Search Publications
Extending Gaia DR2 with HST narrow-field astrometry - II. Refining the method on WISE J163940.83-684738.6
Bedin, L. R.; Fontanive, C.
In the second paper of this series, we perfected our method of linking high-precision Hubble Space Telescope astrometry to the high-accuracy Gaia DR2 absolute reference system to overcome the limitations of relative astrometry with narrow-field cameras. Our test case here is the Y brown dwarf WISE J163940.83-684738.6, observed at different epochs …
Secular changes in the orbits of the quadruple system VW LMi
Kundra, E.; Budaj, J.; Szabó, Gy M. +8 more
VW LMi is the tightest known quadruple system with 2 + 2 hierarchy. It consists of a W UMa-type eclipsing binary (P12 = 0.477 55 d) and another detached non-eclipsing binary (P34 = 7.93 d) orbiting around a common centre of mass in about P1234 = 355 d. We present new observations of the system extending the time ba…
The cooling-down central star of the planetary nebula SwSt 1: a late thermal pulse in a massive post-AGB star?
Hamann, Wolf-Rainer; Todt, Helge; Zijlstra, Albert A. +3 more
SwSt 1 (PN G001.5-06.7) is a bright and compact planetary nebula containing a late [WC]-type central star. Previous studies suggested that the nebular and stellar lines are slowly changing with time. We studied new and archival optical and ultraviolet spectra of the object. The [O III] 4959 and 5007 Å to H β line flux ratios decreased between abou…
The efficiency of nuclear burning during thermonuclear (Type I) bursts as a function of accretion rate
Cavecchi, Y.; Galloway, D. K.; Heger, A. +2 more
We measured the thermonuclear burning efficiency as a function of accretion rate for the Type I X-ray bursts of five low-mass X-ray binary systems. We chose sources with measured neutron star spins and a substantial population of bursts from a large observational sample. The general trend for the burst rate is qualitatively the same for all source…
High-resolution spectroscopy of the high-velocity hot post-AGB star IRAS 18379-1707 (LS 5112)
Hubrig, S.; Parthasarathy, M.; Ikonnikova, N. P. +2 more
The high-resolution (R∼ 48 000) optical spectrum of the B-type supergiant LS 5112, identified as the optical counterpart of the post-AGB candidate IRAS 18379-1707 is analysed. We report the detailed identifications of the observed absorption and emission features in the wavelength range 3700-9200 Å for the first time. The absorption line spectrum …
Variable stars in the field of intermediate-age open cluster NGC 559
Joshi, Y. C.; John, Ancy A.; Maurya, J. +3 more
This work presents the first long-term photometric variability survey of the intermediate-age open cluster NGC 559. Time series V-band photometric observations on 40 nights taken over more than 3 yr with three different telescopes are analysed to search for variable stars in the cluster. We investigate the data for the periodicity analysis and rev…
NaCo polarimetric observations of Sz 91 transitional disc: a remarkable case of dust filtering
Villaver, Eva; Pinte, Christophe; Zurlo, Alice +10 more
We present polarized light observations of the transitional disc around Sz 91 acquired with VLT/NaCo at H (1.7µm) and Ks (2.2µm) bands. We resolve the disc and detect polarized emission up to ∼0.5 arcsec (∼80 au) along with a central cavity at both bands. We computed a radiative transfer model that accounts for the main char…
Analysis of spiral structure in the accretion disc of the nova-like cataclysmic variable EC21178-5417
Groot, P. J.; Woudt, P. A.; Ruiz-Carmona, R. +1 more
We present an extensive Doppler tomography study of the eclipsing nova-like EC21178-5417, which exhibits the classic accretion disc signature in the form of double-peak emission lines in its spectrum. Doppler tomograms confirm the presence of a strong, two-armed spiral pattern visible in the majority of the spectral lines studied. This makes EC211…
Searches for pulsar-like candidates from unidentified objects in the Third Catalog of Hard Fermi-LAT Sources with machine learning techniques
Cheng, K. S.; Takata, J.; Kong, A. K. H. +7 more
We report the results of searching pulsar-like candidates from the unidentified objects in the Third Catalog of Hard Fermi-LAT Sources (3FHL). Using a machine-learning-based classification scheme with a nominal accuracy of $\sim \!98{{\, \rm per\, cent}}$, we have selected 27 pulsar-like objects from 200 unidentified 3FHL sources for an identifica…
Constraining VLBI-optical offsets in high redshift galaxies using strong gravitational lensing
Barnacka, Anna; Spingola, Cristiana
We present a multiwavelength analysis of two highly magnified strong gravitationally lensed galaxies, CLASS B0712+472 and CLASS B1608+656, at redshifts 1.34 and 1.394, respectively, using new VLBI (very long baseline interferometry) and archival Hubble Space Telescope observations. We reconstruct the positions of the radio and optical emissions wi…