Search Publications
SALT revisits DY Cen: a rapidly evolving strontium-rich single helium star
Rao, N. Kameswara; Lambert, David L.; Jeffery, C. Simon
The hydrogen-deficient star DY Cen has been reported as an R CrB-type variable, an extreme helium star (with some hydrogen), and as a single-lined spectroscopic binary. It has been associated with a dramatic change in visual brightness and colour corresponding to a change in effective temperature ( Teff) of some 20 000 K in the last cen…
Unveiling the stellar origin of the Wolf-Rayet nebula NGC 6888 through infrared observations
Guerrero, M. A.; Toalá, J. A.; Santamaría, E. +5 more
We present a comprehensive infrared (IR) study of the iconic Wolf-Rayet (WR) wind-blown bubble NGC 6888 around WR 136. We use Wide-field Infrared Survey Explorer, Spitzer IRAC, and MIPS and Herschel PACS IR images to produce a sharp view of the distribution of dust around WR 136. We complement these IR photometric observations with Spitzer IRS spe…
Eclipse time variations in the post-common envelope binary V470 Cam
Lynas-Gray, A. E.; Clarke, F.; Bogensberger, D. +1 more
Linear or quadratic relations fitted to the time-dependence of post-common envelope binary eclipse times generally give residuals exhibiting a cyclic variation. Among several possible explanations is the presence of one or more orbiting circumbinary objects causing a reflex motion of the binary centre-of-mass, thereby altering the light-travel-tim…
Large-scale changes of the cloud coverage in the ɛ Indi Ba and Bb system
Henning, T.; Lowry, S.; Snodgrass, C. +23 more
We present the results of 14 nights of I-band photometric monitoring of the nearby brown dwarf binary, ɛ Indi Ba and Bb. Observations were acquired over 2 months, with a total of close to 42 h of coverage at a typically high cadence of 1.4 min. At a separation of just 0.7 arcsec, we do not resolve the individual components, and so effectively trea…
Multiwavelength modelling of the circumstellar environment of the massive protostar AFGL 2591 VLA 3
Motte, F.; Beuther, H.; Kuiper, R. +13 more
We have studied the dust density, temperature, and velocity distributions of the archetypal massive young stellar object (MYSO) AFGL 2591. Given its high luminosity ( $L=2\times 10^5\, \mbox{L$_{\odot}$}$ ) and distance (d = 3.3 kpc), AFGL 2591 has one of the highest $\sqrt{L}/d$ ratio, giving better resolved dust emission than any other MYSO. As …
Setting the scene for BUFFALO: a study of the matter distribution in the HFF galaxy cluster MACS J0416.1-2403 and its parallel field
Diego, J. M.; Steinhardt, C. L.; Koekemoer, A. M. +11 more
In the context of the Beyond Ultradeep Frontier Fields And Legacy Observations (BUFFALO) survey, we present a new analysis of the merging galaxy cluster MACS J0416.1-2403 (z = 0.397) and its parallel field using Hubble Frontier Fields (HFF) data. We measure the surface mass density from a weak-lensing analysis and characterize the overall matter d…
X-ray spectra and light curves of cooling novae and a nova like
Sun, Bangzheng; Orio, Marina; Shugarov, Sergey +3 more
We present X-ray observations of novae V2491 Cyg and KT Eri about 9 yr post-outburst of the dwarf nova and post-nova candidate EY Cyg, and of a VY Scl variable. The first three objects were observed with XMM-Newton, KT Eri also with the Chandra ACIS-S camera, V794 Aql with the Chandra ACIS-S camera and High Energy Transmission Gratings. The two re…
η Carinae: high angular resolution continuum, H30α and He30α ALMA images
Cox, Pierre; Nyman, Lars-Åke; Abraham, Zulema +2 more
We present images of η Carinae in the recombination lines H30α and He30α and the underlying continuum with 50 mas resolution (110 au), obtained with ALMA. For the first time, the 230 GHz continuum image is resolved into a compact core, coincident with the binary system position, and a weaker extended structure to the NW of the compact source. Iso-…
Asymmetric distributions of H2O and SiO masers towards V627 Cas
Kim, Dong-Jin; Rioja, María J.; Dodson, Richard +7 more
We performed simultaneous observations of the $\rm H_2O$ 61,6 - 52,3 (22.235080 GHz) and SiO V = 1, 2, J = 1 → 0, SiO V = 1, J = 2 → 1, 3 → 2 (43.122080, 42.820587, 86.243442, and 129.363359 GHz) masers towards the suspected D-type symbiotic star, V627 Cas, using the Korean VLBI Network. Here, we present astrometrically regis…
Counterparts of Far Eastern Guest Stars: Novae, supernovae, or something else?
Hoffmann, Susanne M.; Vogt, Nikolaus
Historical observations of transients are crucial for studies of their long-term evolution. This paper forms part of a series of papers in which we develop methods for the analysis of ancient data of transient events and their usability in modern science. Prior research on this subject by other authors has focused on looking for historical superno…