the pull of the Large Magellanic Cloud on the Milky Way
Erkal, D.; Boubert, D.; Gualandris, A.
Stars slingshotted by the supermassive black hole at the Galactic Centre escape from the Milky Way so quickly that their trajectories are almost straight lines. Previous works have shown how these 'hypervelocity stars' (stars moving faster than the local Galactic escape speed) are subsequently deflected by the gravitational field of the Milky Way …
The distribution of dark matter and gas spanning 6 Mpc around the post-merger galaxy cluster MS 0451-03
Smith, Graham P.; Ellis, Richard S.; Massey, Richard +11 more
Using the largest mosaic of Hubble Space Telescope images around a galaxy cluster, we map the distribution of dark matter throughout an ∼6 × 6 Mpc2 area centred on the cluster MS 0451-03 (z = 0.54, $M_{200}=1.65\times 10^{15}\, {\rm M}_{\odot }$ ). Our joint strong- and weak-lensing analysis shows three possible filaments extending from…
A new and unusual LBV-like outburst from a Wolf-Rayet star in the outskirts of M33
Filippenko, Alexei V.; Kilpatrick, Charles D.; Smith, Nathan +8 more
MCA-1B (also called UIT003) is a luminous hot star in the western outskirts of M33, classified over 20 yr ago with a spectral type of Ofpe/WN9 and identified then as a candidate luminous blue variable (LBV). Palomar Transient Factory data reveal that this star brightened in 2010, with a light curve resembling that of the classic LBV star AF And in…
Bi-abundance photoionization models of planetary nebulae: determining the amount of oxygen in the metal-rich component
Morisset, C.; Gómez-Llanos, V.
We study the hypothesis of high-metallicity clumps being responsible for the abundance discrepancy found in planetary nebulae between the values obtained from recombination and collisionally excited lines. We generate grids of photoionization models combining cold metal-rich clumps emitting the heavy element recombination lines, embedded in a norm…
Visible and near-infrared observations of interstellar comet 2I/Borisov with the 10.4-m GTC and the 3.6-m TNG telescopes
Geier, S.; Lara, L. M.; Moreno, F. +15 more
In this work, we present the results of an observational study of 2I/Borisov carried out with the 10.4-m Gran Telescopio Canarias (GTC) and the 3.6-m Telescopio Nazionale Galileo (TNG), both telescopes located at the Roque de Los Muchachos Observatory, in the island of La Palma (Spain). The study includes images in the visible and near-infrared, a…
The interior of Comet 67P/C-G; revisiting CONSERT results with the exact position of the Philae lander
Kofman, Wlodek; Herique, Alain; Rogez, Yves +3 more
CONSERT, a bistatic radar onboard the Rosetta spacecraft and its Philae lander, was designed to probe the nucleus of comet 67P/Churyumov-Gerasimenko with radio waves at 90 MHz frequency. In 2016 September, the exact position of Philae was retrieved, within the region previously identified by CONSERT. This allowed us to revisit the measurements and…
Using Gaia DR2 to solve differential colour refraction and charge transfer efficiency issues
Lin, F. R.; Peng, Q. Y.; Zheng, Z. J.
The Gaia DR2 catalogue released in 2018 gives information about more than one billion stars, including their extremely precise positions that are not affected by the atmosphere, as well as the magnitudes in the G, RP, and BP passbands. This information provides great potential for the improvement of the ground-based astrometry. Based on Gaia DR2, …
The Swift Bulge Survey: optical and near-IR follow-up featuring a likely symbiotic X-ray binary and a focused wind CV
Maccarone, T. J.; Degenaar, N.; Wijnands, R. +13 more
The nature of very faint X-ray transients (VFXTs) - transient X-ray sources that peak at luminosities L_X≲ 10^{36} { erg s^{-1}} - is poorly understood. The faint and often short-lived outbursts make characterizing VFXTs and their multiwavelength counterparts difficult. In 2017 April we initiated the Swift Bulge Survey, a shallow X-ray survey of ∼…