Search Publications
Role of host galaxy in the formation of multiple stellar populations: analysis of NGC 1786 and NGC 1898
Goudfrooij, Paul; Niederhofer, Florian; Vanaraj, Viswajith
Even after decades of research, the origin of multiple stellar populations in globular clusters (GCs) remains enigmatic. The question as to whether the galaxy environment plays a role in their formation remains unanswered. To that extent, we analysed two classical (>10 Gyr old) Large Magellanic Cloud GCs, NGC 1786 and NGC 1898, using imaging da…
Twin stars as tracers of binary evolution in the Kepler era
Çakırlı, Ömür; Hoyman, Barış; Özdarcan, Orkun +2 more
We present results of the combined photometric and spectroscopic analysis of four systems that are eclipsing binaries with a twin component (mass ratio q ≃ 1). These are exceptional tools to provide information for probing the internal structure of stars. None of the systems were previously recognized as twin binaries. We used a number of high-res…
Using Gaia DR2 to make a systematic comparison between two geometric distortion solutions
Lin, F. R.; Peng, Q. Y.; Zheng, Z. J.
Gaia Data Release 2 (Gaia DR2) provides high accuracy and precision astrometric parameters (position, parallax, and proper motion) for more than 1 billion sources and is revolutionizing astrometry. For a fast-moving target such as an asteroid, with many stars in the field of view that are brighter than the faint limit magnitude of Gaia (21 Gmag), …
The distances of 61 PGCCs in the second galactic quadrant
Huang, Y.; Chen, B. -Q.; Sun, W. -X. +5 more
Determining the distances to the Planck Galactic cold clumps (PGCCs) is crucial for the measurement of their physical parameters and the study of their Galactic distribution. Based on two large catalogues of stars with robust distances and reddening estimates from the literature, we have estimated accurate distances to 61 PGCCs in the second Galac…
Investigating the true nature of three hard X-ray sources
Palazzi, E.; Masetti, N.; Bird, A. J. +6 more
Many of the new high energy sources discovered both by INTEGRAL/IBIS and Swift/BAT have been characterized thanks to extensive, multiband follow-up campaigns, but there are still objects whose nature remains to be asserted. In this paper, we investigate the true nature of three high energy sources, IGR J12134-6015, IGR J16058-7253, and Swift J2037…
Spectroscopic frequency and mode identification of γ Doradus stars HD 109799 and HD 103257
Pollard, K. R.; Brunsden, E.; Shutt, T. R.
Following frequency and mode identification of two candidate γ Doradus stars, HD 103257 and HD 109799, both can be categorized as bona-fide members of the class. Over 250 high-resolution spectra of the two stars were collected at University of Canterbury Mount John Observatory (UCMJO) using the High Efficiency and Resolution Canterbury University …
Multiwavelength observations of the Galactic X-ray binaries IGR J20155+3827 and Swift J1713.4-4219
Masetti, N.; Bird, A. J.; Fiocchi, M. +4 more
In recent years, thanks to the continuous surveys performed by INTEGRAL and Swift satellites, our knowledge of the hard X-ray/soft gamma-ray sky has greatly improved. As a result it is now populated with about 2000 sources, both Galactic and extra-galactic, mainly discovered by IBIS and BAT instruments. Many different follow-up campaigns have been…
Fundamental properties of stars from Kepler and Gaia data: parallax offset and revised scaling relations
Örtel, S.; Yıldız, M.
Data from the space missions Gaia, Kepler, CoRoT and TESS, make it possible to compare parallax and asteroseismic distances. From the ratio of two densities ρsca/ρπ, we obtain an empirical relation fΔν between the asteroseismic large frequency separation and mean density, which is important for more accurate stella…
Imprints of the secondary interstellar hydrogen atoms at 1 AU
Katushkina, O. A.; Izmodenov, V. V.; Alexashov, D. B. +1 more
In this paper, we search for the possible imprints of the secondary interstellar hydrogen atoms created at the heliospheric boundary in the full-sky maps of the hydrogen fluxes at the Earth orbit. By using our three-dimensional time-dependent kinetic model, the maps of the hydrogen fluxes are calculated for different phases of the solar cycle and …
Exploring the robustness of Keplerian signals to the removal of active and telluric features
Butler, R. P.; Jones, H. R. A.; Vogt, S. +2 more
We examine the influence of activity- and telluric-induced radial velocity (RV) signals on high-resolution spectra taken with an iodine absorption cell. We exclude 2- $\mathring{\rm A}$ spectral chunks containing active and telluric lines based on the well-characterized K1V star α Centauri B and illustrate the method on Epsilon Eridani - an active…