Search Publications
Exoplanet transits with next-generation radio telescopes
Pope, Benjamin J. S.; Withers, Paul; Vogt, Marissa F. +1 more
Nearly everything we know about extrasolar planets to date comes from optical astronomy. While exoplanetary aurorae are predicted to be bright at low radio frequencies (<1 GHz), we consider the effect of an exoplanet transit on radio emission from the host star. As radio emission from solar-like stars is concentrated in active regions, a planet…
Ongoing astrometric microlensing events from VVV and Gaia
Evans, N. W.; Belokurov, V.; Lucas, P. W. +2 more
We extend predictive microlensing event searches using the Vista Variables in the Via Lactea survey and the second Gaia data release. We identify two events with maxima in 2019 that require urgent follow-up. First, we predict that the nearby M2 dwarf L 338-152 will align with a background source with a closest approach of 35^{+35}_{-23} mas on 201…
Directly testing gravity with Proxima Centauri
Kroupa, Pavel; Banik, Indranil
The wide binary orbit of Proxima Centauri around α Centauri A and B differs significantly between Newtonian and Milgromian dynamics (MOND). By combining previous calculations of this effect with mock observations generated using a Monte Carlo procedure, we show that this prediction can be tested using high precision astrometry of Proxima Centauri.…
High-degree gravity modes in the single sdB star HD 4539
Heber, U.; Reed, M. D.; Silvotti, R. +6 more
HD 4539 (alias PG 0044 + 097 or EPIC 220641886) is a bright (V = 10.2) long-period V1093 Her-type subdwarf B (sdB) pulsating star that was observed by the Kepler spacecraft in its secondary (K2) mission. We use the K2 light curve (78.7 d) to extract 169 pulsation frequencies, 124 with a robust detection. Most of these frequencies are found in the …
Luminous AGB variables in the dwarf irregular galaxy, NGC 3109
Matsunaga, Noriyuki; Whitelock, Patricia A.; Feast, Michael W. +1 more
In a shallow near-infrared survey of the dwarf irregular galaxy, NGC 3109, near the periphery of the Local Group, we have found eight Mira variables, seven of which appear to be oxygen-rich (O-Miras). The periods range from about 430 d to almost 1500 d. Because of our relatively bright limiting magnitude, only 45 of the more than 400 known carbon …
Machine-learning identification of asteroid groups
Carruba, V.; Aljbaae, S.; Lucchini, A.
Asteroid families are groups of asteroids that share a common origin. They can be the outcome of a collision or be the result of the rotational failure of a parent body or its satellites. Collisional asteroid families have been identified for several decades using hierarchical clustering methods (HCMs) in proper elements domains. In this method, t…
Membership and fundamental parameters of the Praesepe cluster based on Gaia-DR2
Gao, Xin-hua
In this paper, we investigate membership and fundamental astrophysical parameters of the nearby, intermediate-age Praesepe star cluster (M44) based on the Gaia data release 2 (Gaia-DR2). Based on 54 425 stars within a sky area of 5.5° radius, we identify 1111 likely cluster members (≥0.6) in an 11D parameter space based on a combined machine-learn…
Is there a fundamental upper limit to the mass of a star cluster?
Leaman, Ryan; Schinnerer, Eva; van de Ven, Glenn +2 more
The discovery around the turn of the millennium of a population of very massive (M⋆ > 2 × 106 M⊙) compact stellar systems (CSS) with physical properties (radius, velocity dispersion, stellar mass etc.) that are intermediate between those of the classical globular cluster (GC) population and galaxies led to quest…
Ultraviolet and optical spectroscopy of AGB stars showing UV excess
Guerrero, Martín A.; Ortiz, Roberto; Costa, Roberto D. D.
We have examined ultraviolet (UV) and optical UB spectra of 20 UV-emitting Asymptotic Giant Branch (AGB) stars of various variability classes to study the intensity of the continuum and emission lines as a function of stellar visual magnitude to shed light on the origin of their UV emission. A significant fraction (60 per cent) of these stars show…
Asteroseismic modelling of the subgiant µ Herculis using SONG data: lifting the degeneracy between age and model input parameters
Bedding, Timothy R.; Stello, Dennis; Deng, Licai +3 more
We model the oscillations of the SONG target µ Herculis to estimate the parameters of the star. The ℓ = 1 mixed modes of µ Her provide strong constraints on stellar properties. The mass and age given by our asteroseismic modelling are 1.10^{+0.11}_{-0.06} M⊙ and 7.55^{+0.96}_{-0.79} Gyr, respectively. The initial helium abun…